The history of military aviation in World War I is dominated by biplanes, but some of the earliest successful planes used in the war were monoplanes. The French Bleriot XI and the German Taube were two examples of reconnaissance monoplanes from the first days of the war. Combat aircraft represented a different problem altogether. Air performance was still valuable for an armed aircraft, but for almost a year, there was no consensus on the best way to mount weapons onto such a plane. For reasons of simplicity, it was considered ideal to place one or two machine guns in front of the plane, and the pilot could aim the aircraft at its target and fire; the fact that the propeller was in the way remained an intractable problem for some months. In the summer of 1915, the solution was revealed in the form of the Fokker Eindecker.
During the first year of the war, air reconnaissance preceded air combat. In fact, the earliest combats were really examples of two opposing scouts trying to interfere with each other. Early efforts were crude, with pilots firing pistols at each other, but soon better expedients were tried. Many scout planes were designed as two-seaters, and the passenger seat was equipped with a machine gun. This was a successful concept that remained in use on bomber aircraft through the Second World War. Other early warplanes were built as “pushers,” with the propeller placed behind the pilot’s back; such “pushers” could place a machine gun in the front of the plane and fire without fear of harming the propeller.
One promising effort was pioneered by a French pilot, Roland Garros. He experimented with ways to synchronize the machine gun with the propeller, but failed to arrive at a reliable result. As an alternative, he reinforced his propeller blades; this this in place, he could fire his machine gun through the propeller, and if a bullet struck the propeller blade, it would ricochet in another direction. Garros enjoyed a few successes with this device in April 1915, but on the 18th his plane was shot down, and the Germans captured both Garros and his armored propeller.
The Germans had noted duly the success that Garros had enjoyed, although they found the expedient fairly crude. Hoping for an improvement, they turned to Anton Fokker. Fokker was a Dutch aircraft designer who had been working for the German air industry since 1911. He had opened a flying school near Berlin in 1912, and that same year, he began taking in military contracts.
Fokker examined the Garros propeller, and concluded that it had to be possible to regulate the firing of the machine gun to accommodate the propeller. The propeller spun 1200 times each minute, which resulted in 2400 occasions each minute that one of the blades blocked the machine gun. Since the machine gun itself fired only 600 times each minute if fired constantly, it could be regulated so that it fired only when the muzzle was clear.
The result was a synchronizing mechanism known as the interrupter gear. It utilized a cam connected to the engine itself to prevent or permit a shot, depending on the position of the propeller. There would eventually be a patent dispute over this invention; a Swiss designer, Franz Schneider, had registered a synchronizer of his own in 1913, and somehow, nobody in the military had taken notice. As it happened, Fokker was able to argue successfully that his interrupter gear had been created independently.
Testing proved something of a trial for Fokker. He was expected to demonstrate the effectiveness of his device in combat conditions; while it was not unreasonable for the German military to request evidence of this sort before adopting a new technology, it posed a moral quandary for Fokker, who was a Dutch national. He had been given a uniform and all necessary papers, and took to the sky in one of his M5K reconnaissance monoplanes. When at last he encountered a French plane, he found himself unable to pull the trigger. Fortunately for Fokker’s career, however, Lt. Kurt Wintgens scored the device’s first kill on July 1, and the Germans were pleased with the result. They bought both the interrupter gear and the scout plane that had carried; the new fighter was classified as the E I.
By August, the Germans had produced E I’s in some numbers; importantly, two very gifted pilots named Oswald Boelcke and Max Immelmann were assigned the new Eindeckers (monoplanes). Their August 1 counterattack on a British air raid on their airfield is considered the beginning of the “Fokker Scourge,” a period from August 1915 to July 1916 during which the Germans enjoyed air superiority.
In its flying capabilities, the E I was a modest aircraft. With 80 horsepower engine, it was not especially powerful, nor was it exceptionally maneuverable. It was the configuration of its armament alone that gave it the advantage it enjoyed over the Allies, and remarkably, the Allies did not field aircraft of their own with synchronized machine guns until the Battle of the Somme in 1916. During the eleven months of the Eindecker’s heyday, it was upgraded three times. The E II and E III variants had 100 horsepower engines, and the E IV, which appeared in January, had a 160 horsepower engine. The E IV was issued with two machine guns, and on a trial basis, Max Immelmann flew one with three, although he did not favor the practice.
As long as the Allies had failed to imitate the German synchronizer, the Eindecker was sufficient to maintain superiority in the air. It was a time when pilots like Boelcke and Immelmann were able to innovate in the realm of air tactics; Immelmann in particular is famous for a turning maneuver that is still known today as the Immelmann Turn. In a real sense, the Eindecker pilots created the tactics of fighter combat.
The strategic use of the Eindeckers remained primitive, however. Eindeckers generally flew singly or in pairs, often in an escort role. When enemy planes were encountered, individual Allied pilots faced a high likelihood of being shot down, but others had a good chance of escaping. Larger formations would only come later in the war.
The Fokker Scourge began a gradual decline in February 1916, culminating with the opening of the Somme Offensive in July. There were several reasons for this. For one, the French began releasing its own fighters in squadrons, and numbers told against the pairs of Fokkers that the Germans had released. Secondly, Allied technology was improving. While the Allies still had not imitated the interrupter gear, new planes like the DH 2 (a pusher with the machine gun mounted in front) and the Nieuport 11 (a biplane with the machine gun mounted on the upper wing) were able to outperform the Eindeckers. Finally, the Germans concluded that the Eindeckers had been modified as much as possible, and any further improvement would have to come with the adoption of a different airframe.
The eclipse of the Eindecker mirrored other developments. It began in the skies over Verdun, and concluded with the British offensive at the Somme. Defeats suffered by its greatest aces demonstrated the change in circumstances. Oswald Boelcke had been downed by a Nieuport, although he survived the crash and went on to reform German aviation practices in light of the new dangers. Max Immelmann was killed on June 18; the exact cause of his crash was never proven. He may have been shot down by enemy fire, or he may have been hit by friendly anti-aircraft fire. There remained some suspicion about the possibility of catastrophic mechanical failure, and the death of Immelman led to the reassignment of Boelcke.
The new wave of Allied fighter planes, organized in squadrons, ended the Fokker Scourge, and soon the Eindeckers would be superseded by new planes like the Albatros. During their heyday, however, the Eindeckers defined the role of fighter aircraft. Their own pilots, and the Allied pilots who were mustered against them, created most of the tactics used by fighter pilots throughout the twentieth century. The greatest of them, Immelmann and Boelcke, both died in 1916, but remained very influential. A modest scout aircraft with a temporarily crushing advantage in armament, the Eindecker changed the course of military aviation.
Sources:
Cowin, Hugh W. German and Austrian Aviation of World War I: A Pictorial Chronicle of the Airmen and Aircraft That Forged German Airpower. Osprey, 2000
Herris, Jack et al. Essential Aircraft Identification Guide: Aircraft of World War I 1914-1918. Amber, 2010
Livesey, Anthony. Great Battles of World War I. Smithmark Publishers, Inc. 1997
Treadwell, Terry C. et al. The First Air War: A Pictorial History 1914-1919. Sterling, 1998
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