The airframe began as a near-copy of the Morane-Saulnier Type H, a French sporting and scouting monoplane Fokker’s firm studied closely. Fokker rebuilt it in his own idiom — a welded chrome-molybdenum steel-tube fuselage in place of wood, and his characteristic one-piece warping wing — producing the unarmed M.5 reconnaissance monoplane, from which the armed A-series and then the E-series (Eindecker) fighters were derived.

The decisive addition, the synchronisation gear, has a tangled history that is often told too simply. The concept was not Fokker’s: the Swiss engineer Franz Schneider had patented a synchroniser in 1913, and the Frenchman Raymond Saulnier had experimented with one in 1914 before falling back on crude propeller deflector wedges — the same bullet-deflecting plates that Roland Garros famously used in early 1915 (a different, cruder solution than true synchronisation). When Garros was forced down behind German lines in April 1915, his deflector-equipped Morane was captured. The popular story that Fokker then personally invented synchronisation in 48 hours is a marketing legend Fokker himself encouraged. In reality his engineers — among them Heinrich Lübbe and colleagues — developed a practical pushrod interrupter that timed the gun rather than deflecting bullets. The honest summary: the working mechanism is popularly credited to Fokker but built on earlier ideas, and engineered by his team.

Early Eindeckers (E.I) usually carried a single air-cooled lMG 08 — the aircraft version of the Maxim-derived MG 08, universally nicknamed “Spandau” after the arsenal that built it. The gun was fixed, pointing straight forward over the cowling, and fed by a fabric or metal-link belt. The Fokker Stangensteuerung (“pushrod control”) took a drive off the engine and, through a system of cams and rods, physically interrupted the gun’s firing at the instants a blade was in front of the muzzle. Rate of fire dropped a little compared with a free-firing gun, but the pilot could now hold the target in his sights and shoot down the line of flight.

Later variants raised the firepower: the E.IV was designed around two — occasionally three — synchronised guns, though the extra weight and the drag hurt an airframe that was already struggling to keep up with newer Allied fighters. Reliability of the gear varied; jams and the occasional shot-through propeller blade were not unknown, and pilots treated the mechanism with respect.

By the standards of even 1916 the Eindecker was not pleasant to fly. Roll was commanded by warping the flexible wing via cables to a control “cloche”, which was heavy and imprecise and grew worse as speed rose. The rotary engine had essentially one power setting; pilots managed thrust by “blipping” the ignition with a button, cutting and restoring the spark. The spinning mass of the engine produced strong gyroscopic precession, so the aircraft turned readily one way and reluctantly the other — a quirk skilled pilots exploited and novices feared.

Performance was modest: an E.III made roughly 130–140 km/h flat out and took a long time to reach its ceiling of about 3,600 m. It was the gun and the tactics of men like Boelcke — diving out of the sun, attacking from the blind spot behind and below a two-seater — that turned this ordinary flying machine into a killer.

E.I (1915): first production fighter version, ~80 hp Oberursel U.0, one gun — the machine that opened the Fokker Scourge. E.II: a mostly parallel development with the more powerful ~100 hp U.I rotary and a slightly shorter wing. E.III: the most numerous and best-known variant, ~100 hp, one gun, the definitive Eindecker and the type most often preserved. E.IV: an attempt to keep the design competitive with a heavier ~160 hp two-row Oberursel U.III and twin guns; the bigger engine was unreliable and the airframe was by then outclassed. Total production of all Eindecker variants is usually given as about 416 aircraft, though sources disagree and the figure should be treated as approximate.

No reliable unit price or cost-per-flight-hour survives for the Eindecker. In 1915 military aircraft were procured in small batches under wartime conditions; the currency (the pre-inflation gold Mark), the accounting, and the record-keeping simply do not translate into a meaningful modern figure. Any “cost” you see quoted for an original Eindecker is effectively invented.

What can be said is that the type was cheap and quick to build by the standards of the day — a steel-tube fuselage and a simple warping wooden wing, powered by an existing rotary engine. The real running cost today attaches to the airworthy reproductions flown by collections such as The Vintage Aviator in New Zealand: rotary engines are thirsty, temperamental and expensive to maintain, and hand-built WWI aircraft demand specialist care. Operating estimates for such machines run from several hundred dollars to over a thousand dollars per flying hour — but that is a modern reproduction figure, clearly flagged as an estimate, not a historical cost.

Production totals for the Eindecker are quoted inconsistently across references. The commonly cited overall figure is about 416 aircraft across the E.I, E.II, E.III and E.IV, with the E.III the most numerous. Some sources break the numbers down differently or count the unarmed M.5 monoplanes and A-series scouts alongside the fighters, which inflates or deflates the tally depending on how you draw the line. Treat any precise breakdown as an approximation; the honest statement is that Eindeckers were built in the low hundreds, never in the thousands, and that only a handful were ever at the front simultaneously — part of why so few genuine airframes survive today.