Junkers T 29 29 pioneered the patented Junkers "Doppelflügel" "double wing" control system - whose concept was used through to the Third Reich's Junkers Ju 87 "Stuka" dive bomber - using full span ailerons, later used for both ailerons and flaps, hinged just below the wing trailing edge and fully exposing the entire control surface cross-section to the slipstream, forming a slot between the two surfaces. In normal flight these were used as standard ailerons, but they could be lowered like flaps for landing whilst retaining the differential movement needed for lateral control. The fuselage was flat sided with rounded decking, the Junkers
Junkers T 29 L1a inline engine cowled with its cylinder heads slightly exposed. Pilot and passenger sat side by side over the wing in a cockpit open apart from a longitudinal arch over their heads to protect them like a roll bar, set perpendicularly to the similar cross-fuselage device only used directly "behind" the cockpit on the Junkers J 2, the Junkers J 7 experimental duralumin-structure monoplane and production Junkers D.I fighter of the late World War I years. This unusual feature reminded observers of a handle and earned the J 29 the nickname "Bügeleisen" (en: flat iron). The fuselage tapered to the