Fokker Eindecker fighters

The Fokker Eindecker fighters were a series of German World War I monoplane single-seat fighter aircraft designed by Dutch engineer Anthony Fokker. Developed in April 1915, the first Eindecker ("Monoplane") was the first purpose-built German fighter aircraft and the first aircraft to be fitted with a synchronization gear, enabling the pilot to fire a machine gun through the arc of the propeller without striking the blades. The Eindecker granted the German Air Service a degree of air superiority from July 1915 until early 1916. This period was known as the "Fokker Scourge," during which Allied aviators regarded their poorly armed aircraft as "Fokker Fodder".

Design and development
The Eindecker was based on Fokker's unarmed Fokker M.5K scout (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. It was fitted with an early version of the Fokker 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 the "prototype" Eindecker aircraft, (Fokker factory number 216) used for Fokker's initial synchronizer trials is closely associated with Leutnant Otto Parschau, who was allotted this aircraft, then a Fokker A-series monoplane with the Idflieg military serial number A.16/15, at the beginning of World War I. This unarmed monoplane had previously "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 the first year of the war with this aircraft, flying it on both the Eastern and Western fronts. At some stage he had the words "Lt. Parschau" painted on the right upper side of the fuselage behind the cockpit. This aircraft had its main fuel tank located behind the cockpit.

In late July 1915, while it was based at Douai with Feldflieger Abteilung 62, the Fokker factory outfitted Parschau's aircraft with the first trial version of the Fokker Stangensteuerung synchronizer and a Parabellum MG14 light machine gun. Parschau made several attempts at aerial combat during June 1915, but at this stage the gear proved very unreliable, the Parabellum gun repeatedly jamming in action. The aircraft was later returned for factory armament installation trials. At this time the wing was lowered to mid-fuselage, as in production Eindeckers, although this modification was not fitted to the initial batch of five M.5K/MG production prototypes. Production E.Is, and all further Fokker Eindeckers, were also fitted with the definitive version of the Stangensteuerung gear, with a large cam wheel replacing the early drive taken from the oil pump driveshaft.

One distinctive feature of the appearance of all the sheet metal paneling on the Eindeckers was a special form of "dragged" engine turning peformed on all their surfaces, both exposed and internal parts. The exact reasoning for this appearance feature is not exactly known, with one theory surmising that the duralumin panels were being mechanically "clad" in pure aluminum, through using discs of pure aluminum to impress such a cladding directly into the sheet metal parts' surfaces in short, irregular paths, repeated all over the Eindeckers' sheet metal cowl and associated fuselage panels.

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 the monoplanes of the time, even when fitted with ailerons, often had unpredictable or unresponsive roll control due to the flexibility of their externally braced 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. The larger diameter of the E.II's nine-cylinder rotary mandated raising the upper nose paneling to match the larger-diameter cowl the U.I required — this also caused the outer edges of the upper nose paneling to overhang the fuselage's upper longerons, making it necessary to add "soffit"-like surfaces, projecting outwards and upwards from the upper longerons' forwardmost length behind the cowl to fully enclose the nose once more on all E.II and E.III aircraft. 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 (the exact breakdown by type is nor clear, although the E.III was the most important model).

Operational history


The first Eindecker victory, though unconfirmed, was achieved by Leutnant Wintgens on 1 July 1915 when, while flying one of the five M.5K/MG production prototype aircraft, numbered 'E.5/15', he forced down a French Morane-Saulnier L two seat "parasol" monoplane. By this time the first E.Is were arriving as supplementary equipment, one per unit as "attached" aircraft, for the ordinary Feldflieger Abteilung - initially to provide escort protection for their usual quantity of six two-seat reconnaissance biplanes per unit.

Three days after his "unconfirmed" victory, Wintgens downed another "Morane Parasol" with the same E.5/15 aircraft, and a full fortnight after his initial engagement, on 15 July 1915, he became the first Eindecker pilot to be credited with such an official victory.

The two most famous Eindecker pilots were Oswald Boelcke (initially flying M.5K/MG aircraft E.3/15) and Max Immelmann, both of Feldflieger Abteilung 62, who scored their first kills in E.Is in August 1915 while sharing Boelcke's E.3/15 aircraft. Leutnant Otto Parschau, who was instrumental in the introduction of the Eindecker from the very start, flew the M.5K/MG aircraft numbered E.1/15, after the Fokker factory took back his worn-out A.16/15 aircraft. Immelmann shortly thereafter received an early production E.I, bearing IdFlieg serial number E.13/15 for his personal use, which survived past the end of the war.

Oswald Boelcke scored the most Eindecker victories - 19 out of his final tally of 40. His last victory in an Eindecker occurred on 27 June 1916. Max Immelmann had the second-highest Eindecker score. He achieved all of his 15 victories in the type before being killed when his E.III broke up in June 1916 after the synchronisation mechanism failed, causing at least 7 bullets to shoot through one propeller blade, which broke off. The resulting vibrations were so severe that the loads exceeded the structural limits of the aircraft. 11 pilots scored five or more victories in the Eindecker. Boelcke, Immelmann and Wintgens all received Germany's highest military decoration, the Pour le Mérite or "Blue Max", while flying the Eindecker, after each pilot passed the then-required eight victory total for each aviator.

The arrival in early 1916 of the Airco DH.2 and Royal Aircraft Factory F.E.2 and F.E.8 pusher aircraft, along with the French Nieuport 11, brought the dominance of the Eindecker to an end, and with it, the "Fokker Scourge". Wintgens flew the E.IV version of the Eindecker long enough to have been confronted by the much more advanced SPAD S.VII fighter of French flying ace Alfred Heurteaux on September 25, 1916, which resulted in Heurteaux fatally bringing down Wintgens, as Huerteaux's victory number eight.

Variants

 * Fokker M.5
 * Fokkers first monoplane unarmed scout, in effect the "airframe prototype" of all the early Fokker Eindeckers.


 * Fokker M.5K
 * K for Kleine - short span wings


 * Fokker M.5L
 * L for Lange - long span wings


 * Fokker M.5K/MG
 * Pre-production batch, with /MG suffix for maschinengewehr - machine gun, five built (see A.III).


 * Fokker A.II
 * Military designation for the M.5L unarmed scouting aircraft with three bracing cables per wing and powered by a 80hp Oberursel U.0 rotary engine; at least one was built.


 * Fokker A.III
 * Military designation for the M.5K unarmed scouting aircraft powered by a 80hp Oberursel U.0 rotary engine; 5 built (see M.5K/MG).


 * Fokker E.I
 * Production armed scout aircraft powered by a 80hp Oberursel U.0 rotary engine, 68 built


 * Fokker E.II
 * Improved production armed scout aircraft powered by a 100hp Oberursel U.I rotary engine, 49 built


 * Fokker E.III
 * The major production variant also powered by a 100hp Oberursel U.I rotary engine with improved structure and equipment, 249 built


 * Fokker E.IV
 * The final version of the early Eindeckers the E.IV was slightly enlarged, fitted with a 14-cyl. Oberursel U.III engine and two machine guns above the forward fuselage, 49 built

Note:The Fokker E.V bore no direct relation to the earlier Eindeckers, being a parasol aircraft, only built in small numbers before production switched to the improved Fokker D.VIII.

Survivors
Only one original Eindecker remains. On 8 April 1916, a novice German pilot took off from Valenciennes with a new E.III (IdFlieg serial number 210/16) bound for Wasquehal but became lost in haze and landed at a British aerodrome east of St. Omer. He was forced to surrender before he realised his error and could destroy the aircraft. The E.III was test-flown against the Morane-Saulnier N and other Allied types at St. Omer before going to Upavon in Wiltshire for evaluation and finally going on museum display. It now resides at the Science Museum in London. Immelmann's original E.I, with IdFlieg-issued serial E.13/15, also survived the war and went on display in Dresden where it was destroyed by Allied bombing during World War II.