Книги
Centennial Perspective
J.Herris, J.Leckscheid
Fokker Aircraft of WWI. Vol.5: 1918 Designs Part 1: Prototypes & D.VI
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J.Herris, J.Leckscheid - Fokker Aircraft of WWI. Vol.5: 1918 Designs Part 1: Prototypes & D.VI /Centennial Perspective/ (55)
The Fokker V17 monoplane fighter prototype provides an interesting contrast to the AEG G.V and emphasizes the size of the G.V.
The Fokker V17, work number 2147, powered by a 110 hp Oberursel UR.II participated in the First Fighter Competition. Here it is parked next to an AEG G.V to contrast the difference in size.
Full view of the same D.VI minus cowling; note the full-chord Balkenkreuz on the lower wing having 5:4 proportions. A lineup of Kest 4b Albatros D.Va fighters serves as the backdrop, with D.5351/17 "3" seen at right. (Peter M. Grosz Collection/STDB)
Fokker D.VI 1688/18 is seen here on the Kest 4b airfield at Freiburg. The aircraft is still in factory finish, seen behind it is Albatros D.Va D.5629/17 "4". (Reinhard Zankl)
Fokker V9
The order to commence work on the Fokker V9 (Works Number 1831) experimental biplane was placed to the Fokker experimental workshop on 24 August 1917, just as the first Fokker Triplanes (then still carrying the F.I designation) were about to reach the front.
The fuselage design of the V9 mirrored that of the Triplane; the fuselages of both aircraft were almost identical and they were powered by the same engine. Had both aircraft been developed at the same time, it would not be wrong to say that the V9 was the cantilever biplane fraternal twin of the F.I/Dr.I.
As it was, the V9 was completed in October 1917, when production of the Dr.I was getting into full swing. It participated in the First Fighter Competition at Adlershof in January 1918, still powered by the 110 hp Oberursel Ur.II rotary engine.
The biplane configuration reduced drag compared to the Dr.I, so was a bit faster. Its performance, particularly at high altitude, was limited by use of the low-power rotary engine, and the fact that the low-compression Oberursel engine lost power with altitude faster than the inline engines then available in Germany. More advanced rotary engines, such as the Siemens-Halske Sh.III, which retained much of its power at increasing altitudes, were not yet cleared to enter mass-production. The aircraft’s low aspect-ratio wings, while very sturdy, also increased induced drag, further limiting performance at altitude.
After some further development of the wing and strut design, it was later entered into production under the military designation Fokker D.VI.
Fokker V9 Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span 7.70 m
Area 16.5 m2
General: Length 5.90 m
Height 2.80 m
Empty Weight 381 kg
Loaded Weight 572 kg
Climb: 1000m 2.5 min
2000m 4.7 min
3000m 7.7 min
4000m 11.0 min
5000m 15.5 min
Fokker V12
The Fokker V12 (Works Number 1980) was delivered without engine and armament to Austria-Hungary on 3 January 1918 and was equipped at MAG with the 150 hp Steyr-Le Rhone. The probable military number of the V12 in Austro-Hungarian service was 90.04. In June, based on the good flight results of the V12, the LFT ordered 14 series D.VIs from Fokker in Schwerin, seven of which were delivered. Works Number 1980 participated as “MAG-Fokker 150 hp Le Rhone biplane” in the Austro-Hungarian fighter competition in Aspern in July. In the accounts of the disbanded Austro-Hungarian air force after the end of the war, Works Number 1980 was designated V12. When it was commissioned on 22 October 1917, it was still running as a V13 with a 160 hp Siemens Sh.III engine. At that time, on 29 October 1917, another machine V12 [Works Number 1982] was ordered as a biplane with 110 hp Ur.II. In a Fokker compilation of May 1919, Works Number. 1982 was then designated V13, which was sent to Budapest together with the V7 [Works Number 1981] on 3 January 1918. It is unclear whether the contradictory information is only a spelling error in the little documentation available or was as convoluted as described, whereby no systematic designations of prototypes seem to be recognizable.
Fokker V12 Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span 7.68 m
Area 24.0 m2
General: Length 7.50 m
Height 3.05 m
Empty Weight 592 kg
Loaded Weight 821 kg
Climb: 1000m 3 min
2000m 6.5 min
3000m 11 min
4000m 17.3 min
5000m 22.5 min
Fokker V13
At least three different biplanes carried the V13 designation, possibly only temporarily. Probably some of these are errors in the surviving Fokker documents. Works Number 1980 was sent together with the V7 (Works Number 1981) to Budapest for MAG on 3 January 1918, where both received the Steyr-built Le Rhone. In the 1919/1920 period, Works Number 1980 was also referred to as the V12. Works Numbers 1983 and 2054 flew as the V13-I and V13-II at the First Fighter Competition at Adlershof in January 1918, the latter with a pre-series 160 hp Siemens & Halske Sh.III engine. Works Number 1983 was originally ordered on 2 November 1917 as the V14 with 160 hp Le Rhone. The order for Works Number 2054 as the V13 biplane was placed on 26 November 1917. On the first day of the Adlershof competition (21 January 1918), Anthony Fokker impressed the Idflieg representatives with a dramatic aerobatic flight in the V13-I. When the official climb measurements by Idflieg began on January 25, the V13-I went out of control while the pilot was adjusting its prototype Ur.III engine and rammed the Fokker V18, but the damage to its lower wing was quickly repaired. On January 26,1918, Fokker pilot Schutzenmeister reached an altitude of 6000 meters on the V13-I in 22.7 minutes. However, the engines of the two V13s in the competition, which had not yet been officially approved for production, caused many an aborted flight. In terms of construction, the V13 was a V9 with a slightly extended fuselage.
Fokker V13-I Specifications
Engine: 145 hp Oberursel Ur.III
Wing: Span 6.75 m
Area 17.4 m2
General: Length 6.35 m
Height 2.82 m
Empty Weight 472 kg
Loaded Weight 644 kg
Climb: 2000m 4.5 min
3000m 7.7 min
4000m 11.0 min
5000m 16.2 min
Fokker V13-II Specifications (as V13-I except)
Engine: 160 hp Oberursel Ur.III
Height 3.20 m
Loaded Weight 669 kg
Fokker V14
Works Number 1983 was ordered on 2 November 1917 with the designation V14. V14 was a biplane with UR.III rotary and participated as a V13 in the first fighter competition at Adlershof.
Fokker V15
There is no data available on the V15.
Fokker V16
The design of the V16 was similar to the V7 triplane with the middle wings omitted to explore the flight characteristics; the upper and lower wings were enlarged.
V16, w/n 2085, was ordered on 3 December 1917 with a 110 hp Oberursel UR.II rotary engine. The wings were cantilever and their surface area was specified as 16.6 m2 in the documentation, slightly smaller than the 18.66 m2 of the production Dr.I.
The purpose of V16 was to investigate the aerodynamic effect of a larger wing gap. The result was deterioration and flight testing was stopped.
Fokker D.VI
Between 20 January and 12 February Idflieg held the First Fighter Competition at Berlin-Adlershof, and Fokker demonstrated both inline-engined and rotary-engined prototypes there. Entered by Fokker in the latter category were three biplanes, the V9, powered by the 110 hp Oberursel Ur.II, the V13-I, powered by the eleven-cylinder Oberursel Ur.III, which was rated at 145 hp, and the V13-II, which was powered by the 160 hp eleven-cylinder Siemens & Halske Sh.III engine. Both eleven-cylinder engines were still considered experimental, but were hoped to be ready for mass-production soon.
The Siemens-Halske Sh.III was demonstrated in several other types by other manufacturers, too, and turned out to be troublesome in most of these at the competition. Yet, it entered production before the Ur.III did, although its initial service would quickly prove the need for further perfection to the engine.
While being of very similar appearance, the two V 13 prototypes were 33 cm longer than the V 9, while having 5 cm shorter wingspan.
Of the three engines mentioned, only the Ur.II was already in mass production and frontline use as the powerplant of the Fokker Dr.I triplane. The Fokker Dr.I was introduced into widespread combat use with several elite Jagdstaffeln around the turn of 1917/18. Pilots very much appreciated the superb rate of climb and excellent maneuverability offered by it. However, it quickly became obvious to the men who flew the type that its horizontal speed was insufficient to keep up with many of the enemy fighters it faced in daily combat.
The triplane design, while offering excellent climb and maneuverability, simply produced too much drag. Since the 110 hp Oberursel Ur.II that powered the Dr.I was in full-scale production, and its more powerful successor, the eleven-cylinder Ur.III, promising to deliver around 145 hp, was still not ready to enter service, a new airframe providing faster speed with the existing engine, had to be designed.
The V 9 and the two V 13s had performed well enough at the competition for Idflieg to award Fokker a production order for 120 airframes that were officially designated D.VI in March. These were to be powered by the readily available Oberursel Ur.II, so the smaller V 9 served as the base version for the final production version of the D.VI.
At this point two important factors have to taken into account. First, Fokker Triplane production at Schwerin was rapidly approaching the end. Out of 320 examples that had been ordered in total, only 21 machines remained to be completed after 31 March. With production of the triplane tapering off, a faster rotary-engined successor was needed. Since the D.VI offered better speed and slightly better low-altitude climb than the triplane, it was chosen as the follow-up model in the Schwerin production halls.
Second, at the same time, another Fokker type had emerged as the winner in the inline-engined category, the Fokker D.VII. This is the type that was truly intended as a replacement for both the outdated Albatros D.V/Va as well as the Fokker Dr.I, as is graphically illustrated by the initial production orders for the D.VII. Right after the end of the competition, in February, 400 D.VIIs were ordered from Albatros, while an initial order for 300 examples was awarded to Fokker. For the Fokker company, this meant that while the Dr.I was being phased out of production, preparations had to be made to begin the manufacture of two different airframe types simultaneously. The fact that these were powered by different engine types complicated matters further.
Fokker took a very economical approach to face, this challenge. A fuselage very closely based on that of the Dr.I was chosen for the D.VI production version. Length of both fuselages was practically identical (5776 mm for the D.VI versus 5770 mm for the Dr.I). Of course, the fuselage between the cockpit and the engine was modified for the biplane configuration; the attachment for the middle wing was eliminated and the lower wing cutout was enlarged because it had a greater chord. The Dr.I tailplane layout was carried over to the D.VII, too.
For the production wings of the D.VI an equally clever solution was found. The chord of the lower wings for both the D.VI and the D.VII was identical (1.20 meters), and the same was true for the upper wings of both types (1.60 meters). Consequently, identical wing ribs could be manufactured for both. In fact, when comparing drawings of the wings of the D.VI to those of the wings of the Fokker D.VII, it becomes apparent that the D.VI wing design was nothing but a shortened D.VII wing. The wing ribs were of identical proportions on both types, and even the ailerons were alike.
These similarities in design considerably eased serial production of the D.VI, and the first example of the new type (D.1631/18) was accepted at Schwerin on 26 April 1918.
From a logical standpoint, it seems that the D.VI was primarily put into production to make the best use of the UR.II engines as they were coming off the production line. It is likely that Fokker was requested to manufacture airframes at roughly the same rate as he received the rotary engines that powered it, in order not to interfere with Fokker D.VII production, which had absolute priority. This, however, is a mere assumption that is not backed up by available contemporary references.
An initial order for 120 machines was placed, and this low number clearly indicates that the Fokker D.VI was not intended to serve at the front in large quantities. Eventually, as the development of better-performing types progressed, even this relatively modest production order would be cut in half.
The first 23 production examples of the D.VI were accepted at Schwerin in May 1918, and a further 26 followed in June, none in July, and the last nine in August. After 60 aircraft were completed, Idflieg terminated half of their production order in favor of the Fokker E.V.
Both types were powered by the same engine, but the E.V was faster and had a better rate of climb. Being a parasol monoplane, it also offered better downward visibility than a biplane, and the combination of these three factors spelled the end for the D.VI. Additionally, in all probability it was also easier to manufacture than all previous Fokker types. Thus, production of the D.VI turned out to be very shortlived, making room for the E.V as soon as it passed the customary static loads test.
By the end of June, 21 Fokker D.VI were listed in the front line inventory, this number modestly increasing to 27 at the end of August. Compared to the 407 Fokker D.VIIs already at the front and 118 Fokker Dr.Is still serving with various units on 30 June, it is readily apparent that the D.VI was not intended to play a major role in frontline combat.
This is proven by the fact that no Jasta which had been previously equipped with the Fokker Dr.I received the D.VI as a replacement. This role was fulfilled by the Fokker D.VII, which had become the favorite mount of the Jasta pilots in a very short time. Instead, The D.VI was supplied to units serving on “quieter” sections of the front, and to home defense units.
Royal Bavarian Jagdstaffel 80 was one of the former units. At least six examples were supplied to the Jasta in June 1918 to partially replace their older Albatros D.Va fighters. The pilots were pleased with their new planes, which offered good maneuverability and immediate responsiveness to the controls.
Few reports of pilots having flown the D.VI are known, but they generally praised the type. However, overall performance of the D.VI was not as good as that of the Fokker D.VII, especially at altitude. The low-powered nine-cylinder rotary engine lost performance at altitude, and since combats took place at ever increasing altitudes, this was a considerable penalty.
Small numbers of the D.VI are known to have been delivered, amongst other units, to Jastas 64, 71, and 75, as well as to several Kests. The fast rate of climb of the rotary-powered fighter made them an ideal candidate for the interceptor role, and the engine required almost no warming up, unlike inline engines.
The Jagdstaffelschulen also received several examples, but the low number of 60 aircraft produced prevented the D.VI from making a lasting impression, either on the German pilots or their opponents. However, it is interesting to note that no example is known to have been captured intact by the Allies before the Armistice.
As production of the Fokker D.VI was getting underway, the first examples of a more powerful rotary engine became available. The nine-cylinder 170 hp Goebel Goe.III engine had successfully completed the prescribed 50-hours duration test in April, and twelve D.VI (military numbers 1637/18, 1639/18 & 1640/18,1643/18 and 1679/18 - 1676/18) received the new engine. The Goebel had a slightly bigger diameter (1050 mm) than the Ur.II (960 mm), but was also a nine-cylinder engine. Apparently Idflieg intended to use the D.VI as a frontline evaluation mount for the Goebel, which actually delivered between 165-178 hp depending upon altitude. In theory, the increased performance promised to solve the speed issues while giving an even faster rate of climb.
Unfortunately, no records or reports of this evaluation have been found, but the facts speak for themselves. No examples of the Goebel engine were later seen in the Fokker E.V when it reached the front in August, and it only reappears later in October 1918 in several prototypes during the Third Fighter Competition in Adlershof. Just before the Armistice, it was intended as the standard powerplant for the Kondor E.IIIa parasol fighter, but by then it was too late.
The fact that no photograph showing a D.VI powered by the Goe.III serving with a Jasta or Kest is known is also noteworthy. Obviously, the engine was not yet ready for frontline service and required further fine-tuning, just as was initially the case with the Siemens-Halske Sh.III.
In retrospect, the main purpose of the D.VI was to provide an interim solution that would be an improvement over the triplane and that could make good use of the available Oberursel engines. But the appearance of the simpler, better-performing Fokker E.V parasol quickly ended its short career. Yet its basic design would resurface once more in the shape of the Fokker V.33 just before the end of the war.
Fokker D.VI Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span upper 7.20 m
Span lower 5.81 m
Chord upper 1.60 m
Chord upper 1.20 m
Gap 1.25 m
Area 17.1 m2
General: Length 5.78 m
Height 2.65 m
Empty Weight 395 kg
Loaded Weight 588 kg
Climb: 1000 m 2.6 min.
2000 m 5.9 min.
3000 m 10.7 min.
4000 m 17.3 min.
5000 m 28.0 min
Fokker D.VI Production Orders
Order Date Qty Serial Nos. Notes
March 1918 120 D.1630-1749/18 60 aircraft, serials 1630-1689/18, were built. The rest were cancelled to produce the D.VIII that used the same engine.
May 1918 150 Unknown Cancelled to produce the D.VIII.
“The Fokker D.VI aircraft flown by the Staffel during the month of August experienced frequent cylinder seizures of the Le Rhone 110 hp rotary engine. The Fokker D.VI was very maneuverable at low altitudes, but it took about one hour to reach the altitude of 5000 meters. It was very slow and unmaneuverable at these altitudes. In Fokker D.VI 1679/18, one cylinder had seized, because the pilot did not immediately recognize the error and continued to fly at full throttle, tearing the connecting rod from the pistons and pushing the broken connecting rod between the threads of the cylinder and the casing, causing the cylinder to break loose and break the main spar of the lower wing. The aircraft crashed out of control [steuerlos] from about 1000 meters. The Ricinus substitute oil No. B237 [and] B238 has served well as long as the Staffel has flown the Fokker D VI.”
Source: The Activity Report of the Wurttbg.Jagstaffel Nr. 64 for the period from August 1 to September 30,1918.
Fokker V33
The Fokker V33 was a small, rotary-powered biplane fighter derived from the Fokker V9 that was tested at Schwerin in August 1918. It was tested with both the 110 hp Oberursel Ur.II (a 9-cylinder engine) and the 145 hp Ur.III (an 11-cylinder engine). Both versions had the same dimensions, but the Ur.III-powered version was heavier due to its heavier engine. The empty weight of the Ur.III-powered version was 396 kg and the loaded weight was 616 kg.
Fitted with the 110 hp Ur.II, the V33 climb rate approximated that of the more powerful V29 up to 4000 meters, but fell behind above that altitude. Unfortunately, data for the V33 climb rate when fitted with the 145 hp Ur.III are not available.
After the war, Fokker flew the V33 in Holland. Dutch newspaper reports mention aerobatic demonstrations of what was then described as a sports plane with an 80 hp Le Rhone engine in the summer of 1919.
Fokker V33 Specifications
Engine: 110 hp Oberursel Ur.II
145 hp Oberursel Ur.III
Wing: Span 7.24 m
Area 13.7 m2
General: Length 5.456 m
Height 2.385 m
Empty Weight 360 kg
Loaded Weight 560 kg
Maximum Speed (Ur.II & Ur.III): 200 km/h
Climb (Ur.II): 3000m 7.5 min
4000m 11 min
5000m 17 min
6000m 24 min
Endurance: 1.5 hrs
The order to commence work on the Fokker V9 (Works Number 1831) experimental biplane was placed to the Fokker experimental workshop on 24 August 1917, just as the first Fokker Triplanes (then still carrying the F.I designation) were about to reach the front.
The fuselage design of the V9 mirrored that of the Triplane; the fuselages of both aircraft were almost identical and they were powered by the same engine. Had both aircraft been developed at the same time, it would not be wrong to say that the V9 was the cantilever biplane fraternal twin of the F.I/Dr.I.
As it was, the V9 was completed in October 1917, when production of the Dr.I was getting into full swing. It participated in the First Fighter Competition at Adlershof in January 1918, still powered by the 110 hp Oberursel Ur.II rotary engine.
The biplane configuration reduced drag compared to the Dr.I, so was a bit faster. Its performance, particularly at high altitude, was limited by use of the low-power rotary engine, and the fact that the low-compression Oberursel engine lost power with altitude faster than the inline engines then available in Germany. More advanced rotary engines, such as the Siemens-Halske Sh.III, which retained much of its power at increasing altitudes, were not yet cleared to enter mass-production. The aircraft’s low aspect-ratio wings, while very sturdy, also increased induced drag, further limiting performance at altitude.
After some further development of the wing and strut design, it was later entered into production under the military designation Fokker D.VI.
Fokker V9 Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span 7.70 m
Area 16.5 m2
General: Length 5.90 m
Height 2.80 m
Empty Weight 381 kg
Loaded Weight 572 kg
Climb: 1000m 2.5 min
2000m 4.7 min
3000m 7.7 min
4000m 11.0 min
5000m 15.5 min
Fokker V12
The Fokker V12 (Works Number 1980) was delivered without engine and armament to Austria-Hungary on 3 January 1918 and was equipped at MAG with the 150 hp Steyr-Le Rhone. The probable military number of the V12 in Austro-Hungarian service was 90.04. In June, based on the good flight results of the V12, the LFT ordered 14 series D.VIs from Fokker in Schwerin, seven of which were delivered. Works Number 1980 participated as “MAG-Fokker 150 hp Le Rhone biplane” in the Austro-Hungarian fighter competition in Aspern in July. In the accounts of the disbanded Austro-Hungarian air force after the end of the war, Works Number 1980 was designated V12. When it was commissioned on 22 October 1917, it was still running as a V13 with a 160 hp Siemens Sh.III engine. At that time, on 29 October 1917, another machine V12 [Works Number 1982] was ordered as a biplane with 110 hp Ur.II. In a Fokker compilation of May 1919, Works Number. 1982 was then designated V13, which was sent to Budapest together with the V7 [Works Number 1981] on 3 January 1918. It is unclear whether the contradictory information is only a spelling error in the little documentation available or was as convoluted as described, whereby no systematic designations of prototypes seem to be recognizable.
Fokker V12 Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span 7.68 m
Area 24.0 m2
General: Length 7.50 m
Height 3.05 m
Empty Weight 592 kg
Loaded Weight 821 kg
Climb: 1000m 3 min
2000m 6.5 min
3000m 11 min
4000m 17.3 min
5000m 22.5 min
Fokker V13
At least three different biplanes carried the V13 designation, possibly only temporarily. Probably some of these are errors in the surviving Fokker documents. Works Number 1980 was sent together with the V7 (Works Number 1981) to Budapest for MAG on 3 January 1918, where both received the Steyr-built Le Rhone. In the 1919/1920 period, Works Number 1980 was also referred to as the V12. Works Numbers 1983 and 2054 flew as the V13-I and V13-II at the First Fighter Competition at Adlershof in January 1918, the latter with a pre-series 160 hp Siemens & Halske Sh.III engine. Works Number 1983 was originally ordered on 2 November 1917 as the V14 with 160 hp Le Rhone. The order for Works Number 2054 as the V13 biplane was placed on 26 November 1917. On the first day of the Adlershof competition (21 January 1918), Anthony Fokker impressed the Idflieg representatives with a dramatic aerobatic flight in the V13-I. When the official climb measurements by Idflieg began on January 25, the V13-I went out of control while the pilot was adjusting its prototype Ur.III engine and rammed the Fokker V18, but the damage to its lower wing was quickly repaired. On January 26,1918, Fokker pilot Schutzenmeister reached an altitude of 6000 meters on the V13-I in 22.7 minutes. However, the engines of the two V13s in the competition, which had not yet been officially approved for production, caused many an aborted flight. In terms of construction, the V13 was a V9 with a slightly extended fuselage.
Fokker V13-I Specifications
Engine: 145 hp Oberursel Ur.III
Wing: Span 6.75 m
Area 17.4 m2
General: Length 6.35 m
Height 2.82 m
Empty Weight 472 kg
Loaded Weight 644 kg
Climb: 2000m 4.5 min
3000m 7.7 min
4000m 11.0 min
5000m 16.2 min
Fokker V13-II Specifications (as V13-I except)
Engine: 160 hp Oberursel Ur.III
Height 3.20 m
Loaded Weight 669 kg
Fokker V14
Works Number 1983 was ordered on 2 November 1917 with the designation V14. V14 was a biplane with UR.III rotary and participated as a V13 in the first fighter competition at Adlershof.
Fokker V15
There is no data available on the V15.
Fokker V16
The design of the V16 was similar to the V7 triplane with the middle wings omitted to explore the flight characteristics; the upper and lower wings were enlarged.
V16, w/n 2085, was ordered on 3 December 1917 with a 110 hp Oberursel UR.II rotary engine. The wings were cantilever and their surface area was specified as 16.6 m2 in the documentation, slightly smaller than the 18.66 m2 of the production Dr.I.
The purpose of V16 was to investigate the aerodynamic effect of a larger wing gap. The result was deterioration and flight testing was stopped.
Fokker D.VI
Between 20 January and 12 February Idflieg held the First Fighter Competition at Berlin-Adlershof, and Fokker demonstrated both inline-engined and rotary-engined prototypes there. Entered by Fokker in the latter category were three biplanes, the V9, powered by the 110 hp Oberursel Ur.II, the V13-I, powered by the eleven-cylinder Oberursel Ur.III, which was rated at 145 hp, and the V13-II, which was powered by the 160 hp eleven-cylinder Siemens & Halske Sh.III engine. Both eleven-cylinder engines were still considered experimental, but were hoped to be ready for mass-production soon.
The Siemens-Halske Sh.III was demonstrated in several other types by other manufacturers, too, and turned out to be troublesome in most of these at the competition. Yet, it entered production before the Ur.III did, although its initial service would quickly prove the need for further perfection to the engine.
While being of very similar appearance, the two V 13 prototypes were 33 cm longer than the V 9, while having 5 cm shorter wingspan.
Of the three engines mentioned, only the Ur.II was already in mass production and frontline use as the powerplant of the Fokker Dr.I triplane. The Fokker Dr.I was introduced into widespread combat use with several elite Jagdstaffeln around the turn of 1917/18. Pilots very much appreciated the superb rate of climb and excellent maneuverability offered by it. However, it quickly became obvious to the men who flew the type that its horizontal speed was insufficient to keep up with many of the enemy fighters it faced in daily combat.
The triplane design, while offering excellent climb and maneuverability, simply produced too much drag. Since the 110 hp Oberursel Ur.II that powered the Dr.I was in full-scale production, and its more powerful successor, the eleven-cylinder Ur.III, promising to deliver around 145 hp, was still not ready to enter service, a new airframe providing faster speed with the existing engine, had to be designed.
The V 9 and the two V 13s had performed well enough at the competition for Idflieg to award Fokker a production order for 120 airframes that were officially designated D.VI in March. These were to be powered by the readily available Oberursel Ur.II, so the smaller V 9 served as the base version for the final production version of the D.VI.
At this point two important factors have to taken into account. First, Fokker Triplane production at Schwerin was rapidly approaching the end. Out of 320 examples that had been ordered in total, only 21 machines remained to be completed after 31 March. With production of the triplane tapering off, a faster rotary-engined successor was needed. Since the D.VI offered better speed and slightly better low-altitude climb than the triplane, it was chosen as the follow-up model in the Schwerin production halls.
Second, at the same time, another Fokker type had emerged as the winner in the inline-engined category, the Fokker D.VII. This is the type that was truly intended as a replacement for both the outdated Albatros D.V/Va as well as the Fokker Dr.I, as is graphically illustrated by the initial production orders for the D.VII. Right after the end of the competition, in February, 400 D.VIIs were ordered from Albatros, while an initial order for 300 examples was awarded to Fokker. For the Fokker company, this meant that while the Dr.I was being phased out of production, preparations had to be made to begin the manufacture of two different airframe types simultaneously. The fact that these were powered by different engine types complicated matters further.
Fokker took a very economical approach to face, this challenge. A fuselage very closely based on that of the Dr.I was chosen for the D.VI production version. Length of both fuselages was practically identical (5776 mm for the D.VI versus 5770 mm for the Dr.I). Of course, the fuselage between the cockpit and the engine was modified for the biplane configuration; the attachment for the middle wing was eliminated and the lower wing cutout was enlarged because it had a greater chord. The Dr.I tailplane layout was carried over to the D.VII, too.
For the production wings of the D.VI an equally clever solution was found. The chord of the lower wings for both the D.VI and the D.VII was identical (1.20 meters), and the same was true for the upper wings of both types (1.60 meters). Consequently, identical wing ribs could be manufactured for both. In fact, when comparing drawings of the wings of the D.VI to those of the wings of the Fokker D.VII, it becomes apparent that the D.VI wing design was nothing but a shortened D.VII wing. The wing ribs were of identical proportions on both types, and even the ailerons were alike.
These similarities in design considerably eased serial production of the D.VI, and the first example of the new type (D.1631/18) was accepted at Schwerin on 26 April 1918.
From a logical standpoint, it seems that the D.VI was primarily put into production to make the best use of the UR.II engines as they were coming off the production line. It is likely that Fokker was requested to manufacture airframes at roughly the same rate as he received the rotary engines that powered it, in order not to interfere with Fokker D.VII production, which had absolute priority. This, however, is a mere assumption that is not backed up by available contemporary references.
An initial order for 120 machines was placed, and this low number clearly indicates that the Fokker D.VI was not intended to serve at the front in large quantities. Eventually, as the development of better-performing types progressed, even this relatively modest production order would be cut in half.
The first 23 production examples of the D.VI were accepted at Schwerin in May 1918, and a further 26 followed in June, none in July, and the last nine in August. After 60 aircraft were completed, Idflieg terminated half of their production order in favor of the Fokker E.V.
Both types were powered by the same engine, but the E.V was faster and had a better rate of climb. Being a parasol monoplane, it also offered better downward visibility than a biplane, and the combination of these three factors spelled the end for the D.VI. Additionally, in all probability it was also easier to manufacture than all previous Fokker types. Thus, production of the D.VI turned out to be very shortlived, making room for the E.V as soon as it passed the customary static loads test.
By the end of June, 21 Fokker D.VI were listed in the front line inventory, this number modestly increasing to 27 at the end of August. Compared to the 407 Fokker D.VIIs already at the front and 118 Fokker Dr.Is still serving with various units on 30 June, it is readily apparent that the D.VI was not intended to play a major role in frontline combat.
This is proven by the fact that no Jasta which had been previously equipped with the Fokker Dr.I received the D.VI as a replacement. This role was fulfilled by the Fokker D.VII, which had become the favorite mount of the Jasta pilots in a very short time. Instead, The D.VI was supplied to units serving on “quieter” sections of the front, and to home defense units.
Royal Bavarian Jagdstaffel 80 was one of the former units. At least six examples were supplied to the Jasta in June 1918 to partially replace their older Albatros D.Va fighters. The pilots were pleased with their new planes, which offered good maneuverability and immediate responsiveness to the controls.
Few reports of pilots having flown the D.VI are known, but they generally praised the type. However, overall performance of the D.VI was not as good as that of the Fokker D.VII, especially at altitude. The low-powered nine-cylinder rotary engine lost performance at altitude, and since combats took place at ever increasing altitudes, this was a considerable penalty.
Small numbers of the D.VI are known to have been delivered, amongst other units, to Jastas 64, 71, and 75, as well as to several Kests. The fast rate of climb of the rotary-powered fighter made them an ideal candidate for the interceptor role, and the engine required almost no warming up, unlike inline engines.
The Jagdstaffelschulen also received several examples, but the low number of 60 aircraft produced prevented the D.VI from making a lasting impression, either on the German pilots or their opponents. However, it is interesting to note that no example is known to have been captured intact by the Allies before the Armistice.
As production of the Fokker D.VI was getting underway, the first examples of a more powerful rotary engine became available. The nine-cylinder 170 hp Goebel Goe.III engine had successfully completed the prescribed 50-hours duration test in April, and twelve D.VI (military numbers 1637/18, 1639/18 & 1640/18,1643/18 and 1679/18 - 1676/18) received the new engine. The Goebel had a slightly bigger diameter (1050 mm) than the Ur.II (960 mm), but was also a nine-cylinder engine. Apparently Idflieg intended to use the D.VI as a frontline evaluation mount for the Goebel, which actually delivered between 165-178 hp depending upon altitude. In theory, the increased performance promised to solve the speed issues while giving an even faster rate of climb.
Unfortunately, no records or reports of this evaluation have been found, but the facts speak for themselves. No examples of the Goebel engine were later seen in the Fokker E.V when it reached the front in August, and it only reappears later in October 1918 in several prototypes during the Third Fighter Competition in Adlershof. Just before the Armistice, it was intended as the standard powerplant for the Kondor E.IIIa parasol fighter, but by then it was too late.
The fact that no photograph showing a D.VI powered by the Goe.III serving with a Jasta or Kest is known is also noteworthy. Obviously, the engine was not yet ready for frontline service and required further fine-tuning, just as was initially the case with the Siemens-Halske Sh.III.
In retrospect, the main purpose of the D.VI was to provide an interim solution that would be an improvement over the triplane and that could make good use of the available Oberursel engines. But the appearance of the simpler, better-performing Fokker E.V parasol quickly ended its short career. Yet its basic design would resurface once more in the shape of the Fokker V.33 just before the end of the war.
Fokker D.VI Specifications
Engine: 110 hp Oberursel Ur.II
Wing: Span upper 7.20 m
Span lower 5.81 m
Chord upper 1.60 m
Chord upper 1.20 m
Gap 1.25 m
Area 17.1 m2
General: Length 5.78 m
Height 2.65 m
Empty Weight 395 kg
Loaded Weight 588 kg
Climb: 1000 m 2.6 min.
2000 m 5.9 min.
3000 m 10.7 min.
4000 m 17.3 min.
5000 m 28.0 min
Fokker D.VI Production Orders
Order Date Qty Serial Nos. Notes
March 1918 120 D.1630-1749/18 60 aircraft, serials 1630-1689/18, were built. The rest were cancelled to produce the D.VIII that used the same engine.
May 1918 150 Unknown Cancelled to produce the D.VIII.
“The Fokker D.VI aircraft flown by the Staffel during the month of August experienced frequent cylinder seizures of the Le Rhone 110 hp rotary engine. The Fokker D.VI was very maneuverable at low altitudes, but it took about one hour to reach the altitude of 5000 meters. It was very slow and unmaneuverable at these altitudes. In Fokker D.VI 1679/18, one cylinder had seized, because the pilot did not immediately recognize the error and continued to fly at full throttle, tearing the connecting rod from the pistons and pushing the broken connecting rod between the threads of the cylinder and the casing, causing the cylinder to break loose and break the main spar of the lower wing. The aircraft crashed out of control [steuerlos] from about 1000 meters. The Ricinus substitute oil No. B237 [and] B238 has served well as long as the Staffel has flown the Fokker D VI.”
Source: The Activity Report of the Wurttbg.Jagstaffel Nr. 64 for the period from August 1 to September 30,1918.
Fokker V33
The Fokker V33 was a small, rotary-powered biplane fighter derived from the Fokker V9 that was tested at Schwerin in August 1918. It was tested with both the 110 hp Oberursel Ur.II (a 9-cylinder engine) and the 145 hp Ur.III (an 11-cylinder engine). Both versions had the same dimensions, but the Ur.III-powered version was heavier due to its heavier engine. The empty weight of the Ur.III-powered version was 396 kg and the loaded weight was 616 kg.
Fitted with the 110 hp Ur.II, the V33 climb rate approximated that of the more powerful V29 up to 4000 meters, but fell behind above that altitude. Unfortunately, data for the V33 climb rate when fitted with the 145 hp Ur.III are not available.
After the war, Fokker flew the V33 in Holland. Dutch newspaper reports mention aerobatic demonstrations of what was then described as a sports plane with an 80 hp Le Rhone engine in the summer of 1919.
Fokker V33 Specifications
Engine: 110 hp Oberursel Ur.II
145 hp Oberursel Ur.III
Wing: Span 7.24 m
Area 13.7 m2
General: Length 5.456 m
Height 2.385 m
Empty Weight 360 kg
Loaded Weight 560 kg
Maximum Speed (Ur.II & Ur.III): 200 km/h
Climb (Ur.II): 3000m 7.5 min
4000m 11 min
5000m 17 min
6000m 24 min
Endurance: 1.5 hrs
Fokker D.VI 1661/18 of Oblt. Erwin Wenig, Staffelfuhrer of Jagdstaffel 80, Summer 1918
Fokker D.VI 1661/18, Lt. Josef Filbig, Jasta 80b, Summer 1918
Note: Originally this aircraft was flown by Oblt. Wenig. When Lt. Filbig joined the Jasta he took over 1661/18 and painted the black fuselage band blue.
Note: Originally this aircraft was flown by Oblt. Wenig. When Lt. Filbig joined the Jasta he took over 1661/18 and painted the black fuselage band blue.
Fokker D.VI Fratz of Lt. Kurt Seit, Jasta 80, summer 1918
Fokker D.VI of Kest 1a.
Fokker D.VI of KEST 1b, a Home Defence unit based at Karlsruhe. The aircraft was powered by an Oberursel Ur.II rotary engine of 120 hp. (Profile by Bob Pearson)
The Fokker V.9, Works Number 1831, photographed at the First Fighter Competition. (Peter M. Grosz Collection/STDB)
This photo of the Fokker V9 shows its heritage as a derivative of the Dr.I triplane. The fuselage and tail are essentially the same with the minor differences required by its biplane configuration.
The Fokker V9 prototype at Schwerin; the worker and tail support trestle have been retouched in a rough manner. The cabane and interplane strut layout as well as the wing design foreshadows that of the Fokker D.VII.
Front and rear views of the Fokker V9 shows Fokker's attempt at streamlining.
Fokker D.VI (Prototyp V 12), Nr. 1980, vorgesehene Serie 04.100
A factory photo of Fokker V12, Works Number 1980, a D.VI prototype and a sister ship to experimental Triplane V.7R, WN 1981. Both were shipped to Hungary on 3 January 1918 and fitted with identical cowlings, Steyr-LeRhones, and propellers. Fourteen V12s were originally ordered as D.VIs, and seven were delivered and fitted with A-H Steyr-LeRhones, props, and Schwarzlose machine guns. The other five were converted to D.VII orders. The D.VIs continued to fly until the last was lost in 1926.
A factory photo of Fokker V12, Works Number 1980, a D.VI prototype and a sister ship to experimental Triplane V.7R, WN 1981. Both were shipped to Hungary on 3 January 1918 and fitted with identical cowlings, Steyr-LeRhones, and propellers. Fourteen V12s were originally ordered as D.VIs, and seven were delivered and fitted with A-H Steyr-LeRhones, props, and Schwarzlose machine guns. The other five were converted to D.VII orders. The D.VIs continued to fly until the last was lost in 1926.
Fokker V13-II, Fokker Works number 2054, the second of two V13 prototypes, participated in the First Fighter Competition powered by a 160 hp Siemens-Halske Sh.III. The V13-I, works number 1980, was powered by the 145 hp Oberursel UR.III. The Fokker V13 prototypes featured the N-strut design used by the production Fokker D.VI. (Peter M. Grosz Collection/STDB)
The first production D.VI 1631/18, the true production prototype, was photographed at Adlershof during its Typenprufung in April/early May 1918. Its works number was 2613. The D.VI had excellent visibility for the pilot, was very maneuverable, and was light and sensitive on the controls, a real pilot's airplane. It just needed more power than its 110 hp Oberursel UR.II offered to be a first-class fighter. Comparison of the D.VI specifications with the V17 monoplane prototype using the same engine reveals the great improvement in performance of the monoplane configuration. The V17 probably should have been selected for production instead of the D.VI because its performance was far superior, but its monoplane configuration was suspect and the wing obscured the pilot's downward field of view.
The tail of Fokker D.VI 1631/18 has been put up on a trestle in order to allow a frontal shot to be taken. (Peter M. Grosz Collection/STDB)
Jasta 80b Staffelfuhrer Oblt. Erwin Wenig with his dog in front of his Fokker D VI 1661/18; the Fokker Werknummer 2643 is visible on the struts. His personal marking consisted of a black fuselage section aft of the cockpit, edged by narrow black bands on both sides. (Bruno Schmaling)
Fokker D.VI 1661/18, flown by Oblt. Erwin Wenig shows the Jagdstaffel 80 unit marking of a white stripe, applied herewith a narrow black border, on each side of the elevator. A white stripe was painted on the center section of the upper part of the top wing as Staffelfuhrer identification marking. (Bruno Schmaling)
Серийный "Фоккер" D.VI, вид спереди. Снимок сделан летом 1918 года.
Frontal view of Wenig's new Fokker taken around the same time as the photo above. The streamlined rear-view mirror in the upper wing cutout and the offset "Axial" decals help to identify the aircraft in other photos. (Bruno Schmaling)
Frontal view of Wenig's new Fokker taken around the same time as the photo above. The streamlined rear-view mirror in the upper wing cutout and the offset "Axial" decals help to identify the aircraft in other photos. (Bruno Schmaling)
Wenig's Fokker D.VI 1661/18 shows up in several Jasta 80b photos, and seen here are two members of the Jagdstaffel posing in front of this plane. In the lower photo, the units special duties officer (not pilot) Oblt. Max Speidel seized the opportunity for a snapshot. (Peter M. Grosz Collection/STDB; above also Bruno Schmaling).
A rare lineup of Fokker D.VI fighters of Jagdstaffel 80b (the 'b' suffix denotes a Bavarian unit) at Morsberg (now Marimont-les-Benestroff), with Wenig's 1661/18 heading the six planes. The photo was taken at the same time as the two portrait shots. (Alex Imrie)
Pilots from Jasta 80b pose in front of what appears to be the Staffelfuhrer's Fokker D.VI 1661/18 for a cheerful group photo. (Peter M. Grosz Collection/STDB)
Around the same time, the groundcrew of Jasta 80b gathered in front of a D.VI for their own snapshot. Comparison of the leading edge details indicates that another Fokker served as the backdrop for this picture. (Peter M. Grosz Collection/STDB)
At some later point, Jasta 80b member Lt.d.R. Josef Filbig was photographed with the aircraft. By then, the black center section had been re-painted Bavarian blue, and the name "Jette" had been added below the cockpit. (Tobias Weber)
Photo retouching 1918-style! While all details of the uniform in this photo match those of Josef Filbig seen in the photo above, the head of another unknown individual has been montaged into the photo here.
The prop and rear-view mirror indicate that this photo again shows 1661/18 in yet another, later paint scheme. The cowling now appears in a light color, while the white borders of the mid-fuselage marking have disappeared. This section now looks dark again. While difficult to make out, the facial features of the pilot do resemble those of Filbig. (Peter M. Grosz Collection/STDB)
Fokker D.VI 1688/18 is seen here on the Kest 4b airfield at Freiburg. The aircraft is still in factory finish, seen behind it is Albatros D.Va D.5629/17 "4". (Reinhard Zankl)
Fokker D.VI 1689/18 is seen here at the Flugpark in the area of Armee-Abteilung B. Numerically, this was the last aircraft built, being accepted on 8 June, and photographed here on 21 June. However, chronologically the last two D.VIs to be accepted at Schwerin for the Fliegertruppe were 1637/18 and 1639/18 on 1 August 1918.
The little-known Fokker D.VI was a biplane derivative of the famous Fokker Triplane. Arguably, it is the fighter that Fokker should have introduced instead of the Dr.I Triplane, but Idflieg was suffering the worst of its 'Triplane Craze' at the time and wanted a triplane. The D.VI was faster than the Dr.I Triplane and nearly as maneuverable. Its climb rate at altitude suffered from its detail design; to simplify production the same wing ribs were used as for the heavier, Mercedes-powered D.VII that was produced in parallel. The resulting D.VI wings had shorter span and a low aspect ratio. Coupled with its rotary engine that lost power at altitude faster than competing in-line engines such as the Mercedes in the D.VII, its climb rate at altitude suffered.
The little-known Fokker D.VI was a biplane derivative of the famous Fokker Triplane. Arguably, it is the fighter that Fokker should have introduced instead of the Dr.I Triplane, but Idflieg was suffering the worst of its 'Triplane Craze' at the time and wanted a triplane. The D.VI was faster than the Dr.I Triplane and nearly as maneuverable. Its climb rate at altitude suffered from its detail design; to simplify production the same wing ribs were used as for the heavier, Mercedes-powered D.VII that was produced in parallel. The resulting D.VI wings had shorter span and a low aspect ratio. Coupled with its rotary engine that lost power at altitude faster than competing in-line engines such as the Mercedes in the D.VII, its climb rate at altitude suffered.
Fok. D.VI, 110-h.p. Le Rhone.
A very early-production Fokker D.VI on the airfield at Schwerin-Gorries. The cowling is still unpainted, the machine guns remain to be fitted, and the first version of the Balkenkreuz marking with the 15 cm white borders is applied on wings and fuselage. (Reinhard Zankl)
A very early-production Fokker D.VI on the airfield at Schwerin-Gorries. The cowling is still unpainted, the machine guns remain to be fitted, and the first version of the Balkenkreuz marking with the 15 cm white borders is applied on wings and fuselage. (Reinhard Zankl)
A Kest 1a Fokker D.VI on the airfield at Mannheim. The cowling has been painted in a light color interpreted as light blue for the profile. Personal marking of a double pennant, interpreted as black and white, is seen below the cockpit. The fuselage cross has been converted from the earlier full white border version by extending the black cross arms. For some reason there are contradicting overall dimensions given for the D.VI in various contemporary sources. (Peter M. Grosz Collection/STDB; also Bruno Schmaling).
While this photo of the Kest 1b D.VI is of less than perfect quality, it shows the small "thin" Balkenkreuz on the upper wing to good advantage. None of the available photos of this aircraft shows the military or factory works number clearly. (Peter M. Grosz Collection/STDB)
Fokker D.VI taken over by the USAS postwar as part of the Armistice agreement. Three D.VI fighters, 1639/18, 1655/18, and 1676/18, were shipped to the US from Romorantin on 2 April 1919. At least one was assigned USAS serial number AS 94033 and McCook Field number P-385. The tail markings suggest possible previous service with Jasta 71. (Peter M. Grosz Collection/STDB)
This unarmed Fokker D.VI trainer probably served at Jastaschule II at Nivelles, where the application of numbers in the style seen here was common. (Peter M. Grosz Collection/STDB)
Fokker D.VI marked with an "X" was operated by an unidentified unit. Interestingly, the fuselage cross remains in its original shape even though a personal marking has been applied to the plane. (Peter M. Grosz Collection/STDB)
These photos may show the same Fokker D.VI from Jasta 80b: above at Morsberg in the summer of 1918, below in December 1918 after it was taken over by the USAS. By then the fuselage a nd nose paintjob had changed somewhat, but the modified lower wing crosses are identical. This may be the aircraft in which Otto Fuchs was photographed. (Peter M. Grosz Collection/STDB)
The Fokker D.VI was a smaller, lighter version of the D.VII powered by a 110 hp Oberursel. This one is serving with Jasta 80b. Somewhat more maneuverable than the larger D.VII and slightly faster at low altitude, the low-powered rotary limited the D.VI to production of only 120 aircraft. The more powerful inline engines in the D.VII gave it better performance at higher altitudes, where most combats were fought by 1918.
The Fokker D.VI was a smaller, lighter version of the D.VII powered by a 110 hp Oberursel. This one is serving with Jasta 80b. Somewhat more maneuverable than the larger D.VII and slightly faster at low altitude, the low-powered rotary limited the D.VI to production of only 120 aircraft. The more powerful inline engines in the D.VII gave it better performance at higher altitudes, where most combats were fought by 1918.
A pilot of Jasta 80b posing with a Fokker D.VI of Jasta 80b. This is the second aircraft seen in the earlier Jasta 80b lineup photo. (Museum der Pfalz via Greg VanWyngarden)
Lt. Otto Fuchs of Jasta 77b photographed in the cockpit of a Fokker D.VI of Jasta 80b while he visited the unit. (Dr. Volker Koos)
Pilot Otto Fuchs in a Fokker D.VI of Jasta 80b. At the time he was serving in Jasta 77b, and Jasta 77b shared an airfield with Jasta 80, where both were part of "Jagdgruppe Raben" which consisted of Jastas 3, 18, 54, 77, and 80. Otto Fuchs told historian Bruno Schmaling that he and other pilots of Jasta 77 visited Jasta 80 and in reverse. When he was at Morsberg he of course flew the Fokker D VI, but he was not very impressed. (Dr. Volker Koos)
Lt. Kurt Seit and his Fokker D.VI Fratz at last a 80b. Bavarian colors (blue & white) were used for the personal markings. The aircraft carried 5-color printed camouflage fabric on its wings. (Peter M. Grosz Collection/STDB)
A better look at the face marking of "Fratz" is provided by this snapshot of two mechanics. (Bruno Schmaling)
A Fokker D.VI serving with Kest 7 at Dusseldorf with late-war think national markings. The pilot has been identified as Lt. Hoffmann. (Peter M. Grosz Collection/STDB)
The same aircraft was often used as a backdrop for several pilots, and this is the case here with this anonymous Fokker D.VI from Kest 7 in late 1918. In an almost identical photo seen earlier in this book, a Lt. Hoffmann poses with the fighter, while here another unit member has his picture taken with the Fokker fighter. The fuselage crosses have been modified to the thin Balkenkreuz typical for late-war fighters.
A view of the same aircraft at Karlsruhe. Just visible is the lower wing cross, the vertical cross arm extends from leading to the trailing edge of the wing. The tonality of the two-color fuselage band looks a bit different in all four photos of the plane, and it has been interpreted as yellow-red-yellow for the profile. Karlsruhe is located in the Grand Duchy of Baden, and these are the colors of the Baden coat of arms. (Reinhard Zankl)
A single Fokker D.VI of Kest 1b is seen here with several Fokker D.VIIs at Karlsruhe. The fuselage and rudder cross have been converted by extending the black cross arms. The Fokker company logo decal is visible on the bottom of the rudder, and next to it the Fokker Werknummer has been marked. Unfortunately, it is too indistinct to be read clearly. (Above: Greg VanWyngarden, Below: Reinhard Zankl)
A pilot and seven members of the maintenance crew of Jasta 75 pose in front of their Fokker D.VI at Habsheim airfield. The hangar marked "A10" behind them was formerly used by the Aviatik company, the inscription still being faintly visible on the roof arch. (Peter M. Grosz Collection/STDB)
Full view of the same aircraft, showing that the bottom of the axle wing was painted light blue. On the lower part of the cowling, the dark green paint has been worn off by the castor oil spewing out of the Oberursel engine. (Peter M. Grosz Collection/STDB).
This unidentified Fokker D VI was photographed at Lachen-Speyerdorf. The stains on the engine cowling indicate an emergency landing due to an engine defect such as piston seizure. Putting that in context to the location, the aircraft may have been from Kest 1a or 1b. (Reinhard Kastner)
This D.VI was apparently evaluated by the French after the war, and it is being pushed back into the hangar. The castor oil stains on the cowling were usually removed by the groundcrew after each flight. But since the evaluation was probably fairly short the new owners did not bother with this. (Peter M. Grosz Collection/STDB)
This Fokker D.VI in French hands after the war may be the same aircraft pictured above. At this point, the machine guns had been removed. On this D.VI, the rudder cross has been slimmed down to the final 8:1 proportions, which was not always done on older aircraft. This may be a hint that this particular D.VI actually saw use until the final days of the war, which was the case with a few Fokker Triplanes as well. On fall days with a low cloud ceiling, the rotary-engined Fokker fighters were still rather useful. (Greg VanWyngarden)
Groundcrew members of Kest 4b assemble in front of the new plane for a group photo. This may have been the first fighter powered by the Oberursel Ur.II engine delivered to the unit, and the mechanics were probably curious to have a look at the engine. (Peter M. Grosz Collection/STDB)
Full view of the same D.VI minus cowling; note the full-chord Balkenkreuz on the lower wing having 5:4 proportions. A lineup of Kest 4b Albatros D.Va fighters serves as the backdrop, with D.5351/17 "3" seen at right. (Peter M. Grosz Collection/STDB)
A trio of D.VIs, at least one of them from Jasta 80b, seen amongst Fokker D.VIIs and Roland D.VIs after being turned over to the French after the armistice. The photo was probably taken at Neunkirchen or Saargemund. Many surrendered German fighters were gathered here. (Peter M. Grosz Collection/STDB)
The Fokker V33 was derived from the V9 prototype. It was tested with both the 110 hp Oberursel Ur.II and the 145 hp Oberursel Ur.III. Its rudder was a different shape than the customary Fokker comma shape.
The Fokker V33 was derived from the V9 prototype. It was tested with both the 110 hp Oberursel Ur.II and the 145 hp Oberursel Ur.III. The engine fitted here appears to be the Ur.III.
The Fokker V33 was derived from the V9 prototype. It was tested with both the 110 hp Oberursel Ur.II and the 145 hp Oberursel Ur.III. Its high altitude climb rate did not match the BMW-powered Fokker V.29.
The Fokker V33 in the Netherlands postwar.
The Fokker V33 prototype under construction with the 145 hp Oberursel Ur.III.
Fokker V.9
Fokker V 13
Fokker V 33
Fokker D.VI 1661/18 of Oblt. Erwin Wenig, Staffelfuhrer of Jagdstaffel 80, Summer 1918
Fokker D.VI Fratz of Lt. Kurt Seit, Jasta 80, summer 1918
Fokker D.VI
Fokker D.VI
Fokker D.VI
Fokker V.11
Keen to evaluate the potential of the new cantilever wing design, Fokker ordered another biplane fighter from his workshop on 20 September 1917. This particular aircraft was assigned the works number 1883, and was given the Fokker designation V11. The basic design of its airframe very closely resembled that of the V9, being enlarged to make up for the additional size, weight, and power of the inline engine. Available photos taken during construction of V11 show that it was, initially at least, powered by a Mercedes D.III engine, which shows clear signs of previous use. This invites suggestion that this engine may have been second-handed from another Fokker aircraft, possibly a D.IV which had been returned to the factory, or maybe even from the V2, V3, V6, or V8 prototypes.
The rear fuselages of both the V9 and the initial V11 very closely resembled that of the Fokker Triplane, which seems a reasonable design concept considering the initial successes demonstrated by the two Fokker F.Is at the front.
Unlike the V9, the V11 sported no undercarriage axle wing, indicating this component may have been considered better-suited for the rotary-engined fighters.
The first performance and weight figures for this aircraft were recorded at Schwerin as early as mid-October 1917, indicating that the aircraft was completed roughly three to four weeks after the experimental workshop received their order.
Conventional wisdom has it that the aircraft was shipped to Adlershof to take part in the First Fighter Competition on 18. January 1918, a date confirmed by Fokker records. At the competition it was reportedly test-flown by Manfred Freiherr von Richthofen (and others), who universally praised its performance but criticised its lack of directional stability, especially in a dive, as well as its tendency to swing in flight.
In order to remedy this deficiency, Fokker supposedly rushed over his most experienced welders from Schwerin in order to lengthen the fuselage “over the weekend”, and voila, the modifications turned Vll into the clear winner of the competition.
While this makes for an amazing narrative, some indications make this story somewhat hard to believe. To begin with, it would imply that the pretty obvious defects mentioned had escaped the attention of Fokker and his team of test pilots at Schwerin over a period of two months. This seems somewhat unlikely, and even more importantly, all available photos of Vll in its initial shape were taken at Schwerin. No known photo taken at Adlershof shows the aircraft in its initial guise.
Furthermore, when comparing photos of the freshly-completed V11-I to the modified V11-II, which was photographed at Adlershof, it becomes obvious that the modifications did not just comprise of lengthening and deepening the rear fuselage. The wing area was reduced by integrating the ailerons into the wing, adding a cut-out to the wing centre-section, and possibly reducing the chord of the wings. A larger-capacity radiator was fitted, and a 170 hp Mercedes D.IIIa engine now powered the aircraft - the upright air pump ahead of the first cylinder is now clearly visible. The familiar “streaked” camouflage scheme had been applied, but no works number is visible.
A look at a graph documenting the wing loads of Fokker aircraft shows that a wing load of approximately 34,2 kg/m2 was recorded for V11 in mid-October 1917. By early January, before the aircraft was shipped to Adlershof, a wing loading of around 41,29 kg/m2 was recorded for V11. This clearly indicates that by then, the lengthened fuselage and reduced wing area (now 20.2 m2) had been applied to the aircraft, resulting in V11-II. Interestingly, the wing area of V1-II was now exactly that of the D.VII production aircraft.
Taking all this into account, the aircraft appeared markedly different from its first appearance, and to this day it is not entirely clear if the photos show a radically-rebuilt airframe or two completely different planes. Certainly, Fokker records only mention the works number 1883 for V11, implying that it was indeed just one aircraft.
On the other hand, the sheer extent of modifications, which literally cover almost the entire airframe, suggests the existence of two aircraft under the V11 designation.
After Fokker received his initial production order for the D.VII, V11 was included into this batch of 300 aircraft where it was assigned the military number 227/18. This way, Fokker obtained payment from the authorities for an experimental aircraft which he had originally financed out of his own pocket. All indications are that V11 was destroyed during the type-test procedure at Adlershof in February 1918, where load-tests were carried out on the airframe, proving it to exceed all specified load factors.
The question whether the V11 or the V18 was the true prototype of the D.VII is impossible to answer. While the V11-II was picked as the winner of the First Fighter Competition, the production D.VII inherited features from both of these aircraft, and a few entirely new details as well. In a way, the V11 and V18 were two parallel paths that eventually merged into the Fokker D.VII by late February 1918.
Fokker V11-II Specifications
Engine: 160 hp Mercedes D.III
Wing: Span 8.72 m
Area 24.0 m2
General: Length 6.90 m
Height 3.05 m
Empty Weight 592 kg
Loaded Weight 821 kg
Climb: 1000m 3 min
2000m 6.5 min
3000m 11 min
4000m 17.3 min
5000m 22.5 min
Fokker V18
The Fokker V18 experimental aircraft, given the Fokker works number 2116, was closely related to the Vll and must be seen as the second prototype ancestor to the aircraft that eventually entered serial production under the military designation Fokker D.VII.
From the start, this machine had a taller rear fuselage that already closely resembled that of the later D.VII. Importantly for its flying qualities, it had much enlarged vertical tail surfaces for better stability. The leading edge of the horizontal tailplane was curved, resembling the shape of the component on the early Fokker F.Is. As was the case on the Triplane, the curved leading edge of the horizontal tail surfaces was not adopted for production aircraft.
The construction order for the Fokker V18 was dated 12 December 1917; work on the aircraft proceeded quickly. It was sent to Adlershof on 17 January 1918, actually a day before the V11 was, in order to participate in the First Fighter Competition. Once again, Fokker records document the aircraft had a 160 hp Mercedes D.III, while photos prove it was in fact powered by a D.IIIa.
Without a doubt, Fokker wanted to assure that his latest designs were powered by the better-performing engine during the competition.
On 25 January 1918, V18 was damaged as a result of an accident. As the result of an Oberursel maintenance man making a mistake while adjusting the engine of Fokker V13, which was parked nearby, the rotary-engined prototype made a sudden hop that was halted by the tip of the lower left wing of V18. However, the damage was quickly repaired, and testing of V18 resumed on 27 January.
Like Vll, the aircraft was missing the axle wing that was a standard component on the Fokker Dr. I, as well as on all of Fokker's 1918 production aircraft.
After Fokker received his initial production order for the D.VII, the V18 prototype was absorbed into this batch of 300 aircraft, where it was assigned the military number 228/18. However, it is unknown if it was ever fully brought up to D.VII production standards, or if this inclusion into the first batch was merely intended to assure that Fokker would receive payment for his prototype investment.
Fokker V18 Specifications
Engine: 170 hp Mercedes D.IIIa
Wing:
Span 8.72 m
Area 23.1 m2
General: Length 7.03 m
Height 2.9 m
Empty Weight 634 kg
Loaded Weight 860 kg
Climb: 2000m 5.3 min
3000m 10.5 min
4000m 17.3 min
5000m 26.0 min
Fokker V21
For many years, the true identity of the Fokker V21 had researchers puzzled. It was known that this aircraft had been assigned the Fokker Works Number 2310, but since a rudder showing just this works number was seen on a Mercedes-powered mid-wing monoplane, it was determined that this must have been the V21. Thanks to the research of the much-missed historian Alex Imrie we know that this mid-wing monoplane was, in fact, Fokker V23, Works Number 2443. When said photograph was taken, V23 mounted a “comma"-shaped rudder which was originally fitted to the real V21, and this component was marked with the Fokker Works Number 2310.
The true Fokker V21 was, in fact, the Fokker D.VII production prototype, and it is termed exactly that in official Fokker records. Unfortunately, the few available photographs of V21 only show it being fitted with the final tail-plane, featuring the tall rudder complete with the fin as seen on the production Fokker D.VIIs.
In these photos the aircraft is painted in the overall “streaked” scheme known so well from the Fokker Dr.I, which was still in full production at Schwerin when the V21 first appeared in February 1918. Records documenting wing data and engine performance mention the D.VII for the first time during this month, and in this context it is possible to determine that V21 was indeed the D.VII “pattern aircraft”.
It is noteworthy that the Iron Cross markings were also applied in an identical way to that seen on the Dr.I, being marked on a rectangular white background, a style of application that had become obsolete by an Idflieg instruction dating back as far as October 1916!
The fact that the initial small rudder, which was apparently first fitted to V21, was then transplanted to V23 proves that even by early February the final D.VII production configuration had not yet been determined. Last-minute modifications were still being carried out then.
Streaky fabric covering aside, the details seen on V21 match those of the first production D.VIIs, including the wing layout and the type of radiator fitted to the airframe. Some very minor details differed, but on the whole it can be seen as the true “pre-production” Fokker D.VII.
Unsurprisingly, the overall dimensions recorded for V21 match those of the D.VII.
On 22 May, V21 aka Werknummer 2310, was sent to Flz.A.Gr 6 (the aircraft testing department) at Adlershof, in order to participate in the upcoming Second Fighter Competition.
We hear about it one more time on 17 October, when it was sent to the Central Acceptance Commission at Berlin-Johannisthal.
Fokker V21 Specifications
Engine: 160 hp Mercedes D.III
Wing:
Span 8.90 m
Area 20.2 m2
General: Length 6.945 m
Height 2.945 m
Empty Weight 652 kg
Loaded Weight 870 kg
Climb: 2000m 7.0 min
3000m 12.0 min
4000m 19.5 min
5000m 27.0 min
Fokker V22
After the victory of Fokker’s new D.VII fighter in the First Fighter Competition, Austrian pilots were given the opportunity to fly the first prototype. Fokker wrote to the Austro-Hungarian Fliegerarsenal (Flars) as early as 19 February 1918 that he could deliver 40 D.VIIs a month to Austria if he could get the necessary quota of steel tubes. In four weeks, he wanted to have two samples of the D.VII ready for the LFT. The first was the V22, powered by the 200 hp (19000 series) Austro-Daimler engine and a four-bladed Jaray propeller and steel tube fuselage.
The V22 carried the Fokker Works number 2342, and this reveals that it was “sandwiched” into the early Fokker D.VII fighters, between 256/18 (w/n 2341) and 257/18 (w/n 2343). As such, it was a series-production airframe that was adapted for installation of the Austrian engine and armament. This is an important fact that has to be kept in mind when reading the later objections brought up by the Austrian authorities against license manufacture of the aircraft.
A second projected prototype was to have a plywood fuselage, intended as a fallback solution in case a lack of steel tubing would prevent serial production either in Austro-Hungaria or in Schwerin as an “export” version. However, as early as March 1918, Idflieg officer Oblt. Reichelt indicated that a number of wagon-loads of steel tube could be supplied to ensure production at or for the Austro-Hungarian empire. On 2 March, Fokker requested the delivery of two 8 mm Schwarzlose M16s for the V22, which was to receive the latest version of Fokker’s central control system. He had agreed to deliver the V22 readily-equipped to full military standards. Of course, this would allow for an evaluation of the type under realistic circumstances.
On 15 and 16 March 1918, Austrian Stabsfeldwebel Franz Kuttner flew the V22 at Schwerin-Gorries. Kuttner had previously been a Fokker flight instructor. During these evaluations, a climb time to 3000 meters was recorded in 8 to 9 Minutes, while 5000 meters were reached in 17 1/2 to 19 minutes. The aircraft was reported to have very good flight characteristics, offered remarkably good visibility as was very maneuverable.
In early April, the Austrian War Ministery purchased the aircraft, which was delivered to MAG on 24 April 1918. Fokker invoiced Flars via MAG on 13 June, the price of the airframe was 30.000 Marks.
Thorough testing by the Fliegerasenal at Wien-Aspern followed under Austrian military serial number 90.05. Flars representatives were initially opposed to serial production of the aircraft, expecting equal or better performance from their own new or improved fighter designs.
An Austrian report dated 20 April listed seven points that supposedly prevented production of the type by an Austro-Hungarian manufacturer under licence. These points document an obvious ignorance of facts that can only be explained by a massive bias of the Austro-Hungarian authorities against the Fokker design. For this reason, they are repeated in full here:
“The aircraft presented cannot be considered to enter series production with us.
1) The performance should be equalled by our new single-seaters (powered) by the 225 hp Daimler and 240 hp Hiero (engines), possibly even exceeding it. (author's note: This is a reference to the Oeffag D.III, Berg D.I, Phoenix D.III, and WKF D.I fighters)
2) By the time license manufacture is fully underway (5 months or more) our new single-seaters are already available.
3) 19000-engines (i.e. the 200 hp variant of the Austro-Daimler fitted to the V22) are no longer in production.
4) Range is less than that of our single-seaters. In that context, useful load must be reduced in order to increase the fuel capacity.
5) In spite of the lower useful load, 190 kg versus 240 kg in our planes, the total weight is higher than that of the Berg single-seater.
6) In terms of structural strength, the Fokker will likely lag far behind our single-seaters.
7) Installation of machine guns and visibility, especially ahead at eye level, are impeccable, but should be ideally equalled by our new single-seaters.”
Regarding point 1: For the most part, this remark can be interpreted as wishful thinking. The Oeffag D.III was a licence-built version of the Albatros D.III, a 1916-vintage design that can be considered completely outdated by April 1918. The Berg was structurally weak, even when powered by lighter, less powerful versions of the Austro-Daimler. Finally, the Phoenix was also a design that had reached the limits of further development.
Regarding 2: As it turned out, the only new design hinted at, the WKF D.I, would not enter frontline service before the end of the war. The other three designs, powered by the 225 hp Daimler and 240 hp Hiero engines, did see service, but were merely evolutions of old and, more or less, proven designs.
Regarding 3: This objection cheerfully ignores the fact that 225 hp Daimler engine could have been easily installed in the V22 - had an example of it been made available to Fokker. That was not the case at the time. Flars officials obviously feared that it would give the Fokker an improved performance that could not be matched even by the new domestic designs powered by the same engine.
Regarding 4: The only new design hinted at, the WKF D.I, would not enter frontline service before the end of the war. The other three designs, powered by the 225 hp Daimler and 240 hp Hiero engines, did see service, but were evolutions of old designs
Regarding 5: Available records indicate that the V22 was indeed tested with a useful load of 190 Kg. Endurance of the WKF D.I was 2 hours and 30 minutes, one hour more than that of the V22, but it weighed 1005 Kg, almost 100 KG more than the V22.
Regarding 6: By that time, the D.VII had passed all mandatory German load tests with flying colors, and since the V22 was nothing but a modified D.VII these results could be applied to the V22 as well. In spite of this, as late as 09 July, the Austrian authorities noted that the V22 was not cleared to be flown by frontline pilots since calculations concerning structural strength were not (yet) available.
The Berg D.I had suffered from structural failure of its wings during its entire frontline life, the Oeffag D.III featured a single-spar lower wing versus the V22's double spar lower wing. All Austro-Hungarian designs had wooden fuselages that offered inferior survivability for the pilot in case of a crash compared to the steel-tube fuselage used by Fokker design.
Regarding 7: Positioning the radiator in the nose of the D.VII meant that no water pipes coming down from the upper wing obstructed the forward view for the pilot, as was the case of several of the competing designs. Mounting the machine guns on top of the fuselage alone did not ensure good forward visibility from the cockpit.
Aside from the points quoted, this report completely ignores the most important technical advance of the V22: its cantilever wing that rendered rigging wires completely obsolete. In this context it is worth mentioning that all domestic designs that are hinted at in the report (Oeffag D.III, Berg D.I, Phoenix D.III, and WKF D.I) still featured the now obsolete thin airfoil rigged wings.
V22 took part in the fighter evaluation flight in Wien-Aspern from July 9 to 23, 1918, where LFT pilots were forbidden to fly it, due to a lack of documents proving the structural integrity of the aircraft. This happened at a time when hundreds of D.VIIs were serving without any sign of structural defects in dozens of Fliegertrupper Jagdstaffeln on the Western Front! Therefore, Fokker’s MAG-Chief Seekatz organized a presentation of the aircraft by German Lt. Mallinckrodt to the LFT chief. By August the examination of the Fokker D.VII, as it was now referred to, had been successfully concluded, and orders for Austro-Hungarian use could be placed, at last.
Fokker V22 Specifications
Engine: 200 hp Austro-Daimler (MAG)
Wing: Span 8.90 m
Area 20.2 m2
General: Length 6.945 m
Height 2.945 m
Empty Weight 689 kg
Loaded Weight 908 kg
Max Speed 210 km/h
Climb: 2000m 5.0 min
3000m 9.0 min
4000m 13.5 min
5000m 19.0 min
Fokker V24
The Fokker V24, Works Number 2612, was a version of the D.VII with a heavier, more powerful, overcompressed 200 hp Benz Bz.IVu engine. After acceptance flights by pilot Gross on 26 April 1918, the V24 took part in the Second Fighter Competition at Adlershof.
This same engine was also tested in the Pfalz D.XIV, a slightly enlarged derivative of the Pfalz D.XII. However, unlike Pfalz, the Fokker V24 had the same wings as the standard Fokker D.VII. The V24 and Pfalz D.XIV were compared with one another during the Second Fighter Competition. In four climb flights between May 27 and June 13, the Pfalz D.XIV, with a starting weight of 1032 kg, averaged 24.2 minutes climb to 5,000m and the V24, at a starting weight of 1006 kg, averaged 22.3 minutes, results that were roughly equivalent.
The additional weight of the Benz Bz.IVu offset the advantage of its greater power, and both performance and maneuverability with the Benz Bz.IVu were not as good as with the 185 hp BMW IIIa. Combined with the need for the Bz.IVu for two-seaters, this eliminated further consideration of the Benz engine for fighter use.
After the climb competition with the Pfalz D.XIV, the V24 was converted to a BMW IIIa engine and after conversion was delivered to ZAK on 17 October 1918.
Fokker V24 Specifications
Engine: 200 hp Benz Bz.IVu
Wing: Span 8.90 m
Area 20.2 m2
General: Length 7.14 m
Height 3.15 m
Empty Weight 750 kg
Loaded Weight 989 kg
Climb: 2000m 6.0 min
3000m 8.5 min
4000m 12.5 min
5000m 16.3 min
Keen to evaluate the potential of the new cantilever wing design, Fokker ordered another biplane fighter from his workshop on 20 September 1917. This particular aircraft was assigned the works number 1883, and was given the Fokker designation V11. The basic design of its airframe very closely resembled that of the V9, being enlarged to make up for the additional size, weight, and power of the inline engine. Available photos taken during construction of V11 show that it was, initially at least, powered by a Mercedes D.III engine, which shows clear signs of previous use. This invites suggestion that this engine may have been second-handed from another Fokker aircraft, possibly a D.IV which had been returned to the factory, or maybe even from the V2, V3, V6, or V8 prototypes.
The rear fuselages of both the V9 and the initial V11 very closely resembled that of the Fokker Triplane, which seems a reasonable design concept considering the initial successes demonstrated by the two Fokker F.Is at the front.
Unlike the V9, the V11 sported no undercarriage axle wing, indicating this component may have been considered better-suited for the rotary-engined fighters.
The first performance and weight figures for this aircraft were recorded at Schwerin as early as mid-October 1917, indicating that the aircraft was completed roughly three to four weeks after the experimental workshop received their order.
Conventional wisdom has it that the aircraft was shipped to Adlershof to take part in the First Fighter Competition on 18. January 1918, a date confirmed by Fokker records. At the competition it was reportedly test-flown by Manfred Freiherr von Richthofen (and others), who universally praised its performance but criticised its lack of directional stability, especially in a dive, as well as its tendency to swing in flight.
In order to remedy this deficiency, Fokker supposedly rushed over his most experienced welders from Schwerin in order to lengthen the fuselage “over the weekend”, and voila, the modifications turned Vll into the clear winner of the competition.
While this makes for an amazing narrative, some indications make this story somewhat hard to believe. To begin with, it would imply that the pretty obvious defects mentioned had escaped the attention of Fokker and his team of test pilots at Schwerin over a period of two months. This seems somewhat unlikely, and even more importantly, all available photos of Vll in its initial shape were taken at Schwerin. No known photo taken at Adlershof shows the aircraft in its initial guise.
Furthermore, when comparing photos of the freshly-completed V11-I to the modified V11-II, which was photographed at Adlershof, it becomes obvious that the modifications did not just comprise of lengthening and deepening the rear fuselage. The wing area was reduced by integrating the ailerons into the wing, adding a cut-out to the wing centre-section, and possibly reducing the chord of the wings. A larger-capacity radiator was fitted, and a 170 hp Mercedes D.IIIa engine now powered the aircraft - the upright air pump ahead of the first cylinder is now clearly visible. The familiar “streaked” camouflage scheme had been applied, but no works number is visible.
A look at a graph documenting the wing loads of Fokker aircraft shows that a wing load of approximately 34,2 kg/m2 was recorded for V11 in mid-October 1917. By early January, before the aircraft was shipped to Adlershof, a wing loading of around 41,29 kg/m2 was recorded for V11. This clearly indicates that by then, the lengthened fuselage and reduced wing area (now 20.2 m2) had been applied to the aircraft, resulting in V11-II. Interestingly, the wing area of V1-II was now exactly that of the D.VII production aircraft.
Taking all this into account, the aircraft appeared markedly different from its first appearance, and to this day it is not entirely clear if the photos show a radically-rebuilt airframe or two completely different planes. Certainly, Fokker records only mention the works number 1883 for V11, implying that it was indeed just one aircraft.
On the other hand, the sheer extent of modifications, which literally cover almost the entire airframe, suggests the existence of two aircraft under the V11 designation.
After Fokker received his initial production order for the D.VII, V11 was included into this batch of 300 aircraft where it was assigned the military number 227/18. This way, Fokker obtained payment from the authorities for an experimental aircraft which he had originally financed out of his own pocket. All indications are that V11 was destroyed during the type-test procedure at Adlershof in February 1918, where load-tests were carried out on the airframe, proving it to exceed all specified load factors.
The question whether the V11 or the V18 was the true prototype of the D.VII is impossible to answer. While the V11-II was picked as the winner of the First Fighter Competition, the production D.VII inherited features from both of these aircraft, and a few entirely new details as well. In a way, the V11 and V18 were two parallel paths that eventually merged into the Fokker D.VII by late February 1918.
Fokker V11-II Specifications
Engine: 160 hp Mercedes D.III
Wing: Span 8.72 m
Area 24.0 m2
General: Length 6.90 m
Height 3.05 m
Empty Weight 592 kg
Loaded Weight 821 kg
Climb: 1000m 3 min
2000m 6.5 min
3000m 11 min
4000m 17.3 min
5000m 22.5 min
Fokker V18
The Fokker V18 experimental aircraft, given the Fokker works number 2116, was closely related to the Vll and must be seen as the second prototype ancestor to the aircraft that eventually entered serial production under the military designation Fokker D.VII.
From the start, this machine had a taller rear fuselage that already closely resembled that of the later D.VII. Importantly for its flying qualities, it had much enlarged vertical tail surfaces for better stability. The leading edge of the horizontal tailplane was curved, resembling the shape of the component on the early Fokker F.Is. As was the case on the Triplane, the curved leading edge of the horizontal tail surfaces was not adopted for production aircraft.
The construction order for the Fokker V18 was dated 12 December 1917; work on the aircraft proceeded quickly. It was sent to Adlershof on 17 January 1918, actually a day before the V11 was, in order to participate in the First Fighter Competition. Once again, Fokker records document the aircraft had a 160 hp Mercedes D.III, while photos prove it was in fact powered by a D.IIIa.
Without a doubt, Fokker wanted to assure that his latest designs were powered by the better-performing engine during the competition.
On 25 January 1918, V18 was damaged as a result of an accident. As the result of an Oberursel maintenance man making a mistake while adjusting the engine of Fokker V13, which was parked nearby, the rotary-engined prototype made a sudden hop that was halted by the tip of the lower left wing of V18. However, the damage was quickly repaired, and testing of V18 resumed on 27 January.
Like Vll, the aircraft was missing the axle wing that was a standard component on the Fokker Dr. I, as well as on all of Fokker's 1918 production aircraft.
After Fokker received his initial production order for the D.VII, the V18 prototype was absorbed into this batch of 300 aircraft, where it was assigned the military number 228/18. However, it is unknown if it was ever fully brought up to D.VII production standards, or if this inclusion into the first batch was merely intended to assure that Fokker would receive payment for his prototype investment.
Fokker V18 Specifications
Engine: 170 hp Mercedes D.IIIa
Wing:
Span 8.72 m
Area 23.1 m2
General: Length 7.03 m
Height 2.9 m
Empty Weight 634 kg
Loaded Weight 860 kg
Climb: 2000m 5.3 min
3000m 10.5 min
4000m 17.3 min
5000m 26.0 min
Fokker V21
For many years, the true identity of the Fokker V21 had researchers puzzled. It was known that this aircraft had been assigned the Fokker Works Number 2310, but since a rudder showing just this works number was seen on a Mercedes-powered mid-wing monoplane, it was determined that this must have been the V21. Thanks to the research of the much-missed historian Alex Imrie we know that this mid-wing monoplane was, in fact, Fokker V23, Works Number 2443. When said photograph was taken, V23 mounted a “comma"-shaped rudder which was originally fitted to the real V21, and this component was marked with the Fokker Works Number 2310.
The true Fokker V21 was, in fact, the Fokker D.VII production prototype, and it is termed exactly that in official Fokker records. Unfortunately, the few available photographs of V21 only show it being fitted with the final tail-plane, featuring the tall rudder complete with the fin as seen on the production Fokker D.VIIs.
In these photos the aircraft is painted in the overall “streaked” scheme known so well from the Fokker Dr.I, which was still in full production at Schwerin when the V21 first appeared in February 1918. Records documenting wing data and engine performance mention the D.VII for the first time during this month, and in this context it is possible to determine that V21 was indeed the D.VII “pattern aircraft”.
It is noteworthy that the Iron Cross markings were also applied in an identical way to that seen on the Dr.I, being marked on a rectangular white background, a style of application that had become obsolete by an Idflieg instruction dating back as far as October 1916!
The fact that the initial small rudder, which was apparently first fitted to V21, was then transplanted to V23 proves that even by early February the final D.VII production configuration had not yet been determined. Last-minute modifications were still being carried out then.
Streaky fabric covering aside, the details seen on V21 match those of the first production D.VIIs, including the wing layout and the type of radiator fitted to the airframe. Some very minor details differed, but on the whole it can be seen as the true “pre-production” Fokker D.VII.
Unsurprisingly, the overall dimensions recorded for V21 match those of the D.VII.
On 22 May, V21 aka Werknummer 2310, was sent to Flz.A.Gr 6 (the aircraft testing department) at Adlershof, in order to participate in the upcoming Second Fighter Competition.
We hear about it one more time on 17 October, when it was sent to the Central Acceptance Commission at Berlin-Johannisthal.
Fokker V21 Specifications
Engine: 160 hp Mercedes D.III
Wing:
Span 8.90 m
Area 20.2 m2
General: Length 6.945 m
Height 2.945 m
Empty Weight 652 kg
Loaded Weight 870 kg
Climb: 2000m 7.0 min
3000m 12.0 min
4000m 19.5 min
5000m 27.0 min
Fokker V22
After the victory of Fokker’s new D.VII fighter in the First Fighter Competition, Austrian pilots were given the opportunity to fly the first prototype. Fokker wrote to the Austro-Hungarian Fliegerarsenal (Flars) as early as 19 February 1918 that he could deliver 40 D.VIIs a month to Austria if he could get the necessary quota of steel tubes. In four weeks, he wanted to have two samples of the D.VII ready for the LFT. The first was the V22, powered by the 200 hp (19000 series) Austro-Daimler engine and a four-bladed Jaray propeller and steel tube fuselage.
The V22 carried the Fokker Works number 2342, and this reveals that it was “sandwiched” into the early Fokker D.VII fighters, between 256/18 (w/n 2341) and 257/18 (w/n 2343). As such, it was a series-production airframe that was adapted for installation of the Austrian engine and armament. This is an important fact that has to be kept in mind when reading the later objections brought up by the Austrian authorities against license manufacture of the aircraft.
A second projected prototype was to have a plywood fuselage, intended as a fallback solution in case a lack of steel tubing would prevent serial production either in Austro-Hungaria or in Schwerin as an “export” version. However, as early as March 1918, Idflieg officer Oblt. Reichelt indicated that a number of wagon-loads of steel tube could be supplied to ensure production at or for the Austro-Hungarian empire. On 2 March, Fokker requested the delivery of two 8 mm Schwarzlose M16s for the V22, which was to receive the latest version of Fokker’s central control system. He had agreed to deliver the V22 readily-equipped to full military standards. Of course, this would allow for an evaluation of the type under realistic circumstances.
On 15 and 16 March 1918, Austrian Stabsfeldwebel Franz Kuttner flew the V22 at Schwerin-Gorries. Kuttner had previously been a Fokker flight instructor. During these evaluations, a climb time to 3000 meters was recorded in 8 to 9 Minutes, while 5000 meters were reached in 17 1/2 to 19 minutes. The aircraft was reported to have very good flight characteristics, offered remarkably good visibility as was very maneuverable.
In early April, the Austrian War Ministery purchased the aircraft, which was delivered to MAG on 24 April 1918. Fokker invoiced Flars via MAG on 13 June, the price of the airframe was 30.000 Marks.
Thorough testing by the Fliegerasenal at Wien-Aspern followed under Austrian military serial number 90.05. Flars representatives were initially opposed to serial production of the aircraft, expecting equal or better performance from their own new or improved fighter designs.
An Austrian report dated 20 April listed seven points that supposedly prevented production of the type by an Austro-Hungarian manufacturer under licence. These points document an obvious ignorance of facts that can only be explained by a massive bias of the Austro-Hungarian authorities against the Fokker design. For this reason, they are repeated in full here:
“The aircraft presented cannot be considered to enter series production with us.
1) The performance should be equalled by our new single-seaters (powered) by the 225 hp Daimler and 240 hp Hiero (engines), possibly even exceeding it. (author's note: This is a reference to the Oeffag D.III, Berg D.I, Phoenix D.III, and WKF D.I fighters)
2) By the time license manufacture is fully underway (5 months or more) our new single-seaters are already available.
3) 19000-engines (i.e. the 200 hp variant of the Austro-Daimler fitted to the V22) are no longer in production.
4) Range is less than that of our single-seaters. In that context, useful load must be reduced in order to increase the fuel capacity.
5) In spite of the lower useful load, 190 kg versus 240 kg in our planes, the total weight is higher than that of the Berg single-seater.
6) In terms of structural strength, the Fokker will likely lag far behind our single-seaters.
7) Installation of machine guns and visibility, especially ahead at eye level, are impeccable, but should be ideally equalled by our new single-seaters.”
Regarding point 1: For the most part, this remark can be interpreted as wishful thinking. The Oeffag D.III was a licence-built version of the Albatros D.III, a 1916-vintage design that can be considered completely outdated by April 1918. The Berg was structurally weak, even when powered by lighter, less powerful versions of the Austro-Daimler. Finally, the Phoenix was also a design that had reached the limits of further development.
Regarding 2: As it turned out, the only new design hinted at, the WKF D.I, would not enter frontline service before the end of the war. The other three designs, powered by the 225 hp Daimler and 240 hp Hiero engines, did see service, but were merely evolutions of old and, more or less, proven designs.
Regarding 3: This objection cheerfully ignores the fact that 225 hp Daimler engine could have been easily installed in the V22 - had an example of it been made available to Fokker. That was not the case at the time. Flars officials obviously feared that it would give the Fokker an improved performance that could not be matched even by the new domestic designs powered by the same engine.
Regarding 4: The only new design hinted at, the WKF D.I, would not enter frontline service before the end of the war. The other three designs, powered by the 225 hp Daimler and 240 hp Hiero engines, did see service, but were evolutions of old designs
Regarding 5: Available records indicate that the V22 was indeed tested with a useful load of 190 Kg. Endurance of the WKF D.I was 2 hours and 30 minutes, one hour more than that of the V22, but it weighed 1005 Kg, almost 100 KG more than the V22.
Regarding 6: By that time, the D.VII had passed all mandatory German load tests with flying colors, and since the V22 was nothing but a modified D.VII these results could be applied to the V22 as well. In spite of this, as late as 09 July, the Austrian authorities noted that the V22 was not cleared to be flown by frontline pilots since calculations concerning structural strength were not (yet) available.
The Berg D.I had suffered from structural failure of its wings during its entire frontline life, the Oeffag D.III featured a single-spar lower wing versus the V22's double spar lower wing. All Austro-Hungarian designs had wooden fuselages that offered inferior survivability for the pilot in case of a crash compared to the steel-tube fuselage used by Fokker design.
Regarding 7: Positioning the radiator in the nose of the D.VII meant that no water pipes coming down from the upper wing obstructed the forward view for the pilot, as was the case of several of the competing designs. Mounting the machine guns on top of the fuselage alone did not ensure good forward visibility from the cockpit.
Aside from the points quoted, this report completely ignores the most important technical advance of the V22: its cantilever wing that rendered rigging wires completely obsolete. In this context it is worth mentioning that all domestic designs that are hinted at in the report (Oeffag D.III, Berg D.I, Phoenix D.III, and WKF D.I) still featured the now obsolete thin airfoil rigged wings.
V22 took part in the fighter evaluation flight in Wien-Aspern from July 9 to 23, 1918, where LFT pilots were forbidden to fly it, due to a lack of documents proving the structural integrity of the aircraft. This happened at a time when hundreds of D.VIIs were serving without any sign of structural defects in dozens of Fliegertrupper Jagdstaffeln on the Western Front! Therefore, Fokker’s MAG-Chief Seekatz organized a presentation of the aircraft by German Lt. Mallinckrodt to the LFT chief. By August the examination of the Fokker D.VII, as it was now referred to, had been successfully concluded, and orders for Austro-Hungarian use could be placed, at last.
Fokker V22 Specifications
Engine: 200 hp Austro-Daimler (MAG)
Wing: Span 8.90 m
Area 20.2 m2
General: Length 6.945 m
Height 2.945 m
Empty Weight 689 kg
Loaded Weight 908 kg
Max Speed 210 km/h
Climb: 2000m 5.0 min
3000m 9.0 min
4000m 13.5 min
5000m 19.0 min
Fokker V24
The Fokker V24, Works Number 2612, was a version of the D.VII with a heavier, more powerful, overcompressed 200 hp Benz Bz.IVu engine. After acceptance flights by pilot Gross on 26 April 1918, the V24 took part in the Second Fighter Competition at Adlershof.
This same engine was also tested in the Pfalz D.XIV, a slightly enlarged derivative of the Pfalz D.XII. However, unlike Pfalz, the Fokker V24 had the same wings as the standard Fokker D.VII. The V24 and Pfalz D.XIV were compared with one another during the Second Fighter Competition. In four climb flights between May 27 and June 13, the Pfalz D.XIV, with a starting weight of 1032 kg, averaged 24.2 minutes climb to 5,000m and the V24, at a starting weight of 1006 kg, averaged 22.3 minutes, results that were roughly equivalent.
The additional weight of the Benz Bz.IVu offset the advantage of its greater power, and both performance and maneuverability with the Benz Bz.IVu were not as good as with the 185 hp BMW IIIa. Combined with the need for the Bz.IVu for two-seaters, this eliminated further consideration of the Benz engine for fighter use.
After the climb competition with the Pfalz D.XIV, the V24 was converted to a BMW IIIa engine and after conversion was delivered to ZAK on 17 October 1918.
Fokker V24 Specifications
Engine: 200 hp Benz Bz.IVu
Wing: Span 8.90 m
Area 20.2 m2
General: Length 7.14 m
Height 3.15 m
Empty Weight 750 kg
Loaded Weight 989 kg
Climb: 2000m 6.0 min
3000m 8.5 min
4000m 12.5 min
5000m 16.3 min
Fokker D.VII 262/18 of Emil Thuy
The Fokker V11, works number 1883, participated in the First Fighter Competition powered by a 160 hp Mercedes D.III engine. It is seen here in its original form with short fuselage and no fixed fin, clear indication of its Triplane heritage. (Peter M. Grosz Collection/STDB)
Fokker V11 in its original form. There was no central cut-out in the wing trailing edge, and the balance portions of the elevators had straight-edged tips. The short fuselage without fixed fin made the aircraft directionally unstable and challenging to fly; it was certainly not suitable for operational use.
Fokker V11 in its original form. There is slight dihedral on the upper wing and the undercarriage axle does not have an airfoil. The nose radiator was simple and effective. The wing design was excellent both structurally and aerodynamically, being strong, relatively simple, and offering exceptional stall characteristics, (Peter M. Grosz Collection/STDB)
The Fokker V11, work number 1883, in revised form with longer fuselage that imparted greater stability. (Peter M. Grosz Collection/STDB)
The modified V.11 with revised ailerons and new tail unit. The upper wing has been moved aft, necessitating a small cut-out in the trailing edge to improve the pilot’s upward view.
The modified V.11 with revised ailerons and new tail unit. The upper wing has been moved aft, necessitating a small cut-out in the trailing edge to improve the pilot’s upward view.
The Fokker V18 was based on the same formula as the V11 but had larger vertical tail surfaces for improved stability.
In this front view, V18 closely resembled its sister aircraft V11. The light-colored tip of the lower left wing indicates this photo, as well as the other frontal view, were taken after the damage suffered on 25 January had been repaired.
The Fokker V18 was based on the same formula as the V11 but had larger vertical tail surfaces for improved stability.
Fokker V18, works number 2116, at the First Fighter Competition at Adlershof in late January/early February 1918. The curved leading edge of the horizontal tailplane is in evidence. This was of a very similar shape to that seen on the Fokker F.I Triplanes. The somewhat ungainly tail fin appears to have been retro-fitted, and its shape loosely resembles a s
V22 was camouflaged before it was sent to MAG factory and designated 90.05. In this photo it has Fokker 2-bladed propeller. Fokker triplane prototype 90.03 is in the left background. (Peter M. Grosz collection/STDB)