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The main bomber types used by the R.A.F. during the Second World War

BOMBS FOR A STIRLING. The Stirling seen here is bombing up in readiness for the night’s operations. Its bomb load, which is three times that of a Wellington, is carried internally in three long bays running almost the whole length of the aircraft. The lugs, which can be seen on the bombs in the foreground, are for attaching the bombs to the bomb carrier. The Stirling carries a crew of seven.

THE design of every bomber is a compromise between a number of conflicting requirements, and the best bomber is the one in which this compromise has been most happily solved. The requirements of take-off performance, speed, bomb carrying capacity, manoeuvrability, defence, range and proper facilities for the crew must be carefully balanced. Bombers, however, are not yet standardized in one type, and the purpose for which they are required will affect the emphasis that is placed on one or more of these requirements. For instance, in the tip-and-run day bomber, such as the Mosquito, the emphasis may be placed on speed and manoeuvrability. On the other hand, in the night bomber, which must be capable of deep penetration into enemy territory, while speed is obviously important, the most essential qualities are range and bomb carrying capacity.

When the designer lays out his projected bomber aircraft, the first thing he will ask is how long a take-off run can be tolerated. The longer the run the greater the load that can be taken into the air with a given wing area, and therefore the answer to this question is one of the principal factors governing the geometry of the aircraft. The length of the take-off run is limited by the size of the aerodromes from which the bomber will operate and on their freedom from surrounding obstructions, such as high ground, trees, buildings, etc., it is for this reason that the Air Ministry has always insisted on the provision of aerodromes of a size sufficient to prevent bomber design being hampered by inadequate take-off run.

With this question settled, the designer knows his maximum length of run and the rate of climb which his aircraft must have after it has taken off. If our aerodromes provide, say, a clear run of 1,500 yards in one direction for use when there is no wind and 1,200 yards in two or three other directions, we can very safely give the designer a take-off run of 1,500 yards in still air to clear a 50-foot obstacle.

BOMBER AIRCRAFT OF THE R.A.F. Details of engines and maximum speeds of seven well-known types of British bombers. They are all used for long range night bombing with the exception of the Boston which is a medium bomber. The Mosquito is a light day and night bomber and was the fastest aircraft in the world at the time.

The landing run in a bomber is of less importance as the aircraft will be lightly loaded, as normally the bombs will have been dropped and most of the fuel used up. If a bomber should have to return for any reason before it has reached the sea or the enemy country and the bombs cannot therefore be got rid of, arrangements are provided for jettisoning the bulk of the fuel so as to reduce the load before landing. The fuses of the bombs can be made safe so that apart from an outbreak of fire even if the aircraft crashes the bombs will not explode.

The next requirement, that of speed, depends on the engine power which the designer can provide consistent with the size and construction of the aircraft, and on the cleanness of the streamlining.

The requirement of defensive power conflicts very much with speed as it entails the provision of power operated gun turrets with good arcs of fire and good fields of view for the gunners, which cannot be provided without interference with the perfect streamline shape of the aircraft. Defensive power does not, however, consist only in the provision of good gun positions. That may be called the active side of defensive power, but there is in addition the very important

passive side which consists of the provision of armour, self-sealing tanks, bullet-proof glass and so forth.

Good facilities for the crew also conflict with the requirement of speed, as they demand a hull of sufficient size to give reasonable accommodation to the crew for flights often lasting nine or ten hours, and good fields of view for the pilot and bomb aimer which again are difficult to reconcile with the perfect streamline shape.

SELF-SEALING PETROL TANK. Diagram showing principle of one type of self-sealing fuel tank used in bomber aircraft. When a bullet or other projectile penetrates the tank the petrol acts on the plastic rubber lining, of which it is a solvent, and the hole is thereby automatically sealed.

The range of an aircraft is the distance it can fly without landing to refuel. The requirement of range chiefly conflicts with the bomb load and these two requirements are therefore made as interchangeable as possible by the provision of large tanks and large bomb carrying capacity.

This arrangement allows the aircraft to fly a very long distance with a small bomb load or a short distance with a very large bomb load, although with tanks full and bombs on all the racks the air-craft would be so overloaded that it would probably be unable to take off. This enables the best possible use to be made of the load carrying capacity of the bomber for both short and long journeys over enemy territory.

A very careful study of these factors and their application to air warfare has, since the war of 1914-18, been a principal preoccupation of the Air Staff. They realized very clearly that one of the main lessons of the last war was the supreme importance in air warfare of technical superiority. It has a profound influence on the morale of the air crews and consequently on their ability to carry out, day after day, their difficult and dangerous tasks. The fruits of this study ensured that the Royal Air Force entered the war equipped with aircraft which, type for type, had no equal in the world, and were certainly much superior to their German and Italian counterparts. More than four years after the war began this superiority is still maintained. The Luftwaffe has no aircraft which can be considered equal to the modern British types.

Enemy Bombers

Generally speaking, the British bombers are altogether more highly specialized than those of the Luftwaffe.

The Germans designed no bombers specifically for use at night, and, when their daylight offensive ended in a costly failure in the autumn of 1940, they were compelled to alter their whole policy and adopt night bombing as the main feature of their air offensive with aircraft that were not very well suited to this particular task.

The day bomber, which always runs the risk of being intercepted and overwhelmed by superior numbers of enemy fighters, is compelled to fly in formation so that the guns of one aircraft may cover the blind spots of another. In order to make full use of the advantages of formation flying, pilots must be trained to an extremely high standard of skill and must keep in constant practice.

Much experimental work was done during the years of peace to determine the best type of formation to adopt to minimize casualties both from fighter attack and anti-aircraft fire, and the huge unwieldy formations escorted by fighters to which the Germans pinned their faith have never been popular in the Royal Air Force. The British always preferred to operate with comparatively small manoeuvrable formations with the aircraft so disposed as to give each other the maximum possible support in the face of enemy attack.

BOMBERS OVER THE SEA. The increasing range and armament of aircraft has made them invaluable in the work of submarine detection and destruction. By means of gunfire, bombs and depth-charges they can often cripple submarines. This disabled U-boat was forced to surrender to a Hudson aircraft.

The heavy night bomber with its powerful defensive armament and relative freedom from fighter attack, does not require, except possibly on very bright moonlight nights, to fly in formation. It flies alone and the main difficulty of its task is accurate navigation to its target area in the dark, the finding of the precise target and the successful return to its base. When it is remembered that this must be carried out in all weathers, not excluding fog, it will be realized that the provision of the best facilities for navigation is vital in a night bomber.

This preliminary survey will give us some idea of what sort of aeroplane the bomber should be. The tip-and-run day bomber will be a fast twin-engined monoplane with a bomb carrying capacity of about one ton and a range of about 1,500 miles. This will give it an operational radius of action of about 600 miles. It should have a top speed of over 300 miles per hour, and should be easily manoeuvrable. The Mosquito conforms to this general description, although its speed is considerably greater. Its armament consists of four fixed cannon and the same number of machine guns in the nose.

Modern Night Bombers

The latest type of night bomber is multi-engined with a cruising speed of 300 miles per hour, and a range of 3,000 miles with some six to eight tons weight of bombs. It is equipped with power-driven turrets in the nose and tail and amidships, each carrying a powerful battery of guns. Britain has several such types, notably the Short Stirling, Handley Page Halifax, Avro Lancaster, and the American Flying Fortresses and Liberators.

THE SHORT STIRLING. Dimensions of Britain’s largest four-engine bomber. The Stirling is powered by four 1,600 h.p. Bristol Hercules 14-cylinder engines and carries a crew of seven. Its bomb load is about 8 tons.

In the war of 1914-18 our bombers were constructed of wood, reinforced with steel tubes and braced with steel wires. As their speed and weight increased it became obvious that wooden construction would no longer suffice, and preparations were made to change over to metal construction. This was an entirely new branch of engineering, in which we had no experience to guide us and the rival claims of steel and light alloys were pressed by rival constructors. After much trial and error it was found that in order to compete with light alloys for weight, steel had to be of paper thinness, and it was impossible to guarantee its immunity from rust, a small amount of which might dangerously reduce it strength. Nowadays, for all practical purposes throughout the world, the stressed skin method of construction using light alloys is universal for high performance aircraft. The only notable exception is the wooden construction of the Mosquito. The stressed skin method consists of using frames and stringers, rather like those of a ship, but very much lightened and refined, with a thin metal skin riveted on to it. This system is extremely strong and reasonably simple to build. An alternative scheme used for the Wellington bombers is the geodetic system in which the framework of the aircraft resembles a basket-like network made of corrugated light alloy strips.

HANDLEY-PAGE HALIFAX. The Halifax, although slightly smaller than the Stirling in length and height, has a similar wing span of 99 feet. Its twin tail fins and distinctive nose make it simple to identify.

The system is ingenious and has certain advantages in construction, but it requires about the same structural weight as the stressed skin method. It has, moreover, the disadvantage that large holes, such as are required for the removal or changing of fuel tanks, cannot be made in the framework and that the whole aircraft must be covered with linen fabric. This reduces its all-weather qualities, which is an important matter in time of war, when hangars are seldom used and our bombers are dispersed round the aerodrome in the open day and night, summer and winter, in all weathers.

Much work has been done in recent years in protecting aircraft from the effects of corrosion. Light alloys receive a special anodic treatment which not only protects them from the effects of rain and exposure to the air, but also prevents them from being damaged by salt water or sea air.

The preparation of a suitable scheme of protective colouring is of great importance to a bomber. The upper surface must be coloured so as to harmonize with the ground, so that dispersed aircraft in the open do not give away the camouflage of our aerodromes, while the undersides must be toned so as to be inconspicuous against the sky. Day and night bombers therefore require different colouration for their undersides, the day bombers being painted a pale blue, the night bombers are treate with a special matt black dope. This dope has a remarkable power of absorbing light and reflects very little when the aircraft is caught in the beam of a searchlight.

CONTROLS OF A STIRLING BOMBER. Interior view of pilot's compartment of a Stirling four-engine bomber showing instrument panel. With so many controls every moment of the trip demands the pilot's utmost concentration. He must be able to handle them calmly and correctly even at the most critical junctures. The key to the various dials and instruments is given below.

DETAILS OF STIRLING COCKPIT. 1, time of flight clock; 2, blind approach indicator; 3, wheel brake pressure gauge; 4-7, engine boost gauges; 8—11, engine revolution indicators; 12, bomb jettison controls; 13, air-speed indicator; 14, artificial horizon; 15, rate of climb indicator; 16, undercarriage position indicator; 17, time of flight clock; 18, undercarriage master switch; 19, bomb emergency switch; 20, altimeter; 21, drift indicator; 22, turn and bank indicator; 23, bomb release switch; 24, undercarriage indicator switch; 25, vacuum gauge; 26-27, bomb-door warning lights; 28-29, airscrew de-icing controls; 30, oxygen regulator unit; 31, pilot’s control columns; 32, rudder control; 33, control box, including: (a), engine control levers; (b), undercarriage retraction control; (c), landing lamp control; (d), aircrew variable pitch control; 34, the aircraft compass.

The first impression produced on entering a, modern heavy bomber is surprise at its amazing complexity. In every direction run large numbers of pipes, electric leads and controls, while the engineer’s control panel has scores of gauges and many cocks by which the fuel distribution is automatically controlled from the tanks to the engines.

The Pilot’s Cockpit

A casual glance at the pilot’s dashboard would lead one to suppose that the number of gauges and instruments is limited only by inability to find room for any more, while all round the pilot’s cockpit are the numerous switches and levers which control the engines; the lever for actuating the flaps, which enable the pilot to make the gliding angle steeper; the gear for operating the undercarriage; the trimming tabs which trim the aeroplane and enable it to fly “hands off”, and the control for the dashboard lighting. Then there is the compass; a very important instrument indeed. In modern bombers a master compass, placed where it is as free as possible from magnetic interference, controls a number of repeaters. One of these is required by the pilot.

The wireless operator’s station is surrounded by all the complicated apparatus which enables him not only to keep in constant communication with his home base, but to assist the navigator by obtaining bearings from direction finding wireless stations in this country and even, in certain circumstances, those of the enemy. There is also the radio telephone which enables the crew to establish short range communication with an aerodrome or to talk to another aircraft in the air, and the inter-communication telephone which enables the crew to talk to one another. In addition, there is the apparatus which enables the aircraft to return home on a wireless beacon and to make its approach and landing on the airfield in anything short of the densest fog.

In the navigator’s station we find a compass and a large plotting table with a screened electric lamp, charts, maps, rulers, dividers and pencils. There is also his sextant for fixing his position by taking observations of the stars and an ingenious instrument for plotting his position on the map from these observations without the need for working out complicated sums in arithmetic. Near to him is the astrodome, a perspex dome in the roof through which he operates his sextant. Near at hand also is the drift sight, through which he can ascertain the drift of the aircraft even at night.

Then there are the power operated turrets, which enable the gunners, by means of a simple control, to bring their powerful battery of machine guns to bear on an attacking fighter. The turrets are a tight fit for any but small men when in flying clothes, and air gunners, like jockeys, should be of small size and light weight.

REAR GUN TURRET OF A BOMBER.

Interior of the Fraser-Nash power-operated rear gun turret as fitted to bombers. The numbers indicate: 1, sight; 2, trunnions carrying guns for vertical traverse; 3, breech blocks of four Browning machine guns; 4, ammunition belts; 5, firing buttons for four guns; 6, control grips; 7, ammunition boxes; 8, gunner’s seat; 9, gunner’s safety belt. The exterior of this gun turret is illustrated elsewhere in this article.

In the nose of the aircraft is the bomb sight, a very important instrument. Its purpose is to tell the bomb aimer the correct moment at which to drop the bombs in order to ensure that they hit the target. When we recollect that an aircraft travelling in the air is free to move in all three dimensions, it is easy to believe that the problem is not a simple one. So many things enter into it. The speed at which the aircraft approaches the target is the resultant of the aircraft’s own speed and the speed of the wind at the height at which it is flying. The direction from which it approaches the target is the resultant of the direction in which the aircraft is pointing and the direction of the wind at that height. It is therefore most important that the bomb aimer should be able to know not only the speed and direction of his aircraft, but also the speed and direction of the wind

which is affecting it. This is by no means an easy thing to discover; it can be done by measuring the angle of drift of the aircraft and calculating it from that; or a tachometric sight can be used which automatically solves the problem by measuring the apparent velocity of the target from the aircraft itself.. The sight must also allow for the time of fall of the bomb, since, when it is released, the bomb has a forward speed equal to that of the aircraft, and during the time that it is falling to earth it will travel forward a long distance. The time of fall is proportional to the height at which it is released and the sight must therefore be adjusted to allow for this factor. The resistance of the air will gradually slow up the forward speed of the bomb and this produces what is called “trail angle”, which must also be allowed for. The modern tachometric sight, gyroscopically stabilized and fully automatic in its operation, even releasing the bombs electrically at the right moment without any action on the part of the bomb aimer, is a marvel of ingenuity.

THE MAN WHO AIMS THE BOMBS. The entire flight of a bomber across hundreds of miles of hostile territory may be wasted if the man who aims the bombs is a fraction of a second out in timing their release. The picture shows the air observer at the bomb sights in the nose of a Stirling four-engined bomber.

The bombs can be released either all together as a “salvo” or in succession as a “stick. In order to drop the bombs in a stick an ingenious piece of mechanism is employed called the bomb distributor. This can be set so as to allow any desired interval between the release of each bomb, and also makes it possible to select the order in which the bombs are released. For example, if it is desired to drop a stick of bombs with a distance of 100 feet between each bomb, it is easy to calculate the interval — thus at, say, 165 miles per hour the aircraft travels approximately 250 feet in a second, and the time interval required to be set on the distributor would be two-fifths of a second.

Another very useful piece of equipment is the automatic pilot, popularly known as “George”. An aeroplane flying in the air is free to pitch, roll or yaw, and the automatic pilot must therefore be capable of controlling it in all three axes. For this, three separate gyroscopes are required, each connected to a servo-motor or pneumatic system which, acting upon the controls, is able to correct any tendency for it to alter its trim. If, therefore, a bump should force the nose of the aircraft down, the gyroscope controlling the pitching movement would at once bring into operation the mechanism which would raise the elevator, depress the tail and so bring the nose back to its original position. The automatic pilot will therefore keep the aeroplane flying steadily along a given course at a given height and at the same time keep it laterally stable.

GEORGE, THE AUTOMATIC PILOT.

A, directional control indicator; B, elevation indicator; C, gyroscope to hold aircraft on even keel; D, course-setting control; e, control column untouched by pilot when automatic pilot is in operation; F, valves controlling air cylinders operated by movement of gyroscope; G, H and j, compressed air cylinders for operating rudder, ailerons and elevators. In electrical types, servo motors replace the pneumatic system, and although one gyroscope is sufficient to counteract any alteration of the axis of the machine, three are generally employed

In addition to all this astonishing complexity, the bomber’s equipment is governed by yet another very important factor, the need for making everything as light as possible. The role of the bomber is to carry the maximum weight of bombs to the target and drop them with accuracy, and the weight of all this ancillary equipment detracts from the ability of the bomber to carry bombs. Nothing therefore can be allowed to have a place unless it justifies its weight by assisting the crew to fly and navigate the aircraft and drop their bombs with accuracy on the target. In addition, every piece of equipment is itself made as light as possible. A fraction of an ounce scraped away here, a penny-weight there, the substitution of a light alloy or bakelite for a heavier substance, will add up into a saving of hundreds of pounds of weight, which means that another heavy bomb can be carried. This need for saving weight has had the effect of refining the bomber’s equipment, and has put a premium on good design and really first-class workmanship.

Let us now think for a moment about the problem of operating these bombers. In the days of the war of 1914-1918, and for some time afterwards, it was customary to focus attention on the pilot. Most aircraft were single-seaters and two seaters, and the pilot was the all-important person. He was usually an officer, and the remainder of the crew until recent times possessed an inferior status. Those days are now past, and all members of bombers air crews enjoy equal status, although it is true that only a pilot may be captain of the aircraft. The Bomber Command of the Royal Air Force never talks about “pilots”, but always about “air crews”, and everything possible is done to encourage and foster team work among the crew. Team work is the secret of success in the operation of a modern bomber, and it is for this reason that, during the later part of their training, air crews work together as a team. The pilots, the air observers, who navigate and aim the bombs, the wireless operators, the air gunners, and the flight engineers, all go to their separate schools at first where they learn their own basic trade. They then go to an operational training unit where they are formed into a crew and begin to learn team work. The duties of all members of the crew are carefully defined as far as their principal tasks are concerned, but the captain of each aircraft is responsible for arranging the details of the duties of his crew and for seeing that they carry them out punctually and efficiently.

EXTERIOR OF THE REAR GUN TURRET OF A WHITLEY. Exterior view of the Fraser-Nash power-operated, four-gun turret, the interior of which is illustrated earlier in this article. The turret can be made to rotate by means of a simple control, and the gunner can rapidly bring a powerful concentration of fire to bear on the enemy from his four Browning machine guns. The transparency is bullet resisting and splinter proof. Slightly modified and improved turrets are used on the more modern four-engined bombers.

We have seen in the previous paragraphs how complex is the equipment carried by the modern bomber, and it is no exaggeration to say that faulty manipulation of this equipment on the part of any member of the crew is only too likely to end in disaster to the aircraft. Each man must carry out his duties with the most painstaking care. No haste, no preoccupation can excuse a false move which will end in disaster. It can be imagined how difficult it is to instil this precision and almost superhuman patience and care into young men, for youth is traditionally given to impatience and irresponsibility. To assist them in their difficult job a very carefully worked out drill is employed which lays down the sequence of operations and enables the captain, with the minimum of talking, to ensure that each member of the crew is at his place and has carried out at the correct time the duty which has been allotted to him.

It is a guiding principle in laying down the composition of crews of large bombers that there must be at least two men capable of carrying out each major task. Thus, there are two pilots, the senior of whom is the captain of the aircraft. Either of them can not only fly the aircraft, but can, in emergency, do the work of the air observer. The two wireless operators are also air gunners, and so is the flight engineer. Thus, if any one member of the crew should become a casualty there is another man available to take on his work and play his part in carrying out the task allotted and bringing the aircraft safely back to its base.

ARMSTRONG-WHITWORTH WHITLEY. The Whitley bomber, like the Wellington, carries a crew of five. It has a wing span of 84 feet, a length of 70 feet 6 inches, and a height of 15 feet. Its service ceiling is 25,000 feet and its top speed is about 245 m.p.h. The Whitleys were the machines which bore the brunt of the leaflet and bombing raids carried out by the R.A.F. in the early days of the war.

The captain of the aircraft, like the captain of a ship, is responsible for the safety of his aircraft and for carrying out the orders given to him by his superior officer. He is also the first pilot of the aircraft and he will certainly make it his responsibility to take off the aircraft when fully loaded, and also to land it unless conditions are quite straightforward. Upon his judgment will rest the decision

to go on or to turn back in bad weather or other emergencies, and he will decide the tactical method of approach to the target. If the aircraft gets into difficulties he will decide whether to order the crew to “bale out” or whether it would be better for them to stick to the aircraft and try to land. When attacked by enemy fighters he will fight his aircraft, controlling its manoeuvres and giving instructions to the gunners in the various turrets. He is responsible for checking the work of the navigator and for seeing that crew drill and flying discipline are correctly maintained. His is a very responsible and important position, and it is remarkable that captains of aircraft more often than not are young men scarcely out of their teens. No doubt they are the same young men whose irresponsibility in a sports car often calls down on them the denunciation of their seniors, but when they are on the job in their bombers they are serious, well disciplined and responsible leaders.

The second pilot, who may be regarded as a captain under training, will take over the controls of the aircraft when the captain is busy with his other responsibilities and as he grows more experienced, may even be allowed to do all the flying. He is also capable, in emergency, of manning the front gun turret, aiming the bombs or completely taking over the navigation of the aircraft.

To the air observer is allotted the very important duty of navigating the aircraft to the target and home again and of finding and identifying the target and aiming the bombs, though in the modern four-engined aircraft a separate air gunner is carried to do the bomb aiming. It is not too much to say that the success of a bombing mission depends on his faithful discharge of his task.

SPARKS’ OFFICE. Wireless operator's station in a heavy bomber. He keeps in touch with the outside world, and in bad weather the safety of the aircraft may well depend on the skill with which he carries out his task.

The wireless operator is responsible for maintaining communication with the outside world. From time to time, as requested by the air observer, he will obtain fixes of the aircraft’s position from the direction finding wireless stations. In bad weather conditions the safety of the aircraft may well depend on the skill and accuracy of this man.

The air gunner, perhaps, has the most arduous and thankless task of all. Squeezed into a power operated turret, he does his work in isolation. He is cut off, not only from the outside world, but also from the other members of the crew for many hours at a time, except for the slender link provided by his intercommunication telephone. Throughout long hours of darkness he must maintain a constant vigilance, searching the night sky for signs of enemy fighters. For long periods, for weeks together, he may not see an enemy fighter, but one night suddenly the attack will come. When it does come the gunner may only have a few seconds in which to swing his guns into position and fire. He has, however, the satisfaction of knowing that his powerful battery of guns has a very good chance of sending the enemy fighter crashing down to the earth below.

FLIGHT ENGINEER. The flight engineer is usually carried only in bombers with more than two engines. He watches over the gauges and dials that register the performance and condition of the engines, but he also acts as an air gunner if necessary.

The flight engineer is usually carried only in bombers which have more than two engines. His task is to watch over all the tell-tale gauges which record the condition and performance of the engines, and to control the petrol supply and the temperature of the engines. In a four-engined bomber he may have to watch as many as thirty different instruments which will tell him the cylinder temperature, the temperature of the oil going into the engine and coming out again, the oil pressure, the fuel pressure, and the boost pressure, while he must watch the fuel-contents gauge so as to change over the supply from tanks which have been emptied to those which are still full. All this used to be the responsibility of one of the pilots and still is part of their duty in twin-engined bombers. In multi-engined aircraft, however, the work is sufficiently complicated and responsible to require the whole time attention of one man. In addition, the flight engineer is trained as an air gunner, so that he can man a gun if necessary.

To complete the picture which this brief survey has attempted to convey, it must be remembered that the crew of a bomber are not only carrying out delicate and responsible tasks in a cramped and noisy aeroplane, but they are doing so, even in the height of summer, in conditions of extreme cold and rarified air. In a civil air liner it is possible to seal up the passengers’ cabin and supply it with heated air so that the travellers may sit in comfort in their ordinary clothes. It is not possible in the same way to seal up a military aircraft equipped with turrets, cameras, bomb sights, etc., and although heated air is supplied, it cannot be made so effective. If the hull of the aircraft is penetrated by bullets or shell splinters, the outside air, which may well be at a temperature of 50 deg. or 60 deg. Fahrenheit below freezing point, will rush in. The crews must therefore wear thick, warm clothing, which cannot be otherwise than hampering and to some extent uncomfortable. In the turrets, which are even more exposed, electrically heated clothing, gloves and boots must be worn.

The rarefied air at the great altitudes at which military aircraft must be prepared to fly makes the provision of oxygen necessary for the crew. This is carried in high-pressure metal bottles and led by pipes to each crew station. It is inhaled by each member of the crew through a mask which is permanently worn and connected to the supply point by a flexible pipe. Included also in the mask is the microphone for the intercommunication telephone.

The bomber aircraft, like any other piece of machinery, is subject to constant modification and improvement. Very little of its equipment remains the same for more than a few months at a time,

for continuous research and development are going on with the object of eradicating weaknesses and improving its efficiency. The guiding principle underlying this research and development is that complication in design and production can be tolerated if it leads to simplicity in operation. The work of air crews under the severe conditions that have been briefly described above must be made as simple as possible, for there can be no doubt that in the air the number of mistakes a man will make is directly proportional to the amount of complication involved in the task.

Such is the bomber aircraft of today, a complicated, deadly weapon of war, as yet in its infancy, little more than a quarter of a century old. While it would be rash to attempt to prophesy the trend of its future development, it is quite safe to say that it will not grow less complicated, nor will it become less deadly.

WELLINGTONS ON THE WING. The Vickers Wellington long range bomber is easily recognizable by its long narrow wings and single large tail fin. It has a wing span of 86 feet 2 inches, a length of 64 feet 7 inches, and a height of 17 feet 5 inches. It carries a crew of five and has a ceiling of 26,300 feet. It is armed with power-operated turrets in nose and tail. Its top speed is 250 m.p.h.

You can read more on the “American Help for the R.A.F.”, “Development of the Bomber” and “Work of the Bomber Crews” on this website.