The Siemens-Schuckert Werke S.S.W. DDr I was an unusual triplane fighter powered by a pair of engines mounted on the centre line, one pusher and one tractor engine.
The main fuselage resembled an egg, with one Siemens-Halske Sh I engine at each end and the pilot's open cockpit between them. The middle wing was built into the fuselage, with the upper and lower wings carried by two sets of struts on each side.
The rear engine powered a shorter bladed four blade propeller, which rotated within a rectangular frame that connected the wings to the two rudders and single elevator. These were built onto the left, right and upper edges of the rear end of this frame. The front engine powered a larger two blade propeller. The DDr I was armed with two forward firing LMG 08/15 machine guns.
The design of the DDr I was shown to Idflieg in June 1917, and Siemens were given an order to produce a prototype. The prototype was ready by November 1917, but it crashed early into its maiden flight. Even the short period spent in the air had revealed problems with stability and engine controls, and the aircraft wasn't rebuilt. Plans for a DDr II, powered by the Sh III engine, were abandoned.
Engine: Two Siemens- Halske Sh I rotary engines
Power: 120hp each
Span: 39ft 9 1/4in
Length: 19ft 0 3/8in
Empty weight: 1,496lb
Loaded weight: 2,002lb
Armament: Twin Spandau LMG 08/15 machine guns