Dunne D . 6 The Dunne D . 6 was one of J . W . Dunne ' s swept wing tailless aircraft designed to have automatic stability , flying about 1911 . It was a single seat , single engined pusher monoplane with the Dunne - Capper glider and its powered version as antecedents , and was developed into the Dunne D . 7 . Design and development . Although J . W . Dunne is best known for his inherently stable tailless biplanes like the D . 5 and D . 8 , he also developed a series of inherently stable monoplanes . He had submitted a monoplane design to the War Office in 1905 before he joined the Balloon / Aircraft Factory at Farnborough , though they rejected it . In 1907 , employed by the Balloon Factory and encouraged by its head Colonel John Capper who also contributed to the engineering , Dunne built a parasol winged monoplane glider known as the Dunne - Capper glider . All Dunne ' s tailless aircraft had swept wings with marked washout ( reduction of angle of incidence ) at the tips . Since sweepback placed the tips well behind the centre of gravity , they provided longitudinal ( pitch ) stability in just the same way as a conventional tailplane , mounted at lower incidence than the wing . Both the D . 5 and the monoplanes had wing camber which increased outwards , though the wing profiles varied differently . The biplanes gained yaw stability from fixed panels between the wings at the tips , but the monoplanes used down - turned wingtips instead . The glider mounted this wing above a pair of transverse A - frames , linked by longitudinal members that supported the pilot ' s arms ; he controlled the aircraft by moving his weight . Several of Dunne ' s aircraft from his Balloon Factory period were tested at Blair Atholl in Scotland to maintain secrecy , and it seems the Dunne - Capper glider was one of these . Piloted by Capper , these tests were not successful . This glider had been built with the intention of adding an engine , but this was not done until early in 1911 , when a 60 hp ( 45 kW ) Green was added in a pusher configuration . The wing now had wingtip elevons for control , though because of the down - turned tips these also provided some rudder - like forces . This version of the Dunne - Capper monoplane was tested at Larkhill on Salisbury Plain in January 1911 but failed to take off . As a result , a third A - frame was added to the structure supporting engine and pilot . The earlier undercarriage with two wheels on the rear A - frame and skids at the front was replaced by one with two pairs of wheels at the back and two more wheels at the front . It is not known if this version was more successful . The D . 6 , major parts of which were built by Short Bothers , used a similar wing with a very different structure supporting it , the engine , pilot and undercarriage . The wing was straight edged , tapering from a central chord of 6 ft 3 in ( 1 . 91 m ) to 5 ft 0 in ( 1 . 52 m ) at the tips . The leading edge was swept at 35° . The A - frames with kingposts on the centreline were replaced with a pair of rectangular frames which extended above and below the wings , linked at the bottom by two transverse members . These frames served as double kingposts from which each wing was wire braced above and below . A substantial undercarriage structure was mounted at the bottom of the frames , comprising a long pair of skids which extended from the pusher propeller line well forward beyond the nacelle and curving strongly upwards . Each skid was multiply braced to its frame and inwards to the nacelle ; the pair were joined by a cross strut near the forward tip . Both carried a pair of wheels and , at the rear , an articulated and sprung extension to absorb landing shocks . The nacelle that carried the pilot ' s seat and the engine behind him was no more than an open wooden framework . The same Green engine was used as before , driving a two bladed , 7 ft 3 in ( 2 . 21 m ) diameter propeller . A tall , rectangular radiator was placed longitudinally above the wing , positioned to raise the centre of gravity as high as possible . A pair of levers , one for each hand , controlled the aircraft . This aircraft was tested at Eastchurch airfield on the Isle of Sheppey in June 1911 , flown by Dunne . It seems to have been hard to fly , for other tried but failed to master it . Nonetheless , Col Capper was sufficiently interested to order a version of it , designated the Dunne D . 7 or D . 7 " Auto Safety " . This was very similar to the D . 6 , but had a 1 ft ( 305 mm ) shorter span and a 50 hp ( 37 kW ) 7 - cylinder Gnome rotary engine . It first appeared , not quite ready for flight , at the Olympia Aero Show in March 1911 and was on test with the D . 6 at Eastchurch that June . Dunne was pleased with the improved performance . In January 1912 Dunne demonstrated the D . 7 to members of the Royal Aeronautical Society , writing a note whilst flying hands off at 60 mph . During 1912 the D . 6 was modified into a two seater , the Dunne D . 7 bis , with a 70 hp ( 52 kW ) Gnome to cope with the increased load . It had the shorter span wing of the D . 7 , but a centrally mounted surface was added to improve pitch control . This aircraft was successfully flown at Villacoublay in France by either Dunne or N . S . Percival in April 1913 .