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Siemens-Schuckert DD 5

Страна: Германия

Год: 1915


Siemens-Schuckert - B - 1915 - Германия<– –>Siemens-Schuckert - E.I/E.II/E.III - 1915 - Германия

O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Siemens-Schuckert D D5
   This single-seat biplane, of which only a single example was built, bore a strong resemblance to the earlier Type B. It was built in 1916 and featured tapered wings with steel tube spars and a ply-covered fuselage similar to the E I-III. It was presented to Idflieg for acceptance trials, during which it was rejected on grounds of poor aerodynamic qualities and restricted visibility from the cockpit. Engine, 110 h.p. Siemens-Halske Sh I. Armament, one Spandau machine-gun.

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


   The first single-seat fighter biplane to be designed by Franz Steffen (who was subsequently to lose his life while demonstrating the E II monoplane), the DD 5 featured sharply tapered wings built up around steel tube spars, steel I-type interplane struts and a similar fuselage and tail to those of the E I monoplane. Powered by a 100 hp Siemens-Halske Sh I nine-cylinder rotary engine, the DD 5 was tested by the Idflieg in August 1916, but was rejected owing to its poor aerodynamic qualities and the restricted field of view provided by the cockpit. Armament comprised a single 7,9-mm LMG 08/15 machine gun. Only one prototype of the DD 5 was built and tested, development being discontinued in favour of an almost identical copy of the Nieuport 11 that was being developed (as the D I) in parallel. No specification for the DD 5 is available.

J.Herris Siemens-Schuckert Aircraft of WWI (A Centennial Perspective on Great War Airplanes 12)


   Designed by Franz Steffen, the SSW DD 5 was basically an E.I airframe with a biplane wing cellule, and was SSW's first biplane fighter. Power remained a 110 hp Siemens-Halske Sh.I counter-rotary engine, and a single synchronized machine gun was fitted. Tubular steel was used for the wing spars and I-struts. Tested in August 1916, it was rejected because of poor field of view for the pilot and poor handling qualities. Development then focused on the SSW D.I.
   Unusually for a WWI aircraft, the DD 5's wing planform tapered from the fuselage to the wing tips,- most WWI featured wings of rectangular planform as seen in the SSW E-types. Tapered wings are more efficient because they generate less induced drag (drag induced by creating lift, which generates vortices at the wing tips) and also reduce weight, which is likely why the designer used taper.
   However, tapered wings aggravate the tendency of the wing to stall first at the tips. Since the ailerons are normally fitted at the tips of the wings for greatest effectiveness, the tendency of the wing to stall first at the tips is very dangerous because it robs the pilot of roll control in a critical situation, increasing the likelihood of the aircraft entering an unintended spin. Most designers of the time 'washed out' the angle of incidence at the wing tips to prevent the wing from stalling at the tip first, and more sophisticated means were developed later to prevent tip stall. However, a look at the DD 5 shows no evidence of any aerodynamic measures designed into the wing to alleviate the tip stall problem, undoubtedly resulting in poor handling near stalling speed.

J.Herris - Siemens-Schuckert Aircraft of World War I /Centennial Perspective/ (12)
SSW DD 5 prototype
J.Herris - Weird Wings of WWI /Centennial Perspective/ (70)
The SSW DD 5 prototype designed by Franz Steffen was SSW's first biplane fighter design. The wing spars and I-struts were made of steel tubes, and the aircraft has a robust appearance despite the narrow I-struts. Other than the biplane wing cellule, the rest of the aircraft was derived from the E.I monoplane fighter, including its 110 hp Siemens-Halske Sh.I counter-rotary engine and single synchronized gun. The DD 5 was rejected due to poor handling qualities, probably related to its tapered wing planform that aggravated the tendency of the wing tips to stall first, which seriously reduced the pilot's ability to control aircraft roll during a critical flight regime.
J.Herris - Weird Wings of WWI /Centennial Perspective/ (70)
The SSW DD 5 prototype biplane fighter in the foreground was a biplane development of the SSW E.I in the background. Unusually for a WWI aircraft, the DD 5 had tapered wings which likely compromised its low-speed handling.
The joint brainchild of the Steffen Brothers, Franz and Bruno, the Siemens-Schuckert Werke D 5 single seat fighter was completed in the autumn of 1915, but progressed no further than the prototype stage. Visible in the background is the same company's E I prototype, a developed version of which killed designer/pilot Franz Steffen in June 1916.
J.Herris - Weird Wings of WWI /Centennial Perspective/ (70)
The SSW DD 5 was a clean design but the wide cabane struts near the pilot must have restricted his field of view.
W.Green, G.Swanborough - The Complete Book of Fighters
The single prototype of the DD 5 was rejected owing to poor aerodynamic qualities.