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In Memoriam

Klaas Willem Jonker
(Wilko)
† April 30, 2018

On Monday 30 April 2018, Wilko Jonker died after a long illness at the age of 58. He leaves behind a wife and two children. The Dutch military aviation and plastic modeling were his hobby and on this website he shared all the knowledge he has collected over the years. His hobby has been able to distract him from the persistent disease in his body until the last week of his life. The contacts with other hobbyists were a major support for him.

This website will be maintained by different people for as long as possible, so that other enthusiasts can continue to benefit from extensive content.

Fokker D.VII

History

The development of the Fokker D.VII finds its way back to the Fokker V.4, the forerunner of the Fokker Dr.I. In order to counterpart the allied air supremacy in summer 1917 the German aircraft factories was demanded to develop a new aircraft. Two aircraft , based on the Fokker V.4 were designed by Fokker. The Fokker V.9, a biplane equipped with initially an Oberursel rated 80 hp, but soon replaced with a 110 hp Le Rhône. Also Fokker V.11 was designed, a biplane with a Mercedes D.III rated 160 hp.
First flights with the V.11 were in December 1917.
The tail of the V.11 was identical to the tail of the V.9, but was changed later and a triangular fin was added.
Also the ailerons were revised and the fuselage enlarged with about 40 cm just behind the centre of gravity.
The aircraft was much better and safer to fly now and was now considered as the real prototype of the Fokker D.VII.
As an interim aircraft the Fokker V.13 entered service as Fokker D.VI, but few were built.
Evaluation of the V.11 was at air base Adlershof, Berlin the well known German pilot Von Richthofen thought the aircraft not suitable to act as for fighter.
It was difficult to handle and direction unstable. It was very manoeuvrable and performed very well, though the climbing speed was rather slow.
Suggesting necessary repairs the V.11 was revised and altered during the weekend. A test flight done by Fokker himself showed the aircraft was much better now.
Fokker persisted Von Richthofen to fly the aircraft again, because several minor steering changes had been added.
Von Richthofen was very surprised about these small modifications and advised other pilot to fly the plane also.
One problem was the rather poor climbing speed of the aircraft equipped with Mercedes D.III engine.
Other engines were available, such as 185 ph Benz Bz. IIIa and 195 hp Benz Bz. IIIb, which would improved the plane, but these engines were not in production yet.
The only available alternative was the 185 hp BMW IIIa, an new engine just entered production. The problem with this engine was that it was not available on large scale yet.

Fokker was ordered to produce a first series of 400 aircraft.
IdFlieg (Inspektion der fliegertruppen), realized that such a large order could not be produced by Fokker- Schwerin only, so the Albatros factories were ordered to produce the Fokker D.VII under licence. Albatros built the Fokker at their two locations, to know Albatros-Werke GmbH at Johannistal and the OstDeutsche Albatros Werke at Schneidemühl.
The aircraft built at Johannistal were designated as Fokker D.VII (Alb), whereas the Fokkers built at Schneidemühl were designated as Fokker D.VII (OAW).
In the end Albatros built more Fokkers D.VII than Fokker did.
One of the problems was that Fokker didn't have any drawings, just sketches and notes. Albatros had to produce production drawings by itself, based on a Fokker built D.VII. This fact plus the use of factory specific standards and production techniques, caused the three Fokker models to resemble much, but hardly any part could be exchanged, not only between the Fokker built aircraft, but also between the Fokker built at both Albatros factories.
The Albatros produced aircraft were thought to be of a better quality than the Fokker built examples, which suffered leaking fuel tanks.

I have to figure out the exact differences between the three models.

Fokker D.VIIF.

The first aircraft were delivered in April 1918 and were equipped with the Mercedes D.III. The original design of this engine dated from 1914/1915 and during the Summer the Mercedes D.III proofed to be insufficient. The allied aircraft used engines rated 220 hp or more, whereas two seats aircraft were equipped with engines rated 350 hp or more.

The German reconnaissance aircraft were equipped with engines rated 260 hp, and performed worse.
The new Benz Bz IIIa rated 200 hp wasn't tested yet in a Fokker D.VII, though one D.VII was experimental equipped with a Benz IVü rated 240 hp.
This aircraft, Fokker V.24 had a much better climbing performance than the original aircraft. The manoeuvrability and high wing load of this model made it unsuitable for the rough air field at the front. The V.24 was later equipped with an BMW IIIa rated 185 hp.
This aircraft was tested in June 1918 and showed excellent climbing capabilities and a better performance a large heights. The installation of this engine differed hardly from the installation of the Mercedes engine, though the radiator was larger, because the engine could produce a power of 240 hp for a while at ground level. This new version was very successful and received the designation Fokker D.VIIF.
It was decided to equip as much as possible Fokkers D.VII with the BMW engine. The only limiting factor was the production speed of the engines.

In Hungary the Allgemeine Ungarische Maschinen-Fabrik A.G. (MAG) built a Fokker D.VII variant.equipped with an Austo-Daimler engine rated 210 hp. Th fuselage was shorter. It was meant to be used by the Austrian army, but wasn't used operational.
Several modifications were tested and especially after the war several engines were used.
Platz and Fokker thought it a good idea to develop a two seats version of the D.VII.The armament was removed and a seat was added in front of the pilot (near the centre of gravity).
This aircraft had an enlarged fuel tank added between the wheels, as was used on the Fokker V.36. The internal fuel tank in the fuselage could be made smaller. This development led to the Fokker C.I

 

Technical information Fokker D.VII(F) (LVA)
Dimensions:
Length: 7,0 m Wingspan: 8,93 m
Height: 2,75 m Wing area: 20 m2
Weights:
Empty weight: Mercedes D.IIIaü: 959 kg
BMW D.IIIa: 910 kg
Max. start weight: Mercedes D.IIIaü: 959 kg
BMW D.IIIa: 910 kg
Performances:
Max.speed: Mercedes D.IIIaü: 183 km/u
BMW D.IIIa: 205 km/u
Rate of climb: - m/min
Range: Mercedes D.IIIaü: ca 1,5 hrsr
BMW D.IIIa: ca 2 hrs
Service ceiling: Mercedes D.IIIaü: 6000 m
BMW D.IIIa: 7000 m
Miscellaneous:
Engine type: One Mercedes D.IIIa rated 160 hp;
Fokker D.VIIF: one BMW IIIa rated 185 hp.
Crew: One pilot
Armament: Two fixed Spandau LMG 08/15 machine guns
Later replaced by two Vickers 7.92 mm machine guns.

 

Technical Information Fokker D.VII (NEIAF)
Dimensions:
Length: 7,0 m Wing span: 8,93 m
Height: 2,75 m Wing area: 20 m2
Weights:
Empty weight: 670 kg Max. start weight: 960 kg
Performance:
Max. speed: 189 km/u Climbing speed: - m.min
Cruising speed: - km/hr    
Range: - km Service ceiling: ca 7500 m
Miscellaneous:
Engine type: One Armstrong Siddeley Puma rated 230 hp.
Crew:

One aviator

Armament: None.

 

Technical Information Fokker D.VIIF (RNlNAS)
Dimensions:
Length: 7,0 m Wing span: 8,9 m
Height: 2,75 m Wing area: 20 m2
Weights:
Empty weight: 700 kg Max. start weight: 850 kg
Performance:
Max. speed: 190 km/hr climbing speed: - m/min
Cruising speed: - km.hr    
Range: - km Service ceiling: ca 7500 m
Miscellaneous:
Engine type: One 185 hp BMW IIIa; from 1925 one 250 hp BMW IV.
Crew: One aviator
Armament: Two fixed forward firing Spandau LMG 08/15 machine-guns.