De Havilland DH 108

de Havilland Aircraft Company

Industry	Aerospace
Founded	1920
Founder	Geoffrey de Havilland
Headquarters	Hatfield , United Kingdom
Products	Aircraft including the DH 108 "Swallow"

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The de Havilland DH 108 "Swallow" was a British experimental aircraft conceptualised by John Carver Meadows Frost in October 1945. It featured a tailless design with swept wings and a single vertical stabilizer, resembling the layout of the German wartime Messerschmitt Me 163 Komet. Initially intended to assess the handling qualities of swept wings at both low and high subsonic speeds for the early tailless concept of the Comet airliner, three units were manufactured following Air Ministry specification E.18/45. After the Comet adopted a conventional tail configuration, the DH 108s were repurposed to explore swept wing behaviour at speeds approaching and exceeding sound barrier thresholds. Unfortunately, all three prototypes were lost in fatal accidents.

Design and development

The DH 108 combined the fuselage and powerplant of the de Havilland Vampire with an extended fuselage featuring a single vertical fin and swept wings. Proposed in 1944 as a test platform for tailless aerodynamics—particularly for the initially tailless, swept-wing design of the DH.106 Comet—the aircraft retained noticeable elements from its fighter predecessor, especially in the forward fuselage which included the original nose, cockpit, and related components from the Vampire. Although the Comet eventually incorporated a more conventional tail arrangement, de Havilland proceeded with developing the DH 108 to gather fundamental aerodynamic data useful for the subsequent DH.110. Two airframes were selected from the production line of English Electric Vampire F1 fighters to serve as the basis for this project. The Ministry of Supply assigned the name "Swallow" to this model, although this designation was never officially embraced by de Havilland.

The aircraft’s new metal wings featured a sweep angle of approximately 43°, resulting in an area about fifteen percent larger than that of standard Vampire wings. Control surfaces included a traditional rudder paired with elevons—combined elevator and aileron surfaces—positioned outboard of split trailing-edge flaps. While retaining the Vampire’s fuselage structure, ongoing development introduced modifications such as a redesigned nose section and a more streamlined, reinforced canopy.

Testing

The initial DH 108 prototype, bearing the serial number TG283, featured a wing swept at 43° and took to the skies for its maiden flight on 15 May 1946 at RAF Woodbridge. Engineered to study low-speed handling characteristics, this model was limited to a maximum speed of 280 mph (450 km/h). Geoffrey de Havilland Jr., the chief test pilot and son of the company's founder Geoffrey de Havilland, performed a demonstration flight with the DH 108 during the 1946 Society of British Aircraft Constructors (SBAC) airshow held at Radlett. Subsequent low-speed evaluations intended to improve airflow clearance around the rear fuselage at high angles of attack led to fitting the first prototype with extended Sea Vampire landing gear.

Following this, the second prototype, TG306, designed for high-speed testing, incorporated a 45° swept wing equipped with automatic leading-edge Handley Page slats and was powered by a de Havilland Goblin 3 turbojet. It flew shortly thereafter in June 1946. This version featured several design enhancements, including an elongated, more aerodynamic nose and a smaller canopy supported by a reinforced metal frame, achieved by lowering the pilot’s seat. While preparing for a World Speed Record attempt and assessing high-speed handling, TG306 experienced a catastrophic structural failure on 27 September 1946 during a dive from approximately 10,000 ft (3,048 m) at Mach 0.9, resulting in a crash into the Thames Estuary. Tragically, Geoffrey de Havilland Jr. lost his life in this accident. Although early wind tunnel tests had indicated potential flight instability, the pitch oscillations encountered at high speed were unforeseen. The investigation concluded that as airflow built up at Mach 0.9, the aircraft entered a shock stall causing extreme stress on both fuselage and wings. This led to cracking of the main spar roots and immediate backward folding of the wings.

File:DeHavilland Swallow VW120 NAN7-49.jpg

VW120 in flight, circa 1949

In response to the loss of TG306, a third aircraft was commissioned to continue high-speed experimentation. Known as VW120, this final prototype differed from earlier versions by featuring a sleeker pointed nose and a smaller, reinforced canopy made possible by lowering the pilot’s seating position—this redesign also allowed installation of an ejection seat. To address previous pitch oscillation issues thought responsible for earlier failures, power-boosted elevators were implemented. Equipped with an upgraded Goblin 4 engine delivering 3,738 lbf (16.67 kN) thrust, VW120 possessed the capability to reach supersonic speeds. Its first flight took place on 24 July 1947 under the control of John Cunningham, famed wartime nightfighter ace who later became the inaugural pilot of the de Havilland Comet jet airliner in 1949.

Recognized as a vital platform for advancing high-speed flight knowledge, VW120 was prepared for an attempt to break the World Speed Record then held by a Gloster Meteor at 616 mph (991 km/h). The earlier prototype TG306 had served as backup before its destruction. On 12 April 1948, piloted by Cunningham, VW120 set a new World Air Speed Record at 604.98 mph (974.02 km/h) over a measured 62-mile (100 km) circuit. Later that year, on 6 September 1948, John Derry is believed to have likely surpassed the speed of sound during a shallow dive from an altitude of 40,000 ft (12,195 m) descending to 30,000 ft (9,145 m). Test pilot Captain Eric "Winkle" Brown—who survived a crash involving the DH 108 in 1949—famously described it as "a killer".

In 1949, VW120 showcased its capabilities during an aerial demonstration at Farnborough and secured third place in the Society of British Aircraft Constructors Challenge Trophy Air Race before being transferred to the Ministry of Supply for further testing at RAE Farnborough. Unfortunately, on 15 February 1950 it crashed near Brickhill, Buckinghamshire, resulting in the death of test pilot Squadron Leader Stuart Muller-Rowland. Initial accident investigations attributed the cause to pilot incapacitation due to faulty oxygen equipment; however, this explanation was later dismissed by the coroner’s report which confirmed that death resulted from a broken neck.

The left wing failed during a dive just above Brickhill garage—this event is believed to have caused an audible "bang" reported by local witnesses. The subsequent swishing noises were attributed to rapid spinning caused by loss of one wing. The aircraft ultimately struck an oak tree in nearby woods before coming down; impact marks remained visible for decades afterward. Military personnel quickly dismantled and removed both the airframe and right wing from the site while recovering the left wing from adjacent fields north of Brickhill.

At the crash scene, a German farm laborer encountered a local garage mechanic who had rushed there to assist; unfortunately, they found that the pilot had already perished.

Years later in 2001, an individual conducting a metal detector search near the crash location discovered several cone-shaped mounting bolts that had been detached during on-site dismantling. The tree struck by the DH 108 was also located with visible scarring still evident.

Finally, on 1 May 1950 during low-speed sideslip and stall tests, the first prototype TG283 was lost in an accident near Hartley Wintney, resulting in fatal injuries to pilot Squadron Leader George Genders AFC DFM. After ejecting from an inverted spin at low altitude, his parachute failed to deploy properly before impact. Collectively, all three Swallow prototypes completed approximately 480 flights before their respective losses.

Legacy

The DH108 marked several pioneering achievements for British aviation: it was the inaugural British jet aircraft featuring swept wings and also the first British jet to be designed without a conventional tail.

Operators

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• Royal Aircraft Establishment

Specifications (DH 108 VW120: third prototype)

File:De Havilland DH.108 Swallow (VW120) drawings 1949.jpg

De Havilland DH.108 Swallow

See also

Bibliography

• Brown, Eric. "A Doomed Swallow... Yet a Forerunner of Summer". Air Enthusiast, No. 10, July–September 1979, pp. 1–7. Template:ISSN.
• Buttler, Tony and Jean-Louis Delezenne. X-Planes of Europe: Classified Research Aircraft from the Golden Era 1946-1974. Manchester, UK: Hikoki Publications, 2015. ISBN 978-1-90210-948-0
• Davies, R.E.G. and Philip J. Birtles. Comet: The First Jet Airliner in the World. McLean, Virginia: Paladwr Press, 1999. ISBN 1-888962-14-3.
• Jackson, A.J. de Havilland Aircraft Since 1915. London: Putnam, 1962. No ISBN.
• Jones, Barry. "Tailless Trio" Aeroplane Monthly, May 1993, Vol. 21, No. 5. pp. 34–41, 45. Template:ISSN.
• McPhee, Andrew. "Unusual Wings – de Havilland DH.108" Unreal Aircraft. Retrieved: 4 September 2005.
• Pelletier, Alain J. "Pursuing the Ideal Aircraft: The Life and Times of the Flying Wing, Part Two". Air Enthusiast, No. 65, September–October 1996, pp. 8–19. Template:ISSN.
• Rivas, Brian. A Very British Sound Barrier: DH108, A Tale of Bravery, Success and Tragedy. Walton on Thames, UK: Red Kite, 2012. ISBN 978-1-90659-204-2.
• Watkins, David. de Havilland Vampire: The Complete Story. Thrupp, Stroud, UK: Budding Books, 1996. ISBN 1-84015-023-8.
• Winchester, Jim. Concept Aircraft: Prototypes, X-Planes and Experimental Designs. Kent, UK: Grange Books plc., 2005. ISBN 978-1-84013-809-2.

External links

• Overview of the three aircraft at Jets45
• Report on the Brickhill crash of VW120 Archived 3 March 2016 at the Wayback Machine
• Archived British Aircraft Directory entry for DH.108
• "The D.H.108 – Final Photographs of the Aircraft on Which Geoffrey de Havilland Perished," Flight article covering de Havilland's fatal accident