W.Green, G.Swanborough The Complete Book of Fighters

W.K.F. 80.06 Austria-Hungary

   A single-bay staggered biplane following closely on the W.K.F. 80.05 triplane and possessing a number of common features, such as the Fischrumpf, the W.K.F. 80.06 was similarly powered with a 200 hp Austro-Daimler engine and was also of wooden construction with plywood skinning. First flown early in 1918, the W.K.F. 80.06 was fitted with its twin synchronised Schwarzlose gun armament during February, and, in March, it demonstrated the ability to attain an altitude of 16,405 ft (5 000 m) within 22 min, matching the climb of such fighters as the Albatros D III (Oef) and Phonix D II. Re-engined with a 230 hp Hiero, the prototype arrived at Aspern for official testing on 30 April 1918, but was written off as a result of a crash. A second, modified prototype, the W.K.F. 80.06B powered by a 225 hp Austro-Daimler engine, was delivered to Aspern. Ing Alfred Gassner had elected to reduce the wing gap and fit ailerons to both wings of the 80.06B, and, as a weight-saving measure, had replaced the plywood skinning of the wings with fabric. The prototype was flown at Aspern in July 1918 during the Fighter Evaluation along side two fundamentally similar prototypes, the W.K.F. 80.10 and 80.12, these differing from the 80.06B essentially in having the 230 hp Hiero engine. As a result of the excellent performance demonstrated by these prototypes, W.K.F. was awarded a production contract for the fighter as the D I, flight testing of the W.K.F. 80.06B continuing through August 1918. The end of hostilities terminated the W.K.F. D I programme. The 230 hp Hiero-engined fighter achieved an altitude of 16,405 ft (5 000 m) within 18 min and a maximum speed of 121 mph (195 km/h), no further data being available.

P.Grosz, G.Haddow, P.Shiemer Austro-Hungarian Army Aircraft of World War One (Flying Machines)

WKF 80.06 and 80.06B

  While the 80.05 triplane was nearing completion in October 1917, the design of the elegant WKF 80.06 fighter prototype was well under way. The choice of a suitable airfoil was being investigated in Professor Knoller's wind tunnel. As conceived by Gassner, the hexagonal Fischrumpf (fish fuselage) formed a delicately streamlined shape tapering down to a faired plywood tail empennage. Veneer-covered wings combined with conventional strut and wire bracing gave the cellule great inherent strength. The first flight date is not known, but occurred before the machine guns were installed in February 1918. In the course of performance trials in March, the 80.06, powered by a 200 hp Daimler engine, attained 5000 meters (16,405 ft) in the respectable time of 22 minutes, matching the climb of 200 hp production fighters such as the Albatros D.III(Oef) and Phonix D.II. Refitted with a 230 hp Hiero engine, the 80.06 arrived at Aspern on 30 April 1918, but a severe crash ended the flight program and thwarted the static load tests which had been scheduled for July 1918.
  As a replacement, WKF built a new prototype, designated 80.06B and powered by the new 225 hp Daimler engine. The extensively redesigned airframe featured a longer nose, a larger tail fin, reduced wing gap, and ailerons fitted to both wings. Significantly, Gassner switched to fabric-covered wings as a weight-saving measure and to facilitate production. The WKF 80.06B, in effect a new aircraft, participated in the July 1918 Fighter Evaluation at Aspern in concert with the Hiero-engined WKF 80.10 and 80.12 prototypes. All three fighters were reported as being similar in design but the 80.06B was probably the most advanced. As a result of the excellent performance achieved by the WKF contingent, the design was chosen for production under the designation WKF D.I. Whether the innovative throttle mounted on the control-column (80.06B), praised by the pilots, was used on production aircraft is not known. To iron out last-minute problems, flight testing of the 80.06B continued through August 1918. The prototype was last reported stored in good condition at Aspern on 31 October 1918.

WKF 80.06 Specifications
Engine: 200 hp Daimler
Wing: Span Upper 8.80 m (28.87 ft)
Span Lower 8.40 m (27.56 ft)
Chord Upper 1.70 m (5.58 ft)
Chord Lower 1.60 m (5.25 ft)
Gap 1.66 m (5.45 ft)
Stagger 0.45 m (1.48 ft)
Total Wing Area 26.4 sq m (284 sq ft)
General: Empty Weight 650 kg (1433 lb)
Loaded Weight 915 kg (2018 lb)

WKF 80.06B Specifications
Engine: 225 hp Daimler
Wing: Total Wing Area 26.2sq. m (282 sq ft)
General: Empty Weight 732 kg (1614 lb)
Loaded Weight 1004 kg (2214 lb)
Climb: 1000m (3,281 ft) in 2 min 30 sec
2000m (6,562 ft) in 5 min 26 sec
3000m (9,843 ft) in 10 min 18 sec
4000m (13,124 ft) in 15 min 30 sec
5000m (16,405 ft) in 25 min 45 sec


WKF 80.10

  For the forthcoming Fighter Evaluation at Aspern on 9-13 July 1918, WKF prepared three prototypes: the 80.06B, 80.10, and 80.12. Very little is known about the last two prototypes, but they differed little from the basic 80.06B layout and were powered by the 230 hp Hiero engine. In the course of the climb competition, the 80.10 was flown by several pilots on 21 May 1918. The 80.10 prototype reached 5000 meters (16,405 ft) in the average time of 21:30 minutes and 6000 meters (19,686 ft) in 28:20 minutes, a very fine showing indeed.
  Among the fighter aces present at Aspern, Hauptmann Maximilian Perini, Oberleutnants Linke-Crawford, Friedrich, Gawel, and von Fiala all took turns evaluating the 80.10. Von Fiala had this to say:
  This aircraft also good. Machine gun installation incomplete. Flight characteristics: maneuvrable, elevator operation symmetrical. Extreme tail-heaviness was not corrected by the company. Aileron connection strut broke owing to vibration, actuation similar to Sopwith. Throttle must be moved from the fuselage wall.
  In the comparative climb tests, the 80.10 was exceeded only by the much lighter (by 77kg - 170lb) Aviatik D.I 338.03. Further data is lacking.

WKF 80.10
Engine: 230 hp Hiero
Wing: Total Wing Area 26.2 sq. m (282 sq ft)
General: Empty Weight 754 kg (1663 lb)
Loaded Weight 1012 kg (2231 lb)
Climb: 1000m (3,281 ft) in 2 min 10 sec
2000m (6,562 ft) in 5 min 15 sec
3000m (9,843 ft) in 9 min 20 sec
4000m (13,124 ft) in 14 min 55 sec
5000m (16,405 ft) in 21 min 15 sec
6000m (19,686 ft) in 28 min 20 sec


WKF 80.12

  The 80.12 fighter prototype was first reported at Aspern on 27 May 1918 and like the 80.10, was powered by a 230 hp Hiero engine. The 80.12, the third fighter entered by WKF in the Fighter Evaluation, was reported even more tail-heavy than the 80.10, so much so that it was impossible to complete the scheduled climb and altitude flights and had to be withdrawn. In July, the 80.12 prototype was used as a test vehicle for developing a suitable top wing radiator in preparation for releasing the design to production under the designation WKF D.I.


WKF D.I Series 85

  WKF had the satisfaction of seeing the WKF D.I series 85 fighter chosen for production, based on the fine showing of the 80.06B and 80.10 prototypes. Initially the LFT command saw fit to hedge its position, having been burned by premature production in the past. Forty-eight WKF D.I fighters had been specified in the 24 August 1918 production program, but implementation remained provisional. The LFT cautioned that
  The test program is being conducted on a priority basis to ascertain whether the WKF D-type is equal to other fighters now in development. If the WKF fighter should demonstrate even an iota less performance than the Fokker D.VII, then WKF will be given a type of equal performance to build.
  In the event this should occur, the LFT proposed the new Pfalz D.XV, which the Germans regarded as equivalent to the Fokker D.VII.
  However, the WKF D.I prevailed. The exact date when the WKF D.I was ordered is unknown, but by mid-September WKF had production approval in hand for 48 D.I fighters, powered by the 230 hp Hiero engine and numbered 85.01 to 85.48. Twenty aircraft were scheduled for delivery in December 1918 and the balance in January 1919.
  Externally the design, supervised by Ingenieur Alfred Gassner, adhered closely to the 80.06B layout with only minor changes. The interplane struts were now canted inward and faired, the tail surfaces enlarged slightly, and the ailerons independently actuated. Internally, the D.I was fitted with full military equipment. Twin synchronized Schwarzlose M 16R machine guns were mounted on the decking within the pilot's reach. The D.I could also operate as a photo-reconnaissance fighter, and space was provided for a 70 or 90 cm camera behind the cockpit. A window at the pilot's feet and a cowl-mounted Sottoscope facilitated terrain recognition. The D.I was provided with an installation rarely seen in WW I fighters: a wireless transmitter and receiver to "receive signals from a director aircraft." As with all late Austro-Hungarian aircraft, a seat parachute was standard equipment.
  Making great progress, WKF appeared to be ahead of schedule. Schieferl reported that the first production fighters were undergoing military acceptance when the war ended. As of 31 October 1918 the resident Flars officer had accepted two completed fighters. Flight testing and assembly work continued and in January 1919, twenty-four D.I fighters were reported stored in good condition at the WKF factory.
  In February 1919, two D.I fighters were flown from Hennersdorf to Wiener-Neustadt for demonstration to a Polish military commission. However, the planned purchase of 20 fighters failed to materialize because during the flight exhibition both aircraft were defective or damaged.

WKF D.I Series 85 Specifications
Engine: 230 hp Hiero
Wing: Chord Upper 1.70 m (5.58 ft)
Chord Lower 1.50 m (4.92 ft)
Stagger 0.48 m (1.57 ft)
General: Length 7.10 m (23.29 ft)
Loaded Weight 1000 kg (2205 lb)
Maximum Speed: 195 km/hr (121 mph)
Climb: 5000m (16,405 ft) in 21 min

E.Hauke, W.Schroeder, B.Totschinger Die Flugzeuge der k.u.k. Luftfahrtruppe und Seeflieger 1914-1918

80. Flugzeuge der Wiener Karosserie-Fabrik (W.K.F.) Wien und Hennersdorf
80.06 W.K.F. DD Prototype für D.I Ba 85 Dm 200
80.06B W.K.F. DD Prototype für D.I Ba 85 (Neubau) Dm 200
80.07 W.K.F. DD D-Type Versuch für D.I Dm 185
80.10 W.K.F. DD D-Type Versuch für D.I H 200
80.12 W.K.F. DD Prototype für D.I Ba 85 H 230
85.01 — 85.07 W.K.F. D.I H 230