O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
Siemens-Schuckert D VI
Last of the S.S.W. fighters, the D VI parasol was due to replace the D IV on the production line, but only two machines (3054 and 3055/17) were completed. The strut-braced wing carried overhung balanced ailerons and, peculiarly, increased in depth of section from centre-section outwards to about mid span of each panel, then decreased in depth again towards the tips. A jettisonable fuel tank underneath the fuselage was a unique feature of this aeroplane. Flight trials were carried out from February to May 1919, during which period one machine was destroyed, but not before very encouraging climb and speed figures had been achieved. Engine, 160 h.p. Siemens-Halske Sh IIIa. Span, 9.37 m. (30 ft. 8 7/8 in.). Length, 6.5 m. (21 ft. 4 in.). Area, 12.46 sq.m. (135 sq.ft.). Weights: Empty, 540 kg. (1,188 lb.). Loaded, 710 kg. (1,562 lb.). Speed, 220 km.hr. (137.5 m.p.h.). Climb, 6,000 m. (19,680 ft.) in 16 min. Duration, 2 hr.
J.Herris Siemens-Schuckert Aircraft of WWI (A Centennial Perspective on Great War Airplanes 12)
As early as June 1917, Siemens-Schuckert presented its project drawings for a parasol monoplane fighter, the SSW D.Ic, to a conference of interested Idflieg officials. The parasol project was developed by Dipl.-Ing. Glockner, who was the deputy to the Chief Engineer of the SSW aircraft section, Dipl.-Ing. Harald Wolff. But because the triplane vogue was enjoying its peak popularity in Idflieg circles at this time, the parasol design was rejected.
It was not until April 1918 that SSW succeeded in obtaining a contract from Idflieg for construction of three experimental parasol fighters. The drawings were presented to Idflieg in June, at which time the company was allowed, at its request, to substitute wooden wings for the duraluminum wings originally planned. Several months previously SSW had experienced difficulty with the dural spars used in the thin profile wings of an experimental SSW D.III fighter. Now work could proceed on the detail drawings and a full-size mock-up of the parasol fighter was built, followed by construction of the three prototypes.
On August 12, 1918 Idflieg assigned the designation E.IV to the new fighter, but this designation was changed to D.VI the next month when Idflieg abandoned the E-type designation as obsolete. It was intended to replace the SSW D.IV with D.VI series production provided the D.VI had the required performance. However, work on the prototypes proceeded slowly, and at the time of the Armistice only one prototype was almost complete. Of the other two prototypes, Idflieg decreed that only the one nearest completion be finished. The two D.VI parasol fighters were given serial numbers 3054/17 and 3055/17, numbers originally assigned to the earlier SSW Dr.II triplane project that had been cancelled.
At the end of January 1919 the first D.VI, 3054/17, was shipped to Berlin-Staaken, assembled there, and made its first test flight on February 3, 1919. On March 12, 1919 Lt. Hans-Joachim Rath of the Government Inspection office at SSW took off on the acceptance flight. In reaching the altitude of 7,200 meters, the D.VI showed a climb of 6,000 meters in 16 minutes and 7,000 meters in 22 minutes. Total flying weight of 3054/17 was 705.5 kg.
As was the case with the SSW D.III, D.IV, and D.V, the left wing of the D.VI was about 10 cm longer than the right in order to cancel the torque effect. However, in the case of the D.VI, the left wing was originally too long and had to be shortened to correct difficulties experienced during right turns.
The acceptance flight of the second D.VI, 3055/17, also piloted by Lt. Rath, took place on April 2, 1919 at Staaken. The measured climb was 6,000 meters in 20.4 minutes. The take-off run was measured at about 30 meters and landing run at about 80 meters. The measured speeds in level flight were:
Altitude: 2,000 m 220 km/h
3,000 m 210 km/h
4,000 m 190 km/h
5,000 m 185 km/h
On 30 April 1919, Lt. Mohnike took off in 3055/17 to ferry the aircraft to the Flugzeugmeisterei (Aircraft Testing Section at Idflieg} at Adlershof. During the flight the aircraft caught fire, the pilot, a well-known and experienced fighter pilot, dove to the ground and landed safely, although the aircraft was totally destroyed. Lt. Mohnike had forgotten to release the jettisonable fuel tank (German Patent 342 084). Examination of the wreckage showed the fuel lines were all in order, but the solder joint on the emergency fuel tank's strainer had broken and could have allowed fuel to leak over the carburetor into the aircraft.
In May 1919 the other D.VI, 3054/17, was also involved in an accident. After many flights the aircraft was flown by an Idflieg pilot to Doberitz. During landing the left wing broke off, fracturing at the strut attachment points. After a thorough examination the accident commission came to the conclusion that the wing had been damaged prior to the flight by carelessness or sabotage. At this time, sabotage was a strong possibility given the turbulent political conditions in post-war Germany.
The damaged wing was repaired with the permission of the Flugzeugmeisterei. The airplane was to be sent to Adlershof for static load tests in July 1919 but these never occurred. At this time there were organizations in Germany who wanted to save valuable aircraft and not surrender them to the Allied Armistice Commission, so for a time the last D.VI was hidden in Berlin-Siemensstadt. However, the chauffeur of Herr von Siemens sold information about the hiding place to the Armistice Commission, whereupon the D.VI was found and destroyed.
W.Green, G.Swanborough The Complete Book of Fighters
SIEMENS-SCHUCKERT (SSW) D VI Germany
The SSW was awarded a contract by the Idflieg in April 1918 for the development of a single-seat parasol mono¬plane fighter powered by the Sh IIIa rotary engine, three prototypes being ordered under the designation E IV, but this being changed to D VI in the following September. A unique feature of the D VI was the provision of a jettisonable main fuel tank beneath the fuselage. No prototype was completed prior to the Armistice, but two emerged in 1919, flight trials being carried out between February and May of that year. During these one of the prototypes was destroyed and the other was allegedly sabotaged by SSW workers to prevent it falling into the hands of the Allied Control Commission.
Max speed, 137 mph (220 km/h).
Time to 19,685 ft (6 000 m), 16 min.
Range, 217 mis (350 km).
Empty weight, 1,190 lb (540 kg).
Loaded weight, 1,565 lb (710 kg).
Span, 30 ft 8 7/8 in (9,37 m).
Length, 21 ft 3 7/8 in (6,50 m).
Height, 8 ft 11 in (2,72 m).
Wing area, 134.12 sq ft (12,46 m2).