Dunne D.8
Encyclopedia
The Dunne D.8 of 1912 was one of a series of tailless
swept wing
biplanes, designed by J. W. Dunne
to have inherent stability. One of the few built was the only Dunne aircraft to fly, albeit very briefly, with the Royal Flying Corps
(RFC). Others were used by the US Signal Corps and United States Navy
and the short-lived Canadian Aviation Corps
. It was the latter's first and only warplane.
at Farnborough
during 1906–09. To preserve military secrecy testing was done at Blair Atholl
in Scotland
. After leaving Farnborough, Dunne set up a private company, the Blair-Atholl Syndicate Ltd. Its first aircraft was the Dunne D.5. When this crashed in 1911 it was rebuilt as the D.8. The two models shared very similar wings and the same engine, but the D.8 had a single pusher propeller instead of the chain-driven pair of the D.5. Their fuselages and undercarriages were also different.
The D.8 was a tailless four bay unstaggered biplane with its wings swept at 32°. Its constant chord wings were built up around two spruce
spars, the forward one forming the leading edge. To help achieve stability the incidence
and interplane gap decreased outboard, the former becoming negative. This washout
on tips well behind the centre of gravity provided longitudinal stability in the same way as a conventional tailplane, set at lower incidence than the wings. Camber
increased outwards. Simple, near parallel, pairs of interplane struts joined the spars. The outer interplane struts were enclosed with fabric, forming fixed side curtains that provided directional (yaw) stability. Wing tip elevons were used for control, operated by a pair of levers, one either side of the pilot. The D.8 initially used just a pair of these, mounted on the upper wing, a rectangular cutout in the side curtains allowing for their movement as on the D.5. Large parts of the aircraft were built by Short Brothers
.
The D.8's water-cooled 4-cylinder, 60 hp (45 kW) Green
engine directly drove a four-bladed pusher propeller, saving weight compared with the D.5's chain drive. Though it is not certain when the propeller was changed, most photographs show the Green engine driving a two-bladed airscrew. As a consequence of the propeller position the fuselage was shortened at the rear; it was also extended in the nose. This first D.8 seems to have been a single-seater like its D.5 predecessor, the pilot sitting at mid chord.
Contemporary sources remarked on the complexity of the D.8's undercarriage, which combined a narrow track pair of sprung wheels pair with wingtip skids. Part of its complication came from opposing springing in the absence of dampers, and part from an elaborate anti-noseover skid.
In this form the D.8 first flew in June 1912 at Eastchurch
. It attended the Larkhill
Military trial in August 1912, though it did not take part in the competition. It flew regularly at Eastchurch through 1911 and 1912 and was still active there in November 1912. Despite the two handed arrangement of the D.8's controls, the one-handed Capt. A.D. Carden gained his Royal Aero Club
Aviator's Certificate on it in June 1912.
It is not known if this machine was later modified aerodynamically, but by August 1913 the Green engine had been replaced by an 80 hp (60 kW) 7-cylinder Gnome
rotary engine
. This much shorter engine also powered the second aircraft, which was a two-seater with the pilot placed just ahead of the wing leading edge and the passenger (who had dual control) at the trailing edge. There were now control surfaces on both upper and lower wings, the side curtains having a pair of tapered notches to allow them to move. Each of the upper wings carried a pair of elevons, nearly doubling the control surface area, though it is not certain if these moved as one or differentially. It first flew, with Felix at the controls, on 18 October 1913.
In August 1913 Commandant Felix piloted a D.8 across the English Channel
from Eastchurch to Villacoublay. Nieuport
had obtained a licence to build the D.8 and Felix gave demonstration flights in France on their behalf.A Nieuport-built Dunne appeared at the Paris Aero Salon in December 1913. Like the second D.8 it was a Gnome powered two-seater, but with significant differences both aerodynamically and structurally. It combined the double upper wing elevons into a single surface and had very rounded rear wingtips. The fuselage was slightly modified and built around steel tubes rather than wood. The interplane struts were streamlined steel tubes. It also had a strikingly simplified undercarriage.
Dunne had obtained a War Office
order for two D.8s, though one was cancelled because of late delivery. One, possibly the machine flown in October 1913 and certainly similar to it, was delivered to Farnborough on 3 March 1914. It made several flights on 11 March piloted by N.S.Percival, who had flown the first D.8 many times at Eastchurch and was now a RFC officer. Though it carried the RFC number 366, there is no record of it flying again though it may have survived until at least the summer of 1914. The general judgement was that in the search for balance between stability and controllability, the Dunne design overemphasised the former.
There is a full scale, non-flying replica of a Burgess-Dunne in the RCAF Memorial Museum, CFB Trenton
, Ontario
, largely built by Barry D. MacKeracher.
Tailless aircraft
A tailless aircraft traditionally has all its horizontal control surfaces on its main wing surface. It has no horizontal stabilizer - either tailplane or canard foreplane . A 'tailless' type usually still has a vertical stabilising fin and control surface...
swept wing
Swept wing
A swept wing is a wing planform favored for high subsonic jet speeds first investigated by Germany during the Second World War. Since the introduction of the MiG-15 and North American F-86 which demonstrated a decisive superiority over the slower first generation of straight-wing jet fighters...
biplanes, designed by J. W. Dunne
John William Dunne
John William Dunne FRAeS was an Anglo-Irish aeronautical engineer and author. In the field of parapsychology, he achieved a preeminence through his theories on dreams and authoring books preoccupied with the question of the nature of time...
to have inherent stability. One of the few built was the only Dunne aircraft to fly, albeit very briefly, with the Royal Flying Corps
Royal Flying Corps
The Royal Flying Corps was the over-land air arm of the British military during most of the First World War. During the early part of the war, the RFC's responsibilities were centred on support of the British Army, via artillery co-operation and photographic reconnaissance...
(RFC). Others were used by the US Signal Corps and United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
and the short-lived Canadian Aviation Corps
Canadian Aviation Corps
Canadian Aviation Corps was an early attempt to create an air force for Canada at the beginning of the First World War. The unit was created in 1914 and was attached to the Canadian Expeditionary Force. The CAC had a maximum strength of three personnel and one aircraft which was delivered but...
. It was the latter's first and only warplane.
Design and development
J. W. Dunne's first swept biplane wing aircraft, designed to have automatic stability, dated from his employment at the Balloon (later) Aircraft FactoryRoyal Aircraft Establishment
The Royal Aircraft Establishment , was a British research establishment, known by several different names during its history, that eventually came under the aegis of the UK Ministry of Defence , before finally losing its identity in mergers with other institutions.The first site was at Farnborough...
at Farnborough
Farnborough Airfield
Farnborough Airport or TAG London Farnborough Airport is an airport situated in Farnborough, Rushmoor, Hampshire, England...
during 1906–09. To preserve military secrecy testing was done at Blair Atholl
Blair Atholl
Blair Atholl is a small town in Perthshire, Scotland, built about the confluence of the Rivers Tilt and Garry in one of the few areas of flat land in the midst of the Grampian Mountains. The Gaelic place-name Blair, from blàr, 'field, plain', refers to this location...
in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
. After leaving Farnborough, Dunne set up a private company, the Blair-Atholl Syndicate Ltd. Its first aircraft was the Dunne D.5. When this crashed in 1911 it was rebuilt as the D.8. The two models shared very similar wings and the same engine, but the D.8 had a single pusher propeller instead of the chain-driven pair of the D.5. Their fuselages and undercarriages were also different.
The D.8 was a tailless four bay unstaggered biplane with its wings swept at 32°. Its constant chord wings were built up around two spruce
Spruce
A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...
spars, the forward one forming the leading edge. To help achieve stability the incidence
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example:* in the approach of a ray to a surface, or* the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.-Optics:In geometric...
and interplane gap decreased outboard, the former becoming negative. This washout
Washout (aviation)
Washout refers to a feature of wing design to deliberately reduce the lift distribution across the span of the wing of an aircraft. The wing is designed so that angle of incidence is higher at the wing roots and decreases across the span, becoming lowest at the wing tip...
on tips well behind the centre of gravity provided longitudinal stability in the same way as a conventional tailplane, set at lower incidence than the wings. Camber
Camber (aerodynamics)
Camber, in aeronautics and aeronautical engineering, is the asymmetry between the top and the bottom surfaces of an aerofoil. An aerofoil that is not cambered is called a symmetric aerofoil...
increased outwards. Simple, near parallel, pairs of interplane struts joined the spars. The outer interplane struts were enclosed with fabric, forming fixed side curtains that provided directional (yaw) stability. Wing tip elevons were used for control, operated by a pair of levers, one either side of the pilot. The D.8 initially used just a pair of these, mounted on the upper wing, a rectangular cutout in the side curtains allowing for their movement as on the D.5. Large parts of the aircraft were built by Short Brothers
Short Brothers
Short Brothers plc is a British aerospace company, usually referred to simply as Shorts, that is now based in Belfast, Northern Ireland. Founded in 1908, Shorts was the first company in the world to make production aircraft and was a manufacturer of flying boats during the 1920s, 1930s, and 1940s...
.
The D.8's water-cooled 4-cylinder, 60 hp (45 kW) Green
Green Engine Co
The Green Engine Co was an early British aero engine manufacturer. It was founded by Gustavus Green in Bexhill to produce engines of his design during the first two decades of the 20th century. Actual manufacturing was carried out at the Aster Engineering Company of Wembley...
engine directly drove a four-bladed pusher propeller, saving weight compared with the D.5's chain drive. Though it is not certain when the propeller was changed, most photographs show the Green engine driving a two-bladed airscrew. As a consequence of the propeller position the fuselage was shortened at the rear; it was also extended in the nose. This first D.8 seems to have been a single-seater like its D.5 predecessor, the pilot sitting at mid chord.
Contemporary sources remarked on the complexity of the D.8's undercarriage, which combined a narrow track pair of sprung wheels pair with wingtip skids. Part of its complication came from opposing springing in the absence of dampers, and part from an elaborate anti-noseover skid.
In this form the D.8 first flew in June 1912 at Eastchurch
Eastchurch
Eastchurch is a village on the Isle of Sheppey, in the English county of Kent, two miles east of Minster.The village website claims "... it has a history steeped in stories of piracy and smugglers".- Aviation history :...
. It attended the Larkhill
Larkhill
Larkhill is a garrison town in the civil parish of Durrington, Wiltshire, England. It is a short distance west of Durrington village proper and north of the prehistoric monument of Stonehenge. It is about north of Salisbury....
Military trial in August 1912, though it did not take part in the competition. It flew regularly at Eastchurch through 1911 and 1912 and was still active there in November 1912. Despite the two handed arrangement of the D.8's controls, the one-handed Capt. A.D. Carden gained his Royal Aero Club
Royal Aero Club
The Royal Aero Club is the national co-ordinating body for Air Sport in the United Kingdom.The Aero Club was founded in 1901 by Frank Hedges Butler, his daughter Vera and the Hon Charles Rolls , partly inspired by the Aero Club of France...
Aviator's Certificate on it in June 1912.
It is not known if this machine was later modified aerodynamically, but by August 1913 the Green engine had been replaced by an 80 hp (60 kW) 7-cylinder Gnome
Gnome et Rhône
Gnome et Rhône was a major French aircraft engine manufacturer. Between 1914 and 1918 they produced 25,000 of their 9-cylinder Delta and Le Rhône 110 hp rotary designs, while another 75,000 were produced by various licensees, powering the majority of aircraft in the first half of the war on...
rotary engine
Rotary engine
The rotary engine was an early type of internal-combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary and the entire cylinder block rotated around it...
. This much shorter engine also powered the second aircraft, which was a two-seater with the pilot placed just ahead of the wing leading edge and the passenger (who had dual control) at the trailing edge. There were now control surfaces on both upper and lower wings, the side curtains having a pair of tapered notches to allow them to move. Each of the upper wings carried a pair of elevons, nearly doubling the control surface area, though it is not certain if these moved as one or differentially. It first flew, with Felix at the controls, on 18 October 1913.
In August 1913 Commandant Felix piloted a D.8 across the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...
from Eastchurch to Villacoublay. Nieuport
Nieuport
Nieuport, later Nieuport-Delage, was a French aeroplane company that primarily built racing aircraft before World War I and fighter aircraft during World War I and between the wars.-Beginnings:...
had obtained a licence to build the D.8 and Felix gave demonstration flights in France on their behalf.A Nieuport-built Dunne appeared at the Paris Aero Salon in December 1913. Like the second D.8 it was a Gnome powered two-seater, but with significant differences both aerodynamically and structurally. It combined the double upper wing elevons into a single surface and had very rounded rear wingtips. The fuselage was slightly modified and built around steel tubes rather than wood. The interplane struts were streamlined steel tubes. It also had a strikingly simplified undercarriage.
Dunne had obtained a War Office
War Office
The War Office was a department of the British Government, responsible for the administration of the British Army between the 17th century and 1964, when its functions were transferred to the Ministry of Defence...
order for two D.8s, though one was cancelled because of late delivery. One, possibly the machine flown in October 1913 and certainly similar to it, was delivered to Farnborough on 3 March 1914. It made several flights on 11 March piloted by N.S.Percival, who had flown the first D.8 many times at Eastchurch and was now a RFC officer. Though it carried the RFC number 366, there is no record of it flying again though it may have survived until at least the summer of 1914. The general judgement was that in the search for balance between stability and controllability, the Dunne design overemphasised the former.
Variants
- D.10 A shorter span (45 ft, 13.7 m) two-seat Gnome powered version, later converted to D.8.
- Burgess-Dunne The Burgess Company and Curtiss, based in Marblehead, Mass, USA gained the US manufacturing rights and built a series of aircraft based on the D.8. They became known as Burgess-Dunne machines and were mostly single-float planes. The first flew in March 1914, piloted by Clifford Webster. Apart from wingtip floats the wings were identical to those of the D8, but the fuselage was revised with a distinct nacelle containing a more enclosed cockpit. The aircraft was a single-seater, with the heavier 100 hp (75 kW) Curtiss OXX2Curtiss OXX|-References:* Molson, K. M. "The Curtiss OX-5 Engine." Journal of the American Aviation Historical Society.* US Department of Transportation Federal Aviation Administration Type Certificate Data Sheet Curtiss OXX-6...
water-cooled engine moved forwards, shortening the fuselage and with its radiator placed between engine and pilot. The single float was 17 ft 8 in long (5.38 m), shallow and flat bottomed viewed from in front, with a single step. The prototype behaved well in the air and on the water. The second machine was very similar to the first, but room was made for a second seat by replacing the single fuselage mounted radiator with a pair fixed to the rear float struts.
- The second machine was bought by the Canadian government for the Canadian Aviation Corps and was their first military aircraft. It was shipped to EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
for service in World War IWorld War IWorld War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, but was seriously damaged in transit and not used. The third machine, another two-seater but powered by a Salmson M-9 radial providing 135 hp (100 kW), was delivered to the US Signal Corps in either 1914 or 1915. Two were also delivered to the US Navy as type AH-7, fitted with a 90 hp (60 kW) Curtiss engine and AH-10 with the 100 hp Curtiss. The latter set a US altitude record of 10,000 fft (3,050 m) on 23 April 1915. One Burgess-Dunne was configured as a landplane for a time.
- The Dunne-Burgess types were
- BDI - as the prototype.
- BD - as the second aircraft, first aimed at the military market then as a sports plane.
- BDH - a two-seater with a 140 hp (104 kW) Sturtevant V-8 engine and a slightly increased span (46 ft, 14.0 m).
- BDF - a three-seat, flying boat variant with the Curtiss engine but a span increased to 53 ft (16.2 m).
There is a full scale, non-flying replica of a Burgess-Dunne in the RCAF Memorial Museum, CFB Trenton
CFB Trenton
Canadian Forces Base Trenton , is a Canadian Forces base located northeast of Trenton, Ontario. It is operated as an air force base by the Royal Canadian Air Force and is the hub for air transport operations in Canada and abroad...
, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, largely built by Barry D. MacKeracher.