The Siemens-Schuckert DDr.I was a World War I German twin engine, push-pull configuration triplane fighter aircraft.

The unusual DDr.I was one of the first aircraft to have two engines on the same centre line, one in tractor configuration and the other a pusher, an arrangement usually known as tandem push-pull.

It was a triplane with constant chord, straight edged, square tipped wings of equal span and marked stagger.

[1][2] The smoothly faired and contoured short fuselage of the DDr.I positioned the open pilot's cockpit between two 110 hp (82 kW) Siemens-Halske Sh.I nine cylinder rotary engines, one with a two blade tractor propeller and the other driving a four blade pusher turning just aft of the lower wing trailing edge.

There were no fixed rear surfaces; the single piece, constant chord elevator reached between the two upper beams and a pair of similarly shaped rudder went from the upper to the lower beams, hinged further aft than the elevator but with their lower ends on a hinged frame that moved with it.