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 D.I Junkers D.I The Junkers D.I (factory designation J 9) was a monoplane fighter aircraft produced in Germany late in World War I, significant for becoming the first all-metal fighter to enter service. The prototype, a private venture by Junkers designated the J 7, first flew on 17 September 1917, going through nearly a half-dozen detail changes in its design during its tests. When it was demonstrated to the "Idflieg" early the following year it proved impressive enough to result in an order for three additional aircraft for trials. However, the changes made by Junkers were significant enough for the firm