The influence of war

At the outbreak of War in August 1914 there was no real appreciation of the aeroplane as a weapon. In fact the German advance across Belgium and a large part of France was made mainly on foot, with horses drawing the greater part of the artillery and supplies, so unmechanized was life in those days. The aeroplane was regarded mainly as a means of reconnaissance . The Germans had several hundred, the French not quite as many and ourselves, as always, had very few.

The British Royal Flying Corps took to France a heterogeneous collection of biplanes and monoplanes, tractors and pushers. Yet, despite our unpreparedness, it was from Britain that the first seeds of the most devastating weapon yet devised were sown. In the Vickers Gun Bus was the germ of the fighter. This was a two-seater pusher biplane of neat and unexceptional design, with the pilot seated behind the passenger. The latter had a belt-fed Vickers machine-gun on a pillar mounting that allowed it to be trained in any forward direction. The Gun Bus was not fast even by current standards, how could it be with only 100 h.p. and the drag of all its struts and wires? But it did allow that gun to be mounted in the nose, so making it an aggressor. The tractor biplanes and monoplanes were faster, but the whirling propeller prevented any forward shooting except at an oblique angle that made accuracy virtually impossible.

The tractor biplanes proved excellent for reconnaissance, they could cruise at eighty or ninety miles an hour, some doing as much as a hundred in emergency, and the observer could make notes to bring back to base. In this country we had two very fast single seaters in service, the Sopwith Tabloid and the Bristol Bullet, but they were not very useful, because they carried no observer and they could not be armed. True, pilots carried revolvers and occasionally fired at each other in the air, while sometimes an observer even tried to do some shooting with a rifle or a Lewis gun.

It certainly looked as if the aeroplane would be defenceless, unless one was going to be restricted to lumbering pushers like the Gun Bus. So sure were the authorities that this was the case, that the official Royal Aircraft Factory at Farnborough

designed the F.E. series of "Fighting Experimental" (originally the letters meant Farman Experimental) pusher biplanes, of which the most notable were the F.E.2 and the F.E.8. The F.E.2 aeroplanes, there were five or six variants, were twoseaters , much larger (and slower) than the Gun Bus, where the observer did the shooting. The F.E.8 of 1915 was a singleseater , small and manoeuvrable, in which the pilot had a single Lewis gun that fired forward—either level or pointing upward. These pusher fighters could shoot, but they had a hard job to catch the enemy!

So the position in 1914 was that there were "fast" reconnaissance aeroplanes, while the only armed machines were too slow to catch the others. But if an aeroplane could go and look at the enemy, it surely ought to hurt him in some direct way? It was not long before the first bombing raid was made. Three Avro biplanes—of trainer type and performance—belonging to the Royal Naval Air Service bombed (piloted by SquadronCommander E. F. Briggs, Flight-Commander J. T. Babbington and Lieut. S. V. Sippe) the Zeppelin sheds at Friedrichshafen on November 21st, 1914. This was a vital target, because in those days the airships of Germany were the only really effective offensive air weapons.

The R.N.A.S. also had the task of patrolling the coasts of Britain, the North Sea and the English Channel. For this work they used any available landplane, float seaplanes and a very few flying-boats.

The Navy had, at first, been even more conservative than the Army about adopting the new device—it could scarcely be * called a weapon at that stage. However, owing to the efforts of Captain Murray Sueter, a small band of enthusiasts had started flying at Eastchurch on the Kent side of the Thantes Estuary in 1911. This modest beginning led to the formation of a Naval Wing of the Royal Flying Corps. As may be imagined, this situation was scarcely to the liking of the Senior Service and, just before the outbreak of War, in July 1914, the separate Royal Naval Air Service was formed. This separation gave the Navy a better chance of developing aeroplanes to its own needs, but also led to such a fierce competition for supplies between the two services that, on April 1st, 1918, the R.F.C. and R.N.A.S. were again merged to become the Royal Air Force.

At the outbreak of the War the R.N.A.S. had only one constructor who specialized in making aeroplanes for their particular needs, this was Short Brothers of Rochester. Their early seaplanes look weird contraptions by present-day standards , even more queer than their landplane contemporaries. To get the comparatively heavy aeroplanes off the water with the low-powered engines of those days they had wings of large span and area. Because of the way the control wires were connected, the ailerons used to droop right down when the seaplanes were stationary, giving them a tatterdemalion, hangdog appearance. This rag-and-bone man look was further enhanced by the five floats appended to the wings and fuselage by an imposing array of struts and wires. The reason for the many floats was the fact that little was then known about the technique of hydroplaning. The bulk of the weight was supported by two flat-bottomed mahogany floats and the extremities, wingtips and tail, were kept above water by smaller floats. This system of making buoyant what was essentially a land aeroplane was destined to survive almost unaltered for over ten years. An important feature, and a remarkable engineering achievement for its day, was that these Short biplanes had wings arranged to fold round hinges on the rear spar, so that they could be easily stowed aboard ship.

Another seaplane used by the R.N.A.S. in the early days of the War was the Sopwith Schneider. This was an adaptation of an adaptation. In the days of Brooklands flying before the war, Harry Hawker had flown about and won many races in his beautiful and realistic little Sopwith Tabloid—100 h.p., 100 m.p.h. When T. O. M. Sopwith decided to enter for the 1914 seaplane contest for the Coupe Jaques Schneider, a trophy presented for annual competition by the French arms magnate, he had a special version of the Tabloid built. This machine had the 160 h.p. Gnome engine and was mounted on floats. Despite a forced landing due to engine trouble, Howard Pixton managed to re-start and win comfortably. The Schneider Trophy Contest (as it is better known in this country) had not only been a speed event, it had also included a fairly severe seaworthiness test and the R.N.A.S. decided that the winner might well suit their purposes. Therefore, a version was ordered and, with numerous modifications, made first by the parent company and later by Blackburns and Faireys, the type remained in service until the end of the war as the "Schneider Baby" and the "Hamble Baby".

At the outbreak of war, the American aircraft industry had not shown much inventiveness and most of its designs were crude. There was, however, one notable exception; Glen Curtiss was a man who had original and effective thoughts on what a flying-boat should be like. He, almost alone among the pioneers, felt that a seaplane should be a boat with wings and not an aeroplane with floats. The Curtiss boat had a mahogany hull with a shape surprisingly akin to those of today—slender, long and with a single step. On top of the hull were mounted the biplane wings, with the engine or engines between them and the airscrews well clear of all spray. It was a naval officer, Lieut. John Porte, R.N., who had worked with Curtiss, who persuaded the Lords of the Admiralty to buy some and he then set about developing them in Britain. In their original form the Curtiss boats were not very seaworthy for our rugged shores, but their developments, particularly the F-2 and F-3 series evolved at the Royal Navy's seaplane experimental establishment at Felixstowe were excellent seaboats.

These specialized naval aeroplanes were about the earliest cases of design for a purpose and development along a line dictated by expediency. By 1915, however, the stalemate of trench warfare on the Western Front had started the struggle for aerial supremacy that was to continue, ever increasing in intensity, until the close of hostilities. It was from this struggle for survival of the fittest that the aeroplane evolved, almost by a process of natural selection, along the different lines dictated by its many duties.

Baulked in their advance across France by the Battle of the Marne and the stand of the British Expeditionary Force, the German armies found that their carefully planned numerical superiority in aeroplanes for reconnaissance had failed. Unarmed , they were being attacked by Allied pilots who fired at them with rifles and revolvers and, of course, there was the Vickers Gun Bus. Something had to be done about this and it was a young Dutch pilot/designer, Antony Fokker, who provided the answer. He built a single-seater monoplane, not a very good one in fact and sometimes called a "poor copy" of the French Morane, but to it he fitted a device that allowed a machine-gun to be fired through the propeller. This device was called an interrupter gear and was a mechanism connected to the engine that stopped the gun from firing whenever a propeller blade was in front of the muzzle. This was a very important event for it heralded the birth of the fighter, as we know it today, in which the pilot aims his aeroplane at the target. This invention immediately put the tractor aeroplane, with its superior performance, in the ascendancy which it never lost.

As with most important inventions, other minds were on the same track. Crude efforts were made by the Allies to combine a tractor's performance with the power to fire ahead. Nieuport mounted a Lewis gun on a rail above the top plane to fire over the airscrew, while some attempts were made to fit steel deflector plates on the propeller blades (notably on a Morane flown by Roland Garros), but this was too heavy. Characteristically, the British authorities clung to a belief in the pusher and they put two such fighters into service with the R.F.C., the D.H.2 and the F.E.8., these checked the Fokker supremacy, but were both hopelessly out-classed because of their layout when the Albatros D I biplane reached the front. Constantinesco, a Roumanian engineer, invented a synchronizing gear in which a hydraulic relay from the engine fired the gun only when the propeller was clear, but he had a hard time convincing the authorities of the value of his device and it was not adopted for a year after the Fokker gear. First the R.F.C. had to try the Vickers and Kauper interrupter gears and lose many men under the "Fokker Scourge".

It was the Fokker monoplane that produced the first "ace", Max Immelmann, who gave his name to the climbing turn he used to attack his victims, pushers and unarmed B.E.s from the rear.

The tractor fighting scout, as the single-seater was then called, was characterized by its small size, giving manoeuvrability , by its having as powerful an engine as could be found, by its short nose, with the pilot close up behind the wing and a machine-gun on top of the cowling just ahead of the cockpit. Pilots were always asking for more speed, faster climb and greater ceiling—and always for a better view. Speed was increased by fitting more powerful engines and learning the advantages of streamlining. The extra engine power helped both climb and ceiling. The pilot's view was, however, the problem which probably gave the designer most food for thought.

In the early aeroplanes a pilot needed to see where he was going, that is straight ahead in flight and downward when landing. On reconnaissance the need was not much different, but once the fighter arrived it was rearward view that mattered. If an aeroplane was trying to escape it ran away, which meant that its tail was unprotected. Similarly, the way to surprise an aeroplane was to catch it from behind. From the designer's viewpoint, however, a good place to put the weight of the pilot was under (or over) the wing and that is where you see the crew in most of the early aeroplanes.

The Fokker Scourge led to a decided emphasis on moving the pilots of the smaller aeroplanes aft of the wing where they could see above and behind. It was still a tricky business getting the balance of weight right while keeping the fuselage short— which was necessary in order to maintain manoeuvrability, for the larger an aeroplane the more clumsily it turns. Staggering the wing was a common method of giving the pilot as good a view as possible and at the same time keeping his weight near the centre of lift. Because of these conflicting needs the usual compromise was to get the pilot just behind the top plane and to cut out the trailing edge, and either make an opening between the spars of the centre section or cover it with celluloid. This was not a good system because any cutting away of the wing caused turbulent air flow and increased drag, while the celluloid panels soon became discoloured and gave a false sense of security. Two notable attempts were made at an unconventional approach to the problem of upward and forward view, the D.H.5 of 1916 and the Sopwith Dolphin of 1917 in which the top plane was staggered backward, but this wing arrangement caused a sharp, vicious stall and was soon dropped.

Late in 1915 a new approach to the fighter problem was made by the Sopwith Aviation Company. They designed a two-seater of simple form in which the pilot was armed with a single Vickers gun, with interrupter gear, and his observer had a Lewis gun on a Scarff mounting. An important innovation here was that, for the first time, the pilot sat in front. In the earlier officially designed biplanes, such as the B.E.2, the pilot sat behind, and the only means of arming was to fit a Lewis gun to fire diagonally forward. As an aeroplane this new Sopwith was simple enough, save for one feature that gave it its name. In order to keep down drag the wings had only one pair of struts on each side and the centre section was held to the fuselage by a widespread W of steel tubes. Because of this it was known as the "1| Strutter". The idea of the two-seater fighter was, of course, that it could both bite and sting, but, naturally, there was the penalty of weight and drag which kept the performance down—even so it was a great improvement over the Gun Bus.

Despite its shortcomings, the "1f Strutter" was a sufficiently practical solution to appeal to the French, who rapidly adopted it and had it built by the Hanriot company. The French aeroplanes were in action before the end of 1915 and were an immediate success, but the British authorities, with characteristic tardiness, did not get the "1f Strutter" to the front until 1916, by which time its performance was outclassed by new German types. Nevertheless, the "i\ Strutter" did mark the beginning of a line of evolution that was to continue until 1940 with such outstanding aeroplanes as the Boulton Paul Defiant and Messerschmitt Me 11o. During one year on the Western Front, the three "1f Strutter" squadrons of the R.F.C. shot down forty-one enemy aeroplanes. Others of the type were used by the R.N.A.S. both from shore bases and from ships. In 1917 the Bristol Fighter took over the duties of the "z\ Strutter". Here the designer added more power in the shape of a 250 h.p. Rolls-Royce Falcon water-cooled engine to improve performance. The vee-type engine gave a longer nose and, because it had a car-type radiator, the weight ahead of the wing could be balanced by moving the pilot aft of the wing. This, in turn, meant that pilot and observer were close together where they could operate as a team and this was one of the chief reasons why the "Brisfit" became one of the great successes of the First World War. Because of its greater weight the Bristol Fighter had larger span wings than the "1| Strutter" with more interplane struts to brace them. An unusual feature was the mounting of the fuselage between the wings, this raised the pilot, so that he was high enough to see both above and below the top plane.

The French never showed much interest in the two-seater fighter, possibly because of their liking for the romantic "ace" system, whereby they grouped their best pilots in crack escadrilles, such as the Cygognes. The Germans also developed some well-defended reconnaissance types of which one, the Hannoveraner, was virtually a two-seater fighter. Here the principle was the same as the Bristol—close-grouping of the crew, two guns, good view—but the result was achieved very differently. The German designer reduced the gap between his wings as much as possible so that by having a very deep fuselage he could give his crew the essential view above and below the top plane. He also gave the lower plane a smaller chord to make it less obstructive to downward view. A unique innovation was the narrowing and deepening of the rear fuselage to form the fin and the fitting of a biplane tail, both being refinements to improve the observer's rearward field of fire. This layout was made possible by having a plywood-covered fuselage , a popular practice in Germany, where timber was more plentiful than fabric under the Allied blockade.

Another "specialist" aeroplane born of the needs of the First World War was, of course, the bomber—though even at its zenith it was a very mild forerunner of those of the Second World War and the giants of today.

At first, bombs were hung by both belligerents on any aeroplane available that could lift them off the ground, and they were aimed with the crudest of sights, such as a cross wire and bead that permitted the pilot or observer to line the aeroplane on the target with an allowance for drift. Most twoseaters going into service were fitted to carry bombs, but as these were hung under the fuselage or wings they did little to influence the shape of the aeroplane. It soon became apparent that no single-engined aeroplane could carry enough bombs to cause much damage except for very short journeys. The two sides sent these single-engined bombers over by day to attack supply dumps, headquarters, fighter aerodromes and other targets close behind the lines—what we now call tactical targets connected with the armies in the field. Strategic bombing was, not unnaturally, a conception of the German mind —the bombing of open towns that is. It was in order to attack London, the centre of moral resistance in the reasoning of the Hun, that the multi-engined bomber was born. At that time colloquially known as the Gotha, the big twin-engined German bombers actually emanated from several other factories besides the Gothaer Waggenfabriek.

First requirements of the bomber were to lift more weight, both bombs and fuel, and to do this larger wings were the first essential, coupled with more power to pull them through the air. Speed was not much considered and instead a pattern of defensive fire was developed. The big German bombers were scaled up from the smaller aeroplanes of the day and a description of the most generally used type of Gotha is pretty representative of those which, during 1917 and early 1918, made heavy formation raids in daylight on London.

The Gotha's upper plane had a span of 77 ft., the lower slightly less, and the total wing area was just under 1,000 sq. ft. The wing structure was of wood, fabric covered, and with the contemporary forest of strut and wire interplane bracing. The fuselage was only 41 ft. long (about the same as a Meteor single-seater fighter) yet it housed a gunner/bomb-aimer in the nose, a pilot behind him and another gunner under the wing trailing edge with both upward and downward firing guns. A feature of the German bomber was the use of pusher engines (in the Gotha the 260 h.p. water-cooled Mercedes) which had a distinctive beat all their own that helped recognition. The bomb load was about 1,000 lb. and the total weight about

four tons (half and two-thirds of the Meteor, respectively) the cruising speed about 70 m.p.h., at 12,000 ft., yet this was the true progenitor of the Flying Fortress of the Second World War.

The Gothas were used in formation daylight raids where their concentrated fire made them almost impregnable— particularly against the ill-armed fighters retained for home defence at that time. So effective were the German bomber raids that crack fighter squadrons had to be withdrawn from the hard-pressed Western Front to combat them—a story repeated on the other foot with the Germans and the U.S.A.A.F. daylight raids in 1944. After the arrival of the fighters, the bombers came by night.

The British and French authorities did not do much about large aeroplanes until the Gotha attacks drove home to them the need for some reprisal weapon. Two British constructors were given the task of designing big bombers: Handley Page, who built the O/400 and V/1500 and Vickers, who made the Vimy. The first Handley Page, the O/100, built for the R.N.A.S., actually ante-dated the Gothas, but in its original form it was specially designed to drop large bombs on Zeebrugge, the U-boat base, a short-range target.

For its day the O/400 was a remarkable aeroplane; built on conventional lines it probably achieved the maximum in efficiency for its purpose that was possible with the knowledge then available. Its two 375 h.p. Rolls-Royce Eagle twelvecylinder water-cooled engines gave it a speed of 93 m.p.h. at 10,000 ft. With a wing span of 100 ft., area 1,630 sq. ft., it could lift over a ton of bombs for an all-up weight of 14,000 lb.

To allow stowage in canvas field hangars, the wings were made to fold. The capacious fuselage housed a gunner/observer in the nose, a pilot in a double cockpit which had spare dual controls, one or two rear gunners with both upward and downward firing Lewis guns, and the bombs, suspended by their noses. It was this internal bomb stowage that did much to give the O/400 its relatively good turn of speed and fully loaded radius of about 250 miles.

The Handley Page bomber was the first to be able to deliver a really good punch, but it soon became evident that losses were going to be high. One contributory reason for this was that, owing to faulty navigation, the first O/400 to go to France was delivered intact on a German aerodrome—thereby eliminating all the element of surprise! Shortages of engines in Britain, one of the most acute supply problems of the period, limited deliveries and so it was even more important to reduce losses. Because of this situation the heads of the R.F.C. decided to use the large bombers at night—and so was born the British policy of night bombing that was to achieve its mighty climax in the saturation raids on Germany in 1944.

The Handley Page V/1500 was an enlarged four-engined development that could carry over two tons of bombs and it had a gun position in the tail of the fuselage—another historic innovation. When the Armistice was signed three of these aeroplanes were ready to carry out an attack on Berlin. Another duty mooted for the V-1500, by an American, General Mitchell, was the dropping by parachute of a division of machine-gunners as a means of breaking the deadlock of trench warfare without the ghastly losses of "going over the top". So the V/1500 can be said to have a place in history nearly a quarter of a century ahead of its time.

One of the regular duties of the aeroplane throughout any war is its original role of reconnaissance. General reconnaissance into enemy territory was soon relegated to the faster twoseaters for which automatic cameras were developed to replace the relative inaccuracy of visual observation and verbal report . A special form of this work was spotting for artillery; a tedious operation consisting of flying up and down near the lines directing artillery fire by wireless telegraphy. Similar duties were carried out by kite balloons, so that it is obvious that a good vantage point for observation, rather than performance , was the prime consideration. Because of this, the duty was relegated to slow and otherwise useless aeroplanes, first the defenceless B.E.2C and later the cumbersome R.E.8— the initials R.E. stood for Reconnaissance Experimental. The latter, designed by the official Royal Aircraft Establishment, was an aeroplane of poor performance though remarkably stable—so stable in fact that there is a recorded occasion of one flying for several hours and landing perfectly after its crew had been killed. With an eight-cylinder vee air-cooled engine that had a large air scoop and tall exhaust stacks, a bent-up fuselage shape, huge overhang on the top plane and a wonderful array of wire bracing, it is scarcely surprising that this survival of pre-War practice should have been given the name of "Harry Tate" after the music-hall comedian whose sketches always included some troublesome piece of machinery.

It is a fact that the important functions of the artilleryobservation aeroplane have always been relegated to aeroplanes of poor performance even to this day.

These then were the main classes of aeroplane that came out of the First World War: the single-seater fighting scout, the single-engined two-seater reconnaissance light bomber, the multi-engined bomber and the flying-boat. Until 1917 only the two latter showed any very marked change other than a general "cleaning up" and, of course, the steady rise in engine power. In fact, the urgency of war probably retarded progress in aerodynamic and structural technique, because it was so much easier to put in a larger engine than wait for the results of painstaking research.

Most rapid development was in the field of the scouts of romantic single combat. By 1916 both sides were vieing with each other to make faster, more manoeuvrable aircraft. The combat height was steadily increasing, as first one side and then the other managed to gain the altitude that gave the initial advantage of a diving attack.

Power was the pre-requisite to each advance, but there was a significant difference between British and German fighters. The French had perfected the lightweight rotary engine, we in Britain had no good small water-cooled engine and so almost all our fighters had rotaries. The Germans were not successful with rotaries, relying on the Oberursel, a copy of the French Gnome, for their needs, but they did excel with reliable sixcylinder water-cooled engines. The result of this was that while in England we made light manoeuvrable single-seaters the Germans tended toward weight and speed. The French, on the other hand, realizing that the limit in power for the rotary was about 150 b.h.p. set to work and built a compact, light watercooled engine, the Hispano-Suiza vee eight of 150 to 200 h.p. This engine allowed designers to make aeroplanes with a combination of speed and manoeuvrability.

In 1916 the Allies had the Nieuport Scout, the Sopwith Pup and the Sopwith Triplane; each with a rotary engine, highly manoeuvrable and capable of about 105 m.p.h. The Nieuport and the Pup were tiny things, delightful to fly, and able to carry the pilot, one gun and fuel for about an hour and a half. Apart from the fact that the French designer chose to give his pilot a good view by having a large low-set top plane and very small lower plane—hence the name sesquiplane often applied to it—while the British engineer used fairly heavy stagger and a high-set top plane, they were similar in design.

The Sopwith Triplane was an attempt, and a successful one, to obtain a high rate of climb. In 1916 nothing was known about high-lift wing sections and the designers thought that

only the thinnest possible wing would give speed. Therefore they often sacrificed climb for speed when making that compromise which is represented by any aeroplane. By using three relatively small wings a very fast climb was attained with a compact, manoeuvrable aeroplane—and the pilot had an excellent all-round view. Unfortunately, structural knowledge was unsound in those days and the wings of the Triplane were weak and liable to come off in a fast dive. Despite its weakness the Triplane was a good fighter and with his "Black Maria" Flight-Lieutenant Raymond Collishaw, R.N.A.S., won both the D.S.C. and D.S.O. for shooting down twenty-nine German aeroplanes in June and July 1917. It is necessary to explain that Collishaw's Black Flight (so called because the planes of its five Canadian pilots were painted black) was part of No. 10' Squadron, a R.N.A.S. unit operating in France with the R.F.C. and later to become No. 210 Squadron R.A.F. j

At this period the outstanding German fighter was the Albatros. There were actually a series of them—like the Sopwith family—all very similar, of which the D I, D III and D V were the best. While we were content with 110 h.p., the Germans had gone up to 160 h.p.: where we had fabric-covered rectangular fuselages, they had gone to beautifully streamlined wooden monocoques—a real step forward had been made. The water-cooled engine and plywood fuselage increased the weight, which had to be catered for by an extra three or four feet in span, but against this slight loss could be set a gain of some 15-20 m.p.h. in speed. Everything in the Albatros was as clean as it could be made; the engine was almost completely cowled, low-drag surface radiators were used and wing bracing was kept to a minimum.

The Allies' reply to the Albatros was threefold. The French came up with the SPAD S-7, Britain with the Sopwith Camel and the S.E.5. The first of these was a compact little aeroplane with a 150 h.p. Hispano-Suiza water-cooled engine which had the speed of the Albatros, coupled with great strength and manoeuvrability. By careful use of fabric over light wooden formers an excellently streamlined fuselage was obtained and the tiny wings were sturdily strutted and wired for strength without too much drag.

The Camel lacked the grace of the French machine, but it was small and it had a 130 h.p. Clerget rotary. This resulted in extreme manoeuvrability, to the point of being tricky to fly, because reaction to the flywheel effect of the rotating engine was always trying to throw the aeroplane round the opposite

way. However, if a Camel pilot lived to go into action he became a great fighter for, properly handled, it could outmanoeuvre anything else, particularly in right-hand turns. Used by both the R.F.C. and the R.N.A.S., the Camel accounted for nearly 1,300 enemy aeroplanes, including a considerable number of night bombers.

The S.E.5 was yet another approach to the fighting scout layout. Designed at the Royal Aircraft Establishment by H. P. Folland, this was a neatly straightforward, one might say classic, aeroplane with the 150 h.p. Hispano-Suiza—later as the S.E.5a with either a 200, 220 or 240 h.p. engine. Generally compact and with nothing superfluous, the S.E. had a similar performance to the Albatros without resort to monocoque fuselage or surface radiator, just plain fabric and car-type honeycomb. It had, too, a curious armament; one synchronized Vickers gun and one Lewis gun on a rail arranged to fire above the airscrew. The idea behind this was that the synchronizing gear halved the fire rate of the Vickers gun, while the Lewis was uninterrupted. It is amazing, though, how pilots used to pull down the butt of their Lewis gun and change a heavy drum of ammunition in the blast of the slipstream while flying the aeroplane in the violent manoeuvring of combat.

The main criticism of the S.E., which was at one time the mount of our greatest aces Mick Mannock, Billy Bishop, James McCudden, is that it was too stable for a fighter; but that is a matter of opinion and an argument that has not been settled to this day.

The Germans, or rather their Dutch employee Antony Fokker, had the final word in the fighter struggle with the D VII, the best all-round aeroplane of them all. The D VII was outstanding as an aeroplane not only for its performance but for its design, both structurally and aerodynamically. In 1917 Fokker had already broken with tradition when he designed a triplane, the D.R.1, with unbraced wings, but although this had been the favourite mount of the German ace of aces Manfred von Richthofen, it had proved weak like the Sopwith and was discarded. In his biography Fokker wrote that the first version of his new biplane had no wing struts at all and, being a pilot, he had himself thrown it about in front of the High Command to prove its strength. Officialdom was, however, unconvinced , so Fokker re-submitted his design with light (dummy) struts between the wings—and it was accepted! In 1918 aluminium was a light, soft metal used for cowlings, while its alloys were used in engines and were virtually unknown in the airframe. Steel was the only metal for fittings and because of its weight the quantity was restricted. Fokker decided to change this. The fuselage of his D VII was made of a framework of welded mild steel tubes at a time when welding was considered a very doubtful process—good and bad welds look alike and can only be checked by breaking them or using X-rays, hence the distrust. He further used welded steel tubes for the framework of the tail and streamlined steel tubes for wing struts and undercarriage. The wings were made in one piece each, the lower one bolted to the bottom of the fuselage, the upper supported by struts from the top and bottom longerons of the fuselage. The N-shaped interplane struts, if we are to believe Antony Fokker, were for confidence only— they were certainly lightly made. The fuselage shape was simple and more British than German, as was the nose radiator,

Fokker wing construction

two Spandau machine-guns were mounted on the cowling. The wing was the most unconventional component: instead of a thin "high-speed" wing the aerofoil section was thick and highly curved, moreover it tapered in thickness from root to tip. These dimensions made possible what engineers call a cantilever, or self-bracing, structure and this was the historically important feature of the D VII. The internal structure, with two box spars and plywood web ribs, was quite new and was really the beginning of the structure of an aeroplane wing as we know it today, even though wood and fabric were used instead of light alloy.

Also in Germany at the end of the war was another advanced development, for a new company, Junkers, had started to make all-metal aeroplanes of a peculiar type. The first of these was a large biplane, rather like an overgrown and clumsy edition of the D VII, which was heavily armoured, and was used for ground attack—another new duty. The resemblance between these aeroplanes and the later Fokkers was not surprising , since the companies were working together; Fokker

supplied the aerodynamic knowledge, Junkers their engineering experience and facilities. The armoured ground attack biplane was a dead-end experiment as an aeroplane, but it introduced the familiar Junkers corrugated aluminium loadcarrying skin for the first time. It was followed by two lowwing monoplanes that were the progenitors of the long line of Junkers commercial aeroplanes that came out between the Wars—so another milestone had been reached.