Aviation Technology in World War I

In 1914, all countries of the world entered the war with aircraft without any weapons except for the personal weapons of the pilots ( rifle or pistol ). As aeronautical reconnaissance increasingly began to affect the course of hostilities on the ground, arose the need for weapons capable of preventing enemy attempts to penetrate into the airspace. It quickly became clear that the fire from hand weapons in an air battle was practically useless.

In early 1915, the British and the French began to put the first machine-gun armament on aircraft. Since the propeller hindered the firing, initially the machine guns were placed on the machines with a pushing screw located from the rear and not interfering with the fire in the nasal hemisphere. The first fighter in the world was the British Vickers FB5 , specially built for air combat with the help of a turret mounted machine gun. Nevertheless, the design features of the aircraft with the propeller screw at the time did not allow for the development of sufficiently high speeds, and the interception of high-speed scouts was difficult.

After some time, the French offered to solve the problem of shooting through the screw: metal covers on the lower parts of the blades. The bullets that hit the lining were reflected without damaging the wooden propeller. This decision proved to be no more than satisfactory: firstly, the ammunition was quickly wasted due to the hit of a part of the bullets in the propeller blades, and secondly, the impacts of the bullets still gradually deformed the propeller . Nevertheless, due to such temporary measures, the Entente aviation managed to gain for a while the preponderance over the Central Powers.

On April 1, 1915, Sergeant Garro on the Morane-Saulnier L fighter was first shot down by a machine gun firing through a rotating propeller of an airplane. Not to damage the screw allowed metal reflectors installed on the Garro plane after the visit of the company Moran-Solnier . By May 1915, Fokker had developed a successful version of the synchronizer. This device allowed to fire through the screw of the aircraft: the mechanism allowed the gun to fire only when there was no blade in front of the barrel. The synchronizer was first installed on the Fokker EI fighter .

The appearance of squadrons of German fighters in the summer of 1915 was completely unexpected for the Entente: all its fighters had an outdated scheme and were inferior to the Fokker apparatus. From the summer of 1915 to the spring of 1916, the Germans dominated the sky over the Western Front, ensuring a significant advantage. This position began to be called ” Beach of Fokker ”

Only in the summer of 1916, the Entente managed to restore the situation. The arrival on the front of maneuverable light biplanes of British and French designers , superior in maneuverability to the early Fokker fighters, made it possible to change the course of the war in the air in favor of the Entente. Initially, the Entente was experiencing problems with synchronizers, so usually the machine guns of the Entente fighters of that time were located above the propeller, in the upper biplane wing.

The Germans responded by the appearance of new Albatros D.II biplanes in August 1916, and Albatros D.III in December, which had a streamlined fuselage of the semi – monocoque type . Due to a more durable, lightweight and streamlined fuselage , the Germans gave their cars the best flight performance. This allowed them to once again get a significant technical advantage, and April 1917 went down in history as a “bloody April”: the Entente aviation again began to suffer heavy losses.

During April 1917, the British lost 245 aircraft, 211 pilots were killed or went missing and 108 were taken prisoner . The Germans lost only 60 airplanes in battle. This clearly demonstrated the advantage of the semi-monococcal regimen over previously used ones.

The Entente’s reply, however, was quick and effective. By the summer of 1917, the appearance of new fighters Royal Aircraft Factory SE5 , Sopwith Camel and SPAD, allowed to restore the state of affairs in the air war. The main advantage of the Entente was the best state of the Anglo-French engine building. In addition, since 1917, Germany began to experience a severe shortage of resources.

As a result, by 1918, the aviation of the Entente achieved both qualitative and quantitative superiority in the air over the Western Front. German aviation was no longer able to claim more than a temporary achievement of local domination on the front. In an attempt to reverse the situation, the Germans tried to develop new tactical methods (for example, during the summer offensive of 1918, air strikes were first widely used at airfields to destroy enemy aircraft on the ground), but such measures could not change the overall unfavorable situation .


The motors
Almost all of the first airplanes that entered the World War had common features such as high stability and the presence of a “push” engine.

The first feature is linked to the need to provide inexperienced drivers, many of whom entered into combat after only three or four hours of training, a device that allowed them to correct their errors and to return happily to the base. The need for stability was also linked to the characteristics of the reconnaissance flight, which provided for a straight flight at a constant height to be able to take clear images of the terrain. When the pilots’ experience increased, it was possible to build more unstable devices that allowed them to perform difficult maneuvers during combat.

The second feature, taken from the traditional Flyer 1 model of the Wright brothers , remained until it was estimated that visibility was more important than speed. But the evolution of air combat features increasingly demanded aircraft designers to create devices with high speed, maneuverability and high service ceiling, and the “push” engine quickly became obsolete.

From the point of view of the evolution of the engines, the First World War also marked the overcoming of the rotating engine . The latter is characterized by the presence of rotating pistons around the central axis of the engine, and by the use of air cooling . To guarantee good performance in terms of power / weight ratio, these were widely exceeded by online engines , cooled by water . The rotating motors, however, remained in use throughout the course of the conflict, so that in 1918 Sopwith still continued to produce them.

Even in the arms point of view, the plane experienced a strong and rapid development, also linked to rapid changes in operating conditions.

Initially, pilots carried their personal weapons, such as pistols and rifles, to face armed confrontations with other planes, or launched hand grenades against troops on the ground.

As the conflict progressed, the increase in power of the engine allowed us to carry an ever-increasing weight of payload on board and mobile machine gun could be mounted on board. They were mounted on the front, where they could be used directly by the pilot, but there were also numerous versions on the back, in biplane observers / bomber aircraft such as Sopwith 1½ Strutter English or Caproni Ca.3 Italian. The front machine guns were mounted in planes where initially it could be shot over the radiusrotation, with obvious driving difficulties for the pilot. The following invention was the interruption mechanism, which allowed to shoot without impact against the propeller and that allowed to mount the machine guns in a fixed position, with obvious positive effects in terms of usability. Another improvement was the development and refinement of the point of view, and the installation of the trigger in the steering lever.

In spite of the technological evolution of the armament on board, the pilots still had with them their pistol. It was not strange that, in the event that the plane was ignited during the combat, and given the lack of a escape route (the parachute , first tested in 1912, was not yet used) use of the gun allowed them to have a quick and painless death. In this regard, recent research has suggested that even the Italian Italian Francesco Baracca died in this way.

Problems with the installation of machine guns

The Propeller Propulsion Solution
In 1912, the designers of the British company Vickers experimented with airplanes equipped with machine guns. The first result was Vickers EFB.1 , which was presented in an air show in 1913, and in February 1915 it was improved with the Vickers FB5 .

These pioneers of combat aircraft, such as the Royal Aircraft Factory FE2 and the Airco DH.1 , had a propulsion configuration. This arrangement, in which the engine and helix are behind the pilot, offered an optimal position for machine guns, which could fire directly forward without being hindered by the propeller. However, this option offers less power than a “classical” arrangement, because the elements needed to maintain the tail, the hardest to install due to the helix, which increased the resistance. This did not stop the FE2d, a more powerful version of the FE2, becoming a formidable opponent, although as of 1917 aircraft of this type were too slow to catch the opponent.

Synchronization of machine guns
In a device where the helix is located behind, the machine gun on the front provides offensive capability, while in a two-seater plane of conventional design, the machine gun on the back gives defensive capability to the aircraft. So there was a strong demand for a system that allowed the placement of the machine gun and the propeller in the front, especially in the single-seaters that would carry out most of the war battles. It seemed natural to put the machine gunner between the helix and the pilot so that you could aim and shoot during an air combat, but this configuration had an obvious problem, some of the bullets impacted the helix and quickly destroyed it.

The first interrupted shooting tests were carried out before the war in many countries. On July 15, 1913, Franz Schneider , former editor of the Nieuport, joined the Luftverkehrsgesellschaft and patented a synchronization system. The Russian brothers Poplavko and Edwards developed a similar system, conceiving the first British device. All these devices failed to attract the attention of the senior officers due to a certain inertia and the terrible results and errors, which included the bullets that bounced the pilot and the destruction of the helix.

The Lewis Mark I machine gun , used in most of the first Allied aircraft, was impossible to synchronize due to its open bolt cycle . In this configuration, when one wanted to shoot he had to advance the relay, load the next bullet and pull the bolt back to lock and be able to shoot. Therefore, it was impossible to predict the exact moment of the bullet’s exit, which is annoying when it is wanted to shoot between the shafts of a helix.

The Maxim machine gun , used by the Allies ( heavy machine guns Vickers ) and the Germans ( Maschinengewehr 08 ), had a locked bolt device , where the bullet is already charged and locked, and the shot is the next phase of the cycle. Therefore, it was possible to accurately determine the moment in which the bullet would pass through the propeller.

The standard machine gun of the French army, the Hotchkiss Mle 1914 , was difficult to synchronize due to its rigid chargers. The company Morane-Saulnier developed propellers equipped with metallic «deflectors» placed in the parts where they could touch the bullets. Roland Garros experimented with this system with a Morane-Saulnier Type L in April 1915. He did so to lower several German aircraft, but turned out to be an inadequate and dangerous solution. Finally Garros suffered a mechanical failure and was forced to land behind the enemy lines, where he was captured by the Germans. The German High Command transferred the Morane de Garros to the Fokker company , which already produced monoplans for the German army, with orders to copy its design. The deflectors system was incompatible with the German ammunition covered with steel and, therefore, the engineers were forced to return to the idea of synchronization, which gave rise to the Fokker Eindecker series . Airplanes with these devices, known by the Allies as the ” Flagell Fokker “, offered Germany an air superiority. The psychological effect was devastating because until that time the allied dominance was relatively unquestionable and the vulnerability of the former reconnaissance aircraft, such as BE2 , was demonstrated .

Other methods
Another solution was that the machine gun fired at the top of the propeller. The machine gun was attached, for example, to the upper wing of the biplanes and required a complex fixation while increasing friction. Changing the charger or restarting it if it had stopped was often difficult even though the machine gun was mounted near the pilot.

Finally, the excellent Foster assembly on the British aircraft was widespread , using the Lewis machine gun in this configuration. This arrangement allowed to change the charger easily and to shoot upwards to attack the enemy in its blind spot under the tail. However, this configuration was only possible in biplanes with a rather solid upper wing to withstand the mounting voltages. In addition, this configuration was less rigid than the previous one and caused a dispersion of the bullets.

The first versions of Bristol Scouts entered air combat in 1915 and had a Lewis machine gun shooting on the helix, and sometimes (recklessly) firing through the helix without the synchronization device.

Captain Lanoe Hawker of the Royal Flying Corps arranged his machine gun on the left side of the plane to be able to fire at a 30 ° lateral angle . It was successful to lower three two-plane observation aircraft on July 25 , 1915 and obtained the first Cross of the Victory granted to an aviator.

Armement antiaircraft
At the beginning of the war, the reconnaissance aircraft were not armed, as the hunting units were not yet formed, but soon the air battles began to appear above the front line.

For this battle, the search for superior weapons became a priority. Along with the machine guns, the aviators made use of air-to-air rockets, like the rockets Li Prieur against the airships. The guns were tested without retracement and the automatic guns , but pushed the devices to the limits of their possibilities with disappointing results. Another innovation was the air-air bombardment if a game could fly over a Zeppelin. They designed the fléchettes (small darts of steel ) for this function.

The need for improvement was not limited to air combat. On the ground, methods developed before the war were used to deter enemy planes that were approaching. The artillery shells exploded into the air forming the rubbish clouds called Archie by the British.

The airships and balloon observations were the main targets for hunters equipped with incendiary ammunition . The hydrogen for the zeppelins became extremely flammable.

Aviation Security
After the outbreak of the war, special anti-aircraft guns and machine guns began to appear. At first they were mountain cannons with an increased angle of barrel elevation, then, as the threat increased, special anti-aircraft guns were developed capable of sending the projectile to a high altitude. There appeared both stationary batteries and mobile, on an automobile or cavalry base and even antiaircraft parts of samocatchers . For night anti-aircraft fire, anti – aircraft guns were actively used .

Of particular importance was the early warning of an air attack. The time of the rise of interceptor aircraft to a high altitude in the First World War was significant. To provide a warning about the appearance of bombers, the chain of advanced detection posts, capable of detecting enemy aircraft at a considerable distance from their target, was being created. By the end of the war, experiments with sonication, the detection of aircraft for engine noise began .

The greatest development in the First World was the antiaircraft defense of the Entente, compelled to fight the German raids on its strategic rear. By 1918, in the air defense of the central regions of France and the United Kingdom there were dozens of anti-aircraft guns and fighters, a complex network of telephone-connected posts for sound recording and advanced detection. Nevertheless, to ensure full protection of the rear against air attacks failed: in 1918, German bombers raided London and Paris. The experience of the First World in terms of air defense was summed up in 1932 by Stanley Baldwin in the phrase “the bomber will always find a way” (“The bomber will always get through”).

The air defense of the rear of the Central Powers, which were not subjected to significant strategic bombing, was much more poorly developed and by 1918 was, in fact, in its infancy.

By war’s end, the impact of aerial 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. On the other hand, the artillery, which had perhaps the greatest effect of any military arm in this war, was in very large part as devastating as it was due to the availability of aerial photography and aerial “spotting” by balloon and aircraft. By 1917 weather bad enough to restrict flying was considered as good as “putting the gunner’s eyes out”.

Some, such as then-Brigadier General Billy Mitchell, commander of all American air combat units in France, claimed, “he 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.

During the course of the War, German aircraft losses accounted to 27,637 by all causes, while Entente losses numered over 88,613 lost (52,640 France & 35,973 Great Britain)

Anti-aircraft weaponry
Though aircraft still functioned as vehicles of observation, increasingly they were used as a weapon in themselves. Dog fights erupted in the skies over the front lines, and aircraft went down in flames. From this air-to-air combat, the need grew for better aircraft and gun armament. Aside from machine guns, 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, with the German Becker 20mm autocannon being fitted to a few twin-engined Luftstreitkräfte G-series medium bombers for offensive needs, and at least one late-war Kaiserliche Marine zeppelin for defense – the uniquely armed SPAD S.XII single-seat fighter carried one Vickers machine gun and a special, hand-operated semi-automatic 37mm gun firing through a hollow propeller shaft. Another innovation was air-to-air bombing if a fighter had been fortunate enough to climb higher than an airship. The Ranken dart 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 their significant weight.

First shooting-down of an aeroplane by anti-aircraft artillery
During a bombing raid over Kragujevac on 30 September 1915, private Radoje Ljutovac of the Serbian Army successfully shot down one of the three aircraft. Ljutovac used a slightly modified Turkish cannon captured some years previously. This was the first time that a military aeroplane was shot down with ground-to-air artillery fire, and thus a crucial moment in anti-aircraft warfare.

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 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. 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, Erwin Böhme, and Robert Little.

Strategic bombing
The first aerial bombardment of civilians occurred during World War I. In the opening weeks of the war Zeppelins bombed Liege, Antwerp and Warsaw, and other cities including Paris and Bucharest were targeted. And in January 1915 the Germans began a bombing campaign against England that was to last until 1918, initially using airships. There were 19 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 5 August 1918, resulting in the death of Peter Strasser, commander of the German Naval Airship Department. By the end of the war, 54 airship raids had been undertaken, in which 557 people were killed and 1,358 injured.

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, and by a small force of five Zeppelin-Staaken R.VI “giant” four engined bombers from late September 1917 through to mid-May 1918. Twenty-eight Gotha twin-engined bombers were lost on the raids over England, with no losses for the Zeppelin-Staaken giants. 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 17,000 men to air defenses. Calculations performed on the number of dead to the weight of bombs dropped had a profound effect on attitudes of the British government and population in the interwar years, who believed that “The bomber will always get through”.

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.

To encourage pilots to attack enemy balloons, 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. The premier balloon busting ace was Willy Coppens: 35 of his 37 victories were enemy balloons.

Source from Wikipedia