Aviation in World War I

About ten years after the Wright brothers made the first powered flight, there was still much to be improved upon. Because of limitations of the engine power of the time, the effective payload of aircraft was extremely limited. They were made mostly of hardwood (braced with steel wires) and linen fabric doped with flammable liquid to give them the stiffness required to form a wing surface. Aside from these primitive materials, the rudimentary aviation engineering of the time meant most aircraft were structurally fragile by later standards, and not infrequently broke up in flight especially when performing violent combat maneuvers such as pulling up from steep dives.

As early as 1909, these evolving flying machines were recognised to be not just toys, but weapons:

In 1911, Captain Bertram Dickson, the first British military officer to fly, also correctly prophesied the military use of aircraft. He predicted aircraft would first be used for reconnaissance, but this would develop into each side trying to "hinder or prevent the enemy from obtaining information", which would eventually turn into a battle for control of the skies. This is exactly the sequence of events that would occur several years later.

The first operational use of aircraft in war took place on 23 October 1911 in the Italo-Turkish War, when Captain Carlo Piazza made history’s first reconnaissance flight near Benghazi in a Blériot XI.

The early years of war

From the very start, there was some debate over the uses (or usefulness) of aircraft in warfare. Many senior officers, in particular, remained skeptical.

In Germany the great successes of the early Zeppelin airships had largely overshadowed the importance of heavier-than-air aircraft. Out of a paper strength of about 230 aircraft belonging to the army in August 1914 only 180 or so were of any use. The French military aviation exercises of 1911, 1912, and 1913 had pioneered cooperation with the cavalry (reconnaissance) and artillery (spotting), but the momentum was if anything slacking. Great Britain had "started late" and initially relied largely on the French aircraft industry, especially for aircraft engines. The initial British contribution to the total allied airwar effort in August 1914 (of about 184 aircraft) was three squadrons with about 30 serviceable machines.The US army and navy air services were hopelessly behind – even in 1917, when the United States entered the war, they were to be almost totally dependent on the French and British aircraft industries for combat aircraft.

The initial campaigns of 1914 proved that cavalry could no longer provide the reconnaissance expected by their generals, in the face of the greatly increased firepower of Twentieth century armies. It was quickly realised, on the other hand, that aircraft could at least locate the enemy – even if early air reconnaissance was hampered by the newness of the techniques involved. Early scepticism and low expectations quickly turned to unrealistic demands beyond the capabilities of the primitive aircraft available. Even so, air reconnaissance played a critical role in the "war of movement" of 1914, especially in helping the Allies halt the German invasion of France. On August 22, 1914, British Captain L.E.O. Charlton and Lieutenant V.H.N. Wadham reported German General Alexander von Kluck’s army was preparing to surround the BEF, contradicting all other intelligence. The British High Command listened to the report and started a withdrawal toward Mons, saving the lives of 100,000 soldiers. Later, during the First Battle of Marne, observation planes discovered weak points and exposed flanks in the German lines, allowing the allies to take advantage of them.The Germans' great air "coup" of 1914 (at least according to contemporary propaganda) was at the Battle of Tannenberg in East Prussia where an unexpected Russian attack was reported by Lts. Canter and Mertens, resulting in the Russians' being forced to withdraw.

Early "Western Front" reconnaissance duties

Late in 1914 the lines between the Germans invading France and the Allies stretched from the North Sea to the Alps. The initial “war of movement” largely ceased, and the front became static. Three main functions of short range reconnaissance squadrons had emerged by March 1915.

The first was photographic reconnaissance - building up a complete mosaic map of the enemy trench system. The first air cameras used glass plates (“Kodak” cellulose film had been invented, but did not have sufficient resolution).

Artillery “spotting” – enabled the ranging of artillery on targets invisible to the gunners. Radio telephony had not been invented, so communication was a problem. By March 1915, a two seater on “artillery observation” duties was typically equipped with a primitive radio transmitter transmitting the clicks of a Morse key, but had no receiver. The artillery battery signalled to the aircraft by laying strips of white cloth on the ground in prearranged patterns. These duties were shared with the observation balloon, tethered to the ground. Balloonists could communicate directly with their batteries by field telephone, but were obviously far less flexible in locating targets and reporting the fall of shot.

“Contact patrol” work (called Infanteriefliegerdienst by the Germans) attempted to follow the course of a battle by communicating with advancing infantry while flying over the battlefield. The technology of the period did not permit radio contact, and methods of signalling were necessarily crude, and included dropping messages from the aircraft. Soldiers were naturally reluctant to reveal their positions to aircraft, as it was difficult for them to distinguish between friend and foe.

Early bombing efforts

Typical 1914 aircraft could carry only very small bomb loads - the bombs themselves, and their stowage, were still very elementary, and effective bomb sights were still to be developed. Nonetheless the beginnings of strategic and tactical bombing date from the earliest days of the war. Notable are the raids by the RNAS on the German airship sheds at Dusseldorf, Cologne and Friedrichhafen in September, October and November 1914, as well as the formation of the Brieftauben Abteilung Ostende (or "Ostend carrier pigeon detachment", cover name for the first German strategic bombing unit), which mounted the first token raid over the English Channel in December 1914.

The dawn of air combat

As Dickson had predicted, initially air combat was extremely rare – and definitely subordinate to reconnaissance. There are even numerous stories of the crew of rival reconnaissance aircraft exchanging nothing more belligerent than smiles and waves. This soon progressed to throwing bricks, grenades, and other objects, even rope, which they hoped would tangle the enemy aircraft's propeller. The first aircraft brought down by another was an Austrian resonnaissance rammed on September 8, 1914, by Russian pilot Pyotr Nesterov in Galicia in the Eastern Front (both planes crashed as the result of the attach killing all occupants). Eventually pilots began firing handheld firearms at enemy aircraft. The era of air combat proper, began as more and more aircraft were fitted with machine guns.

Problems mounting machine guns

The pusher solution

As early as 1912, designers at the British firm Vickers were experimenting with machinegun-carrying aircraft – the first concrete result was the Vickers EFB.1, which was featured at the 1913 aero show and appeared in developed form as the FB.5 in February 1915. This pioneering fighter, like the Royal Aircraft Factory FE.2b and the Airco DH.1 were pusher types. The pusher design had the engine and propeller behind the pilot, facing backward, rather than in front, as in a tractor type. This provided an optimal machinegun position, which could be fired directly forward without an obstructing propeller, and reloaded and cleared in flight. The drawback was, pusher designs – because of the struts and rigging necessary to hold their tail units, and the extra drag this entailed – tended at best to have an inferior performance to tractor types with the same engine power. Although the FE.2d, a more powerful version of the FE.2b, remained a formidable opponent well into 1917, pusher fighters were already obsolete – on the whole they failed in a most important criterion, being too slow to catch their quarry.

Machine gun synchronisation

The forward firing gun of a pusher "gun carrier" provided some offensive capability – the mounting of a machine gun firing to the rear from a two seater tractor aircraft gave defensive capability. There was an obvious need for some means to fire a machine gun forward from a tractor aircraft – especially from one of the small, light, "scout" aircraft, adapted from pre-war racers, that were to perform most air combat duties for the rest of the war. It would seem most natural to place the gun between the pilot and the propeller, to be able to aim it as well as service it during a gun jam. However, this presents an obvious problem, a percentage of the bullets will actually strike the propeller, quickly destroying it.

Early experiments with synchronised machine guns were carried out before the war in several countries. Franz Schneider – the former Nieuport designer now working for the L.V.G. concern in Germany patented a synchronisation gear on July 15, 1913. An early Russian gear was designed by a Lieutenant Poplavko, and the Edwards Brothers in England designed the first British example. Finally – the Morane-Saulnier company were working on the problem in 1914. All these early gears failed to attract official attention – partly due to official inertia – but partly also due to the terrifying results of failures of these early synchronising gears, which included dangerously ricocheting bullets as well as disintegrating propellers.

The Lewis gun, used on many early Allied aircraft, proved next to impossible to successfully synchronise due to its open bolt firing cycle. In an open bolt firing cycle, it is impossible to predict the exact time any given round will fire, and for obvious reasons this is a unattractive characteristic in a weapon one is attempting to fire between the spinning blades of a propeller. Photographs of apparently synchronised Lewis gun mountings on RNAS were probably in fact free firing - hardly a satisfactory solution.

Diagram of Fokker's "Zentralsteuerung" synchronization mechanism. Pulling the green handle lowers the red cam follower onto the cam wheel attached to the propeller shaft. When the cam raises the follower, the blue rod is depressed against the spring, enabling the yellow trigger plate to be reached when the purple firing button is pressed. This image shows a side view of one of the original Spandau LMG 08 guns, somewhat different in appearance from the LMG 08/15 later German fighters used.

The Maxim guns used by both the Allies (as the Vickers) and Germany (as the LMG 14 Parabellum and LMG 08 Spandau) had a closed bolt firing cycle that started with a bullet already in the breech and the breech closed, so the firing of the bullet was the next step in the cycle. This meant that the exact instant the round would be fired could be predicted with precision, making these weapons considerably easier to synchronize.

The standard French light machine gun, the Hotchkiss, was also most unamenable to synchronisation due to rounds "hanging fire" – and the Morane-Saulnier company designed a "safety backup" in the form of "deflector blades" (metal wedges) fitted to the propeller at the point where they would be struck by a bullet. Roland Garros trialled this system in a Morane-Saulnier L in April 1915. He managed to score several kills, but it was proved to be an inadequate and dangerous solution. Garros eventually was forced by engine failure (possibly caused by the repeated strain on his aircraft's crankshaft of the "deflected" bullets striking his propeller) to land behind enemy lines, and he, and his aircraft, were captured by the Germans.

Famously – the German High Command passed Garros' Morane to the Fokker company, who already produced Morane type monoplanes for the German Air Service – with orders to copy the latest design. The deflector system was totally unsuitable for the steel jacketed German ammunition so that the Fokker engineers were forced to revisit the synchronisation idea (perhaps infringing Schneider's patent) – resulting in the Eindecker fighter series. Crude as these little monoplanes were, they produced a period of German air superiority, known as the "Fokker Scourge" by the Allies. The psychological effect exceeded the material - the Allies had up to now been more or less unchallenged in the air, and the vulnerability of their older reconnaissance aircraft, especially the British B.E.2 and French Farman pushers, came as a very nasty shock.

Other methods

Another method used at this time to fire a machine gun forward from a tractor design was to mount the gun to fire above the propeller arc. This required the gun to be mounted on the top wing of biplanes and be propped up and secured by complicated, drag inducing mounting in monoplanes. Reaching the gun so that drums or belts could be changed, or jams cleared, presented problems – even when the gun could be mounted relatively close to the pilot. Eventually the excellent Foster mounting became more or less the standard way of mounting a Lewis gun in this position in the R.F.C.- this allowed the gun to slide backward for drum changing, and also to be fired at an upward angle, a very effective way of attacking an enemy from the "blind spot" under his tail. This type of mounting was still only possible for a biplane with a top wing positioned near the apex of the propeller's arc - it put considerable strain on the fragile wing structures of the period, and it was much less rigid than a gun mounting on the fuselage - producing a greater "scatter" of bullets, especially at anything but very short range.

The earliest versions of the Bristol Scout to see aerial combat duty in 1915, the Scout C, had Lewis gun mounts in RNAS service that sometimes were elevated above the propeller arc, and sometimes (in an apparently reckless manner) firing directly through the propeller arc without synchronisation. Captain Lanoe Hawker of the Royal Flying Corps, however, had mounted his Lewis gun just forward of the cockpit to fire forwards and outwards, on the left side of his aircraft's fuselage at about a 30º angle, on his Scout C, with serial number 1611, and with this aircraft on July 25, 1915, managed to defeat three German two seat observation aircraft to earn the first Victoria Cross awarded to a British aviator.

1915: The Fokker Scourge

The first purpose-designed fighter aircraft included the British Vickers F.B.5 - machine gun armament was also fitted to several French types, such as the Morane-Saulnier L and N. Initially the German Air Service lagged behind the Allies in this respect - but this was soon to change dramatically.

In August 1915 the Fokker E.I became operational — this was the first type of aircraft to enter service with a "synchronization gear" (often referred to mistakenly as an "interrupter gear"), which enabled a machine gun to fire through the arc of the propeller without striking its blades. This constituted an important advantage over other contemporary fighter aircraft. This aircraft and its immediate successors - also commonly known as the Eindecker (German for "Monoplane") for the first time supplied an effective equivalent to Allied fighters.

By late 1915 the Germans had achieved air superiority, making Allied access to vital intelligence derived from continual aerial reconnaissance more dangerous to acquire. In particular the essential defencelessness of Allied reconnaissance types was exposed. The first German "ace" pilots - notably Max Immelmann had begun their careers.

The number of actual Allied casualties involved was for various reasons very small compared with the intensive air fighting of 1917/18. The deployment of the eindeckers was less than overwhelming - the new type was issued in ones and twos to existing reconnaissance squadrons - and it was to be nearly a year before the Germans were to follow the British in establishing specialist fighter squadrons. The eindecker was also, in spite of its advanced armament, by no means an outstanding aircraft - being closely based on a pre-war French racer.

Nonetheless - the moral impact of the fact that the Germans were fighting back in the air, and effectively too, created a major scandal in the British press. The ascendency of the eindecker also contributed to the surprise the Germans were able to achieve at the start of the Battle of Verdun - as the French reconnaissance aircraft failed to provide their usual cover of the German positions.

Fortunately for the Allies, two new British fighters were already in production which were a technical match for the Fokker, the F.E.2b and the D.H.2. These were both "pushers" and could fire forwards without gun synchronisation. The F.E.2b reached the front in September 1915, and the D.H.2 in the following February. On the French front, the tiny Nieuport 11, a tractor biplane with a forward firing gun mounted outside the arc of the propeller (on the top wing) also proved more than a match for the German fighter when it entered service in January 1916. With these new types the Allies re-established air superiority in time for the Battle of the Somme, and the "Fokker Scourge" was over.

The Fokker E-III, Airco DH-2, and Nieuport 11 would be the very first in a long line of single seat fighter aircraft used by both sides during the war. Very quickly it became clear the primary role of fighters would be attacking enemy two-seaters, which were becoming increasingly important as sources of reconnaissance and artillery observation, while also escorting and defending friendly two-seaters from enemy fighters. Fighters were also used to attack enemy observation balloons, strafe enemy ground targets, and defend friendly airspace from enemy bombers.

1916: Battle of the Somme

In the aftermath of the Fokker Scourge the need for a larger, better equipped RFC became obvious, and the process of raising many new squadrons was started. In the short term creating new units was easier than producing aircraft to equip them, and training pilots to man them. When the Battle of the Somme started in July 1916 most ordinary RFC squadrons were still equipped with the BE.2c - the same aircraft that had proved such an easy target for the Fokker Eindecker - new types such as the Sopwith 1½ Strutter had to be transferred from production intended for the RNAS. Even more seriously, replacement pilots were being sent to France with pitifully few flying hours.

Nonetheless, air superiority and an "offensive" attitude facilitated the greatly increased involvement of the RFC in the battle itself, in what was known at the time as "trench staffing" - in modern terms close support. For the rest of the war this became a regular routine, with both the attacking and defending infantry in a land battle being constantly liable to attack by machine guns and light bombs from the air. At this time, counter fire from the ground was far less effective than it became later, when the necessary techniques of deflection shooting had been mastered.

Allied air superiority was maintained during the battle, and the increased effectiveness of Allied air activity proved disturbing to the German High Command . A complete reorganisation of the German Luftstreitkräfte followed. This reorganisation eventually produced the German strategic bombing squadrons that were to produce such consternation in England in 1917 and 1918, and the specialist close support squadrons (Schlachtstaffeln) that gave the British infantry such trouble at Cambrai and during the German Spring offensive of 1918 - but its most dramatic effect involved the raising of specialist fighter squadrons or Jagdstaffeln. By the end of 1916 these units, equipped with the new Albatros fighters, had reestablished German air superiority, in spite of their having been formed a full year after similar units had become part of the RFC and the French Aéronautique Militaire.

1917: Bloody April

The first half of 1917 marked a period of German air superiority. These were successful months for the jagdstaffeln and the much larger RFC suffered significantly higher casualties than their opponents. While new Allied fighters such as the Sopwith Pup, Sopwith Triplane, and SPAD S.VII were coming into service, at this stage their numbers were small. On the other hand, the jagdstaffeln were equipped with the new Albatros D.III, which was, in spite of some structural difficulties, "the best fighting scout on the Western Front" at the time. Meanwhile, most RFC two-seater squadrons still flew the BE.2e, a very minor improvement on the BE.2c.

This culminated in the rout of April 1917, known as "Bloody April". The RFC suffered particularly severe losses, although Trenchard's policy of "offensive patrol", placing most of their flying on the German side of the lines, was maintained.

During the last half of 1917, the British Sopwith Camel and S.E.5a and the French SPAD S.XIII became available in numbers. The ordinary two seater squadrons in the RFC received the R.E.8 or the F.K.8, not outstanding warplanes, but far less vulnerable than the BE.2e they replaced. The F.E.2d at last received a worthy replacement in the Bristol F.2b. On the other hand the latest Albatros, the D.V proved to be a disappointment, as was the Pfalz D.III. The exotic Fokker Dr.I was plagued, like the Albatros, with structural problems. By the end of the year the air superiority pendulum had swung once more in the Allies' favour.

Up to 1918: the final years of war

The final year of the war (1918) saw increasing shortages of supplies on the side of the Central Powers. Captured Allied aircraft were scrounged for every available material, even to the point of draining the lubricants from damaged engines just to keep one more German aircraft flyable.

Manfred von Richthofen, the famed Red Baron credited with around 80 victories, was killed in April, possibly by an Australian anti-aircraft machinegunner (although Royal Air Force pilot Captain Arthur Roy Brown was officially credited), and the leadership of Jagdgeschwader 1 eventually passed to Hermann Göring.

Germany introduced the Fokker D.VII, both loved and loathed to the point that the surrender of all surviving examples was specifically ordered by the victorious Allies.

This year also saw the United States increasingly involved. While American volunteers had been flying in Allied squadrons since the early years of the war, not until 1918 did all-American squadrons begin patrolling the skies above the trenches. At first, the Americans were largely supplied with second-rate weapons and obsolete aircraft, such as the Nieuport 28. As American numbers grew, equipment improved, including the SPAD S.XIII, one of the best French aircraft in the war.

Impact

By the war's end, the impact of air missions on the ground war was in retrospect mainly tactical - strategic bombing, in particular, was still very rudimentary indeed. This was partly due to its restricted funding and use, as it was, after all, a new technology. Some, such as then-Brigadier General William "Billy" Mitchell, commander of all American air combat units in France, claimed "the only damage that has come to [Germany] has been through the air". Mitchell was famously controversial in his view that the future of war was not on the ground or at sea, but in the air:

Anti-aircraft weaponry

Though aircraft still functioned as vehicles of observation, increasingly it was used as a weapon in itself. Dog fights erupted in the skies over the front lines - aircraft went down in flames and heroes were born. From this air-to-air combat, the need grew for better aircraft and gun armament. Aside from machineguns, air-to-air rockets were also used, such as the Le Prieur rocket against balloons and airships. Recoilless rifles and autocannons were also attempted but they pushed early fighters to unsafe limits while bringing negligible returns. Another innovation was air-to-air bombing if a fighter had been fortunate enough to climb higher than an airship. The Ranken dart, an incendiary bomb, was designed just for this opportunity.

This need for improvement was not limited to air-to-air combat. On the ground, methods developed before the war were being used to deter enemy aircraft from observation and bombing. Anti-aircraft artillery rounds were fired into the air and exploded into clouds of smoke and fragmentation, called archie by the British.

Anti-aircraft artillery defenses were increasingly used around observation balloons, which became frequent targets of enemy fighters equipped with special incendiary bullets. Because balloons were so flammable, due to the hydrogen used to inflate them, observers were given parachutes, enabling them to jump to safety. Ironically, only a few aircrew had this option, due in part to a mistaken belief they inhibited aggressiveness, and in part to early aircraft being unable to lift their significant weight.

Bombing and reconnaissance

As the stalemate developed on the ground, with both sides unable to advance even a few hundred yards without a major battle and thousands of casualties, aircraft became greatly valued for their role gathering intelligence on enemy positions and bombing the enemy's supplies behind the trench lines. Large aircraft with a pilot and an observer were used to scout enemy positions and bomb their supply bases. Because they were large and slow, these aircraft made easy targets for enemy fighter aircraft. As a result, both sides used fighter aircraft to both attack the enemy's two-seat aircraft and protect their own while carrying out their missions.

While the two-seat bombers and reconnaissance aircraft were slow and vulnerable, they were not defenseless. Two-seaters had the advantage of both forward- and rearward- firing guns. Typically, the pilot controlled fixed guns behind the propeller, similar to guns in a fighter aircraft, while the observer controlled one with which he could cover the arc behind the aircraft. A tactic used by enemy fighter aircraft to avoid fire the from the rear gunner was to attack from slightly below the rear of two-seaters, as the tail gunner was unable to fire below the aircraft. However, two-seaters could counter this tactic by going into a dive at high speeds, aided by their heavy weight. Pursuing a diving two-seater was hazardous for a fighter pilot, as it would place the fighter directly in the rear-gunner's line of fire; several high scoring aces of the war were shot down by "lowly" two-seaters, including Raoul Lufbery and Robert Little.

Strategic bombing

The first ever aerial bombardment of civilians was during World War I. On January 19, 1915, two German Zeppelins dropped 24 fifty-kilogram high-explosive bombs and ineffective three-kilogram incendiaries on Great Yarmouth, Sheringham, King's Lynn, and the surrounding villages. In all, four people were killed, sixteen injured, and monetary damage was estimated at £7,740, although the public and media reaction were out of proportion to the death toll.

There were a further nineteen raids in 1915, in which 37 tons of bombs were dropped, killing 181 people and injuring 455. Raids continued in 1916. London was accidentally bombed in May, and, in July, the Kaiser allowed directed raids against urban centres. There were 23 airship raids in 1916 in which 125 tons of ordnance were dropped, killing 293 people and injuring 691. Gradually British air defenses improved. In 1917 and 1918 there were only eleven Zeppelin raids against England, and the final raid occurred on August 5, 1918, which resulted in the death of KK Peter Strasser, commander of the German Naval Airship Department. By the end of the war, 51 raids had been undertaken, in which 5,806 bombs were dropped, killing 557 people and injuring 1,358.

The Zeppelin raids were complemented by the Gotha G bombers from 1917, which were the first heavier than air bombers to be used for strategic bombing. It has been argued that the raids were effective far beyond material damage in diverting and hampering wartime production, and diverting twelve squadrons and over 10,000 men to air defenses. The calculations which were performed on the number of dead to the weight of bombs dropped would have a profound effect on the attitudes of the British authorities and population in the interwar years.

Observation balloons

Manned observation balloons floating high above the trenches were used as stationary reconnaissance points on the front lines, reporting enemy troop positions and directing artillery fire. Balloons commonly had a crew of two equipped with parachutes: upon an enemy air attack on the flammable balloon, the crew would parachute to safety. Recognized for their value as observer platforms, observation balloons were important targets of enemy aircraft. To defend against air attack, they were heavily protected by large concentrations of antiaircraft guns and patrolled by friendly aircraft. Blimps and balloons helped contribute to the stalemate of the trench warfare of World War I, and contributed to air to air combat for air superiority because of their significant reconnaissance value.

In order to encourage their pilots to attack enemy balloons whenever they were found, both sides counted downing an enemy balloon as an "air-to-air" kill, with the same value as shooting down an enemy aircraft. Some pilots, known as balloon busters, became particularly distinguished by their prowess at shooting down enemy balloons. Perhaps the best known of these was American ace Frank Luke: 14 of his 18 kills were enemy balloons.