BWAF-3

BRITAIN’S
WONDERFUL
AIR FORCE

Part 3

CONTENTS

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CHAPTER 8. WITH THE COASTAL COMMAND

CHAPTER 9. ARMY CO-OPERATION COMMAND

CHAPTER 10. MAINTENANCE AND TRANSPORT

CHAPTER 11. CELESTIAL AND WIRELESS NAVIGATION

CHAPTER 12. AIR PHOTOGRAPHY IN WAR

CHAPTER 13. AMERICAN HELP FOR THE R.A.F.

CHAPTER 14. WEAPONS USED IN ATTACK AND DEFENCE

ACKNOWLEDGMENTS

LIST OF ILLUSTRATIONS

Aircraft of Coastal Command

Avro Anson Reconnaisance aircraft co-operate with the fleet

Short Sunderland flying boat

Constructional details of the Sunderland

Catalina flying boat

Details of the Catalina flying boat

Air/Sea rescue service at work

Houseboat for R.A.F. pilots

Layout of floating rescue station

Details of high-speed rescue launch

Beauforts sweep the narrow seas

Blenheims launch low-level attack

Mine laying by stealth off enemy shores

Torpedoes for the Beauforts

Loading up a Catalina

U-boat surrenders to a Hudson

Lockheed Hudson reconnaisance bomber

Sunderland gunners man their guns

How they used to do Army Co-operation

Mobile headquarters

Interpretation staff at work

Why a low flying plane is difficult to hit

Lysander and Henschel 126 compared

Briefing Mustang pilots

Details of the long range Mustang

Mustangs of Army Co-operation Command in flight

Parachute troops bale out

Troop transport aircraft in use by Britain and Germany

Disused mine becomes bomb store

Inside a repair workshop

At work on a Lockheed Ventura

Atlantic Ferry Control

Navigator of a Whitley bomber

Navigational maps

The magnetic compass

Adjusting a Spitfire’s compass

Navigator's chart board

Fixing the position

Mark IX averaging sextant

Taking an observation

Getting a wireless fix

Navigator plots his course

Navigation exercises for observers

Camouflage revealed by the camera

Inside a mobile dark room

Rushing off the first prints

Interpretation staff at work

How distortion may occur

Progress of a raid on Lille

Taking stereoscopic pictures

Stereoscopic viewing device

Oblique and vertical photographs compared

Focal length of lenses

Theory of oblique photography

Using a hand camera for oblique shots

Desert warfare seen from the air

Mapping from the air

Berlin seen by the night camera

Camera gun in action

Bremen before and after a raid

Hudson over Dunkirk

Harvard advanced trainers

Marylands in the Middle East

Tomahawk and Kittyhawk

American aircraft in service with the R.A.F.

Lockheed Lightning

Details of the Lightning

Principle of the Turbo-supercharger

Boeing Flying Fortress

Bell Airacobra fighter

Consolidated Liberator bomber

The Eagle Squadron

Republic Thunderbolt fighter

Keeping track of enemy raiders

Duty crew at an observer post

Operations Room at Fighter Command

Elements of a sound locator

Diagram of time lag of sound

Construction of a barrage balloon

Inflating a barrage balloon

Device to beat the balloon

Inside a bomb store

Loading a Beaufort torpedo bomber

SOME AIRCRAFT OF COASTAL COMMAND

Engine particulars and top speeds of six types of aircraft used by Coastal Command. The Bristol Beauforts, with torpedoes slung beneath them, are famous for low-level attacks on enemy shipping in very bad weather. The long range Catalinas and Liberators are used for ocean reconnaissance work and sometimes make ﬂights lasting for anything up to 24 hours

CHAPTER 8

With the Coastal Command

Early days of the war. The Scarecrow Patrol. Protection of damaged submarines. Attacks on enemy battleships. Search for the “Bismarck.” Seaplanes and land aircraft. Bombing the Channel ports. Photographic reconnaissance unit. Regional Control. Air/Sea Rescue Service. Beaufort torpedo squadrons. Work of the Blenheim bombers. Patrolling the enemy coastline. Dropping mines from the air. Battle of the Atlantic. Thrills of U-boat hunting. U-boat surrenders to Coastal Command aircraft. Convoy work in the Mediterranean. A typical day’s ﬂying

BEFORE war broke out only a few people had realized the possibilities and the extent of an air war at sea, and in spite of all their efforts they were unable to convince the governments of those days of its importance. So the Coastal Command of the R.A.F. started the war with a grave shortage of both personnel and aircraft. It was equipped with a few excellent ﬂying boats and some that were not quite so good. Its principal land aircraft was the Anson (Fig. 1)—a slow cumbersome reconnaissance bomber that has now reverted to its more natural function of trainer.

THE FIRST COMBATS

It was with this equipment that Coastal Command fought, and fought well, almost the entire air war of the ﬁrst nine months of the war. The aircraft of Bomber Command at that time were conﬁned mainly to dropping leaﬂets over enemy territory and gaining experience that was to be invaluable later on. Fighter Command aircraft during those early months had almost nothing to ﬁght.

But Coastal Command, ill-equipped as it was, was in battle from the dropping of the ﬂag. Within a few days of the declaration of war a Coastal Command Anson had sighted and attacked a U-boat. Within a few hours of the ﬁrst minute of the war Coastal aircraft were escorting shipping convoys and encountering their ﬁrst combats with enemy aircraft. On the very ﬁrst day of the war the Chief of Naval Staff requested that a Coastal Command pilot be specially commended for a most useful piece of reconnaissance work which he had carried out.

AVRO ANSON RECONNAISSANCE AIRCRAFT CO-OPERATE WITH THE FLEET

Fig. 1. Avro Ansons, although slow and cumbersome when compared with some of the later types of aircraft now in use, performed valuable service in the early days of the war, often attacking ten times their number of modern enemy ﬁghters. They patrolled thousands of miles of sea in search of enemy submarines and surface vessels, and so well did they do their work that the Commander-in-Chief declared that they were his “secret weapon.” Although Coastal Command still employs a few Ansons, they are now used in the main as trainers. They have a range of 790 miles, a top speed of 188 m.p.h., and are armed with a single machine gun in the nose and another in a turret on the top of the fuselage

WORK OF THE ANSONS

It was at this tempo that Coastal Command fought its war right up to the days of Dunkirk. And then came its greatest mass effort. The few aircraft that the men of Dunkirk saw hurtling into battle above them during the historic evacuation from the beaches were, in the main, the slow reconnaissance bombers of Coastal Command. Fighting was not their job, but Ansons pitted themselves against ten times their number and more of modern German ﬁghters and more often than not the Ansons won. It was nothing at that time for three Coastal Command aircraft to report that they had engaged forty enemy aircraft, had shot down several and had driven the rest away, for the loss of one of their own number.

With grim humour the pilots coined their own unofficial motto—“Anson is as Anson does.” The commander-in-chief declared that they had proved to be his “secret weapon” at that critical time.

“SCARECROW PATROL”

Even before that time Coastal Command had pulled off the most successful bluff ever put over on Hitler, and the aircraft they used were not war aircraft at all, they were Tiger and Hornet Moths, the elementary trainers. These small and unarmed aircraft were put on to what was called the “Scarecrow Patrol,” which succeeded, with no weapon more lethal than a revolver, in keeping U-boat packs away from our coastwise shipping.

At the start of the war Germany had about sixty ocean-going U-boats which were either crossing the North Sea to seek out the East Coast shipping or were trying to slip out into the Atlantic.

To the cowering mouse any bird looks like a hawk, and to the U-Boat any aircraft spells danger. So Coastal Command sent out their ﬂeet of Tiger and Hornet Moths over the ships, and the very presence of a pair of wings in the sky was suﬂicient to force U-boats to crash-dive and keep even their periscopes below water for fear that the wake would give them away. The “Scarecrow Patrol” undoubtedly saved thousands of tons of British shipping. That was achieved by these trainer aircraft with an endurance of only about two and a half hours and a petrol consumption of not more than fourteen gallons for each sortie.

An instance of the thoroughness of these patrols was a report from one Tiger Moth of “an unidentiﬁed whiteish matter on the water and a bucket partly ﬁlled with dirty water ﬂoating near it”—the relics of a German U-boat sailor interrupted at his ablutions by the necessity of a crash dive.

While the Tiger and Hornet Moths were holding the fort in this way, however, Coastal Command was being rapidly re-equipped with aircraft which could kill as well as ﬁnd.

They started to come into service just in time, for when in April and May 1940 the Germans went through Denmark and into Norway the ﬁrst phase of the war had ﬁnished, and the second came in with a crash.

The ﬁrst phase ended perhaps with one of the high lights of the war—the location of the German prison ship Altmark, and the rescue of the prisoners by H.M.S. Cossack. This stirring feat would have been impossible had not the Altmark been located ﬁrst by reconnaissance aircraft of Coastal Command, which ceaselessly scoured the Norwegian coast, night and day, until they found the ship.

LONG RANGE FIGHTERS

After the Germans went into Norway, Coastal Command North Sea patrols had to ﬂy in face of high performance aircraft working from Norwegian aerodromes, and the Norwegian campaign itself put a very heavy load on the Sunderland ﬂying boats (Figs. 2 and 3) and other aircraft working from Scotland and the Shetlands. On top of that, Coastal Command had no longer to protect shipping only against U-boats but also against enemy aircraft, and the Command’s ﬁrst long range ﬁghter squadrons, equipped with Blenheim ﬁghters, did some magniﬁcent work all along the Norwegian coasts at the limit of their radius. Beauﬁghters, however, have now superseded the Blenheims for this kind of work.

SHORT SUNDERLAND LONG RANGE RECONNAISSANCE FLYING BOAT

Fig. 2. The Sunderland is used chieﬂy for long range reconnaissance. It is one of the largest aircraft in use by the R.A.F., having a wing span of 112 feet 10 inches, a length of 85 feet 4 inches and a height of 32 feet 11 inches. Its top speed is 210 m.p.h., range 1,780 miles and duration 16½ hours. Performance has been improved with later models

CONSTRUCTIONAL DETAILS OF THE SUNDERLAND

Fig. 3. Diagrammatic drawing of a Sunderland showing interior layout and accommodation. The front power operated turret retracts backwards, as shown by the dotted lines, to permit of easy mooring. There is also a four-gun turret in the tail as shown in the inset, and the armament is supplemented by two ﬂank gun stations each with a single machine gun. These are illustrated here. The aircraft carries a large crew and has a ceiling of 20,500-feet

ESCORTING SUBMARINES

As an instance of the extra tasks that accumulated at about this time, British submarines were also active in northern waters, facing immense risks and sometimes, of course, casualties. Not always, however, was a submarine lost because it was hit. Sometimes, badly damaged though it was, it could struggle home provided it could stay on the surface. The danger to be faced, of course, was a further attack by enemy aircraft, and it was against that danger that Coastal Command protected these crippled submarines by ceaseless patrols over them in all kinds of weather. Many British submarines, including the Triumph, and the French submarine Rubis were given successful air escort in this Way.

Another phase of the war began in June, 1940, and imposed a multitude of tasks on to those of anti-submarine protection of the Atlantic convoys and anti-aircraft protection of the East Coast convoys. Aerodromes and harbours in Norway had to be bombed consistently by the American-built Hudsons which were turned suddenly from reconnaissance work into a strong bombing force. Farther south Coastal Command aircraft were thown into the melee along the Dutch and Belgian coasts and over the Channel, which culminated in covering the evacuation from Dunkirk.

Then, in July, 1940, came a new grim phase, one which was to continue for many weary months. The German occupation of France gave the enemy numerous aerodromes which threatened Britain and also new submarine bases on the French-Atlantic coast, which gravely threatened her shipping artery to America. Long range convoy escorts were provided to meet the air menace to shipping outside the radius of action of Spitﬁres and Hurricanes. Long range convoy escorts over the Atlantic had also to be increased to meet the wearing but absolutely essential U-boat hunts.

Another difference in this phase was the necessity of reconnaissance sweeps over the North Sea to prevent German surface raiders getting out into the Atlantic. On several occasions when raiders did try to get out it was aircraft of Coastal Command that spotted them and either drove them back unaided or assisted in turning them away.

ATTACK ON “SCHARNHORST”

Before the Scharnhorst earned her notoriety in Brest she was one of the raiders that tried to put out into the North Sea. A reconnaissance aircraft of Coastal Command spotted her, and Hudsons and Beauforts of the same Command immediately set out to the attack. Scharnhorst was steaming at this time along the Norwegian coast. Besides her naval escort of destroyers she had an air umbrella of ﬁfty Messerschmitts. The attacking forces of Hudsons and Beauforts were far fewer in number and they had to face not only the ﬁfty Messerschmitts but the ﬁre of the warship’s guns. Quite unperturbed by this they carried out their successive attacks and scored in all three direct hits on the Scharnhorst, one of which seriously damaged a gun turret.

The Deutschland—now renamed the Lutzow—provided another instance of Coastal Command reconnaissance through the dirtiest weather. After she had attacked the Rawalpindi she was picked up by aircraft of the Coastal Command and shadowed over hundreds of miles.

Later on in the course of the war came the famous tracking of the Bismarck. It was a Coastal Command aircraft on reconnaissance that ﬁrst reported her presence in harbour at Bergen. It was a naval aircraft, however, which reported that she was gone from Bergen only an hour or two after she had sailed.

“BISMARCK” EPISODE

She was shadowed across the North Sea while British naval forces closed in on her track, and she was picked up by a Sunderland ﬂying boat just as she entered into the ill-fated engagement with H.M.S. Hood. The Sunderland was instrumental in directing other surface ships to the rescue of the few survivors of Hood.

Then the Bismarck was lost for twenty-four hours. The biggest air search in history was at once instituted by Coastal Command, while large naval forces were steaming from all directions towards the areas in which Bismarck was believed to be. But still there was no trace of her. The weather had closed down and visibility was wretched. The aircraft were ﬂying through storms and gales for hour after hour, far out over the ocean. To each of them must be given equal praise for the perseverance and endurance with which they carried out this task. But the one that had the good fortune actually to ﬁnd the Bismarck was a Catalina ﬂying boat (Figs. 4 and 5) which came upon her suddenly as it emerged from cloud and was at once under ﬁre from the battleship’s guns.

Although the Catalina had been hit, and suffered damage, it continued to shadow Bismarck for several hours until naval forces and naval aircraft could get close enough to deliver the death blow.

CONSOLIDATED CATALINA LONG RANGE AMERICAN FLYING BOAT

Fig. 4. The Catalina flying boat is used by Coastal Command for ocean reconnaissance and convoy work. Although the top speed of 190 miles per hour of the earlier models was slower than that of the Sunderland, its 4,000-mile range was greater. During the search for the German battleship “Bismarck” one Catalina remained on patrol continuously for twenty-seven hours

DETAILS OF LAYOUT AND ACCOMMODATION OF THE CATALINA FLYING BOAT

Fig. 5. The Consolidated Catalina incorporates some interesting and unusual features in ﬂying boat design. The ﬂoats, for example, retract outwards to form the tips of the wings, and the rear armament is accommodated in two large blisters, one on either side of the fuselage. Submarine bombs are carried externally on racks beneath the wings, as shown

BEAUFORTS ATTACK “DEUTSCHLAND”

There was one other noteworthy clash with a German surface raider. This was again the Deutschland, but by then she had been renamed Lutzow. She was putting out through the Skagerrak and heading for the Atlantic where most important British convoys were steaming in from America, when a Coastal Command Hudson on reconnaissance discovered her. She was surrounded by destroyers.

Torpedo-carrying Beauforts of Coastal Command were at once dispatched to engage her. Two of them came across her off the south-west coast of Norway, and they carried out at only a few feet above the sea one of the most daring attacks of the air/sea war. “Skidding” over the stern of one of the protecting destroyers they ﬂew into the right position for the attack and launched their torpedoes. It is certain that one of the torpedoes secured a direct hit amidships. The other almost as certainly found its mark, but bad weather and the necessity for avoiding the hail of anti-aircraft ﬁre from the ship prevented the second Beaufort crew from observing the exact result of their attack. It was sufficient, however, to accomplish its purpose. Coastal Command reconnaissance aircraft were arriving now in relays, and they reported the Lutzow had turned back and was endeavouring at a much reduced speed to regain a German port. One of these aircraft, a Blenheim ﬁghter, shadowed her for many miles, right up the Skagerrak. The torpedoes had not sunk her—it would be a lucky torpedo indeed that could sink a modern battleship—but they had forced her into port for repairs. The Atlantic convoys which she had set out to attack, however, went their way umnolested, and another telling blow had been struck against German naval power in the Battle of the Atlantic.

NEW EQUIPMENT

All this, however, still lay in the future for Coastal Command which, as the Germans swept westward, found itself ready to meet the many more gruelling demands which were to be made on it.

Special efforts had been made to reinforce this Command of the R.A.F. in anticipation of the ever heavier role it would have to perform in the near future, and many of its aircraft were brought across to Britain from America.

It had been re-equipped almost as an air force within an air force. By the end of the ﬁrst two years of war Coastal Command was ﬂying bombers, reconnaissance bombers, ﬂying boats and ﬁghters. It was equipped with Sunderland, Catalina, London, Lerwick and Stranraer ﬂying boats together with squadrons of American-built Northrop seaplanes. Its land aircraft included Lockheed Hudsons, Beaufort torpedo-bombers, Blenheim bombers, Liberators, Blenheim ﬁghters, Beauﬁghters and a few Ansons not yet turned over to training (see illustrations here). Today it is using modern four-engine bombers such as the Halifax.

The primary performance of Coastal Command had remained, as it had always been, visual and photographic reconnaissance, but to that basis had been added striking power. The enemy had felt that striking power when he went into Norway and down through Denmark, Holland and Belgium. As he spread into France he felt it even more strongly, for Coastal Command aircraft met him over the Channel and Dunkirk. They also took part in the bombing of the ports which he was occupying.

American Lockheed Hudsons of one squadron alone hammered at Rotterdam night after night until they could report that nearly all of the oil installations which had been left there by the Dutch were now destroyed. Hudsons and Beauforts ranged at that time to Ostend, Calais, Boulogne, Cherbourg, and battled away at the harbour installations and the shipping. At the time of the Dunkirk evacuation itself, Coastal Command added Army Co-operation to its variety of tasks, and day after day its aircraft skimmed the battleﬁelds around the allied perimeter, attacking tanks, armoured columns and gun sites, and shooting up enemy troops on the ground.

Then, as the threat of invasion deepened with the passage of months, it was the invasion preparations in the Channel ports that became the targets. They were bombed by day and by night. The invasion barges and the shipping being constantly harassed and destroyed. Soon it was the submarine bases at Lorient to which Coastal Command turned its attention, and they not only destroyed many of the installations but bombed several U-boats in harbour there.

TWO SERVICES

But all this time the primary task of reconnaissance and of convoying shipping had continued without a break. Even in the stress of these months of warfare, Coastal Command had conceived and developed two major services, not only directed to the war effort, but to the whole techniqiue of flying in the future.

The ﬁrst of these two major services is called Regional Control. The greatest enemy of the Coastal aircraft is not Germany but the weather. And the ﬁght against the weather goes on without the slightest pause. There have been occasions when the only aircraft in the air in the whole of Western Europe have been those of Coastal Command, battling their way through storms on a reconnaissance ﬂight.

In order to help these aircraft to get back safely to land in conditions of “non- ﬂying” weather, Regional Control was devised. It is a system of co-ordinating the standard blind approach landings and the international Q-code of call signs. It is an organization which can pick up a returning aircraft in the thickest fog, lead it away from its fog-bound home base, direct it to quite another part of the country, and bring it down safely. It has already saved the lives of hundreds of air crews. When peace comes again and its secrets can be made known to the world, it will revolutionize bad weather ﬂying for civil aviation.

AIR/SEA RESCUE SERVICE AT WORK

Fig. 6. Many airmen, like those seen above, who have been forced to land in the sea, owe their lives to the vigilance of the Air/Sea Rescue Service which was conceived and developed by Coastal Command. It employs high-speed launches which work in conjunction with patrolling aircraft

The second service devised and carried out by Coastal Command in conjunction with the Admiralty, which is now incorporated in the Directorate-General of Aircraft safety, was the Air/ Sea Rescue Service (Figs. 6—9). The waters that divide Britain from her Continental enemy are friendly indeed, but to returning aircraft at night, badly damaged perhaps, the crews weary and suffering from strain, the water is an enemy. A number of aircraft in these circumstances have “come down in the drink.” Many of their crews have subsequently been saved and brought safely to shore by the Air/Sea Rescue Service. This co-ordinates all the air searches for lost crews that are ﬂoating somewhere in a dinghy with the small fleet of high-speed launches which operate from points all round the coast; and if no high-speed launch is available the Air/Sea Rescue Service ropes in the lifeboats, any ships nearby or any naval forces. Once the lost crew in its dingy has been located by a searching aircraft, every possible expedient is used to get a surface vessel to them.

HOUSEBOAT FOR R.A.F. PILOTS

Fig. 7. The Air/Sea Rescue Service has anchored ﬂoating rescue stations, like that seen above, in the Channel. Here pilots who have been forced down in the sea can ﬁnd shelter and comfort until rescued by one of the high-speed launches

LAYOUT OF FLOATING RESCUE STATION

Fig. 8. Diagram showing general layout of R.A.F. rescue station. The boats, which are painted yellow and red to make them visible from the air, are well provisioned and equipped with food, ﬁrst aid, wireless and other comforts. They have been the means of saving many lives

In addition to the ceaseless watch kept by patrolling aircraft and the constant sweeps of the high-speed rescue launches, the Air/Sea Rescue Service maintains a ﬂeet of ﬂoating rescue stations (Figs. 7 and 8). These are anchored at intervals in waters above which the activities of British aircraft are most thickly concentrated, and any airmen who are forced to abandon their machines over the sea and take to their rubber dinghies, can paddle to these stations and there ﬁnd food, warmth and comfort until they are rescued.

The stations are painted bright yellow and red so that they can be readily recognized from the air. They are well equipped with blankets, food, reading matter and ﬁrst-aid equipment, and there is a wireless set in each. The sterns are made to slope down into the sea so that the airmen can easily climb abroad and drag their dinghies after them. They are visited regularly by the Service’s launches. These ﬂoating stations have been the means of saving the lives of hundreds of airmen—both friend and foe—who have been fortunate enough to bale out in their vicinity.

These are both humanitarian services, but Coastal Command has developed no less formidably in the opposite direction, that of a striking force. The motto of the Command is “We search and strike.” Much of the time must necessarily be occupied by the search, but the strike is by no means forgotten. It is the Coastal Command which thinks always in terms of the offensive. The most vivid instance of this great offensive spirit is the constitution of the squadrons of Beaufort torpedo bombers. They are the most effective striking force of the Coastal Command, and it is certain that they have one of the most hazardous jobs to perform.

DETAILS OF HIGH-SPEED RESCUE LAUNCH

Fig. 9. Rescue launches used by Coastal Command are very fast and well equipped. That seen above is 65 feet long and is powered by three 500 h.p. engines. It carries a crew of nine

BEAUFORTS SWEEP THE NARROW SEAS

Fig. 10. The Bristol Beaufort torpedo bombers seen above are off on an offensive patrol against enemy shipping. This work calls for great courage and judgment on the part of the pilots, who have to descend to within a few feet of the sea in order to release their torpedoes

The Beauforts (Fig. 10), with the torpedoes slung beneath them, rarely ﬂy at higher than 200 feet, and they make their attack at close range from a lower height than that. Coastal Beauforts scour the enemy coastline (and more than the enemy coastline) from Greenland, through Norway, Denmark, Germany, Holland, Belgium and France, down to Bordeaux and far out into the Bay of Biscay. They are the mobile force of the Command. They prefer to ﬂy in bad weather, for it gives them cover from the ships’ gunﬁre, and they direct their torpedoes either by day or night at the shipping with which Germany must necessarily ply up and down the European coast.

With every dislocation of the already overcrowded European railway services, the enemy is forced to attempt more and more coastal transport. A 6,000-ton merchant ship, for instance, can carry as much as ten long goods trains, so the advantages of coastline transports are obvious.

The disadvantages soon became equally obvious to the German seamen, and the gravest disadvantage of them all was the Beaufort torpedo bomber of Coastal Command. One squadron alone, early in its torpedo career, sank 31,000 tons of German shipping within a month, and more than 20,000 tons within seventy-two hours. At the end of a year that squadron alone had sunk, or seriously damaged 103,000 tons of German shipping. But the feat was soon eclipsed when Coastal Command squadrons sank or shattered 100,000 tons of German supply shipping in about seventy-two hours, and kept on adding to the total day by day. In a matter of months nearly 400,000 tons of German shipping had been sunk or disabled.

Every sortie in a Beaufort means ﬂying point blank into a hail of anti-aircraft ﬁre, for the German coasters are always escorted by ﬂak ships—sometimes as many as ﬁve ﬂak ships to a single merchant vessel. The Beaufort makes its run in at a very low height above the water, and pilots often report that they have managed to turn away only just in time to miss hitting the bows of the ship they have attacked with their torpedoes.

The Beauforts sink ships with torpedoes by night as well as by day, picking them out as dim shadows on a dark sea, or black shapes creeping across the moon’s path. These torpedo attacks on supply ships are the normal run of torpedo dropping, but the Beaufort crews are always ready and eager to hunt bigger game.

There was one instance when it was feared that the German battleships Scharnhorst or the Gneisenau might attempt to put out from Brest where they had been held for many months by bombing attacks. A Beaufort attack with torpedoes right inside Brest harbour was decided upon and brilliantly executed. The attacking aircraft had to run the gauntlet of terriﬁc anti-aircraft ﬁre both from the ground defences and the guns of the battleship, yet it pressed home the attack successfully and almost certainly scored a direct hit with its torpedoes. Such an attack is a typical example of the way in which Coastal Command pilots generally press home their attacks in face of most violent opposition and regardless of their own safety.

At one stage in the war a squadron of Blenheims and a squadron of Beauforts were tactically placed so as to command the English Channel, and they were told that their task was to deny the Channel to enemy shipping. Those ships that the Blenheims missed—and since they attacked from about thirty feet high they did not miss many—were then pursued with torpedoes from the Beauforts (Fig. 11).

Scarcely a month after the beginning of these operations the crews of both squadrons were complaining that Jerry never seemed to send them targets any more. The English Channel had been closed, at any rate for the time being, to the Germans.

Similar operations followed soon afterwards off the Dutch islands where there were concentrations of German supply ships. At one stage a newly formed Canadian squadron, ﬂying Hudson aircraft, was set to cover this stretch of the coast. When they had been operating for a little less than a month they had scored certain hits on nine German vessels with a total tonnage of approximately 30,000.

After the outbreak of the Russo-German war another stretch of European coast became an attempted channel for German supply shipping. This was the south-west corner of Norway, around which the Nazis tried to send, by sea, supplies to their armies on the North Russian front. Another Beaufort squadron was given this route to look after, and its successes were as great as those of the sister squadron which guarded the whole of the English Channel.

BLENHEIMS LAUNCH LOW-LEVEL ATTACK

Fig. 11. The Blenheim seen above has just scored a direct hit on a 2,500-ton vessel, which is burning ﬁercely. Such attacks are usually carried out from a height of about 30 feet

There is another way of striking at enemy shipping. The Germans used it against Britain, and Britain in return used it against the Germans. This method is to lay mines from aircraft in the coastal shipping routes which the enemy must use (Fig. 12). Much of this work was done by aircraft of the Coastal Command or naval aircraft working under their orders. Little is heard of these operations. Their results are seldom announced, often indeed are not known at the time; but night after night the mine-laying crews, without any public acclaim and without even the visual satisfaction of a bombing raid, face conditions that demand a courage and a fortitude as great as any that can be shown in the air. The mine laying must be done with precision, at places most likely to catch the German coastwise shipping as it creeps nervously along through in-shore waters, usually under the protection of coastal batteries.

Some of the aircraft which lay these mines used to have open cockpits, giving almost no protection against weather, and in them the air crews sat for hours at a time, almost unable to move, in temperatures well below zero.

MINE LAYING BY STEALTH OFF ENEMY SHORES

Fig. 12. Night after night converted bombers of Coastal Command carry out mine laying sorties over enemy waters in order to harass coastwise shipping, and here is a drawing of a low ﬂying Handley Page Hampden long range aircraft so engaged. Mines enter the sea comparatively gently and automatic parachutes are ﬁtted. The mine’s buoyancy and its sinker combine to locate it at a vulnerable depth. Mine laying calls for the greatest accuracy by the navigators. The above drawing is reproduced here by the courtesy of the “Sphere”

The mines themselves must be laid so close in-shore that the air crews often ﬁnd themselves automatically, though quite needlessly, talking in whispers as they approach. One aircraft, while ﬂying up the coast, was accompanied for several miles by ﬂashes of light from the cliffs—the pocket torches of the German gun crews running to their guns. After the mines have been laid there follow the hazards of a return journey over the sea, often in terrible weather with the thought of petrol shortage just below the surface of the mind.

These are the jobs which Coastal Command pilots refer to as “stooge jobs.” They ﬁnd them boring and extremely dull.

TORPEDOES FOR THE BEAUFORTS

Beauforts carry a single torpedo which is stowed inside the fuselage. It is jacked up into position from special trolleys, like those seen above, which are being hauled by the ground staff at a Coastal Command station. Aircraft torpedoes are slightly more robust than naval ones

Little has been said so far about the biggest battle of all which is being fought by Coastal Command—the Battle of the Atlantic. Little can be said, for it is not only in area the biggest battle the world has ever seen, it is also the most secret battle of history. It is waged over an area of more than 600,000 square miles (a battle front that no German or Russian general has ever dreamed of). In essence it is a simple battle. Britain is trying to bring convoys laden with supplies, and often with troops, from the New World to the Motherland. The Germans, using U-boats, aircraft and surface raiders, are trying to sink those convoys.

In detail the battle is by no means simple, and of those details one cannot write, but this is the main battle of Coastal Command. Its job is to hunt out the U-boats from the air, to sink them if possible, and certainly to locate them; its job is to meet the incoming convoys and give them unceasing escort from the air; its job is to ﬁght off the long range Focke-Wulf aircraft which sweep from southern France to Norway, in an effort to ﬁnd and bomb the convoys.

During the ﬁrst two years of the war alone aircraft of the Command ﬂew a total of approximately ﬁfty million miles over the sea (equal to more than half the distance to the sun). They escorted 8,200 convoys, most of them deep-sea convoys, involving 31,000 operational sorties on this task alone. Enemy naval units or supply ships were attacked 760 times, and the total of enemy tonnage sunk, or so damaged as to be permanently unserviceable, was 295,000 tons.

LOADING UP A CATALINA

The long range Catalina seen above will soon be setting out on an ocean reconnaissance. Alongside is a launch which has brought ammunition for her guns and anti-submarine bombs. The latter will be hoisted into bomb racks situated beneath her wings ready for instant use should an enemy submarine be rash enough to show its periscope above the surface

Aircraft of the Command made 305 attacks on U-boats, nearly all of them in the course of the Battle of the Atlantic. They destroyed seventy-ﬁve enemy aircraft actually approaching to molest convoys, and drove off more than 500 of them, often heavily damaged. Today Coastal Command has an area of ﬁve and a half million square miles of sea to patrol. Many pilots who are serving with the Command have a total of much more than two thousand operational ﬂying hours to their credit in their log-books.

Perhaps the most astonishing feat in the Battle of the Atlantic was the surrender of a German U-boat to Coastal Command aircraft. The U-boat was sighted by a Hudson on its routine patrol and was forced to the surface by bombs.

THE HUDSON ATTACKS

Almost immediately the whole crew started to pour out of the conning tower, probably in an effort to man the guns, but the Hudson immediately attacked them with machine gun ﬁre, and after four such attacks the U-boat crew surrendered, waving a white shirt and a piece of white board to make their intention clear. The Hudson continued to circle the U-boat with guns trained to resume the attack if necessary, while signals were sent off' to base to bring other aircraft to the relief, and surface vessels to take charge of the U-boat.

After three and a half hours a Catalina arrived to take over from the Hudson. She stood jailer in the air for a further seven and a half hours before the ﬁrst naval vessel could get to the scene. In spite of a heavy gale that was running, the Navy got the U-boat crew off and brought the U-boat intact into port. Coastal Command aircraft kept up air escort for a further forty hours until this was accomplished. This was the ﬁrst under-water craft ever to have surrendered to an aircraft (Fig. 13). Once a Coastal Command ﬂying boat was forced to land in the middle of the Atlantic at the height of a gale and remained aﬂoat for seven hours before being reached by a surface vessel. On more than one occasion ﬂying boats have landed alongside torpedoed seamen, drifting exhausted far away from land, and have brought them safely home.

U-BOAT SURRENDERS TO A HUDSON

Fig. 13. The U-boat above, as explained in the text, was forced to surrender by a Coastal Command Hudson, which called up naval forces in order to secure the prize. The U-boat was afterwards brought into port intact. This was the ﬁrst submarine ever to surrender to an aircraft, but since then pilots attached to squadrons of Coastal Command have brought quite a number of German U-boats to the surface by dropping depth charges or bombs

LOCKHEED HUDSON RECONNAISSANCE BOMBER

Designed and built in the United States, the Hudson has done valuable service with Coastal Command. It has a wing span of 65 feet 6 inches and a length of 44 feet 4 inches, and is armed with four machine guns, two in the nose, two in a turret on top of the fuselage

The aircraft of Bomber Command have their objective to bomb, their deﬁnite task assigned to them, and then their sortie is over. Aircraft of Fighter Command have short ﬂights of extreme skill and hazard, packed with excitement, and then they land, but the average sortie of a Coastal Command Catalina, for instance, lasts for eighteen hours. Sometimes they ﬂy for a complete day and night. One Catalina returning to its base at night found the weather unfavourable for alighting, so it ﬂew back to sea and stayed there until daybreak when it could come down in comfort and safety.

DAY AND NIGHT PATROLS

These ﬂights are conducted day by day and night by night far out over the sea. For the most part they are not spectacular but they are invariably gruelling, wearying, a supreme test of airmanship, and a tremendous physical strain. That is typical of most Coastal Command ﬂights either in ﬂying boats or in land aircraft.

A cross section of the Coastal Command aircraft actually in the air on any one day would provide as magniﬁcent a variety of ﬂying as any in the war. Up beyond the Arctic Circle there would be perhaps a long range Hudson traversing the ice-packs, ﬂying around the towering masses of an iceberg or skimming the desolate mountains of Greenland. South of that rules the Atlantic, and here Coastal Command aircraft gather thickly. Many of them are circling round and round the ocean convoys—Catalinas, Liberators, Hudsons. Closer in roam the long range ﬁghters, particularly the Beauﬁghters which are in themselves a romance of the air war. They are the latest and most modern of the long range ﬁghters of Britain. Some of them, manned by Coastal Command personnel, were sent down to Malta when the order went out that the convoys must get through: and get through the convoys did. One force of Beauﬁghters down there shot up thirty-six enemy aircraft in Sicily without loss to themselves, in one hour. No less striking has been their record over waters nearer home. The ﬁrst Beauﬁghter that ever went out over the Atlantic met a Focke-Wulf Kurier within the ﬁrst two hours of its ﬂight. The pilot got the huge enemy raider into his sights and pressed the gun button. Before he had time to take his ﬁnger off the button again the Kurier was falling to pieces in the air in front of him.

To continue the picture of Coastal Command aircraft in the air on any single day: over the Atlantic and around Iceland, the hunt for the U-boats is proceeding for mile after mile over the dull sea. Coastal Command aircraft are ﬂying on pre-determined routes, with every member of the crew staring ﬁxedly at the sea. Once in a while the conning tower or the periscope of a U-boat is sighted, and, with a swift dive, down go the bombs. That part of the picture can be repeated all over the eastern Atlantic, from the north-west approaches far down in the Bay of Biscay; from the Bay of Biscay farther south still off the European land masses to Gibraltar; and from Gibraltar still farther to the south off the west coast of Africa where the Coastal Command aircraft still relentlessly pursue the U-boats and still guard the convoys.

But on this one day we have picked out—on any day—the real concentration of Coastal Command aircraft will be over those waters that surround the British Isles and stretch to the coast that the enemy has occupied. Beauﬁghters are scouring the North Sea; Beauforts, in little ﬂights of three, are dodging up and down the Norwegian Fjords and skimming round the islands where the Nazi shipping lurks.

There are Hudsons along the Danish coast and Hudsons ﬂying farther south still, past the Friesian Islands and into the Heligoland Bight, off Holland maybe Hudsons or Beauforts will attack the enemy shipping, and farther westward at the same time there would be Hudsons, Blenheim ﬁghters or perhaps even an Anson or two searching over the mine-ﬁelds for some dinghy that may contain the crew of a bomber which crashed after last night’s raid on Germany.

SUNDERLAND GUNNERS MAN THEIR GUNS

The Short Sunderland ﬂying boat is sometimes called the “Flying Porcupine” because it bristles with guns. In addition to power operated turrets in nose and tail there are two gun positions amidships, illustrated above, which command a very wide ﬁeld of ﬁre

WATCHDOGS OF THE CHANNEL

All down through the English Channel it would be difficult to miss the aircraft on reconnaissance nosing into the harbours, slipping along the coasts, photographing, reporting back. There will be a Beaufort or two searching the Channel Islands, while farther out to the west will ﬂy the Sunderlands, the Catalinas, the Liberators, the Halifaxes, the Wellingtons and the Hudsons, guarding yet more of England’s precious merchant shipping.

You will certainly ﬁnd Coastal Command aircraft somewhere along the Brittany coast and far out into the Bay of Biscay. The ﬂying boats may be taking down to Gibraltar, and so out to the Middle East, some generals or some important Government officials. Coastal Command men are in the Far East. And as a fringe to all this scene are the photographic reconnaissance aircraft whose boundaries are set wider still, far over Europe to the North Sea or down to the Mediterranean in the south.

THE BREAD AND BUTTER BATTLE

There is no exaggeration about that picture, a typical day’s ﬂying of Coastal Command. It happens every day, and it continues throughout every night. A man could almost count on his ﬁngers the number of hours since the start of the war when there have been no Coastal Command aircraft ﬂying anywhere. And all this has grown from the handful of aircraft and the small ﬂeet of ﬂying boats with which Coastal Command began the war. It started almost as an ancillary command, but from the ﬁrst day of the war it forced recognition that it was an essential army of Britain. Now it has grown into a huge force covering a greater area, as a single Command, than any other complete air force in the World, including the Luftwaffe. It ﬁghts a battle on a gigantic scale over a huge area, and it ﬁghts essentially the “bread and butter” battle of Britain, for if the battle of the ocean is lost and supplies cannot get through, then indeed all is lost. But there is not one scrap of evidence to show that that battle will be lost, and a Coastal Command grown as strong as it stands today is the best guarantee of that victory.

HOW THEY USED TO DO IT

In the early days of Army Co-operation, before the intense development of wireless communication, Lysanders were used to pick up messages from troops in forward positions. The hook suspended from the fuselage of the above machine was used for this purpose and the “T” of white cloth spread out on the ground immediately below was so placed to show the direction of the wind

CHAPTER 9

Army Co-operation Command

Lessons of this war. Need for air “umbrella.” Lysanders outdated. Fast ﬁghters for reconnaissance. The Mustang. Army officers seconded to the Command. R.A.F. pilots have to be military “encyclopedias.” New intelligence systems. Paratroops and airborne troops

THE question of the relationship between air and ground forces has always been a matter of controversy. From the days when the possibilities of the use of an air arm in warfare were ﬁrst visualized, there has been argument as to whether an air force should be merely part of the army under direct army control, or whether it should be a separate concern with its own individual organization and authority and power to operate in its own way.

IMPORTANCE OF AIR COVER

The lessons of the present war have deﬁnitely proved that without air cover the success of any army operation is endangered. From that fact a clear understanding of the position of the air arm is now developing. The use the Germans made of air power when they marched into Poland, to Norway and then through the Low Countries into France ﬁrst suggested the ultimate solution though in no case did they meet with stiff air opposition. More lessons were learned as a result of the war in Greece and the airborne invasion of Crete. Finally, they were put to test and clariﬁed by practical experience in the Egypt and Libya campaigns which began with the defeat of Rommel at El Alamein and continued with his chase across ﬁfteen hundred miles of African desert into Tunisia. Air power, the Royal Air Force, showed itself as the protective cover and advanced striking arm of the Army, its “fourth dimension,” working as an organization of its own but carrying out operations as an integral part of the high command controlling the whole campaign. It became the eyes and ears of the army, its long range artillery reaching where no guns could reach; its ﬁghters were the army’s guerillas and its entire organization was the handmaid of the land force.

But the path to that state had not been easy. It had meant experiment and trial, tribulation and error. It had meant the scrapping of many pre-conceived ideas and the formation within the Royal Air Force of an entirely new command, Army Co-Operation Command, which was to spend two years of unsung and unpublicized effort in the intensive training of personnel in a new technique.

NEW PLANES

It had also meant the complete re-equipment with several new types of aircraft; the provision, for instance, of fast single-seat and well armoured ﬁghters in place of the old and slow Lysanders which it was thought at the beginning of the war would do all that was necessary in the way of army reconnaissance. Light bombers and dive bombers had to be found and carriers for paratroops, as well as gliders and the aircraft to tow them.

The ﬁrst use of the air to give help and assistance to a land force saw the employment of spherical balloons and man lifting kites. Both were used successfully in the Boer War. Then airships, now obsolete, took the place of balloons. When the war of 1914 began, the ﬁrst British aeroplanes to go to France were intended solely for reconnaissance for the army. Everybody knows that they were cumbersome, “bundles of wood and string,” to quote a pilot of those days. They did not carry bombs. Armament was also non-existent, except for the personal choice of some pilots and observers who took revolvers and even shot-guns up in the air with them. But they did a job. They gathered information from behind the enemy lines, even if they never ﬂew very far. Height gave pilots and observers the power to see things that the army commanders and artillery dearly wanted to know about.

It was as though the vantage point that is the dream of every army general, an overlooking hill, had become fact whether he fought in the middle of a ﬂat plain or not. Air power had become vital to the land force. But not just to one force. It was vital to both sides. Both tried to use it and both tried to prevent its use. There was only one thing to be done. An aircraft high in the sky could only be reached by another aircraft, one that was armed to shoot it down. Fighters came into existence and, as under the impetus of war the aeroplane developed rapidly and became a weight carrier, the bomber also arrived. The two arms of the R.A.F. as we knew them when this war began came into existence.

MOBILE HEADQUARTERS

Mustangs have now replaced the Lysander above whose pilot has just returned from a reconnaissance ﬂight and is reporting it to the air liaison oﬂicer. A despatch rider stands by and a machine gunner keeps a look-out for enemy aircraft. The mobile headquarters on the right is equipped with wireless by means of which it keeps in touch with aircraft while on patrol

INTERPRETATION STAFF AT WORK

An army co-op. aircraft has returned from a photographic reconnaissance and the prints are now in the hands of the interpretation staff. With the aid of stereoscopic and other viewing devices they are able to gather valuable and highly accurate information regarding the disposition of enemy troops upon which the army commander will base his future plan of campaign

The ﬁghter, originally purely intended to see that an enemy machine did not reconnoitre or at any rate get back home with the results of its observation, became the means of securing domination of the skies. The bomber, originally intended as a reconnaissance machine and then as something capable of dropping a “shell” in the places just beyond range of the army’s guns, became an offensive weapon capable of interfering with enemy production deep in the interior. Each seemed to be a natural complement to the other and make a whole that ought to work independently of the land forces, be a separate service complete in itself, as distinct from the army as the navy and only co-operating as a separate service. This theory was accepted. The army lost its Royal Flying Corps and the navy its Royal Naval Air Service. They were joined together as the Royal Air Force. The army lost direct control of its eyes and ears.

When this war began, that position, so far as the army and the R.A.F. was concerned, remained, though the Navy had managed to re-establish its Fleet Air Arm, and Coastal Command of the R.A.F. had become a close worker with the Admiralty. The R.A.F. had ﬁghters and bombers which were as modern as the times, but it had few aircraft specially designed for army reconnaissance work and little conception of what that reconnaissance would mean. Both the army and the R.A.F. had also been severely handicapped by pre-war disarmament efforts, one of the effects of which had been for the R.A.F. to conserve what resources it had for R.A.F. purposes pure and simple, the development of its ﬁghters and bombers.

WHY A LOW FLYING PLANE IS DIFFICULT TO HIT

Fig. 1. As shown above, an aircraft ﬂying at 100 feet or less is an extremely difficult target to hit because it remains within the effective arc of ﬁre of the guns for such a very short time

ARMY RECONNAISSANCE

The aircraft that were available for army reconnaissance were of a type that needed certain conditions in order to operate successfully. They had to have freedom of leisurely movement in the air. A low ﬂying plane is hard to hit (Fig. 1). They must be protected by their own ﬁghters or be left entirely alone by the enemy. Neither was possible. The ﬁrst because the R.A.F. had not got enough ﬁghters and the second for the reason that the enemy was not charitably minded.

Speed of the ﬁghter type of aircraft was not considered necessary for army reconnaissance work and the machines used were designed to ensure that the pilot had a good view. They were Lysanders and, for longer range work deep into enemy territory, Blenheims. Aircraft that could act as the army’s primary attacking force, light bombers and ﬁghter bombers were not available. Nor was there a sufﬁciency of ﬁghters. It was not even expected that the Germans would decide to use aircraft in that particular way.

HENSCHEL 126

But the Germans had also designed a slow aircraft specially for army reconnaissance work and had produced the Henschel 126, a machine almost identical with the British Lysander (Fig. 2).

Then came the Battle of France to emphasize the tactics the Germans had used in Poland, Norway and the Low Countries and show that, given air superiority, the dive bomber could be a potent weapon. The Battle of France ended with the withdrawal of the British troops, but a great and important new principle of warfare had been established. It had been made clear that the success or failure of an army depended on the amount of air cover it could command. It was realized that, with ﬁghter cover, land forces had freedom of action, reconnaissance planes could work unmolested and the dive bomber did have a use.

LYSANDER AND HENSCHEL 126 COMPARED

Fig. 2. The main difference lies in the shapes of the wings, which are very distinctive, the Lysander having a straight leading edge and the Henschel’s being swept back. Note also the distinctive shapes and positions of tailplanes and the extra struts of the Henschel

In France the Germans had many times the number of aircraft at the disposal of the British. The German staff was able, consequently to plan every phase of its swift advance with the knowledge that its own troops would be practically immune from air attack and that the Luftwaffe would be delivering concentrated attacks behind the British lines on communications, reserves and dumps. The Germans were able to plan their bombing attacks in the sure knowledge that their tanks and troops would reach certain positions at speciﬁed times. They worked out a detailed time-table which took into account their air movements as well as their land movements. They subordinated everything to this precise co-operation with a result that is now history. They showed the world how air and land forces could, and must, work together, and Britain took heed. Britain formed Army Co-Operation Command within the R.A.F. to put into effect the lessons learned and give the land forces back their air arm. The idea of the relationship between air and land forces had gone almost full circle. The experience of Libya showed later that the Germans can be beaten at their own game—and beaten hard.

BRIEFING MUSTANG PILOTS

The pilots seen above are just off on a reconnaissance. The air intelligence liaison officer explains the purpose of the ﬂight, the area to be reconnoitred, and what is to be looked for

DETAILS OF THE LONG RANGE MUSTANG

Fig. 3. The Mustang is a fast single-seater ﬁghter in service with the Army Co-operation Command of the R.A.F. Though it is American-built it is of British design and has a maximum speed of about 370 miles per hour at 15,000 feet. This aircraft is also much used for reconnaissance work as well as for light bombing, and it specializes in low level attack. Its armament consists of two 0.5 machine guns in the fuselage and three other machine guns in each wing. It is powered by an 1,150 h.p. Allison liquid cooled 12-cylinder “V” type engine. The dimensions of the Mustang are: wing span, 37 feet, length, 32 feet 2 inches; height, 11 feet 8 inches. The wing-tips are similar to those of a Grumman Martlet

SPOTTING FOR THE ARMY

The ﬁrst step taken by Army Co-operation Command was to discard the Lysander and re-arm with fast, well-armoured aircraft. The American Tomahawk was used, then the Kittyhawk and later on the powerful Mustang (Fig. 3). In addition to these faster types of planes the Taylorcraft Auster is also used. Paratroops came into existence. Airborne regiments using gliders were formed. Light bombers suitable for the peculiar needs of the army were produced and pilots were trained in their special use. Fighter bombers were developed for army purposes. Regular army ofﬁcers were seconded to the R.A.F. to work operationally in the Command. R.A.F. men were trained in that mass of knowledge which is vital to the army, since they would be required to supply military information. Pilots had to learn to identify the mark of a German tank, recognize the differences in the types of guns moving along a road and know how to draw the correct inference from a column of motor cyclists with side cars as against a string of motor cyclists. It was not enough that an Army Co-operation pilot could ﬂy. He had to have a thorough knowledge of the German army, its equipment and how it was transported, and of its armoured formations. The pilot had to be something of a military encyclopedia as well as a highly skilled airman.

THE LIAISON SECTION

For this reason there are no R.A.F. Intelligence Officers on the staff of the Command. The intelligence brought back is not of an Air Force nature. It is military information. Each Army Co-operation squadron accordingly works with a small liaison section of three army ofﬁcers who have been specially trained. They are picked men. It is their duty to brief pilots, advise them on their tasks and extract every scrap of military information when they return.

Each of these sections has its own travelling photographic tender where the results of each sortie are processed. To the army liaison officer falls the task of making the ﬁrst interpretation of the pictures brought back. This interpretation, along with the verbal report of the pilot, is telephoned or wirelessed or sent by dispatch rider to headquarters.

Army Co-operation pilots pass through the usual ﬂying schools of the R.A.F. But to this is added a course in the art of military manoeuvre. This, in time, leads them to the specialized training of Army Co-operation headquarters under which also come special training units to instruct airborne troops, parachute organizations.

Much has happened within the Command, apart from the training of pilots to support the army in the Middle East. Pilots have been taught how to give support over here, on the Continent or wherever else they may be needed. For months they trained on their Tomahawks and then on their Mustangs.

MUSTANGS OF ARMY CO-OPERATION COMMAND IN FLIGHT

These fast Mustangs are the aircraft which do the work of army reconnaissance behind the enemy lines. Apart from their high speed, they often ﬂy so low to take photographs that they return to base with evidences that the tops of trees or telegraph wires have been ﬂown through. Fitted with special secret cameras, detailed photographs of small areas can be taken at astonishing speeds. Frequently the pilot of a Mustang will release the shutter of his camera at not more than 50 feet above the ground while travelling at well over 300 miles per hour

The change over from the old Lysander to the fast single seater ﬁghter was much greater than it looks on paper. It was a revolutionary change that compelled the pilot to do the work previously done by a pilot and observer. It compelled one man to do the thinking of two in a few seconds instead of in minutes.

The British pilots got over the difficulty with remarkable speed. The visual and photographic reconnaissance carried out previouslyat a leisurely rate and at a fair height had to be done at hundreds of miles an hour at tree-top height. The pilots had to keep one eye on the ground, one in front of them, a third behind them, a fourth above, a ﬁfth to the right and a sixth to the left. Careful training and the clever placing of a mirror gave them visual powers equal to the imaginary six eyed man. In addition, the pilot had to navigate his machine correctly, read his maps and make pencil notes of everything of importance he saw below.

SUPPORTING THE TROOPS

While undergoing this training the pilots mix with army personnel to gain as much experience as possible of army methods. They take part in numerous exercises and in due course carry out miniature sweeps across the Channel to wreck Dutch, Belgian and French railways and canals. At Dieppe, with conspicuous success, they played the part they had trained for—that of army supporters.

The reconnaissance machine is however only one side of the work of Army Co-op. Light bombers, of which there are several squadrons, are piloted by crews specially trained in the art of giving troops close support. Apart from machine gunning and bombing advanced elements of the enemy, a task also carried out by Hurricane bombers, they have another job of primary importance. The laying of smoke screens or the dropping of smoke bombs to hide from the enemy the activity of our troops on the ground, if not done expertly, might cause the loss of a battle. The smoke is also a useful agent in preventing the enemy from seeing the descent of paratroops.

AIRBORNE FORCES

All glider pilots were at one time also trained by Army Co-operation,and special aerodromes in the Command are set aside for making paratroops air-conscious. The Russians were the ﬁrst to develop the technique of putting into action airborne troops, but the Germans followed their lead rapidly and there is no doubt that the use of parachutists and men in troop carrying aircraft played a large part in the capture and subsequent capitulation of Holland in the spring of 1940, and was largely responsible for similar events in Crete a year later. Naturally such modern developments have been by no means neglected by the Army and the R.A.F.—witness the many successful landings of British paratroops in Italy and elsewhere. Probably the most interesting aspect of this system is that of the employment of parachutists, and discussion on the subject with regard to both Britain’s and Germany’s methods has been considerable.

The parachutist is a soldier by rights and merely uses a formerly unusual means of descent in order to pounce upon his enemy from unexpected directions. All necessary arms, ammunition, explosives for sabotage, food and other supplies, even bicycles, also parachute borne, accompany him on his descent.

His training is not as difficult or alarming as it sounds; in fact the wind is tempered to the shorn lamb to a remarkable degree. Without equipment he is invited to jump from comparatively low heights increasing to something like ten feet on to a gymnasium mat. Partly supported by a suitable tackle of ropes, pulleys and counterweights he is then gradually acclimatized to some of the sensations of a real parachute descent inside a hangar. Concurrent with these activities he is subjected to a course of intensive physical training which attunes him to an exceptional degree of physical ﬁtness and when the time comes for him to do his ﬁrst real descent from an aircraft, he ﬁnds that there is if anything less cause for hesitation than when high diving for the ﬁrst time at a swimming pool.

A disadvantage of parachutist descents is that arrival is roughly equivalent to that following a jump off a ten-foot wall. Added to that is lateral speed due to the wind. The process is apt to be painful, and the parachutist is not always immediately possessed of the enthusiasm necessary in a soldier about to undertake a hazardous operation. Another point is that before he “takes silk,” as he calls it, he may have spent many cramped hours in an aeroplane under conditions of great cold and in darkness.

A typical aeroplane used by the R.A.F. to transport parachutists is the Armstrong-Whitworth Whitley. These twin-engined long range heavy bombers, suitably adapted for the purpose, are shown in action in Fig. 4. Perhaps more mundane—if the activity in which aircraft takes part can be so termed—is the method of transporting personnel in multi-engined aircraft and disembarking them in strategic positions actually on the ground. Typical British and German troop carriers are illustrated in Figs. 5 and 6 for purposes of comparison.

PARACHUTE TROOPS BALE OUT

Fig. 4. Parachute troops leaving Armstrong-Whitworth Whitleys during a demonstration in England. The parachutes open immediately the men leave the plane, making very low altitude jumps possible, thus reducing the time of being exposed to possible sniping

Perhaps of all the methods of transporting troops by air that in which towed gliders are employed is most interesting. The gliders are towed one behind the other in “trains,” as it were, each glider containing six or more fully equipped infantrymen who, unlike parachutists, at ﬁrst busily occupied with preparatory measures, are already in parties under N.C.O.s ready to begin instant hostilities with marshalled equipment on landing.

After being disconnected from their parent craft gliders can reach their objective in complete silence, their gliding range, moreover, may be considerable, and they are released from a great height. Another distinct advantage possessed by the glider is that it can land on its skid with an extremely short run. It can thus avoid either real or artiﬁcial obstacles in ﬁelds such as stooks, trenches, poles, wires, and so on.

TROOP TRANSPORT AIRCRAFT IN USE BY BRITAIN AND GERMANY

Figs. 5 (above) and 6 (below). Front, side and underneath views of some well-known British and German troop carriers. The Harrow and Bombay are somewhat similar in appearance, but can be distinguished by the fully tapered wings of the former and the difference in the shape of the tailplanes. They each have a range of about 2,000 miles. The Hertfordshire, the smallest of the three, is the R.A.F. version of the Flamingo airliner. Its maximum range is about 1,300 miles. Of the German types the best known is the Ju 52. It can accommodate about fourteen fully equipped parachutists and has a range of about 1,000 miles. The Ju 90, formerly a forty-passenger airliner, can carry a load of nearly seven tons. The Blohm and Voss 142 is developed from the long range seaplane, the Ha 139. Both have a range of 3,000 miles, but the 142 is considerably more powerful and faster by about 50 m.p.h.

How many troops the largest practicable glider can carry is still a matter of conjecture; suffice it to say that a considerable force could be, and has been, landed by an enemy without the use of an inordinate number of towing aircraft. Should the latter themselves be troop carriers, their effective capacity could be enormously increased, depending upon the number and size of their satellites, or if not troop carriers they could, as a sideline, carry a useful load of bombs or a useful load of stores and equipment which they could drop by parachute to the troops below.

It is too early to speak with any authority upon the question of transporting light tanks, ready for action, between the undercarriage legs of giant aeroplanes, but it is known that both the Russians and the Germans have carried out experiments in this direction.

It will be seen from what has been written that the duties of an air force in co-operation with or support of an army are many. With the development of modern warfare these will tend to increase rather than diminish. It is comforting to know, however, that no matter how advanced the prosecution of modern warfare may become, Britain’s Royal Air Force is keeping abreast of the times in technical development, and is ready with considerable alacrity to meet all the varied requirements of Britain’s Army whatever they may be and in any circumstances.

DISUSED MINE BECOMES BOMB STORE

In the galleries of a disused coal mine in Britain, hundreds of feet below ground, are stored vast numbers of the various types of bombs which. are being used by the R.A.F. to blast the war industries of the enemy. Here is a store of thousand pound bombs such as are carried by our heavy night bombers into the heart of Germany. Those above will soon be on their way

CHAPTER 10

Maintenance and Transport Commands

Three-quarters of a million items in stock. Missing spare part can keep an aircraft on the ground. Delivery by air if necessary. Football pools helped. New machines ﬂown to save ship space. Birth of the ferry idea. Three routes across the Atlantic. World-wide service. Bombers bring urgent munitions and mails. Flying boats from Bermuda

“GIVE us the tools and we will ﬁnish the job” said Mr. Winston Churchill, broadcasting in February, 1941. The same remark could be made by the various Commands of the R.A.F. and the men about whom we have so far been talking. Without the aircraft, the crews are useless and the organization of the various headquarters so much waste effort. And, behind the aircraft, a vast system of “supply-on-demand” of spare parts is needed, airﬁelds have to be constructed and maintained and protected, and an enormous personnel built up and trained to see that the operational units are always at the peak of efficiency.

BEHIND THE SCENES

It is not within the scope of this book, nor is it possible in the space available, to deal exhaustively with the subject. But no work on the Royal Air Force is complete without some indication of the behind-the-scenes work that goes on to put aircraft into the air and see that they are maintained there. It is the little thing, the often unconsidered triﬂe, that matters. The story of the clockmaker who was called to the army in his registration group and then had to be sent back to civilian life some weeks later because there was nobody left to repair the alarm clocks on which workers relied to get to their factory on time in the morning may not be exactly true, but it is typical. Without him, production in the factory fell through lost hours. The fall in production meant a shortage of a metal needed in aeroplane construction. That meant, in the end, fewer aeroplanes and so it went on. When the ﬁrst assault forces landed on a beach near Algiers at dawn when the North African campaign began, two R.A.F. Servicing Commando Units went with them. They helped to capture Maison Blanche airﬁeld just in time to attend to the ﬁrst Hurricane that landed there. Within three minutes of that British ﬁghter touching down it had been re-armed and re-fuelled and was taking off again—to ﬁght again.

Maintenance Command of the R.A.F. has a raven as its badge, since it is the ravens who “provide,” and it lives up to the full meaning of that one word. It has a standing list of three-quarters of a million items always in stock and it is its proud boast that no aircraft is ever kept on the ground for want of a bolt or a screw or a nut or a spare part, even if that spare part is only in stock four hundred miles away. It will be delivered speedily, by air if necessary, or a motor cyclist dispatch rider will travel all through the night with it so that it is ready to be ﬁtted with the coming of dawn.

INSIDE A REPAIR WORKSHOP

All over Britain, the Middle East and elsewhere the R.A.F. has its own emergency repair workshops, staffed by highly skilled mechanics and ﬁtters. In one of these workshops, pictured above, British ﬁghter aircraft undergo lightning repairs and overhaul for new operations

Manufacture of aircraft is, of course, in the hands of the Ministry of Aircraft Production, but when the machine leaves the factory it is taken over by the Maintenance Command for storage, ﬁnal equipment and delivery, whether it comes to them from an underground British factory or at the hands of Ferry Command (about which we will talk later) from America.

But the Command is not only responsible for aircraft. It exists to supply every material requirement, with the exception of food, stationery and building materials, of the R.A.F. Its three-quarters of a million items, listed in the catalogue which the Command calls its “Vocabulary” include the smallest screw, a four bladed propellor, the pilot’s high altitude ﬂying equipment and the W.A.A.F.’s stockings. Everything is carefully indexed so that a brief signal may describe it and a day to day stocktaking system keeps track of the totals. Whenever a problem in accounting or stock-keeping has arisen, the Command has called on the best business experience available for help. The chief of a famous “football pool” was called in to advise on the rapid handling of vouchers. The head of a ﬁxed-price chain store gave his advice on how to deal with a multitude of small items, and a ﬁrm of haulage contractors gave of their experience in dealing with questions of delivery.

Some of the problems which the Command has to face involve improvements to aircraft which are decided on after they have left the factory. These improvements have to be ﬁtted while the machines are in store. Or it may be that some gadget is so secret that its installation in an aircraft cannot be left to the factory where chance contacts may betray its purpose and basic idea. Then the Command collects the various parts of the gadgets made in widely dispersed parts of the country and ﬁts them together itself.

To pack a ﬁghter squadron for service overseas involves the collection together of more than 8,000 separate items, counting an aircraft engine as one and such spare parts of it as magneto, carburetter as complete items. Actually, if every nut and screw is counted there are 11,000 separate parts to a Rolls Royce engine alone.

A single order from a bomber station may cover an immense range of requirements. They will be packed into a huge lorry and sent on their way. The country is actually divided into seven delivery areas by the Command and even the most remote operational stations are visited by the delivery van at least once in every 48 hours.

AT WORK ON A LOCKHEED VENTURA

Repairs to high-powered aircraft engines call for a great deal of technical skill and patience. This ground crew is servicing a Ventura reconnaissance bomber of the Coastal Command

The handling of explosives is a highly specialised task. In addition to the storage and delivery of bombs, this section of the Command deals with ammunition, pyrotechnics for signalling, oxygen and petrol. The main stores in which the explosives are kept are sometimes hundreds of feet deep in the side of hills.

The salvage of crashed aircraft also comes under the control of the Command, though only about ten per cent. of the actual repairs are done by the Command’s own men. The depots where they work are, however, wonderful training grounds for aircraftsmen and, as soon as mechanics reach a high standard of skill, they are sent to stations to work on the maintenance of aircraft in operational use. The large repair depots and salvage and repair units are so organized that a minor crash or damage from anti-aircraft ﬁre can be put right in record time. A Wellington bomber seen on a station in the early evening ready to take off on a night operational ﬂight in a brand new coat of paint may not necessarily be new and straight from the store into which it was put when delivered by the aircraft factory. Actually it was probably over Bremen or some other German city the night before and came back with a large hole in the fuselage where it had been hit by “ﬂak.” It was a pitiful sight when it came back, but the repair gang, men and women, got to work on it and ﬁnished in time to spray it with a new coat of paint and have it ready for another raid.

FERRY COMMAND

Obviously the thing that the operational pilot needs most is a complete aircraft. It is also the one form of munition of war which can deliver itself so to speak, over great distances without the use of shipping space or lorries or rail wagons. It can be ﬂown and carry freight or passengers in the process as well.

When war began, Britain was short of operational pilots. She needed everyone she could lay hands on and had none to spare for the routine jobs of delivering aircraft by air from factory to the Maintenance Command depots and from there in due course to the operational squadrons to replace those shot down or damaged in combat. To cope with this problem, the A.T.A. (Air Transport Auxiliary) was formed of civil pilots either too old or unsuitable for some other reason to take part in the ﬁerce stress of the war. Famous people such as Amy Johnson and Jim Mollison joined. They did and still do a highly valuable job. Their organization grew. It showed what could be done by the air delivery of aircraft and suddenly, because of their work, the germ of an idea that was eventually to be one of the greatest triumphs of organization the war was to see, took shape. The idea of the air delivery of aircraft across the Atlantic to Britain, to every theatre of war in every part of the world, had birth. Ferry Command came into existence.

FIRST TRANSATLANTIC DELIVERY

The war was only a few months old when the ﬁrst steps for a regular Canada-Britain air mail service which would eventually become the basis of a bomber ferry service were taken. A group of experienced pilots, all men well-known on the world’s air routes, were sent to Canada and reinforced there with civilian pilots from Canada and the United States and service pilots from Coastal Command. A transatlantic ferry pilots’ school was opened in November, 1940, and on Armistice Day that year the ﬁrst trans-atlantic delivery of American built bombers to Britain took place. Seven Lockheed Hudsons took off from Newfoundland under Captain D. C. T. Bennett, D.S.O., and ten hours later landed in Britain. Their ﬂight went so smoothly that instructions were sent for the remainder of a consignment of ﬁfty to take off.

ATLANTIC FERRY CONTROL

At the eastern terminal of Ferry Command somewhere in Britain the control room staff plot the movements of every new plane in its 2,000-mile ﬂight across the Atlantic from Newfoundland

In March, 1941, the following year, the bomber ferry came under the control of the Ministry of Aircraft Production but remained so for only a few months. In June, 1941, Mr. Roosevelt made it known to Mr. Churchill that the United States government was prepared to let U.S. army pilots and crews ferry bombers to Canada and Newfoundland and permit U.S. civilian pilots to ﬂy them across the Atlantic. Later the Air Ministry again took over the ferry service and Ferry Command—now called Transport Command—was formed. Today the Command delivers a steady stream of aircraft across the Atlantic by three main routes, from Newfoundland, from Bermuda and from Brazil to the West Coast of Africa, the route for the Middle East.

The present headquarters of the Command are at the Dorval airport, Montreal, described by Air Chief Marshal Sir Frederick W. Bowhill, G.B.E., K.C.B., head of the Command as “this splendid airport—one of the best I have known, with uninterrupted approaches, modern layout and extensive approaches.” It was completed sufficiently for partial use within ﬁve months of work on it beginning. The forward base at Newfoundland from which the aircraft take off for Britain is another feat of engineering construction. Built on the site of an old forest camp alongside a railway, it is inaccessible by road but it has the widest aeroplane runways in the world. It is under snow for more than six months every year, but giant rotary blowers keep it constantly clear by spraying the snow into banks which sometimes are twenty feet high. Bermuda, which also had to have a good deal of construction work carried out, is used for the dispatch of ﬂying boats. The Command also delivers aircraft across the Paciﬁc to Australia, and sends to India and the terminal airport which is now the lifeline to China.

Regular Transport Command crews are mostly civilians from all over the world. But the greater number of pilots who bring new aircraft across are products of schools of the great Commonwealth Air Training Plan. When they pass out a special course is set them by Transport Command.

NAVIGATOR OF A WHITLEY BOMBER

In the forward compartment of a Whitley long range bomber, the navigator sits at the chart table on which can be seen a bubble sextant and parallel rulers which he uses to plot his course. At the controls sits the captain, whilst the second pilot pours out a welcome cup of hot coffee from a thermos ﬂask. Faster types of planes are now operating with the Whitleys

CHAPTER 11

Celestial and Wireless Navigation

Map reading. Dead reckoning. The magnetic compass. Air-speed indicator. Ground speed. Astronomical navigation. The position line. Use of sextant. Watches and chronometers. Reduction of the observation. Plainsphere, air almanac and air navigation tables. Wireless direction ﬁnding. The beam system. Meteorology. Training of navigator

NO truer remark was ever made about the art of air navigation than that made by the American authority, Commander Weems, when he said: “There are four possible means of ﬁxing an aircraft’s position,” and then added “But there are times when all four are not enough.”

The methods referred to by the commander were, map reading, dead reckoning, astronomical, celestial and wireless direction ﬁnding. Each method is best suited to certain types of problems and when Commander Weems claimed that there were times when all four were not enough he meant that there were circumstances in which each method would fail. Fortunately, all four methods do not usually fail simultaneously, but the moral is clear. The good navigator cannot afford to neglect any one of them.

SCALE OF MAPS

The maps in use in the R.A.F. are of three scales, each scale being a multiple of the others. First of all there is the 1/1,000,000 map which gives a scale of approximately sixteen miles to the inch on the map (Fig. 1). With this scale little detail can be shown of course, but nevertheless a large area can be put on a single map sheet. This map then is used mostly for plotting the track and studying the general lay of the route.

When greater detail is required the 1/500,000 map is used (Fig. 2). This gives approximately eight miles to the inch, and allows each feature to be depicted in greater detail. On this map it is usually possible to recognize the towns and villages of the countryside. Only when one comes to a very congested neighbourhood such as greater London or the industrial parts of the midlands or the Ruhr valley is it essential to have still greater detail. For these areas therefore a map of scale 1/250,000 or approximately four miles to the inch (Fig. 3) is used.

NAVIGATIONAL MAPS

Maps used in the R.A.F. are of three scales, each being a multiple of the others. Fig. 1 (left) is 1/1,000,000 giving approximately sixteen miles to the inch. Fig. 2 (right) is 1/ 500,000 and gives eight miles to the inch. In Fig. 3 (below) the scale is 1/250,000 and gives four miles to the inch.

USE OF WIRELESS

In general, as the ﬂight proceeds the navigator will use maps of larger and larger scale, and the bomb aimer will ﬁnally pick out the target from a special large scale target map or a photograph.

Map reading is one of the most difficult subjects to teach, or, to be more exact, it is probably impossible to teach. It comes with experience in the air and hours of observation. Navigation proper is a much more exact science and comparatively easily taught to any one with average ability. There are navigators who will bring their aircraft to within a few miles of their home stations by navigation proper, and then take out a large scale map of their home countryside and proceed to lose themselves entirely.

Dead reckoning navigation is the art of estimating the aircraft’s position by knowledge of the direction and speed in which it has been moving. This sounds simple enough, but in reality can be quite a complicated process, for here, errors are accumulative. If there is an error in the aircraft’s course or if the speed is not quite accurately known then the estimate of the aircraft’s position will differ from the real position and the disparity will increase with the passage of time.

There are many sources of error in dead reckoning navigation. In the ﬁrst place, the course is set by a magnetic compass (Fig. 4), but there is much magnetic material in the aircraft, and it is necessary to “swing” or adjust the compass very carefully on the ground before it can be made to give the correct reading (Fig. 5). Even after this, it is not absolutely certain that the course as set in the air is always quite accurate. Bombs are of magnetic material. The machine may have been “swung” on the ground with bombs on, but what when the bombs have been released? The machine was “swung” on the ground with its undercarriage down, but in the air the heavy steel tubes of landing gear will ﬁt inside the wings.

THE MAGNETIC COMPASS

Fig. 4. Inverted type aircraft compass. It is ﬁxed in the roof of the aircraft above and in front of the pilot who takes his bearings by means of a mirror. Saving of space is effected

ADJUSTING A SPITFIRE’S COMPASS

Fig. 5. Magnetic compasses are very sensitive instruments, and as there is much magnetic material in an aircraft, they are liable to be affected and give inaccurate readings. In order to overcome this, aircraft are swung on the ground with full load and the compass adjusted accordingly. The Spitﬁre above is being swung on a specially constructed turntable

It has been known for the magnetism of an aircraft to have been substantially changed by ﬂying through an electrical storm with the result the compass had considerable errors. All these are points which have to be continually watched and checked. In the long run, however, the magnetic compass is a superbly reliable and surprisingly accurate instrument.

NAVIGATOR’S CHART BOARD

Close-up view of chart board with adjustable ruler which can be set to take into account such factors as ground speed, wind speed, air speed and so on, interdependent factors to be reckoned with

The next “key” instrument required in dead reckoning navigation is the air-speed indicator. Here again, however, any one who supposes that an air-speed indicator always gives a direct indication of the true air speed would be taking a very optimistic view. First of all, the instrument itself is periodically calibrated on the ground against a master instrument and its errors are noted. Next there is a correction to apply for the position in which the instrument is mounted on the aircraft. This is known as the position error or “P.E.” This is bad enough, but there is worse to come! The instrument is measuring the forward speed of the craft by the pressure of the air stream, so its reading depends on the density of the air itself; the density depends on the temperature and pressure. When ﬂying low these adjustments to the air-speed indicator reading only amount to minor compensations, but when ﬂying high they become very large factors indeed. For example, let us suppose that a bomber goes out on a raid at 20,000 feet where the air temperature is -24 deg. centigrade, and that the navigator sees his air-speed indicator at 165 miles per hour. His combined instrument error and position error correction is usually kept on a card pasted to the instrument board, or inside the cover of his log book. At 165 miles per hour indicated speed, the correction is +9, which means that his corrected indicated speed is 174 miles per hour. Now he takes a computer, that is a special slide rule for correcting air speed. At a pressure height of 20,000 feet and a temperature of -24 deg. centigrade the 174 miles per hour is corrected to a ﬁgure of 238 miles per hour. This at last is his true air speed.

Even now, however, the navigator’s troubles are far from over. He has found his true air speed, but that is only his speed through the air. What of the wind? i.e., the speed of the air over the ground. Perhaps he has a 50-miles-per-hour wind from behind him in which case he is approaching the target at 288 miles per hour. Perhaps the wind is against him, in which case his ground speed is only 188 miles per hour. Perhaps the wind is on the beam, however. In this particular case he is not directly approaching the target but is drifting twelve degrees or so to one side or the other.

It would be quite impossible in this chapter to explain all that is involved in the term “dead reckoning” navigation, but enough has been said to show that it is full of pitfalls for the unwary. The point to remember is that these pitfalls are apt to increase with the passage of time. For example: if a navigator over-estimates his ground speed by ten miles per hour he will plot a position ten miles ahead of his real position for every hour that he ﬂies. After ten hours he would be 100 miles in error. Thus it is very important to obtain other checks on the positions. This may be done either by wireless bearings or position lines from celestial bodies.

Astronomical navigation is the ﬁxing of a craft’s position by observation of the sun, the moon, the planets or the stars. There are many varieties of method, but the underlying principles are similar. In general too, there are three features common to every method. First, the process of “taking a sight,” that is, measuring the “observed altitude” or angle of elevation of the celestial body. This is done with a sextant. Secondly it is necessary to obtain the exact time of the observation by a chronometer or an accurate watch. Thirdly there is the process of reducing the observations of sextant and watch to position lines on the chart. This process, however, involves some small amount of calculation and the use of a naval almanac and some mathematical tables.

It is not possible to obtain the exact position from the observation of any one body. It is only possible to obtain a “position line.” That is, a line somewhere upon the length of which the observer is situated. The position line is at right angles to the direction in which the body is seen. In order to ﬁx the position completely it is necessary to make observations of two celestial bodies and where the position lines of the two cross is of course the exact position (Fig. 6).

FIXING THE POSITION

Fig. 6. Diagram illustrating how bearings are taken by observations from two celestial bodies. The position lines are at right angles to the direction in which the bodies are seen, the point at which they intersect is the “ﬁx”

Air navigation has its roots in sea navigation. The principles are the same and many of the processes are exactly analogous. The marine navigator would however ﬁnd difficulty in recognizing much of the air practice. The lesser degree of observational accuracy in the air coupled with the urgency of extreme speed has resulted in the development of methods far quicker and simpler than were ever dreamed of by navigators at sea.

Despite this it is interesting to ﬁnd that a marine sextant differing little in essential design from those which have been used at sea for generations is still used very successfully in some circumstances in the air. The ﬂying-boat does most of its ﬂying low over the water on convoy work and anti-submarine patrol. The air over the Atlantic is both cloudy and windy, but when the pilot sees a patch of sunlight shining on the sea ahead of him he may dive down and ﬂy even lower above the surface—no higher than the bridge of a ship. His navigator may then get a “snap” sight of the sun’s altitude above the sea horizon. The resulting position line may be exceedingly valuable to the navigator who may have been working on nothing but “dead reckoning” for the past twelve hours. The particular type of sextant now issued to all our ﬂying-boat crews for this purpose is a development of one which was originally made for Alan Gerbault, the French yachtsman who sailed the Firecrest single-handed across the Atlantic Ocean.

Those navigators however who ﬂy high at night, where no natural horizon is available, do not get this advantage. To them the taking of a sight is a more laborious process, for they must use a bubble sextant in which the natural horizon is replaced by a bubble ﬂoating in a liquid. On the ground this instrument will measure an altitude to one minute of arc, and would continue to do so in the air if only the aircraft could be persuaded to ﬂy truly straight and truly level. Unfortunately this never happens. In practice, the aircraft, even when it appears to be ﬂying straight, is in reality weaving slightly from side to side. The motion may be imperceptible to the pilot but to the bubble of the navigator’s sextant it causes large and ﬂuctuating errors. This sextant is one of the many devices on which an air crew’s safety depends.

The only course open to the navigator then is to take many sights and average them. The taking of an observation with a bubble sextant (Fig. 7) may be a far more laborious process than the single observation from the bridge of a ship at sea. It often entails standing at an open hatch with frozen ﬁngers for ﬁve or ten minutes at a time patiently recording a series of from six to two dozen individual observations. In addition to cold and fatigue, lack of oxygen often renders accurate work even more difficult (Fig. 8).

MARK IX AVERAGING SEXTANT

Fig. 7. Bubble sextant used for taking bearings on celestial bodies. It incorporates a device for averaging the results of six observations. The bubble replaces the horizon

TAKING AN OBSERVATION

Fig. 8. Navigator of a Sunderland flying-boat taking an observation by means of a Mk VIII bubble sextant. Depending upon the degree of accuracy, he may have to average out the results of as many as two dozen observations because of the unsteady movement of the aircraft

The ﬁrst bubble sextants issued were designed at the Royal Aircraft Establishment at Farnborough long before the days of R.A.F. expansion, and at a time when very few navigators were trained in the use of the sextant. The demand for the instrument was slight and the sextant was in no way designed for mass production. It was a good rugged instrument and sundry improvements ran up to a MK VIII. In about 1938 it was realized that with the enormously increased range of modern aircraft celestial navigation was going to be more in demand, and with the coming expansion in view the speciﬁcation for a MK IX sextant was drawn up so as to be capable of mass production. This sextant incorporated an ingenious mechanism for averaging the result of six observations, and it could be produced in the large quantities which were required. Although there are a number of MK VIII sextants still doing good service, the MK IX averaging sextant is now standard in the R.A.F.

Without accurate knowledge of Greenwich Time the navigator would be unable to work by astronomical observations, and it is to the Admiralty that we owe the development of the chronometer, and indeed accurate time-pieces of all kinds. The real chronometer is a wonderfully accurate and very delicate piece of work. Not only does it keep time more accurately than is really necessary for air navigation, but the treatment it receives, the ﬂuctuations of temperature and the vibration are sheer cruelty to such a delicate and expensive instrument.

LONG PATROLS

In practice the endurance of aircraft is not great, and time signals are plentiful. Flying-boats are normally on patrol for twelve or fourteen hours while bombers do not as a rule ﬂy for more than eight or ten. The watches issued to navigators in the R.A.F. are wrist watches of good quality which will keep time accurately enough over ﬂights of such duration. They are ﬁtted with a rotatable bezel engraved with a scale of seconds, so that if the long centre seconds hand is not set absolutely accurately, it may be made to read correctly against this outer scale.

When the sextant observation has been made and the exact time of the observation has been noted, it remains to reduce the observation to a position line on the chart. This sounds a very formidable process and until a few years ago it was so. Now, however, it has been made very easy, for those responsible for developing the methods of celestial navigation to be used in the R.A.F. have realized that only the most simple processes were practicable and workable in the air. So simple has it been made that it has been found possible to give navigators as little as three weeks’ instruction in celestial navigation, for them to be able to navigate successfully.

This simplicity has been achieved by the production of three things: a “planisphere,” the “air almanac,” and the “air navigation tables.” Little or no arithmetic is required, and it is not even essential to know the principal stars by name. The planisphere is a kind of map on which the positions of the stars can be found. The principal stars used in navigation are numbered, the numbers correspond with those in the air almanac and also with those in the air navigation tables. The numbers in the air navigation tables are “thumb-holed,” so that a pupil may make an observation and turn up the right page in the tables without even knowing the name of the star with which he is working. In practice, of course, the pupil soon becomes interested and learns to recognize and name the dozen or more stars which he requires. In the old days it used to require some twenty minutes’ work with logarithms before use could be made of an observation: now the position line is on the chart in two or three minutes.

The limitations to the use of celestial navigation are ﬁrstly due to the fact that there is only one sun by day, whichwill give a position line but not a “ﬁx.” Secondly, of course, it is altogether useless when the sky is obscured by cloud.

USE OF WIRELESS

As with other aids to navigation there are many variations in the use of wireless. Essentially the process consists of receiving a signal and detecting the direction from which it is coming. This direction can then be plotted as a bearing on the map and the transmitter which sent the signal will lie somewhere on that line. If a second bearing can be obtained cutting the ﬁrst one, the point where they cross will be the actual position or “ﬁx” as it is called (Fig. 9).

GETTING A WIRELESS “FIX”

Fig. 9. A signal from the aircraft is picked up by two or more D.F. stations who note the bearings. These are then plotted, and where they intersect shows the position.

Now there are two ways of using this; the directive reception may be on the ground or it may be in the aircraft. First, let us consider the organization on the ground.

Suitably disposed all over the British Isles are many direction ﬁnding stations. They are arranged in a number of different groups. There are usually three stations working on the same wave length in each group. If an aircraft is lost or uncertain of its position it calls up on the appropriate wave length and asks for a “ﬁx.” Each of the three “D.F.” stations receives the aircraft’s signals and notes the bearing, that is the direction from which they are coming. Now one of the three stations is a master station and the two others send in the bearings they have received to this one. In the master station all three bearings are plotted and their intersection is the position of the aircraft.

LIMITS TO NAVIGATION METHODS

The master station then signals to the aircraft telling it where it is. This sounds rather a roundabout process, but in practice the service can be extraordinarily prompt. An aircraft is often given its “ﬁx” within one minute of asking for it. In some circumstances a navigator may ask for a single bearing rather than a position, which saves a little time.

There are, of course, various drawbacks and limitations as there are to all methods of navigation. In the ﬁrst place, if the aircraft is close to enemy units and not already discovered by them, it is undesirable for it to break wireless silence and so disclose its position equally to the enemy. Secondly there is the possibility of an enemy ground station answering the aircraft’s call and giving it a bogus position. This happened to the navigator of a night bomber in the ﬁrst few months of the war. He was returning across the North Sea having been badly damaged. The machine was low over the water and only just holding its height. The navigator wanted a bearing to help him steer for the nearest point on the English coast. No sooner had his wireless operator made the signal than a very loud station replied giving him a perfectly false bearing. Fortunately the bearing given was so wrong as to be quite absurd. It was ignored and the aircraft got safely home. To guard against incidents such as this the wireless signals are now put into code and there is a recognition procedure to ensure that both ground station and aircraft can be certain of each other’s identity. A third limitation of this type of wireless aid is that when there are perhaps a hundred or more bombers in the air, the ground stations get so much overworked that the system is bound to become very much congested.

The other way in which wireless bearings are used is by putting the directive receiver into the aircraft. Here the wireless set has a loop receiving aerial, and the wireless operator in the aircraft measures the direction from which a signal is coming. Here the problem is to ﬁnd suitable transmitting stations upon which to take bearings. The German broadcast transmitters usually close down during our raids to deny us this assistance. The Germans themselves established a number of beacon transmitters specially for the purpose and moved them about and changed their call signs and wave lengths hoping that we could not use them as well. The broadcasts of the B.B.C. transmitters, of course, have been arranged in such a way that it is impossible for an enemy aircraft to get an accurate bearing from them at any time.

BEAM SIGNALS

There is one other variety of wireless aid to navigation. That is the beam system which is so universally used on the airlines all over the United States, and which has been brought to a very advanced state of technical development by the Germans. Here a ground station emanates a beam signal in a certain direction. The crew of the aircraft can tell whether or not they are in the beam and so can travel along it. This has the disadvantage, however, that it can only be used on one ﬁxed route and in consequence does not help the navigator who wants to travel in another direction.

NAVIGATOR PLOTS HIS COURSE

Navigator’s station in a Short Sunderland long range ﬂying-boat. The captain is instructing his crew to stand by ready for the take off. The navigator is already at work plotting his course. Sunderlands ﬂy mostly far out over the sea, so a very high standard of navigation is required comparable, in fact, with that of a transatlantic liner, but with far more variable conditions

It would be impossible to give the reader a proper conception of navigation in the R.A.F. without mention of the Meteorological Service. Every R.A.F. station has its “Met. Office,” where the forecasting officer and his assistants study the weather maps and prepare their forecasts. The navigator’s training includes a short course of meteorology, and although he is not expected to be an expert on the subject he should know enough of the meteorologist’s work to enable him to get the full value of his advice. This training also gives him some sympathy for the weather man who is attempting the, at times, impossible task of forecasting the weather round these islands. It is to the “Met. Office” then that the navigator goes last thing before he ﬂies. Here he studies what is known of the weather over his route, and he is told what to expect of the wind, the cloud amounts and the visibility. Often the forecast is correct, usually it is a pretty fair indication of what to expect, sometimes it is quite wrong: no fault of anybody, the weather has just “pulled a fast one” again.

NAVIGATION EXERCISES FOR OBSERVERS

Before they become fully operational, navigators are given a ﬁnal test to make sure that they are fully competent to discharge their very responsible job. The navigator (above, left) seated behind a board on the other side of which is the instructor, is acting in accordance with orders given to him. Electrical instruments record the accuracy with which he carries them out

NAVIGATOR’S SKILL

Each method of navigation works to its best advantage in some conditions, but has drawbacks or limitations in others. No method is perfect, and there are circumstances in which each may be extremely inaccurate. A navigator is rather like a foreman with various workmen at his command, for he must know which of them will serve him best for any particular part of the job in hand. Often too they will come to him with contradictory pieces of evidence and he must weigh up in his mind which, in the circumstances, is more likely to be correct.

The good navigator must ﬁrst of all study the theory of his subject in the class room. Next he must accumulate a store of experience in the air to learn just how the theory works out in practice. Then as each perplexing problem presents itself he must use both his knowledge and experience to make what really amounts to an intelligent guess.

In this chapter we have seen what a very important role must be played by the navigator of any aircraft. There have been quite a number of occasions during the Second World War when ﬂying operations against the enemy have had to be carried out under really unsatisfactory weather conditions, and when almost everything has depended on the skill and alert brain of the bomber’s navigator.

CAMOUFLAGE REVEALED BY THE CAMERA

The value of aerial photography is well illustrated by the above photographs which show how the Binnen Alster, the innermost of two lakes in the centre of Hamburg, was camouﬂaged with rafts to look like a built-up area. A dummy of the Lombardsbruecke, a vital road and rail connexion, was reconstructed, as shown, about 600 yards north of its original position. Photographic interpretation experts soon discovered the ruse, very ingeniousthough it was

CHAPTER 12

Air Photography in War

Purposes of air photography. Interpretation staff. Stereoscopic photographs. Vertical and oblique photographs. Focal length of lenses. Measurement of distances. Mosaics. Night photography. Use of the camera gun. Training of photographic personnel

IN describing the work of the R.A.F., detailed attention must be given to the activities of its air photographers, the more so as their work has a great bearing on the efﬁcient performance of many urgent national duties.

The limitations of visual reconnaissance, due to speeds and heights at which aircraft travel and to the lengthy training necessary before observers can be relied upon to discern and identify the important and to disregard the unimportant, make it expedient that trained staff ofﬁcers, able to study air photographs methodically, and at comparative leisure, and in conjunction with all the other information available, should be the men to draw the vital conclusions as to enemy’s dispositions and intensions.

MODERN DEVELOPMENTS

Air photography for military use was already of great assistance in the war of 1914-1918, and in the intervening years calls have been constantly made on the inventive genius of the scientiﬁc world, on the camera designer, the optician, the chemist, the electrician, and such practical technicians as the fast-working press-photographer—each to play his part in the perfection of apparatus and processes, and to promote speed, accuracy and economy to the greatest degree.

From clumsy plate cameras and slow, improvised dark-room practices have been evolved highly efﬁcient electrically operated ﬁlm cameras, with special lenses, light ﬁlters, shutters, and so on, modern mobile dark-rooms ﬁtted with the latest automatic devices to ensure perfect and speedy production of both negative and prints, and self-contained lighting, heating and refrigerating units ensuring efﬁciency in any climate (Fig. 1).

The pursuit of detailed and extensive knowledge of enemy resources and dispositions must inspire all the important activities of the air photographer.

INSIDE A MOBILE DARK ROOM

Fig. 1. The R.A.F. employs large numbers of mobile dark rooms for the rapid processing of ﬁlms in the ﬁeld. These are ﬁtted with self-contained lighting, heating and refrigerating units ensuring efficiency in any climate. The compact layout of one of these vans is illustrated above

PHOTOGRAPHIC PERSONNEL

Personnel of the R.A.F. who are intimately connected with air photography can be classiﬁed under three heads. First there are those whose duty it is to navigate the aircraft over the area that is indicated, and there to take the photographs. Second comes the technical personnel on the ground, performing subsequent dark-room processes and producing the ﬁnished prints, being also responsible for the maintenance of all apparatus. Finally there is the interpretation personnel, whose work consists of examining each print, extracting from it the fullest relevant information, and passing this information to the staffs and departments concerned in an appropriate and intelligible form.

Before going into further detail let us consider the main purposes fulﬁlled by air photography, since many different demands on procedure are made. Naturally to the three ﬁghting Services speedy and accurate information of enemy activities is vital. Again, the Ministries of Economic Warfare, of Shipping, of Home Security, and so on, can gain valuable information from air photographs, their demands in this respect being far from infrequent.

VALUE OF AIR PHOTOGRAPHS

The main purpose of air photography is for reconnaissance work. An army commander today is reluctant to contemplate any operation unless he has the most accurate and recent information possible of enemy terrain and enemy disposition, actual and potential, relevant to the occasion. Again, the information which is vital to naval operations regarding numbers and types of vessels in enemy harbours, concentrations at sea, the effective state of maintenance and repair facilities at port, and so on, can often be obtained with accuracy and speed by means of air photography.

To the Air Force itself early information as to the results of bombing raids, for example, obtainable mainly by means of air photography, is essential to the most efficient and economical concentration of further activities.

Mapping from air photographs is another important development, whether it be for the study of hitherto uncharted territory over which operations are contemplated, or for ﬁlling in additional detail on maps which already exist.

As soon as details of a required photographic mission are received, an aircraft crew is selected, decisions are made as to what type of camera with what focal length of lens and with what light ﬁlter is to be carried, how many exposures may be required, and what procedure should be adopted. All available maps and other means of identifying the objective are examined, and a weather report is obtained. The intelligence oﬁicer is consulted as to the probable intensity of hostile interference and how it may best be circumvented. While ﬁnal decisions are being made, the ﬁtting in the aircraft of the camera and its releases and sights goes on. The testing of each piece of apparatus as it is installed is a necessary precaution.

The actual taking of the photographs is not less responsible a job than is their subsequent careful processing. It may be necessary to manoeuvre about while clouds clear, and to evade hostile aircraft, until, photograph by photograph, pilot and crew have achieved their mission.

RUSHING OFF THE FIRST PRINTS

Fig. 2. The aircraft has returned with its precious exposures. These are hurried off to the dark rooms where everything is ready. They are quickly developed and dried on large drums (above) after which prints are made (below) and sent to the interpretation staff for detailed examination

As soon as the aircraft lands the exposed ﬁlm is handed to members of the ground technical staff who hurry off to the dark rooms with the precious magazines. Here all has been prepared; developing and ﬁxing solutions have been made up, processing tanks ﬁlled, washing and drying appliances are ready to receive each ﬁlm negative at the appropriate stages, and printing machines waiting to rush off, as may be required, either ﬁrst proofs or large quantities of prints (Fig. 2). Both speed and efficiency are essential, and members of the section work in teams so that no time is lost. In the case of reconnaissance photographs, a few prints from each negative are soon placed in the hands of members of the “interpretation” staff who, in their turn, are holding themselves in readiness to carry smoothly forward the sequence of their duties (Fig. 3).

INTERPRETATION STAFF AT WORK

Fig. 3. The above photograph, taken from the ﬁlm “Target for Tonight,” shows the photographic branch at Bomber Command where experts are busy examining the latest batch of photographs received from an aircraft just back from an enemy area which is to be bombed

INTERPRETATION WORK

At ﬁrst sight the advantages of such specialized team work may not be apparent. It is, however, no longer drummed into us that the camera cannot lie, and even though many of the objects depicted—buildings, railways, rivers, roads and so on—are features familiar to all, it should be remembered that photographs suffer from the fundamental limitation that objects of three dimensions are being recorded on a two-dimensional surface. We know, on looking at a photograph taken on the ground in the plane normal to human vision, that the image of a man standing in front of a house, for example, is not just a ﬂat object in the same plane as the wall of the house, nor is the house itself without the third dimension that nowhere actually exists on the surface of the print. Our innate knowledge and imagination, however, automatically rouses a sub-conscious appreciation of the third dimension, which in direct human vision is made evident by our two eyes each seeing actual objects from a slightly different view point. The effectiveness of this is most marked at close range. For obvious reasons the majority of air photographs have to be taken vertically from great heights, and objects are seen from a normally unfamiliar point of view. Thus only the roofs of buildings may be seen, trees appear as round objects with nothing beneath, and troughs of valleys appear to be no further distant than the crests of hills. These generalizations must be modiﬁed to some extent as regards sunny days with the sun fairly low in the sky, and long shadows accentuate the mind’s perceptions of the third dimension.

A correct or closely approximate appreciation of this third dimension is necessary for obtaining the fullest information about the details of an area under review, and all the specialist skill of the photographic “interpreter” is called into play, whether it be by means of pairing photographs taken from slightly different viewpoints for stereoscopic viewing, by examining shadows, tracks, and so on, or by other intuitive methods. This problem is dealt with later in the chapter.

There are a thousand and one details which might well escape the notice of the uninitiated, but which enable an interpreter to draw deﬁnite conclusions. Nor will he allow himself to be misled by any methods which the enemy may have adopted to deceive the ordinary “reader,” such as camouﬂage, substitution of dummy objects for real ones, and other similar devices.

In passing, reference may be made to the necessity for correct assessment of scale, and therefrom of distances between objects depicted on the photograph. Minute variations of the camera axis from the vertical, due to uncontrollable movement of the aircraft, can cause appreciable variations of scale in different parts of the same photograph (Fig. 4). All these must be determined for highly accurate measurements to be made.

HOW DISTORTION MAY OCCUR

Fig. 4. Minute variations of the camera axis from the vertical, due to uncontrollable movement of the aircraft can cause appreciable variations of scale in different parts of the same photograph as shown exaggerated in the diagram above. The photograph will be oblique

So, armed with the report furnished by the pilot who undertook the mission, with maps, instruments, previous records and other information the interpretation staff get down to work. As soon as they are to hand, all photographs are quickly identiﬁed from maps or previous knowledge, and a quick selection is made, discarding prints or negatives which may be superﬂuous. The total number of copies required from those selected is determined by reference to the original order and then, quoting the serial registration numbers which are automatically recorded on each, instructions are speedily sent to the ground technical staff to run off the required number of prints with the least possible delay.

Meanwhile, a more detailed examination of the ﬁrst prints of the photographic mission is taking place. Compared as necessary with photographs of the same area previously taken, changes in detail, due, maybe, to raids, to movements of shipping at ports, to new military or industrial construction, and so on, are assessed. Fig. 5 shows a photograph taken just after a raid on Lille.

PROGRESS OF A RAID ON LILLE

Fig. 5. Photograph taken during a heavy daylight attack on the important steel and engineering works at Lille and showing how rapidly the attack developed. Smoke from ﬁres which have been started, together with bursting bombs, reveals that hits have been made on the eastern group of buildings and also on other factory buildings to the south and the north-west

As each piece of important information comes to light it is marked by conventional signs, and, after careful checking against other available data, noted on a memorandum. Although photographs are generally taken with a view to studying some clearly deﬁned operation, the interpreters frequently light upon valuable indications of enemy activity in hitherto unsuspected directions.

When each photograph has been thoroughly combed for information, what has been gleaned is noted on duplicate copies as they stream in from the printing section, points of individual importance being emphasized to suit each recipient. Then by quickest route, the annotated prints, together with such explanatory notes as are necessary are distributed to the various headquarters and departments where all the information they reveal plays a very large part in the issue of operation orders and other action.

HEIGHT OF OBJECTS

It would be well to mention here how it is that the height of objects in vertical air photography can be appreciated. It is, of course, only in the centre of an air photograph that are recorded the absolutely vertical light rays reﬂected from objects on the ground. Three-dimensional objects which appear towards the edges of the photograph are recorded by rays which have a minute, though appreciable obliquity, and consequently there is recorded in the case, for instance of a building, a minute oblique portrayal of the wall or walls which appear as being nearest to the centre of the photograph.

TAKING STEREOSCOPIC PHOTOGRAPHS

Fig. 6. When a person looks at an object, the separation of his eyes, each of which sees the object from a slightly different point of view, promotes an unconscious appreciation of the third dimension. Thus, if two consecutive air photographs are taken with an overlap of about two-thirds, and viewed simultaneously, one by each eye, through a simple optical device, a similar appreciation is obtained stereoscopically. The diagram illustrates how these photographs are taken. The separation between the photographs must be calculated with great accuracy or the earth’s contours will appear to be either over-exaggerated or inadequate

In the case of normal human vision of actual objects the separation of the eyes, each, therefore, seeing from a slightly different point of view, promotes an unconscious appreciation of the third, less obvious dimension. Thus it is found that if two consecutive air photographs are taken with perhaps a slightly exaggerated separation (Fig. 6) rather more than proportionate to the height of the aircraft, a similar appreciation is obtainable stereoscopically, a simple optical arrangement (Fig. 7) enabling the two photographs to be viewed simultaneously, one only by one eye and the other by the other. This method is equivalent to looking at the earth through the two eyes of a giant. The appropriate separation is roughly that needed to give a two-thirds overlap. Too great a separation gives too exaggerated an effect to heights, and too small a one a quite inadequate indication. Limitations imposed when applying this principle to oblique photographs are obviously so great that very little advantage has ever been taken of it.

STEREOSCOPIC VIEWING DEVICE

Fig. 7. When stereoscopic pairs of photographs are taken they are viewed simultaneously through a simple optical device, like that shown above, by means of which an appreciation of the third dimension can be obtained, objects photographed appearing to stand out in relief

By far the larger number of air photographs taken by the R.A.F. are vertical photographs, that is, taken with the lens of the camera pointed directly downwards and providing valuable and informative views of the ground in plan (Fig. 8.)

Nevertheless, there are occasions when photographs giving an immediate appreciation of the heights of ground features are of extreme importance. Such photographs, which in appearance are similar to those taken from the tops of high hills, can be obtained if the camera is mounted in a low ﬂying aircraft so that its axis is slightly depressed from the horizontal. The photographs are “obliques” (Fig. 9).

OBLIQUE AND VERTICAL PHOTOGRAPHS COMPARED

Fig. 8 (lower). Vertical photograph of the docks at Dunkirk taken with the camera lens pointing vertically downwards. Fig. 9 (above). Oblique photograph of the same area taken with the lens pointing slightly below the horizontal. Vertical photographs can be taken from any height, but obliques, to be of any value, must be taken by low ﬂying aircraft. The letters indicate warehouses and dockside buildings before and after destruction by air attacks

The comparative advantages and limitations of each type are borne in mind by the authorities when detailing photographic missions.

The vertical photograph has the advantage that it can be usefully taken from any height, however great, thus reducing the chances of any hostile interference.

By ﬁtting lenses of longer or shorter “focal length”—the distance, that is, between the focal point of the lens near its centre, and the centre of the negative behind it—the “scale” of the photograph—expressed as a simpliﬁcation of so many miles on the ground to so many inches on the photograph, or as a representative fraction—can easily be decreased or increased as may be desired for any given height, the area of ground covered on plates of exactly the same size being, of course, at the same time, proportionately decreased or increased.

FOCAL LENGTHS OF LENSES

Fig. 10. Diagram showing areas of country covered by three lenses of 14-inch, 5-inch and 20-inch focal length pointing vertically downwards from a height of 20,000 feet

As an example, if an aircraft ﬂying at 20,000 feet uses a camera of standard ﬁlm dimension 7 in. by 7 in. ﬁtted with a lens of 14 in. focal length, the scale of the resultant photograph expressed as a representative fraction will be 1/17143. In other words 1 inch on the photograph represents 17,143 inches (or roughly 1,430 feet) on the ground, and the area of ground covered by the whole negative is seven times 1,430 feet square, or 10,000 feet by 10,000 feet. By substituting a lens of 20 inches focal length, the scale is increased to 1/12000 but the area covered reduced to 7,000 feet by 7,000 feet. If a lens of only 5 inches focal length is used, the scale is reduced to 1/48000 but the area covered increased to 28,000 feet square or just over twenty-eight square miles. These points will be readily understood from a study of Fig. 10.

Obviously the smaller the scale of photographs taken from the air the more difﬁcult it is to distinguish and identify small objects on the ground, and the solution is not to be found in enlargement from the negative because the grain in its emulsion, also proportionately enlarged, may itself be in the region of as much as 1/200th of an inch.

If, therefore, a wealth of accurate detail is needed, as for instance in assessing bombing results on speciﬁc objectives or in identifying small craft in harbours, it is necessary to use a lens of long focal length, and make a correspondingly greater number of successive exposures, to cover a given area of country. On the other hand, for such a purpose as the preliminary examination of large tracts of country in which the enemy is suspected of establishing new aerodromes, for example, it is easier and more economical to use a lens of short focal length. Oblique photographs by way of comparison, can normally only be taken from low altitudes—say, for instance, from 1,500 to 3,000 feet—with a lens of medium focal length, and in a camera which is aimed at an angle of ﬁfteen to thirty degrees below the horizontal (Fig. 11).

THEORY OF OBLIQUE PHOTOGRAPHY

Fig. 11. Diagram showing areas of country covered by an oblique hand camera with the lens pointing ﬁfteen degrees below the horizontal. Low ﬂying aircraft are usually employed

USING A HAND CAMERA FOR OBLIQUE SHOTS

The observer-gunner of an army aircraft on reconnaissance is seen above taking oblique photographs with a hand camera. For such shots the camera lens is pointed between ﬁfteen and thirty degrees below the horizontal. A lens of medium focal length is generally used

Difficulties such as those involved in efficient mounting preclude the adoption of lenses of long focal length and higher ﬂying. Oblique photography, therefore, is usually conﬁned to special objectives, or territory where the likelihood of serious hostile interference is remote. A typical instance of where obliques may well be of more use than verticals, suggests itself in fast moving desert warfare, where photographs from several angles of forts, and of strong points on escarpments or in deﬁles can be of immense value in determining what tactics should be adopted and even what special equipment is necessary for an attack. Such a photograph is shown in Fig. 12.

DESERT WARFARE SEEN FROM THE AIR

Fig. 12. Oblique photograph taken from an R.A.F. aircraft during the British advance on Bardia, Libya, in January, 1941. Advancing detachments of the Royal Armoured Corps are seen about to capture an Italian defence ring, which is seen in the centre of the picture

Easily understandable, these photographs can be supplied without delay, even by message dropping to the army units engaged in the actual operations, the information given being immediately utilized to best and utmost advantage.

The measurement of distances between objects is far easier in a vertical than in an oblique photograph. In the case of the former unless there was any abnormal deviation of the camera axis from the vertical, the scale can usually be regarded as constant all over the photograph, whereas in the latter the scale progressively decreases from the foreground at the bottom of the print until the horizon near the top is reached, a fan shaped area of country being restricted to a rectangular photograph. If, with an oblique, the angle of depression of the camera axis at the moment of exposure is accurately known—though this is extremely difﬁcult to determine—it is possible in conjunction with other data, to construct what is called a “graticule,” which will enable distances to be calculated within fair limits, but the process is a long one and is therefore rarely adopted in normal service work. Consequently, an air photographer when carrying out oblique photography always endeavours to get his main important objectives in the centre foreground of each photograph so that a general estimate of heights and distances adjacent thereto may be fairly easily estimated within limits, by comparison of some of the features with known similar features.

It will readily be realized that if successive adjacent vertical photographs are accurately taken from a consistent height (Fig. 13), it is possible to piece them together, a part only of each, in “mosaic” form, and so to produce a photographic map of wide stretches of country. In practice, however, minor distortions are almost certain to occur and therefore the accuracy of such mosaics, can at best be only approximate.

MAPPING FROM THE AIR

Fig. 13. Diagram illustrating how a series of successive vertical photographs is taken from the air for map-making purposes. The aircraft ﬂies at a consistent height up and down the area of country to be mapped and each exposure overlaps the previous one by 60 per cent. The lateral overlap, as shown, is 25 per cent. A “mosaic” is then pieced up

The strategic and tactical requirements of the Royal Navy and the Army make heavy demands upon the air photographer. Aircraft are the eyes of all the Services and the camera is by no means the least important attribute of the aircraft at their disposal. It is easy to picture the many objectives, mobile and immobile, of which both the Royal Navy and the Army can by air photography obtain speedy, accurate and vital information.

Quite independently, and within the Air Force itself, air photography plays a most important part in obtaining information on which are based plans for the utilization of its striking power with the utmost efficiency and economy in effort. Happy indeed is the bomb aimer who, from previous study of air photographs of his targets, knows that from whatever direction he may approach them he will have no difficulty in identifying them, and so ensure that his efforts achieve maximum eﬁiciency. Information gained from air photographs as to the locations, strengths and types of enemy air forces assists in the most efficient disposition and employment of our own air forces, both ﬁghter and bomber, to forestall or counter the air effort of the enemy, and so attain essential air superiority.

All bomber aircraft carry a camera with the object of recording photographically the place where the bombs have fallen. It is quite simple to do this by day, and a high standard of air photography in daylight was reached even during the last war. Recently, however, the art of night photography has been developed so successfully that it can be regarded as one of the principal means of ascertaining the effectiveness of the bomber’s work (Fig. 14). As soon as the bombs are released the camera shutter is opened. The ground is, however, dark and nothing is recorded on the ﬁlm except possibly the ﬂashes caused by anti-aircraft gunﬁre or the glow of ﬁres already burning in the target area. The bomb aimer then releases a ﬂash-bomb which has a time fuse allowing it to fall a certain distance before it explodes, giving a ﬂash of tremendous brilliance. The release of this ﬂash-bomb is timed so that it will give its ﬂash a few seconds after the bombs have exploded, thus recording on the ﬁlm a picture of the ground which will include the smoke of the bomb bursts. Immediately after the ﬂash the shutter is closed. From this photograph the exact place at which the bombs have fallen can be accurately plotted. In the latest cameras carried by British aircraft the whole of this process is automatic and is operated by the bomb aimer pressing a button immediately after the bombs have been released.

BERLIN SEEN BY THE NIGHT CAMERA

Fig. 14. This photograph was taken with a night camera in conjunction with a ﬂash bomb during a raid on Berlin. The letters indicate: A, the west harbour; B, Spandau ship canal; C, bombs bursting on inner harbour; D, Konigs Damm bridge and E, Charlottenburg gas holders. The broad streaks of light are searchlights, the narrow ones tracer shells

CAMERA GUNS

Nor would any reference to the value of photography to our Air Force be complete without a brief mention of the part it plays in the preliminary training of its personnel in other activities. In his early training the ﬁghter pilot armed with a camera gun takes a photograph of his mock adversary instead of ﬁring a bullet at him (Fig. 15); the bomber pilot photographs his objective in early training instead of dropping a bomb on it. From calculations based on the position of the image of the opposing aircraft or the bombing objective on the negative, it can readily be ascertained whether the bullet or bomb would have reached its mark and the nature and extent of any error determined.

CAMERA GUN IN ACTION

Fig. 15. During their early training pilots and air gunners are taught to photograph their mock adversary instead of ﬁring at it. Above, the camera gun is seen in use with, inset, a developed photograph showing a “direct hit.” A similar device is used for practice bombing

It is obvious also that air photographs taken at home give an indication of how much will be revealed to the enemy of potential objectives should he carry out a photographic reconnaissance of them.

It will therefore doubtless be agreed that by whatever Service it is employed and into whatever sphere the information so gained is directed, air photographic reconnaissance plays a most vital part in gaining that knowledge which must result in strengthening our whole war effort (Fig. 16).

BREMEN BEFORE AND AFTER A RAID

Fig. 16. Damage to Bremen discovered by the camera. The letters in the top picture show buildings before, and in the bottom picture, after the raid. A. Large shed completely destroyed. B. Eight bays of another shed destroyed. C and D. Two other large sheds on which direct hits have been obtained. E. Four bays of another shed, and two smaller buildings destroyed

The training of the air photographer in whatever capacity he may be employed must of necessity be thorough. One oversight, one mistake, and a vital piece of knowledge which may have far-reaching consequences is lost and effort proportionately weakened. The speed and accuracy which are demanded in the execution of all operational duties are therefore the keynotes of the training of the air photographer of whatever the category to which he belongs.

The ﬂying personnel who may be selected for photographic duties are those who, in their normal air training have shown special qualiﬁcations in navigation and airmanship and also possess a very keen sense of initiative which will ensure that, whatever obstacles be encountered, nothing will deter them from their primary task of securing and delivering the required photographs.

PRACTICE FLIGHTS

A thorough knowledge of the working and manipulation of the photographic apparatus carried in the aircraft, cameras, sights, mountings, etc., is gained either at an appropriate training establishment or from the photographic instructor at a squadron, according to circumstances. Practice ﬂights of progressive difficulty for single photographs, line overlaps and “mosaics” are carried out, and faults and remedies pointed out. A sufficient appreciation of the work of the technical and interpretation personnel must be gained so that, as far as possible, the ﬂying procedure adopted may facilitate their subsequent work.

Trainees for ground technical duties may be either boy entrants who undergo a long ab initio course both theoretical and practical, or specially enlisted aircraftmen who have had previous experience of commercial photography in civil life. Whatever the capabilities of the recruits there is much to learn and unlearn in acquiring the essential knowledge of the special apparatus and methods which are best adapted to the requirements of a modern air force.

The interpretation personnel are selected as far as possible from men who have had previous experience in air photography. Quick perception, an eye for detail, and a logical mind are basic attributes.

Though the work is hard, there is no lack of applicants for this interesting pursuit, the more so as most posts carry commissioned rank on account of their onerous responsibilities.

Trained personnel are supplied by the R.A.F. School of Photography, or other appropriate training establishment.

However proud we may be of the wonderful achievements of our air photographers, it would be idle to pretend that ﬁnality has yet been reached in the design of apparatus, mechanically or optically, in technical processes or in the ancillary instruments and materials, all being necessary for efficient work.

The research laboratories, service and civilian, national and allied, are continuously working on the problems, mechanical, optical and chemical, the solution of which will most certainly increase the usefulness of photography from the air.

HUDSON OVER DUNKIRK

Fig. 1. The Lockheed Hudson, the military version of the Lockheed Fourteen commercial aeroplane, has done considerable duty with Coastal Command as a long range reconnaissance bomber. It has a range of 2,000 miles and has a rotating gun turret ﬁtted to the upper part of the fuselage. The Hudson above is on patrol duty over Dunkirk at the time of the evacuation

CHAPTER 13

American Help for the R.A.F.

Effect of Lease and Lend Act. British inﬂuence on U.S. design. The Lockheed Hudson and the Harvard trainer. Lightning twin-engined ﬁghter. Wright turbo-supercharger. Flying Fortress. Tricycle undercarriage. Havoc night ﬁghter. Bell Airacobra. Liberator bomber. Catalina ﬂying-boat. American dive bombers. Training of R.A.F. pilots in the U.S.A. The Eagle Squadron. What American aid means

THIS chapter has nothing to do with the entry of the United States of America into the war at the end of 1941. It is concerned only with the very considerable help given to the R.A.F. by the United States manufacturers of aircraft and aircraft equipment before America began actual ﬁghting; how that help was provided and how the interchange of information and Britain’s contribution of the store of knowledge she accumulated with every stage of the development of the war gave a tremendous impetus to technical advancement.

ANGLO-AMERICAN CO-OPERATION

Today the United States is still providing Britain with aircraft, though she has her own services to equip. For certain classes of work the R.A.F. relies entirely on American machines, while American pilots likewise ﬂy British types. The Spitﬁre, with which some American ﬁghter squadrons are equipped, is perhaps the outstanding example. The two countries are ﬁghting as one. Their production of aircraft, engines and equipment is organized as a whole. But when the war began it was not so and this is the story of how American help started, developed and ﬁnally became one of the dominating factors in turning the tide of the air operations.

When the United States ﬁrst set out to supply aeroplanes to the R.A.F., Britain had to take what could be spared. At that time the purchaser had both “to pay on the nail” for everything he chose and to do the transporting himself. Britain placed quite large orders under that arrangement, but in March 1941 the Lease and Lend Act was passed by the United States Legislature. That meant that the R.A.F. could have more aeroplanes than it could pay for.

At the end of May President Roosevelt pledged the United States to see that the weapons of war from America should reach the democracies; and that meant that American ships could carry some of the goods and that, if necessary, American warships would convoy them. To British self-help had been added the promise of the generous help America could give.

GUIDANCE FROM BRITAIN

These stages are worth considering as a prelude to estimating the American contribution to Britain’s war effort, not only because they explain the growing momentum of the American aid but also because they are signiﬁcant of British inﬂuence in guiding that aid along paths parallel with those which were being followed in Great Britain. Mere numbers alone would not necessarily have assured the R.A.F. of air superiority. In the Battle of Britain, an enormous advantage in numbers availed the Germans little. Superior quality in men and machines enabled the R.A.F. to throw back the German hordes with tremendous losses. If America had simply ﬂooded the R.A.F. with aircraft of inferior performance and armament, Britain might equally have found herself in the unhappy position of having the numbers but not the strength.

INFLUENCE ON U.S. DESIGN

Some such situation might have arisen if, from the start, the U.S.A. had been handing out largesse to the British. The easy way would have been to go full speed ahead with the types which were already in production. Up to a point the British had to accept that method because of the urgency of their need, but the important point was that they were paying for what they got and were therefore in a position to require modiﬁcations here, more armour there, and guns in different positions. Furthermore, within the limits set by considerations of early delivery, Britain could pick this type and reject that. The result was that she began to direct American development along particular lines and stimulated the production of certain types.

The independence that Britain gained in those early months was well worth the huge sums she undertook to pay the American manufacturers, since it meant that her speciﬁcations were accepted and her views on the types of aeroplane best suited to modern warfare became established.

A trend was established by the British requirements in the early days that inﬂuenced American fashions. As an example of this one need only recall that arrangements were made for the Rolls Royce Merlin engine to be built in America. Production and delivery are now in full swing. Already a water-cooled engine, the Allison, had been produced there, and so a nation which had previously relied on air-cooled engines began think in terms of the slimmer lines and higher speeds which the small frontal area of the liquid-cooled engine permits.

PRE-WAR PURCHASES

Even before the war the British had been buying Hudsons (Fig. 1 above) for reconnaissance work and Harvards (Fig. 2) for advanced training. Both aircraft in improved forms are still being delivered for use by the R.A.F. The Hudson was the commercial aeroplane known as the Lockheed Fourteen, so modiﬁed that a rotating gun turret could be ﬁtted on the upper part of the fuselage just forward of the tail. The North American Harvard was a fast, single-engined trainer.

HARVARD ADVANCED TRAINERS

Fig. 2. North American Harvards play a leading part in the training of ﬁghter pilots for the R.A.F. They are easily recognized by the fully tapered leading edges of their wings, and their distinctive and harsh engine note which sounds somewhat like a two-stroke motor cycle

For a long time the British asked for nothing more, but the French, whose aircraft industry had been shamefully neglected, had been buying much more freely. They had taken delivery of a good many Curtiss Hawk ﬁghters. They were hoping, when the German advance crushed them, to receive aircraft of at least four other types from America. These were the Vought-Sikorsky 156 dive bomber, the Martin 167 twin-engined bomber, the Douglas DB-7 twin-engined bomber and the great Consolidated Model 32, which is a four-engined bomber of a loaded weight of more than eighteen tons and a top speed of 335 miles per hour. It is known in the R.A.F. as the “Liberator” bomber.

When Great Britain found herself standing alone against the Germans in June, 1940, she was able to arrange to take over these orders and so to proﬁt by the time which had already been devoted to them. The Hawk passed into the R.A.F. in slightly modiﬁed form as the Mohawk. The others were named the Martin Maryland, the Douglas Boston and the Consolidated Liberator. The Vought-Sikorsky was named the Chesapeake and passed into service with the Fleet Air Arm.

MARYLANDS IN THE MIDDLE EAST

Fig. 3. Martin Maryland twin-engine bombers ﬁrst proved their worth in the Middle East where they were ﬁrst in service in November, 1940. They also took photographs which led to the Fleet Air Arm attack at Taranto. Above, two machines of a Maryland squadron are seen on active service in the desert. They have a top speed in the neighbourhood of 320 m.p.h.

During the succeeding six months the British Purchasing Commission worked so hard that more than thirty different types of American aeroplanes were being built for the R.A.F. Among them were ten ﬁghters, seven bombers, six reconnaissance types including ﬂying-boats and three types suitable for service in aircraft carriers with the Fleet Air Arm. By the beginning of 1941 many were ﬂowing in large numbers into R.A.F. units in Britain and overseas. The Marylands, for instance, were in service in the Middle East as early as November, 1940 (Fig. 3). They took the photographs which led to the great Fleet Air Arm attack on ships of the Italian Navy in Taranto harbour and returned afterwards to get pictures of the damage done by torpedo bombers of the Fleet Air Arm. Tomahawk ﬁghters (Fig. 4) were ﬁrst reported in action during attacks on German aeroplanes using aerodromes in Syria in the latter part of May, 1941. Before that, Bostons had taken part in bombing raids from Great Britain and the Havoc, the night ﬁghter version of the Boston, had begun to destroy German bombers.

TOMAHAWK AND KITTYHAWK

Fig. 4. The Curtiss Tomahawk ﬁghter (above), like the Maryland, was ﬁrst used operationally in the Middle East. It is extremely fast and manoeuvrable and is the American counterpart of the Hurricane, which it closely resembles. The Kittyhawk (below), is an improved version of the Tomahawk, and it has a maximum speed of about 380 m.p.h.

LEADING TYPES OF AMERICAN AIRCRAFT IN SERVICE WITH THE R.A.F.

Engine particulars and maximum speeds of thirteen types of U.S. aircraft employed by the R.A.F. Many of these incorporate new ideas in aircraft design such as the tricycle undercarriage which is ﬁtted to the Lightning and Airacobra ﬁghters and the Boston and Liberator bombers. The Lightning and the Airacobra are also unusual, the former in having a split fuselage and the latter in having the engine behind the pilot. Both have a top speed of about 400 m.p.h. The Catalina reconnaissance ﬂying-boat is remarkable chieﬂy for its very long range

BRITISH TECHNICAL ADVICE

Operational and technical advice was invited by American manufacturers. In response, Air Chief Marshal Sir Hugh Dowding, who had formerly commanded Fighter Command, led a mission which remained for many months in the United States. British technical men were admitted to the works of the principal aircraft ﬁrms. The rapid results of all these forms of contact were almost startling and they quickly became apparent.

Firms which had previously given the scantiest attention to protecting the vital parts of their aeroplanes from damage by machine gun and anti-aircraft ﬁre now produced in remarkably short time bombers and ﬁghters which had better protection for fuel tanks and pilots than was to be found even in the aeroplanes with which Britain entered the war.

They were typical of the advantages which accrued to the R.A.F. from the readiness of Great Britain to “pay the piper,” and of the consequent willingness of most American manufacturers to allow the British, up to a point, to “call the tune.” The British for their part were only too happy to give all the help they could. A Messerschmitt 110 twin-engined ﬁghter was even shipped across to the United States for examination by American aeronautical engineers so that the best available examples of modern practice on both sides of the war front might be at the disposal of those who had undertaken to build for the R.A.F. out of range of the enemy’s bombers.

LOCKHEED LIGHTNING

The Lockheed Company promptly set itself to produce the P.38 twin-engined ﬁghter (Figs. 5 and 6). It is known as the Lightning, and its speed, according to manufacturers’ reports, is just over 400 miles per hour. It did not see service with the R.A.F. however, as the United States entered the war before it was fully in production. It is now being used by the U.S. Army Air Force. The Douglas Company, for its part, set out to produce a more capacious bomber than anybody had yet contemplated using in war. It designed a huge machine of a loaded weight of seventy-three tons.

LOCKHEED LIGHTNING

Fig. 5. The Lockheed P-38 ﬁghter is a high speed twin-engine aircraft of unusual design. The tail unit is carried on two booms and the central nacelle accommodates the pilot and the armament. The P-38E is a two-seat version of the same machine

DETAILS OF THE LIGHTNING

Fig. 6. Principal parts of the Lightning. This machine has a range of about 1,000 miles and a top speed of more than 400 miles per hour. It is ﬁtted with a tricycle undercarriage and armed with four machine guns and a 23-mm. Madsen shell ﬁring gun ﬁring through the nose

Before the war, the Boeing Company was engaged in producing what it called the Stratoliner, a commercial aeroplane with a hermetically sealed cabin in which the air pressure was to be kept much higher than that in which the aeroplane was ﬂying. The intention was to obtain the speed advantages which come from ﬂying in the thin air at great heights without causing the discomfort which passengers normally suffer from reduced pressure and shortage of oxygen. The Stratoliner was not really supposed to ﬂy in the stratosphere. It was to cruise at heights between 20,000 and 30,000 feet, but to preserve in the passenger cabin an air pressure roughly corresponding to that at 10,000 feet.

The Wright Corporation having provided the supercharged Cyclone engines for the Stratoliner continued its experiments with still more efficient superchargers. For some years engine designers have been examining the possibility of harnessing the wasted energy from engine exhausts to the task of driving superchargers. The gases, as they emerge from the exhausts, possess a large store of energy. This, it had been hoped to apply on the ordinary turbine principle to a piece of special apparatus which in turn would drive the impeller or fan attached to the supercharger (Fig. 7).

PRINCIPLE OF THE TURBO-SUPERCHARGER

Fig. 7. Diagram illustrating how the exhaust gases from the engine can be used to drive the supercharger. Turbo-superchargers are embodied in Wright Cyclone engines such as are ﬁtted to Boeing Flying Fortress bombers, and permit the engine to give unusually high power at heights where ordinarily supercharged engines are giving only a fraction of their rated output

TURBO-SUPERCHARGER

One awkward matter had been to ﬁnd a metallic substance for the turbine blades which could withstand the extremely high temperatures of the exhaust gases. At last the Wright engineers met with success, for the engine which was used originally in the Stratoliner has now appeared for use in military aeroplanes with a turbo-supercharger. This permits the Cyclone engine to give unusually high power at heights where ordinarily supercharged engines are giving only a fraction of their “rated” output. The Boeing Company, having stimulated work in this direction, was the ﬁrst ﬁrm of aircraft constructors to reap the beneﬁt of this new supercharger.

Out of the Boeing Company’s works in 1935 had come the big four-engined bomber described by the United States Army Air Corps as the B .17, and popularly known as the Flying Fortress. In its early form the Flying Fortress, operating at a loaded weight of twenty-two tons, developed a top speed of 250 miles per hour at a height of 13,000 feet. It has undergone various modiﬁcations since war broke out. By far the most important of them was the ﬁtting of the new Cyclone engines. With this type of engine, the new Flying Fortress, or B. 17c, as it is ofﬁcially known, can carry the same load and develop a top speed of 325 miles per hour at a height of 20,000 feet, and is rated for cruising at a speed of 245 miles per hour at 30,000 feet. Bombers of this kind have made many daylight raids with outstanding success on enemy objectives from great heights (Fig. 8).

THE BOEING FLYING FORTRESS

Fig. 8. Known in the U.S. as the B.17C, these machines are equipped with Wright Cyclone engines embodying the turbo-supercharger. They have an exceptionally high service ceiling and can carry a bomb load of about four tons. Their top speed is about 325 m.p.h. at 20,000 feet

“RATED HEIGHT”

No other aeroplane in the world has such a high “rated height.” Many aeroplanes of course can ﬂy at heights above 30,000 feet, but the “rated height” of most military aeroplanes is somewhere between 15,000 and 20,000 feet. The “rated height” is that at which the best combination of speed and load can be obtained. It depends almost wholly on the degree of supercharging which can be given to the engine or engines. The “rated height” of the Spitﬁre ﬁghter, for instance, is 17,000 feet, whereas its “service ceiling”—the height at which it is still capable of climbing at the rate of 100 feet per minute—is well over 30,000 feet.

The beneﬁt to be derived from increasing the height at which the bombers can ﬂy is obvious to all who examine the question of interception by enemy ﬁghters. If the ﬁghters have to climb to great heights to cut off the bombers, there is a fair chance that the raiders may have reached their targets before they can be attacked. Flying high, the bombers may be out of range of the anti-aircraft guns. In certain circumstances they may escape detection altogether. They may get above the “smoke-trail” forming layer of the atmosphere. Also, of course, as sound takes time to travel, great height causes confusion to the ground defences. Aircraft ﬂying fast at a great height will be well in advance of the apparent location of the noise they make. Height indeed is one of the most valuable attributes in air warfare, and in these days of highly accurate bomb sights, it may be no serious deterrent to accurate bombing either in daylight or clear weather.

TRICYCLE UNDERCARRIAGE

There was another form of aeronautical advance in which the United States had “taken a chance.” It had pushed on with the application of the tricycle undercarriage. Some experiments had been made with the new combination of wheels in Great Britain, but whereas the British came slowly and cautiously to this development, the aircraft industry in the United States took its courage in both hands and applied the new idea to quite massive aeroplanes. The Boston twin-engined bomber, weighing some seven and a half tons fully loaded, had a front wheel instead of a tail wheel, from the start. The Liberator, the big four-engined bomber of a loaded weight of eighteen tons, was born, so to speak, with a tricycle undercarriage. The Liberator, by the way, in addition to being used by the U.S. Army for daylight raids, is doing valiant service with the British Coastal Command in the Battle of the Atlantic.

In the end this improvement may prove to have been a good thing. In the early stages, R.A.F. pilots had a certain amount of trouble with the nose wheel. It did not behave well on soft, muddy surfaces, and there was a period at which the front wheel developed the form of wobble known as “shimmying.” A certain amount of modiﬁcation had to be done, and during the interval, British pilots acquired the habit of landing on the two main wheels and of using the front wheel simply as a safeguard against “nosing over,” when the brakes were ﬁrmly applied. The device has thus come to serve one of the principal purposes for which it was intended, and it is well on the way towards fulﬁlling all the other hopes that were reposed on it.

CONTROL IN LANDING

The arguments in favour of the nose wheel are that it helps the take-off by enabling the pilot to start his run with the aeroplane in the ﬂying attitude, that it makes control on the ground easier if there is a steerable wheel in the front, and that landings are simpler because the aeroplane need not be stalled on to the ground and the landing run shorter because the brakes can be put on hard as soon as the wheels touchdown. These are important matters with fast landing speeds and heavy overloads at take-off.

AN UNORTHODOX AMERICAN FIGHTER

Fig. 9. The Bell Airacobra, the principal features of which are illustrated above, is a single-seat ﬁghter with a credited speed of over 400 miles per hour. The engine is placed behind the pilot with a shaft to drive the airscrew running between his legs. Its powerful armament consists of one cannon and four machine guns synchronised to ﬁre through the airscrew

One of the most useful of the night ﬁghters, the Havoc, is ﬁtted with a tricycle undercarriage. This machine is the ﬁghter variant of the Boston and has been operating successfully as a night ﬁghter since the early part of 1941. Another United States ﬁghter which also uses the nose wheel embodies various other novel ideas besides. This is the Bell Airacobra (Fig. 9), a single-engined machine of a top speed of about 400 miles per hour. It is ﬁtted with the new Allison liquid-cooled engine. This is set behind the pilot and drives the airscrew by means of a long shaft which passes between the pilot’s feet to a set of gears arranged to transmit the power to a shorter shaft driving the airscrew. By way of ﬁnal complication, a 37-mm. cannon is placed to ﬁre through the airscrew hub. A British ﬁghter squadron engaged in low level attacks on targets in Northern France and Channel shipping was equipped with the Airacobra towards the end of 1941, but the machine was later superseded by another type.

CATALINA FLYING BOAT

Bearing in mind the fact that the R.A.F. began the war without enough machines in any category, those who look into the matter will realize how valuable some of the American help proved. One of the ﬁrst machines to be delivered to the R.A.F. from the United States was the Catalina ﬂying-boat, the military version of the Guba civil ﬂying-boat* which made a survey ﬂight just before the war across the Indian Ocean from Australia to Africa, calling at small islands on the way. That ﬂying-boat is supposed to have a range of 4,000 miles. During the week in which the German battleship Bismarck was shadowed in May, 1941, one Catalina remained on patrol for twenty-seven hours and must have ﬂown 3,500 miles in the course of that tour of duty.

*The trans-ocean flights of the Guba are described in the book The Sky Beyond, written after the war by the aircraft's captain, Sir Gordon Taylor.

The R.A.F. had no other ﬂying-boat capable of such endurance. The normal range of the Sunderland, the four-engined British ﬂying-boat is 1,780 miles. The two craft are not strictly comparable of course. The Sunderland is faster, is better armed for self-defence and better armoured for protection. It has much greater capacity. In brief, it was built for an entirely different class of work in the relatively narrow seas, whereas the Catalina, or PBY. 5 as the United States Navy calls it, was built for ocean work. A Catalina could ﬂy 1,000 miles westwards over the Atlantic to meet a convoy, could remain cruising protectively in its vicinity for ten hours, and then could ﬂy back to its base without having exhausted its supply of fuel. That was the sort of thing the Coastal Command badly needed when German occupation of France and Norway enabled her to spread her submarine operations over a coastline which was too long for the Navy to watch closely. The Catalinas came at the right time and ﬁtted admirably into a vacant place. They are illustrated in Chapter 8.

America’s chief advance in aircraft technique concerned the production of long range, weight-carrying machines, the day bombers such as the Fortresses, Liberators (Fig. 10), the transports and the ﬂying boats. Britain, having begun the war on the defensive, had to rely to a great extent on ﬁghters. She therefore developed the ﬁghter more rapidly and then concentrated on the night bomber such as the Halifax and Lancaster.

CONSOLIDATED LIBERATOR BOMBER

Fig. 10. The Liberator, illustrated above, was the ﬁrst of the big bombers to be flown direct to Britain. It has a range of 3,000 miles and an exceptional top speed of 335 miles per hour

DIVE-BOMBERS

But there was one type of aircraft to which America paid attention almost alone, the dive-bomber. Britain left dive-bombers out of her early calculations for the simple reason that their use by the Germans had proved that they were ineffective except where there was complete air dominance and that they only had a tactical advantage, not a strategic. Britain, ﬁrst of all, had to get air dominance by means of ﬁghters and she then found that ﬁghter-bombers, such as the Hurricane and Whirlwind, could be used in many cases more effectively than dive-bombers. Today, however, two dive bombers are being produced by the United States for the R.A.F., the Bermuda and Vengeance, but how or where they are being used cannot yet be disclosed.

The old Curtis “Helldiver” of 1937 will be remembered, for it received a good deal of publicity. It is an obsolete model, though its performance was nearly as good as that of the Junkers 87 (the Stuka) which the Germans used largely in Poland and France. Great Britain produced one dive bomber, the Blackburn Skua, especially for the Fleet Air Arm. The Vengeance in particular is a vast improvement on either the “Helldiver” or the Skua and is now reported to have overcome its various “teething” troubles most satisfactorily.

Several large ﬁrms in the United States agreed to share with one another the task of turning out quantities of the types the R.A.F. particularly needed quickly or in great numbers. As one outstanding example there was the agreement of the Boeing, Douglas and Lockheed concerns to co-operate in the building of Fortresses, the high ﬂying bombers. A joint effort on a rather smaller scale was that of the Vultee and the Northrop Companies to turn out the Vultee Vengeance at a high rate. In addition, sections of the motor car industry were turned on to aeronautical work, and huge new factories were set up and equipped with machinery at an amazing rate. The famous Packard ﬁrm is manufacturing the Rolls Royce Merlin engine and Ford’s have erected the world’s largest aeroplane plant at Willow Run for the production of Liberators.

On the industrial side, the expansion of manufacturing capacity was great and rapid. One of the best signs of the rate at which aeroplanes were being turned out was to be found in engine production. Before the United States began building for the R.A.F. the average monthly output of aero-engines stood at 200 to 300 a month. By the end of May, 1942, the rate of production had risen to 15,000 a month, and this has advanced steadily ever since. That represented a total of more than 5,000 aeroplanes, some of which were wanted by the United States for her own air services, but reports showed that the R.A.F. received something exceeding half up to the time when help was extended to Russia.

Delivery of the goods has naturally been as important as making them, and in this respect too the United States gave help in an ascending scale. When the Lease and Lend Act had been passed, British crews were allowed to collect aeroplanes from the makers’ works and to ﬂy them to Newfoundland and Canada on their way to the European front. Until Japan entered the war others were ﬂown from the Paciﬁc coast to Hong Kong and Malaya.

The United States, as a measure of self-defence, established air and naval patrols over the western waters of the Atlantic. When enemy vessels were sighted, she broadcast the information for the beneﬁt of all shipping in the vicinity. Later, after German attacks on several U.S. ships, she announced that her navy would protect all Lease-Lend cargoes between America and Iceland.

Another important factor was the decision of President Roosevelt that, after the defeat of the Italians in Eritrea and Somaliland, the Red Sea need no longer be regarded as a theatre of war, and American ships need no longer be excluded from it. Many ﬁghters from the United States were thereafter delivered by American ships to the R.A.F. in the Middle East. They began to arrive in time for the big operations over Libya. How Ferry Command now delivers American supplies of aircraft and equipment is told in another chapter.

As American opinion hardened against the Germans throughout the summer of 1941, there was a shrewd suspicion in Great Britain that more would soon be done by the United States to accelerate and to ensure the delivery of war material to the R.A.F. That this suspicion was justiﬁed was proved in September, 1941, when the United States decided to protect Lease-Lend cargoes. One slight token of the spirit of the United States Government was the decision to put some of its own Fortresses on a passenger and goods service between America and Great Britain. Another, of greater signiﬁcance, was the agreement to train 8,000 R.A.F. pilot pupils at ﬂying schools in the United States during the year 1941-1942.

Before war between the U.S. and Japan broke out a great many citizens of the United States had crossed into Canada to enlist, with or without subterfuge in the R.A.F. One purely American squadron of the R.A.F., the Eagle Squadron, ﬁrst went into action in the summer of 1941. Later two more Eagle squadrons operated with the R.A.F. until the entry of the United States into the War resulted in all the pilots transferring to the U.S. Army Air Corps. Those pilots now wear two “wings,” the R.A.F. and the U.S.

THE EAGLE SQUADRON

Many citizens of the U.S. enlisted in the R.A.F. and in the summer of 1941 an American squadron, the Eagle squadron, went into action. Some of its ﬂying members are seen above

THUNDERBOLT FIGHTER

The Thunderbolt single-seater American ﬁghter in service with the U.S. Army Air Force in Britain. It is powered by a Pratt and Whitney 2,000 h.p. engine which will carry it to 40,000 feet and gives a top speed of more than 400 miles per hour. Its powerful armament consists of eight 0.5 machine guns with a combined rate of ﬁre of 6,400 rounds a minute

Out of the United States, therefore, we have received in a variety of ways support of good quality and a measure of encouragement which may truly have emerged from the realist outlook declared by many American writers to be the mainspring of American actions, or may have been mixed with a sentimental regard for Great Britain when she stood alone to face the full power of an over-armed, ruthless and fully regimented nation of gangsters. Great Britain began well by placing orders and ﬁnancing the expansion of the United States Aircraft Industry to the value of £500,000,000. She received good value in return, and received it much sooner than she could possibly have done had she waited for the passing of the Lease and Lend Act.

American aid brought greater striking power to the R.A.F., and greatly strengthened that force in the Battle of the Atlantic. In short, it helped Britain to progress from the defensive to the offensive in air warfare, and gave promise of contributing effectively to the most massive air offensive that the world has ever seen.

KEEPING TRACK OF ENEMY RAIDERS

Fig. 1. Plotters at a Royal Observer Corps centre during the Battle of Britain. They are each connected by telephone to three observer posts, and each has a tray of counters for plotting the tracks of enemy aircraft. Overlooking the table, on a raised dais, are the duty crew controller, and the tellers who pass and receive information from adjacent centres

CHAPTER 14

Weapons used in Attack and Defence

Royal Observer Corps. Radiolocation. Control room at a ﬁghter station. Sound locators. Searchlights. A.A. guns. Balloon barrages. High explosive, incendiary and gas bombs. Armour-piercing bombs. Fusing of bombs. Magnetic mines. Aerial torpedoes

THE air defence system in Great Britain is the most highly developed organization of its kind in the world. Brieﬂy it relies upon: ﬁrst, a reporting service; second, ﬁghter aircraft; and third, anti-aircraft guns and balloon barrages.

ROYAL OBSERVER CORPS

Britain’s secret weapon, “radiolocation,” is one-half of the reporting system; the Royal Observer Corps is the other. Radiolocation warns of enemy approach; the duty of the R.O.C. is to keep track of the movements of the enemy over this country. This information is required for two main purposes, ﬁrst to enable ﬁghters to be sent to the right position to intercept the raiders, and second, to enable air-raid warnings to be issued to districts in advanceof the direction in which the raiders are proceeding.

The general system is that of forming a network of observer posts over the area to be observed and to connect the posts by direct telephone to centres where track is kept of aircraft movements.

In charge of each post there is a head observer; an observer group officer with three assistants is responsible for the supervision of each group of posts.

A centre controller with one assistant looks after the administration, training and efficiency of his crews; about twenty-ﬁve men are on duty in a centre at a time. A centre with all its associated posts is known as an observer group and there is an area commandant with two deputies who take charge of each seven observer groups. The headquarters of the Royal Observer Corps is at Fighter Command.

In each ﬁghter group operations room there is an R.O.C. liaison ofﬁcer always on duty who is in direct telephone communication with every observer centre within the ﬁghter group area. He receives regular reports from each one of these centres regarding all events that have been reported by posts, such as types of aircraft seen, the dropping of bombs and ﬂares, aircraft in distress and so on. He passes these immediately to the operations oﬁicer or to the intelligence officer in the ﬁghter group operations room.

R.O.C. CENTRE

At each centre there is a centre room, with a plotting table on which is ﬁtted a squared map, round which are seated the plotters, each with a small switchboard connecting him by direct line to three posts (Fig. 1 above). Each plotter has a tray containing distinctive counters required for plotting tracks and indicating the number and height of any aircraft reported. Walking round the table is the table supervisor watching the tracking, receiving reports from the plotters of information, other than numbered square plots, given by posts. He has a supply of various lettered and numbered symbols, from which he can select the appropriate ones which have to be placed against the leading plotting counter of each separate track.

Overlooking the centre table, on a raised dais, are the duty crew controller, the “teller” passing information to R.A.F. operations rooms, another “teller” passing to and receiving from adjacent centres various items of information, telephonists connected both to the Observer Corps liaison officer at ﬁghter group and to the liaison staff in sector operations room, and the “recorder” who keeps a record of the tracks appearing on the centre table. On this dais is also an alarm officer giving information to selected factories and aerodromes of the movements of enemy aircraft which pass within range.

In order to indicate how the whole system operates let us assume that a centre in a coastal observer group has received information that an enemy raid is approaching over the sea. The raid is allotted a symbol which the table supervisor immediately places in a small moveable stand on the edge of the centre table at the position at which the enemy aircraft are expected to cross the coast.

OBSERVATION POSTS

The plotters connected to the coastal posts warn the crews what to expect. The two men of each post are scanning the sky, No. 1 has set the height bar (Fig. 2) of one of the instruments used to the height given from the centre. One of the two makes use of binoculars. When the enemy aircraft are seen No. 1 estimates their height and readjusts the height bar, if necessary. He then adjusts the sights until they are on the aircraft and says “On.” No. 2 looks at the pointer of the instrument and reports to the centre the appropriate square, the number of aircraft, their height and their direction of ﬂight. After passing his message, he ampliﬁes it later by specifying the type of aircraft and any other information which may be of value. No. 1 keeps his sights on the aircraft and says “On” at frequent intervals. No. 2 reports appropriate squares as the pointer of the instrument moves over them.

DUTY CREW AT AN OBSERVER POST

Fig. 2. Observer posts are manned night and day by two men. No. 1 ascertains the height of the aircraft by means of the instrument shown above, while No. 2 makes reports to the centre as to the number of aircraft, their height, and the direction in which they are ﬂying

The other two of the three posts which are connected to the same plotter at the centre overhear these reports and when possible obtain a correct height which they pass to the plotter at the centre. As the raid proceeds, the plotter at the centre may order one post to cease reporting and another nearer one to carry on. When the raid has passed out of range of the original posts, adjacent posts will have picked it up and the next plotter at the centre will continue the tracking, and so on.

WORK OF PLOTTERS

As soon as a plotter receives a plot he places a counter on the appropriate square. Alongside he places a numeral counter to indicate the number of aircraft and another to indicate their height in thousands of feet. The table supervisor ensures that the raid symbol is started off at the head of the raid when ﬁrst plotted and that it is turned so that it can easily be seen by those on the dais.

Immediately the ﬁrst plotting counter is placed on the table the tellers on the dais begin to “tell” to the R.A.F. operations rooms concerned. In addition, information is passed over the liaison lines regarding the type of aircraft or any other information of importance. The recorder makes a pencil record of the track on a small scale chart and the alarm controller watches the track carefully so as to be ready to warn particular areas.

The duty controller supervises the work of the whole crew and answers any special queries from the R.O.C. liaison officer in the ﬁghter group operations room. As the raid crosses the centre table, the inter-centre teller informs the appropriate adjacent centre of its movements so that all are ready in the adjacent centre to carry on the track when it crosses the observer group boundary.

The tracking by night or in cloudy weather can be continued with almost equal accuracy, but the type, number and height cannot of course be given. Not only can the R.A.F. authorities responsible for interception and the issue of air raid warnings see the picture but the other services and civilian departments interested can also be kept informed.

The work of the Corps referred to above may appear to be simple, and easy to apply, but in reality it is much more complicated than has hitherto appeared. In the example given, one enemy raid came in over the coast and was tracked and passed from centre to centre without difficulty. The problem is entirely different when four or ﬁve hundred enemy aircraft ﬂy in, split up into small formations to attack different targets and at the same time are being intercepted by our ﬁghter squadrons. It is no longer a simple matter of keeping track of a raid ﬂying on a steady course: “dog ﬁghts” are taking place at altitudes where the aircraft can be heard but not seen. Squadrons are wheeling, diving, climbing, and the difficulties of the observers at the posts and the centres are enormously increased. Yet every endeavour must be made to maintain the tracks of the enemy, and in order that confusion shall not arise the tracks of our own aircraft must also be plotted. At night when enemy aircraft are streaming in large numbers across the country singly but close to one another the difficulty of keeping separate tracks of each can be realized.

It is not permissible even yet to discuss the principles of “radiolocation.” Sufﬁce it to say that, as the word implies, it is a radio means of giving observers accurate information of the movement of aircraft. By this new and highly intricate method of detection it is possible for skilled controllers on the ground to guide defending ﬁghters to within visual distance of attacking bombers.

Information gleaned by means of the reporting system is plotted in operations rooms at Fighter Command, ﬁghter groups and stations. Operations rooms are furnished with a large scale map on a table, around which stand telephone operators with their combined headphones and microphones. They are permanently in touch with units of the reporting system, and by means of movable counters they transfer the information received by telephone diagrammatically to the map (Fig. 3). The counters are designed to reveal the positions, numbers, heights and courses of aircraft. The ofﬁcer in control of operations sits at his desk on a raised platform giving him a good view of the map.

OPERATIONS ROOM AT FIGHTER COMMAND

Fig. 3. Here information gleaned from the various reporting systems is plotted on the large scale map on the centre table. The controller, seated in the gallery, overlooks the map and by means of radio telephone he is able to guide ﬁghters into visual contact with the enemy

STATE OF READINESS

Round the room are indicators showing the number of aircraft available for operations, and the “state of readiness” of squadrons. A word of explanation is perhaps necessary here. Squadrons must have their rest periods sometime in the twenty-four hours, and to provide for these and at the same time to allow for sufficient aircraft with crews to be available for operations, a system has been adopted in which the following abbreviations are used: “Released” means that a squadron is off duty till a certain time; “Available,” that a squadron is ready to come to stand-by at short notice; “Readiness,” that a squadron is able to come to stand-by in about ﬁve minutes, though in practice it often happens that a squadron in readiness is ordered to take off immediately; and “Stand-by,” that a squadron is able to take off within the shortest possible time.

At the controller’s side is a microphone, by means of which he can talk to the ﬁghter squadrons, whether on the ground or in the air. Also there are telephones to headquarters as well as to adjoining groups and stations. In most operations rooms there will also be found liaison ofﬁcers whose duty it is to keep the anti-aircraft defences accurately and quickly informed of the movements of both enemy and friendly aircraft, of the height of balloon barrages.

PLOTTING A RAID

Let us imagine ourselves to be actual onlookers standing beside the controller at a ﬁghter station, when suddenly one of the telephonists near the map slides a small frame containing counters of various colours with numbers on each, to a particular part of the map. If we were in one of the more senior headquarters action would be taken on this to give certain districts an air raid warning. We at a ﬁghter station, however, are engrossed with the fact that this is a daylight raid approaching the area for whose defence the station is responsible.

A glance at the squadron state of readiness board shows the controller which squadrons are most readily available, and he at once warns them to stand by, or even to take off immediately, thus allowing them to climb towards the incoming enemy. The enemy’s height is shown on the operations table, and a quick calculation into which wind speeds, distances, speed and rate of climb of our ﬁghters enter, shows when and where interception is likely to occur.

The squadron in the most advanced state of readiness already has its aeroplanes to the leeward side of the aerodrome, ready to take off into wind, with engines warmed up at regular intervals—depending on the time of year. The pilots are near their machines, resting in shelters, with ﬂying kit on, ready to leap aboard their aircraft at a second’s notice.

Now our ﬁghters are off the ground and climbing hard. Information is sent to the ﬁghter leader by radio telephone from the operations room telling him of the enemy’s movements, the movements of other ﬁghter squadrons, and the course to fly to intercept the enemy. The ﬁghter leader controls his formation by radio telephone and it is thus possible to plot his position by direction-ﬁnding wireless, and, at the same time, to indicate his course also, from moment to moment, on the operations room map.

The draughtsman is busy transferring information from the main map to his tracing; the anti-aircraft oﬂicers are telephoning to their batteries; and other squadrons are being brought to stand-by in case it is necessary to reinforce those already in the air. Soon other raids begin to reveal their nearness on the map. We see that the original raid has suddenly turned back towards Northern France before it penetrated inland. It was only a small raid of, say, three aircraft, but coming in now from another direction the counters indicate a formation of at least thirty-six. Here is something for our ﬁghters to get their teeth into, and the controller decides to leave the small formation alone, and to concentrate on the larger one. From the times of their previously plotted positions the speed of the larger formation can be estimated and another quick calculation by the controller gives him the course which his ﬁghters should steer to intercept.

Every one’s attention is now riveted on the counters on the table. It is like a race game played on a dining-room table. The enemy counters alter course, another lightning calculation and the controller’s voice gives the ﬁghter leader another change of course. The counters indicating our ﬁghters get close to the enemy—surely they must be in sight by now—no, a glance at the weather board shows scattered cloud. The ﬁghter leader reports that he has been joined by a second, and yet a third squadron. The controller sighs in relief; he has been able to concentrate a superior force of ﬁghters at the right time, place and height to meet the enemy. At last “enemy sighted” comes through and then a set of crisp, simple orders from the ﬁghter leaders to their ﬂight and section leaders. A wealth of experience, knowledge of his pilots, tactics, lightning appreciation of the enemy’s position and his own, and positions of the sun and clouds inﬂuence these orders. After the ﬁght the leaders inform their units and are given courses to steer to bring them back to their home aerodromes.

SOUND LOCATORS

If we were to pay a visit to a typical searchlight position we would see a curious device mounted on a four-wheeled trailer with a couple of men operating it. It is a sound locator, and consists of a number of sound-reﬂecting elements like very large motor car headlight reﬂectors mounted so as to swing up and down and also round in a circle, so that it can be aimed at any point in the heavens. Sound waves entering a locator are reﬂected from the inner surfaces and become concentrated at a point in the centre of the back of the device, whence they are drawn off by telephones placed on the heads of the operators.

ELEMENTS OF A SOUND LOCATOR

Fig. 4. The instrument swings round a point X. One man listens out on mirrors A and B and swings the locator round until he gets maximum sound. A second man operates mirrors C and D and swings them up and down

The elements of a locator are grouped as shown in Fig. 4. The device swings round the point X. One man listens out on A and B mirrors and swings the instrument round till he gets the sound loudest in A and B. As he is listening to the engine of a rapidly moving aircraft he may have to keep moving the arm A—B round continually to keep the sound loud in his telephones, so that he follows the course of the aircraft by its sound.

A second man operates the mirrors C and D and swings them up and down. It is clear then that by reading off the positions on scales to which the locator is pointing the direction of an aircraft in the sky can be ascertained. By calculating where this direction line crosses that from another locator which is aimed at the same aircraft, its actual position may be known.

High performance of modern aircraft has rendered the operation of sound locators increasingly diﬂicult. With radiolocation, however, the directing of searchlights and anti-aircraft gunﬁre is becoming increasingly quick and accurate.

Consider an aircraft at 20,000 feet approaching at a speed of 240 miles per hour. From 20,000 feet sound takes about seventeen seconds to reach the ground and as in that time the aircraft has travelled forward 1,994 yards, or a little over a mile it follows that the sound locator will be directed at a point that distance behind the aeroplane. This, of course, has to be allowed for in giving directions to searchlights or guns (Fig. 5).

Fig. 5. Diagram of time lag of sound

SEARCHLIGHTS

Few people in England are unfamiliar with the appearance of searchlight beams. The light is produced by means of what is known as an electric arc-lamp, which, brieﬂy, has the advantage of producing a brilliant centre of light. Instead of being dissipated in all directions this light is concentrated by means of an optically designed reﬂector and shot into the sky as a single beam from a source of some millions of candle-power. Searchlights are nearly all mobile and, with their self-contained generating sets, can be quickly moved from place to place.

The searchlights can be turned round and brought up and down so that the beam can be directed at any point in the sky. The scales on the two axes of the light are marked in degrees as are those on the sound locator, so that any readings on one can rapidly be applied to the other. The sound locator operator simply passes his readings, corrected to allow for enemy speed, to the searchlight crews, who set the information on their scales and switch on. If all goes well the beam immediately illuminates the aircraft.

This simple explanation may perhaps make it clear as to how the problem of sound location increases when the sky is full of aircraft, making it very difﬁcult for the operators to keep track of any one individual aeroplane. There are also the various interruptions caused by anti-aircraft barrage, high winds, and any local noises near the sound locator.

The antidote to the searchlight from the bomber’s point of view is to paint the raiding aircraft with black, lustreless paint, to shroud the engine exhaust system so that no red hot pipes or ﬂames are visible and to cut down the cockpit and interior lighting to the bare minimum necessary for navigation and ﬂying. The light likely to be shown by or reﬂected from a bomber is thus reduced to something very small indeed. Night glasses may assist in distinguishing it, however, and, again, searchlights may illuminate the enemy sufficiently to enable one of our night ﬁghters to identify and attack it. Various attempts to overcome this difficulty of seeing our bombers from the ground have been tried by the Germans, and light blue, pink, orange and red searchlights have been seen on various occasions over enemy territory.

The actual A.A. gun positions consist of well camouﬂaged and well protected emplacements spaced some distance apart with attendant range ﬁnders, a predictor and telephones. There is an officer in charge who plots the incoming raids on a large map on the operations table, on information which is continually coming in by telephone. When enemy raiders have approached near enough the searchlights switch on and the battery observers begin to watch through special night glasses for signs of the enemy.

A.A. BATTERY

The problem the battery has to solve is that of trying to hit an object roaring through the air on a course, speed and height, all of which may be altered at any moment at the whim of the pilot, so as soon as the enemy aircraft is sighted by the battery, the officer in charge has to utilize what information he has, or can obtain, as to course, speed and height in order to calculate the point in space at which to ﬁre his guns, so that the shell and the aircraft shall, if possible, arrive at that point simultaneously. One can no more than assume that the enemy will follow a particular course. If he is not being ﬁred on, or if he is approaching an important objective, however, it is probable that he will continue at constant speed on a straight and level course.

FLIGHT OF SHELL

There is then the ﬂight of the shell to consider. It naturally takes time to reach the place where it is designed to meet the aircraft, and during its ﬂight it is subject to effects of wind and temperature. On the assessment of these factors depends the fuse setting, which determines the time between the ﬁring and the bursting of the shell. If all the multitudinous calculations thus involved had to be done without some quick mechanical means, the aircraft would be well out of range before the gun could be ﬁred. The predictor delivers the answer not only at once, but also continuously while it is directed on the enemy.

CONSTRUCTION OF A BARRAGE BALLOON

Fig. 6. Diagram of principal parts of a barrage balloon. It is ﬁlled with hydrogen, and is designed so that if there is a wind extra lift is obtained, the balloon acting as a kite. The mooring cable is attached to the balloon by means of twelve ﬂying wires (see also Fig. 7)

BARRAGE BALLOONS

Balloon barrages also play an important part in protecting important objectives on land and even out at sea. The balloons are made of special fabric and are ﬁlled with hydrogen gas which, being lighter than air, causes the balloon when inﬂated to rise, drawing with it the mooring cable. It is this cable which constitutes the danger to aircraft. Contact with it is almost certain to damage the aeroplane sufficiently to bring it down, either crashing or in a forced landing (Figs. 6 and 7).

The balloon is so designed that if there is a wind, increased lift is obtained, the balloon acting as a kite. It is therefore possible to ﬂy a barrage at greater heights on reasonably windy than on calm days.

Captive balloons are prone to other weather effects such as thunderstorms, when they may act as excellent lightning conductors. If struck by lightning, the balloon is usually set on ﬁre and becomes a total loss. Snow may freeze on the top surface of the balloon and reduce performance owing to the increased weight.

To a casual observer it might appear that owing to the spaces between the balloons in the barrages, there would be plenty of room for aircraft to turn so as to avoid coming in contact with the cables. It is true that on days when there is no cloud, the balloons may be visible to an enemy pilot and he might dive into the barrage to launch his attack, but once within the barrage he might ﬁnd it extremely difficult to avoid the not easily discernible balloon cables as turns at high speed with fast modern monoplanes cannot be carried out in a small space.

But on days when there is a layer of cloud, the balloons will not be visible and it would be a foolhardy act indeed to ﬂy into the barrage area, for it would be impossible to see the balloon cables until too late to avoid them. In these conditions, or at night, it is the knowledge that the balloon barrage exists at a given locality that prevents the pilot going down so that he can sight his target on the ground. In other words, the barrage has affected the pilot’s morale.

This brings us to the second reason for the barrage, and that is to prevent the enemy coming lower than a given height—that is, the top of the barrage. Thus low ﬂying attacks on targets such as cities and war factories are prevented.

INFLATING A BARRAGE BALLOON

Fig. 7. Diagram showing how a barrage balloon is inﬂated with hydrogen. The rudder and stabilizers are not ﬁlled with hydrogen, but with air only by means of air scoops, and air also enters the scoop in front to keep the balloon in shape should any leakage of gas occur

The maximum height to which the barrage can be raised cannot, of course, be divulged, but the greater the height, the greater the weight of cable which has to be lifted. All sorts of tricks can be played with it to outwit and mislead the enemy, such as placing balloons at varying heights, moving balloons up and down during the alert periods, and changing the concentration of balloons.

The enemy has tried out many devices to overcome the danger of hitting balloon cables. One idea which the Germans experimented with was a device to fend off the balloon cable. It was ﬁxed as shown in Fig. 8, but detracted considerably from the aircraft’s performance. Britain had also experimented with various cutting devices on the leading edge of the aircraft’s planes.

DEVICE TO BEAT THE BALLOON

Fig. 8. Diagram illustrating device tried by the Germans to overcome the danger of hitting a balloon cable. Its object was to push the cable clear of the aircraft, but it had the disadvantage of considerably reducing the bomber’s performance. Some Allied aircraft have been ﬁtted with devices to beat the balloon, but it is probable that they also reduce the aircraft’s efficiency

INSIDE A BOMB STORE

The R.A.F. keep their bombs safely stored away underground. When they are required they are loaded into trolleys and hauled to the aircraft. The men seen above are getting a consignment of 500-lb. bombs out of store ready for a big raid on objectives in Germany

The weapons of attack used by aircraft consist of bombs, torpedoes, mines, and ﬁre with shell-ﬁring guns and machine guns. Bombs have high explosive or incendiary ﬁllings. The high explosive bomb consists of metal body ﬁlled with explosive. The effect is designed to be produced either by disruptive effect of blast, which is caused by the sudden release of a large quantity of gases under high pressure when explosion occurs, or through the damage caused by fragments.

BRITAIN’S BIG BOMBS

The blast of a bomb has most effect in a conﬁned space, and thus it is essential for the bomb to penetrate well into the target if maximum disruptive effect is desired. Britain has produced the largest and most effective bomb yet used in this war. It weighs 8,000 1b., is about seven and a half feet long and two and a half feet in diameter. No open space could be found in Britain for testing it, so widespread is the effect of its blast.

Let us consider for a moment the types of high explosive bombs now in use. First of all we have anti-personnel bombs designed to break up when the explosion occurs into the greatest possible number of fragments big enough to produce casualties over a large area. Then there are “general purpose” bombs, which strike a balance between blast and fragment effect. These bombs are not designed to stand up to being dropped on very hard targets, such as the armoured deck of a battleship, and for this purpose we have semi-armour piercing and armour piercing bombs.

The ﬁrst of these have heavy bodies which disintegrate into large fragments. They can penetrate light armour plate and multi-storied buildings, and can be relied upon to reach their maximum depth of penetration into the target without breaking up. The armour piercer is, of course, designed to penetrate well into heavily armoured vessels when dropped from a great enough height.

ANTI-SUBMARINE AND INCENDIARY BOMBS

Among other recent types are the special bombs which have been produced for use against submarines. They contain large charges of high explosive, and, like the depth charge, give an intense pressure wave in water which will cause the hull of a submarine to leak if the explosion is close enough to it.

Incendiary bombs usually depend on phosphorus or magnesium compounds suitably ignited for their effect. They are of various sizes and for convenience are carried in special containers ﬁtted to the bomb cells of the aeroplane, from which they can be scattered over large areas. There are also gas bombs which consist of easily breakable containers ﬁlled with gas in liquid form. It was always laid down that poison gas would never be dropped by the R.A.F. unless the enemy ﬁrst made use of it against us.

BOMB FUSES

Now a word as to the fusing of bombs. The fuse is a device by which the explosive charge in the bomb is made to explode. The explosion may be desired instantaneously when the bomb hits the ground, or after very short intervals of time from small fractions of a second up to several seconds or after long periods, running into days or even weeks. The fuses are ﬁtted either in the nose or tail of the bomb, sometimes in both places, depending on the type of bomb. Nose fusing is usually chosen for instantaneous action and tail fusing for delay functioning. Experiments carried out against specially constructed targets, and results of experience in operations help the Air Staff to decide on the type of bomb and fusing best suited to the particular type of target to be attacked.

Magnetic mines dropped from aircraft do not have cables and sinkers, or anchors attached to them; they remain lying on the bottom of the sea in which they are dropped. They have to be rendered insensitive to the impact of the water when dropped, but to become extremely sensitive afterwards. The dropping of ordinary mines from the air is illustrated here.

LOADING A BEAUFORT TORPEDO BOMBER

Torpedoes dropped from the air are very similar to those used by ships, but are slightly more robust so as to stand up to the impact of being dropped into the sea by fast-ﬂying aircraft. Above, an aircraft torpedo is seen being loaded into the bomb cell of a Bristol Beaufort

TORPEDOES

Another weapon which is used by aircraft is the torpedo. Perhaps of all air weapons the torpedo has proved the most startlingly effective in this war. The most striking examples were afforded by the attacks on the Italian ﬂeet at Taranto and Matapan, the disablement of the Bismarck, and the sinking of the Prince of Wales and Repulse by the Japanese.

The torpedo dropped by aircraft is very similar to the ship’s torpedo; it is slightly more robust as it has to stand being dropped into the sea from an aircraft perhaps ﬂying at 250 miles per hour at a low height of up to 150 feet. It runs a distance considerably shorter than the ship’s torpedo, at a speed of up to forty-ﬁve land miles per hour. Its use is a tremendous test of the courage of the crew of the aircraft as release has to be close to the target. The dropping aircraft has to take rapid evasive action after releasing the torpedo so as to avoid the heavy concentration of ﬁre from the ship’s guns.

Qualiﬁed pilots of the Fleet Air Arm undergo a course of intensive training in the technique of torpedo attack at the Royal Naval Air-Torpedo School somewhere along the coasts of Britain. All their training is carried out under actual battle conditions, and attacks on the target practice ship are made with real torpedoes ﬁtted with dummy heads. These torpedo heads contain a buoyant apparatus so that the torpedoes can rise to the surface after running their course.

ACKNOWLEDGMENTS

The editor has received the welcome co-operation of numerous periodicals and ﬁrms who have given him permission to reproduce photographs and drawings. He takes this opportunity of expressing his gratitude for their help. Below is given a list of the contributors.

The Aeroplane
Flight
Illustrated London News
Life
The Sphere
Henry Hughes & Son
Phillips & Powis
Messrs. Spink & Son
Vickers-Armstrongs, Ltd.