The de Havilland DH 108 "Swallow" was a British experimental aircraft designed by John Carver Meadows Frost in October 1945. The DH 108 featured a tailless, swept wing with a single vertical stabilizer, similar to the layout of the wartime German Messerschmitt Me 163 Komet. Initially designed to evaluate swept wing handling characteristics at low and high subsonic speeds for the proposed early tailless design of the Comet airliner, three examples of the DH 108 were built to Air Ministry specifications E.18/45. With the adoption of a conventional tail for the Comet, the aircraft were used instead to investigate swept wing handling up to supersonic speeds. All three prototypes were lost in fatal crashes.
Employing the main fuselage section and engine of the de Havilland Vampire mated to a longer fuselage with a single fin and swept wings, the de Havilland DH 108 was proposed in 1944 as an aerodynamic test bed for tailless designs, particularly the DH.106 Comet which had initially been considered a tailless, swept-wing concept.[1] Despite the Comet design taking on more conventional features, the value of testing the unique configuration to provide basic data for the DH.110[2] spurred de Havilland to continue development of the DH 108. Selecting two airframes from the English Electric Vampire F 1 production line, the new aircraft had unmistakable similarities to its fighter origins, especially in the original forward fuselage which retained the nose, cockpit and other components of the Vampire. The Ministry of Supply named the DH 108 the "Swallow", a name that was never officially adopted by the company.[3]
The new metal wing incorporating a 43˚ sweepback was approximately 15% greater in area than the standard Vampire wing.[2] Control was based on the conventional rudder in combination with elevons that were part elevator and ailerons, fitted outboard of the split trailing edge flaps.[2] Although the Vampire fuselage was retained, as development continued, a revised nose and streamlined, reinforced canopy were incorporated.[4]
Testing
The first DH 108 prototype, serial numberTG283, had a 43° swept wing, flew on 15 May 1946 at RAF Woodbridge. Designed to investigate low-speed handling, it was capable of only 280mph (450km/h). The de Havilland chief test pilot Geoffrey de Havilland Jr., son of de Havilland company owner-designer Geoffrey de Havilland, gave a display flight in the DH 108 during the 1946 Society of British Aircraft Constructors (SBAC) airshow at Radlett.[5] In later low-speed testing designed to clear the rear fuselage at high angles of attack, the first prototype was fitted with longer Sea Vampire landing gear.[6]
The second, high-speed, prototype, TG306, which had a 45° swept wing incorporating automatic leading-edge Handley Page slats and was powered by a de Havilland Goblin 3 turbojet, flew soon afterwards, in June 1946. Modifications to the design included a longer more streamlined nose and a smaller canopy (framed by a strengthened metal fairing) facilitated by lowering the pilot's seat.[4] While being used to evaluate handling characteristics at high speed in preparation for an attempt on the World Speed Record, on 27 September 1946 TG306 suffered a catastrophic structural failure which occurred in a dive from 10,000ft (3,000m) at Mach 0.9 and crashed in the Thames Estuary. The pilot, Geoffrey de Havilland Jr., was killed in the accident. Early wind tunnel testing had pointed to potentially dangerous flight behaviour, but pitch oscillation at high speed had been unexpected. The subsequent accident investigation centred on a structural failure which occurred as air built up at Mach 0.9, pitching the aircraft into a shock stall that placed tremendous loads on the fuselage and wings. The main spar cracked at the roots causing the wings to immediately fold backwards.[7]
VW120 in flight, about 1949
After the loss of the second prototype, a third aircraft was ordered to continue high-speed trials. VW120 became the third and final prototype. It differed from the first test aircraft in having an more streamlined pointed nose and smaller reinforced canopy (lowering the pilot's seat allowed for a more aerodynamic canopy shape to be employed), with the cockpit redesign allowing an ejection seat to be fitted.[8] Power-boosted elevators had been specified as a means to control the pitch oscillations at the root of the earlier disaster. A more powerful Goblin 4 of 3,738lbf (16.67kN) thrust had the potential to push the DH 108 into the supersonic range. VW120 first flew on 24 July 1947 flown by John Cunningham, the wartime nightfighter ace who became, in 1949, the first person to pilot the de Havilland Comet jet airliner.
Considered an important testbed for high-speed flight, VW120 was readied for an attempt at the World Speed Record then held by a Gloster Meteor at 616mph (991km/h). The second prototype, TG306, was a backup for the attempt before it crashed.[7] On 12 April 1948, VW120 established a new World Air Speed Record of 604.98mph (974.02km/h) on a 62-mile (100km) circuit. Then, on 6 September 1948, John Derry is thought to have probably exceeded the speed of sound in a shallow dive from 40,000ft (12,195m) to 30,000ft (9,145m). The test pilot Captain Eric "Winkle" Brown, who escaped a crash in 1949, described the DH 108 as "a killer".[9]
In 1949, VW120 put on an aerial display at Farnborough and was placed third in the Society of British Aircraft Constructors Challenge Trophy Air Race before being turned over to the Ministry of Supply and test flown at RAE Farnborough.[10] It was destroyed on 15 February 1950 in a crash near Brickhill, Buckinghamshire, killing its test pilot, Squadron LeaderStuart Muller-Rowland. The accident investigation at the time pointed, not to the aircraft, but to a faulty oxygen system that incapacitated the pilot.[10]
The coroner's report confirmed that the pilot died from a broken neck. The failure of the left wing as the plane dived occurred just above the garage at Brickhill. This failure was presumed to be the source of a "bang" described by witnesses at Brickhill. Swishing sounds which were reported came from the aircraft spinning at a high rate due to it having only one wing. It came down in the woods, after glancing off an oak tree: traces of the impact were still visible 50 years later. The airframe and right wing were dismantled by the military, and removed very quickly. The left wing was also recovered from the fields just north of Brickhill.
A nearby German field worker ran over to the crash site and was met by the mechanic from Brickhill garage who had rushed to the crash site in his car to offer assistance. The pilot was already dead.
In 2001, a search at the crash site by a local using a metal detector was successful. He found some of the mounting bolts "cone shaped" that were removed when the remains had been dismantled on-site. The tree that the DH 108 had hit was also found, with the scar still visible. The earlier theory, that a faulty oxygen system was the cause, was ruled out by the coroner in his later report.[citation needed]
Finally, on 1 May 1950, during low-speed sideslip and stall tests, the first prototype, TG283, was lost in a crash at Hartley Wintney killing the pilot, Sqn Ldr George E.C. Genders AFC DFM. After abandoning the aircraft at low altitude in an inverted spin, his parachute failed to open in time. In all, 480 flights had been made by the three Swallows.[11]
Legacy
The DH108 established a number of "firsts" for a British aircraft: it was the first British swept-winged jet aircraft and the first British tailless jet aircraft.
The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or impossible. The term sound barrier is still sometimes used today to refer to aircraft approaching supersonic flight in this high drag regime. Flying faster than sound produces a sonic boom.
The de Havilland DH.106 Comet is the world's first commercial jet airliner. Developed and manufactured by de Havilland in the United Kingdom, the Comet 1 prototype first flew in 1949. It features an aerodynamically clean design with four de Havilland Ghost turbojet engines buried in the wing roots, a pressurised cabin, and large windows. For the era, it offered a relatively quiet, comfortable passenger cabin and was commercially promising at its debut in 1952.
The de Havilland Aircraft Company Limited was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of north London. Operations were later moved to Hatfield in Hertfordshire.
The de Havilland DH.103 Hornet, developed by de Havilland, was a fighter aircraft driven by two piston engines. It further exploited the wooden construction techniques that had been pioneered by the de Havilland Mosquito. Development of the Hornet had started during the Second World War as a private venture. The aircraft was to conduct long range fighter operations in the Pacific Theatre against the Empire of Japan but the war ended before the Hornet reached operational squadron status.
A swept wing is a wing angled either backward or occasionally forward from its root rather than perpendicular to the fuselage.
The de Havilland Vampire is a British jet fighter which was developed and manufactured by the de Havilland Aircraft Company. It was the second jet fighter to be operated by the RAF, after the Gloster Meteor, and the first to be powered by a single jet engine.
The Northrop X-4 Bantam was a prototype small twinjet aircraft manufactured by Northrop Corporation in 1948. It had no horizontal tail surfaces, depending instead on combined elevator and aileron control surfaces for control in pitch and roll attitudes, almost exactly in the manner of the similar-format, rocket-powered Messerschmitt Me 163 of Nazi Germany's Luftwaffe. Some aerodynamicists had proposed that eliminating the horizontal tail would also do away with stability problems at fast speeds resulting from the interaction of supersonic shock waves from the wings and the horizontal stabilizers. The idea had merit, but the flight control systems of that time prevented the X-4 from achieving any success.
The de Havilland Express, also known as the de Havilland D.H.86, was a four-engined passenger aircraft manufactured by the de Havilland Aircraft Company between 1934 and 1937.
The de Havilland DH.110 Sea Vixen is a British twin-engine, twin boom-tailed, two-seat, carrier-based fleet air-defence fighter flown by the Royal Navy's Fleet Air Arm from the 1950s to the early 1970s. The Sea Vixen was designed by the de Havilland Aircraft Company during the late 1940s at its Hatfield aircraft factory in Hertfordshire, developed from the company's earlier first generation jet fighters. It was later called the Hawker Siddeley Sea Vixen after de Havilland was absorbed by the Hawker Siddeley Corporation in 1960.
The Supermarine Attacker is a British single-seat naval jet fighter designed and produced by aircraft manufacturer Supermarine for the Royal Navy's Fleet Air Arm (FAA). It was the first jet fighter to enter operational service with the FAA.
The Saab 29 Tunnan, colloquially also Flygande Tunnan, is an early jet-powered fighter aircraft designed and produced by the Swedish aircraft manufacturer Saab. It was the second turbojet-powered combat aircraft to be developed in Sweden, the first being the Saab 21R, and it was the first Western European fighter to be produced with a swept wing after the Second World War, only being preceded in Western Europe as a whole by the Messerschmitt Me 262 built during the conflict.
The de Havilland Goblin, originally designated as the Halford H-1, is an early turbojet engine designed by Frank Halford and built by de Havilland. The Goblin was the second British jet engine to fly, after Whittle's Power Jets W.1, and the first to pass a type test and receive a type certificate issued for an aircraft propulsion turbine.
The Handley Page HP. 75 Manx was a British experimental aircraft designed by Handley Page that flew test flights in the early 1940s. It was notable for its unconventional design characteristics, being a twin-engine tailless design of pusher configuration.
Geoffrey Raoul de Havilland Jr., OBE was a British test pilot. He was the son of Geoffrey de Havilland, the English aviation pioneer and aircraft designer.
John Carver Meadows Frost was a British aircraft designer. His primary contributions centred on pioneering supersonic British experimental aircraft and as the chief designer who shepherded Canada's first jet fighter project, the Avro Canada CF-100, to completion. He was also the major force behind the Avro Canada VTOL aircraft projects, particularly as the unheralded creator of the Avro Canada flying saucer projects.
The General Aircraft GAL.56 was a family of 1940s British experimental tailless swept wing glider designs.
The Arsenal VG 90 was a French carrier-based jet-engined interceptor developed in the late 1940s. It was intended to compete for an Aéronavale contract and first flew in 1949. It set a speed record for a French aircraft the following year, but both of the completed prototypes were destroyed in fatal crashes and the program was cancelled in 1952 before the third prototype was finished. The Aéronavale contract was eventually awarded to a license-built British aircraft. The remains of the last VG 90 were scrapped in 1978.
On 6 September 1952, a prototype de Havilland DH.110 jet fighter crashed during an aerial display at the Farnborough Airshow in Hampshire, England. The jet disintegrated mid-air during an aerobatic manoeuvre, causing the death of pilot John Derry and onboard flight test observer Anthony Richards. Debris from the aircraft fell onto a crowd of spectators, killing 29 people and injuring 60.
In aeronautics, a tailless aircraft is an aircraft with no other horizontal aerodynamic surface besides its main wing. It may still have a fuselage, vertical tail fin, and/or vertical rudder.
Ronald Eric Bishop CBE FRAeS, commonly referred to as R. E. Bishop, was a British engineer who was the chief designer of the de Havilland Mosquito, one of the most famous aircraft of the Second World War. He also designed the de Havilland Comet jetliner of 1949.
Brown, Eric. "An Ill-fated Swallow... But a Harbinger of Summer". Air Enthusiast, No. 10, July–September 1979, pp.1–7. ISSN0143-5450.
Buttler, Tony and Jean-Louis Delezenne. X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974. Manchester, UK: Hikoki Publications, 2015. ISBN978-1-90210-948-0
Davies, R.E.G. and Philip J. Birtles. Comet: The World's First Jet Airliner. McLean, Virginia: Paladwr Press, 1999. ISBN1-888962-14-3.
Jackson, A.J. de Havilland Aircraft Since 1915. London: Putnam, 1962. No ISBN.
Pelletier, Alain J. "Towards the Ideal Aircraft: The Life and Times of the Flying Wing, Part Two". Air Enthusiast, No. 65, September–October 1996, pp.8–19. ISSN0143-5450.
Rivas, Brian. A Very British Sound Barrier: DH108, A Story of Courage, Triumph and Tragedy. Walton on Thames, UK: Red Kite, 2012. ISBN978-1-90659-204-2.
Watkins, David. de Havilland Vampire: The Complete History. Thrupp, Stroud, UK: Budding Books, 1996. ISBN1-84015-023-8.
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