Dunne D.7

{{Use dmy dates|date=December 2017}} {{Use British English|date=December 2017}} {{Infobox aircraft | name = D.7 | logo = | logo_size = | image = Dunne D.6.png | alt = | caption = | long_caption = | other_names = | aircraft_type = Experimental inherently stable monoplane | aim = | outcome = | related = | national_origin = United Kingdom | manufacturer = The Blair Atholl Syndicate/ Short Brothers | design_group = | designer = J. W. Dunne | builder = | issuer = | status = | owners = | primary_user = | more_users = | service = | major_applications = | proposals = | prototypes = | number_built = 1 | construction_number = | civil_registration = | military_serial = | radio_code = | requirement = | aircraft_carried = | flights = | total_hours = | total_distance = | construction_date = | introduction = | retired = | first_flight = ''c''. June 1911 | initiated = | in_service = | last_flight = | expected = | developed_from = | variants = | developed_into = | preservation = | fate = | predecessors = | successors = | concluded = }} The '''Dunne D.7''' was one of J. W. Dunne's swept wing tailless aircraft designed to have automatic stability, first flying in 1911. It was a single seat, single engined pusher monoplane developed from the unsuccessful D.6.

==Design and development==

Although J. W. Dunne is best known for his inherently stable tailless biplanes such as the D.8, he also developed a series of inherently stable monoplanes. He first submitted a monoplane design to the War Office when he joined the Army Balloon Factory at Farnborough in 1906, but they told him to build a biplane instead.

===D.6=== It wasn't until Dunne left the Balloon Factory and started his own company, the Blair Atholl Aeroplane Syndicate Ltd., that a monoplane could be built. The D.6 was built by Dunne's old commanding officer, Col. J. E. Capper who was also a member of his Blair Atholl Aeroplane Syndicate. It was finished in 1911, with a 60 hp (45 kW) Green in a pusher configuration. Three A-frames supported the wing 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°. 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.<ref>{{Harvnb|Tailless Trials}}</ref> The wing camber increased outwards, causing the outer leading edge to droop further.<ref name="FlightD6"/> The inherent design of the wing provided some directional (yaw) stability, which was augmented on the D.6 using down-turned wingtips. The wing had wingtip elevons for control, though because of the down-turned tips these also provided some rudder-like forces. The D.6 was tested at Larkhill on Salisbury Plain in January 1911 but failed to take off.<ref>Letter from Dunne to Science Museum, 20 June 1928. Archive ref. DM/2177.</ref>

===D.7=== The D.7, major parts of which were manufactured by Short Brothers,<ref>{{Harvnb|Barnes|James|1989|page=506}}</ref> re-used the same wing but with a very different structure supporting it. The heavy A-frames 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.<ref name="FlightD6">The Dunne Monoplane, 1911</ref><ref name="PLD6">{{Harvnb|Lewis|1962|pages=224–6}}</ref>

The nacelle that carried the pilot's seat and the engine behind him was no more than an open wooden framework. Initially, 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.<ref name="FlightD6"/><ref name="PLD6"/>

The modified aircraft first appeared, not quite ready for flight and with a dummy engine, at the Olympia Aero Show in March 1911 where it was described as the "Dunne Auto Safety Aeroplane". It was on test at Eastchurch that June.<ref name="PLD6"/> and Dunne was pleased with the improved performance.<ref>From the British Flying Grounds</ref> It was tested at Eastchurch airfield on the Isle of Sheppey in June 1911, flown by Dunne.

The D.7 was subsequently modified with a 1 ft (305 mm) shorter span and a 50 hp (37 kW) 7-cylinder Gnome rotary engine. 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.<ref name="PLD6"/>

===D.7 bis=== The '''Dunne D.7 bis''' was an improved variant with a 70 hp (52 kW) Gnome rotary engine and capable of carrying a passenger. A joint venture between the syndicate and the French company Astra, it was built in France and successfully flown at Villacoublay by both Dunne and N.S. Percival in April 1913.<ref>The Dunne monoplane in France</ref>

==Specifications (D.7)== {{Aircraft specs |ref=''Flight'', 1911 |prime units?=imp  |genhide= |crew=1 |capacity= |length m= |length ft=21 |length in=0 |length note= |span m= |span ft=36 |span in=0 |span note= |height m= |height ft= |height in= |height note= |wing area sqm= |wing area sqft=230 |wing area note=including elevons |aspect ratio= |airfoil= |empty weight kg= |empty weight lb= |empty weight note= |gross weight kg= |gross weight lb= |gross weight note= |max takeoff weight kg= |max takeoff weight lb= |max takeoff weight note= |fuel capacity= |more general=  |eng1 number=1 |eng1 name=Green |eng1 type=water cooled inline |eng1 kw= |eng1 hp=60 |eng1 kn= |eng1 lbf= |eng1 note= |power original= |thrust original= |eng1 kn-ab= |eng1 lbf-ab= |more power= |prop blade number=2 |prop name= |prop dia m= |prop dia ft=7 |prop dia in=3 |prop note=  |perfhide=Y |max speed kmh= |max speed mph= |max speed kts= |max speed note= |max speed mach= |cruise speed kmh= |cruise speed mph= |cruise speed kts= |cruise speed note= |stall speed kmh= |stall speed mph= |stall speed kts= |stall speed note= |never exceed speed kmh= |never exceed speed mph= |never exceed speed kts= |never exceed speed note= |minimum control speed kmh= |minimum control speed mph= |minimum control speed kts= |minimum control speed note= |range km= |range miles= |range nmi= |range note= |combat range km= |combat range miles= |combat range nmi= |combat range note= |ferry range km= |ferry range miles= |ferry range nmi= |ferry range note= |endurance= |ceiling m= |ceiling ft= |ceiling note= |g limits= |roll rate= |glide ratio= |climb rate ms= |climb rate ftmin= |climb rate note= |time to altitude= |sink rate ms= |sink rate ftmin= |sink rate note= |lift to drag= |wing loading kg/m2= |wing loading lb/sqft= |wing loading note= |disk loading kg/m2= |disk loading lb/sqft= |disk loading note= |power/mass= |thrust/weight= |more performance=  |armament= |guns= |bombs= |rockets= |missiles= |hardpoints= |hardpoint capacity= |hardpoint rockets= |hardpoint missiles= |hardpoint bombs= |hardpoint other= |other armament= |avionics= }}

{{aircontent  |see also= |related= |similar aircraft= |lists= }}

==Notes== {{reflist|2}}

==References== {{refbegin}} *{{cite book |title= Shorts Aircraft since 1900|last1= Barnes|first1=C.H. |last2 =James |first2=D. N.|year=1989 |publisher=Putnam Publishing |location=London |isbn= 0-87021-662-7}} *{{cite book |title= British Aircraft 1809-1914|last=Lewis|first=Peter| year=1962|publisher=Putnam Publishing |location=London }} *{{cite magazine |last= Poulsen |first= C. M. |title=Tailless Trials |magazine=Flight |pages=556–58 |url=http://www.flightglobal.com/PDFArchive/View/1943/1943%20-%201376.html |date= 27 May 1943 |number=1796 |volume=XLIII|ref={{harvid|Tailless Trials}}}} *{{cite magazine |title=The Dunne Monoplane, 1911|magazine= Flight|issue=24 June 1911|pages=542–5 |url= http://www.flightglobal.com/pdfarchive/view/1911/1911%20-%200540.html }} *{{cite magazine |title= From the British Flying Grounds.|magazine=Flight|issue=30 December 1911|page=1140 |url= http://www.flightglobal.com/pdfarchive/view/1911/1911%20-%201132.html }} *{{cite magazine |title= The Dunne monoplane in France.|magazine= Flight|issue=12 April 1913|page=419 |url= http://www.flightglobal.com/pdfarchive/view/1913/1913%20-%200413.html }} {{refend}}

Category:1910s British experimental aircraft D.6 Category:Single-engined pusher aircraft Category:Aircraft first flown in 1911 Category:Tailless aircraft

Dunne D.7

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