Fokker Eindecker Fighters - Design and Development

Design and Development

The Eindecker was based on Fokker's unarmed Fokker M.5K scout, also given the military designation Fokker A.III, itself following very closely the design of the French Morane-Saulnier H shoulder-wing monoplane but using chrome-molybdenum steel tubing for the basic fuselage structure instead of wooden components, which was fitted with a synchronizer mechanism controlling a single Parabellum MG14 machine gun. Anthony Fokker personally demonstrated the system on 23 May 1915, having towed the prototype aircraft behind his touring car to a military airfield near Berlin.

The history of what ended up being the "prototype" Eindecker aircraft, which bore Fokker factory serial number 216, is closely associated with Leutnant Otto Parschau, who was given the "No.216" Fokker A-series monoplane at the beginning of World War I, which bore the Idflieg military serial number A.16/15. This initially unarmed monoplane had belonged to one Oberleutnant von Buttlar, and had been painted a shade of green, the color of von Buttlar's Marburg-based Jäger regiment. Parschau eventually spent most of his first year's time in the war with this aircraft, which was marked with the words "Lt. Parschau" on the right upper side of the fuselage behind the cockpit, flying it on both fronts that the German Empire was involved in combat. A short time before the beginning of June 1915, while based at Douai with Feldflieger Abteilung 62, the Fokker factory outfitted Parschau's aircraft with the Fokker Stangensteuerung synchronizer and a Parabellum MG14 light machine gun for its armament, with which Parschau had tried some initial attempts in aerial combat during June 1915, when the Parabellum gun repeatedly jammed in action. Parschau's aircraft also had an aft-cockpit-located main fuel tank. The aircraft would later be taken back by Fokker for factory armament installation trials, which also allowed the wing location to be lowered to mid-fuselage, a position that would become standard for all regular production Eindeckers. The initial batch of five M.5K/MG production prototypes were completed by the Fokker factory with the shoulder-mount wing mounting location that the original M.5s had used.

All the E.I to E.IV Eindeckers used a gravity fuel tank which had to be constantly filled by hand-pumping from the main fuel tank, which starting with the Fokker E.II was mounted behind the pilot; this task had to be performed up to eight times an hour. Both the rudder and elevator were aerodynamically balanced, and the type had no fixed tail surfaces. This combination rendered the Eindecker very responsive to pitch and yaw. For an inexperienced pilot, the extreme sensitivity of the elevators made level flight difficult; German ace Leutnant Kurt Wintgens, who along with Leutnant Parschau were the primary Luftstreitkräfte pilots responsible for bringing the first armed Fokker monoplanes into active service during the spring and summer of 1915, once stated "lightning is a straight line compared with the barogram of the first solo". The roll response of the Eindecker, on the other hand, was poor. This is often blamed on the use of wing-warping rather than ailerons - although monoplanes of the time, even when fitted with ailerons, often had unpredictable or unresponsive roll control due to the flexibility of their wings.

The main difference between the E.I and E.II was the engine - the former having the seven-cylinder 60 kW (80 hp) Oberursel U.0 rotary engine which was essentially a direct copy of the French-made 60 kW (80 hp) Gnome Lambda seven-cylinder rotary engine, while the latter had the nine-cylinder 75 kW (100 hp) Oberursel U I, a direct copy of the 75 kW (100 hp) Gnome Monosoupape rotary. Both the E.I and E.II versions used the M.5's original 1.88 meter (74 inch) wing chord dimension. Production of the types, built in parallel, depended on engine availability. Many E.IIs were either completed as E.IIIs or upgraded to E.III standard when returned for repair.

The definitive version of the Eindecker was the Fokker E.III, which used a slightly narrower-chord (1.80 meter, or 71 inch) wing than earlier versions. Boelcke's Feldflieger Abteilung 62 began operating the E.III towards the end of 1915. A few E.IIIs were experimentally armed with two 7.92 mm (.312 in) calibre LMG 08 "Spandau" machine guns, while most E.IIIs and the production E.I through E.III Eindecker models used only one of the same model. The final variant was the Fokker E.IV which received a 119 kW (160 hp) Oberursel U.III, 14 cylinder twin-row rotary engine (a copy of the Gnome Double Lambda rotary) and was fitted with twin machine guns as standard, after repeated failure of an experimental triple-gun installation, which was initially intended be standard for the E.IV.

Total production for the entire Fokker E.I through E.IV series was 416 aircraft (one aircraft's type is unknown).