Fokker D.VII – the lethal weapon

[3d by Marek Rys]

The initial order placed with the Fokker factory called for 300 planes. It was followed by further ones, but since the Fokker factory did not possess sufficient production capacity, the construction of Fokker D.VII planes was commissioned to the Albatros Flugzeugwerke in Johannisthal and its subsidiary the Ostdeutsche Albatros Werke (OAW) in Schneidemühl (now Piła). These were 400 planes (serial numbers 527/18 to 926/18) and 200 planes (serial numbers 2000/18 to 2199/18).
Owing to Anthony Fokker’s mercantile skills, his company received 25 000 marks for each manufactured plane, while the subcontractor – the Albatros factory, only 19 000. Fokker also received 5% royalty of the value of each manufactured machine.
Fokker loaned the Albatros factory one complete 230/18 aircraft and it was used as a base for preparing the construction drawings and technology of building welded steel tube fuselage frames.
It must be stressed here, that individual components manufactured by different factories were not interchangeable. The planes differed not only in the internal details, but also in external ones – mainly the location and shape of cooling louvres in the engine cowling, as well as the typeface and location of type and serial number markings.
The first 21 Fokkers were commissioned at the turn of February and March.
In mid April 1918 the first Fokker D.VII machines began arriving at squadrons (Jastas) 4 and 10, which were the part of Jagdgeschwader (JG) 1 under command of Rittm. Richthofen. At the end of April these squadrons had 19 Fokkers, first of which had a serial number 230/18. The second fighter wing, Jagdgeschwader II, was receiving the Fokkers in batches comprised of a few machines in June and July.
Early weeks of the plane’s operation revealed two defects. First was fracturing of the wing canopy ribs at the second spar, but it was quickly remedied by introducing appropriate reinforcements.
Mid-air fires were the second defect, which cost lives of many pilots. First such incident took place on July 15, 1918, when Lt. Friedrich Frienderichs of Jasta 10 was flying balloon busting mission in his D.VII 309/18. His plane burst in flames due to the spontaneous combustion of phosphorous ammunition and the pilot did not survive. Similar accidents happened to other pilots. The cause was soon discovered, when Lt. Bender of Jasta 4 survived such an accident owing to his parachute. It was the incendiary phosphorous ammunition stored in the ammunition boxes located in the engine compartment. Because of the overheating it self-ignited causing a fire. Therefore, it was necessary to improve not only engine cooling, but also that of its entire compartment. The solution was cutting additional cooling louvres in the engine cowling and ventilating holes under the radiator. The air flow from the latter was directed straight onto the ammunition boxes. Initially, these openings were made by individual Jasta workshops, but with time it was done by the manufacturers. Location of the cooling louvres varied on planes manufactured by individual factories.
Another modification was the addition of removable aluminium covers in the front section of the fuselage and alteration of the exhaust manifolds. Twin manifolds, each collected exhausts from three cylinders, that were initially used, were replaced by a single one for all six cylinders. It was installed at the top of the engine.
Introduction of the BMW IIIa engine designed by Bayerische Motorenwerke GmbH considerably increased the Fokker D.VII’s performance. The BMW engines had a 136 kW (185 hp) power output at the altitude of 2000 m. The power dropped with the altitude and at 6000 m it was 90 kW (120 hp). It was forbidden to use full throttle below 2000 m as it reduced the engine’s life-span. The first BMW IIIa engine was installed in Fokker D.VII 231/18. After the first flight on April 25, the factory pilot Neissen authoritatively stated: “the plane with this engine is very good, has an excellent rate of climb and the excess power allows for zooming at extremely high, almost vertical, angle. Then, the plane just hangs on its propeller”. These claims were highly exaggerated, but it must be borne in mind, that rates of climb of airplanes with contemporary engines left much to be desired. The Fokker D.VII equipped with the BMW engine climbed to 6000 m in less than 20 minutes. Maximum cruising speed was over 200km/h. Fokker decided to install the BMW engines in as many planes as possible. Production capacity of the BMW was the limit. By July, just under one hundred BMW IIIa engines were delivered to the Fokker and Albatros factories. Fokker D.VII planes equipped with the BMW engine received an additional “F” suffix in their designation. The Fokkers D.VII F were highly praised by their pilots. Oxygen apparatus was designed to allow flights at altitudes above 5000 metres.
The use of the BMW IIIa engine required increased pilot’s attention. The use of full throttle at the altitudes below 2000m was forbidden, since there was a danger of destroying the engine.

Basic features of the cockpit - floor panel, pilot seat with its frame and the dashboard.

Production rate of the Fokker D.VII aircraft in all the involved factories was relatively high, but it did not fully cover the demands of frontline units for that type of plane. In August 1918 there were 828 Fokkers and slightly more than 300 Albatroses, not including older types like the Fokker Dr.I and Pfalzs in the squadrons.