De Havilland Swallow
Encyclopedia
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 rocket-powered point-defence interceptor. 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 the Air Ministry
specifications E.1/45 and E.11/45. 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.
mated to a longer fuselage with a single tail fin and swept wings, the de Havilland DH 108 was proposed in 1944 as a test "mule" for the DH 106 Comet which had initially considered a tailless, swept-wing concept. Despite the Comet design taking on more conventional features, the value of testing the unique configuration to provide basic data for the DH.110
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.
The new metal wing incorporating a 43˚ sweepback was approximately 15% greater in area than the standard Vampire wing. 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. Although the Vampire fuselage was retained, as development continued, a revised nose and streamlined, reinforced canopy were incorporated.
, serial number
TG283, utilising the Vampire fuselage and a 43° swept wing, flew on 15 May 1946. Designed to investigate low-speed handling, it was capable of only 280 mph (451 km/h). 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
. 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.
The second, high-speed prototype, TG306, with a 45° swept wing incorporating automatic leading-edge Handley Page slats and powered by a de Havilland Goblin 3 turbojet, flew soon after in June 1946. Modifications to the design included a more streamlined, longer nose and a smaller canopy (framed by a strengthened metal fairing) facilitated by lowering the pilot's seat. While being used to evaluate handling characteristics at high-speed, on 27 September 1946 TG306 suffered a catastrophic structural failure
that occurred in a dive from 10,000 ft (3,050 m) 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 behaviours, but pitch oscillation at high-speed had been unexpected. The subsequent accident investigation centred on a structural failure that 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 with the wings immediately folding backwards.
After the loss of the second prototype, VW120 became the third and final prototype based on the newer Vampire F.5 fighter built at Hatfield. It differed from the first test aircraft in that it featured an even more streamlined pointed nose and smaller reinforced canopy (lowering the pilot's seat allowed for a more aerodynamic canopy shape to be employed). 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 3,738 lbf (16.67 kN) 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.
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 616 mph (991 km/h). The second prototype, TG306, was a "back up" for the attempt before it fatally crashed. On 12 April 1948, VW120 established a new World Air Speed Record of 604.98 mph (974.02 km/h) on a 62 mile (100 km) circuit. Then, on 9 September 1948, John Derry
is thought to have probably exceeded the speed of sound
in a shallow dive from 40,000 ft (12,195 m) to 30,000 ft (9,145 m).
In 1949, VW120 put on an aerial display at Farnborough and scored third place 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. It was destroyed on 15 February 1950 in a fatal crash near Brickhill, Buckinghamshire, killing its test pilot, Squadron Leader
Stuart Muller-Rowland. Accident investigation pointed to a faulty oxygen system that incapacitated the pilot.
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, when, 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.
aircraft in the world to achieve this landmark speed.
De Havilland
The de Havilland Aircraft Company was a British aviation manufacturer founded in 1920 when Airco, of which Geoffrey de Havilland had been chief designer, was sold to BSA by the owner George Holt Thomas. De Havilland then set up a company under his name in September of that year at Stag Lane...
DH 108 "Swallow" was a British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
experimental aircraft
Experimental aircraft
An experimental aircraft is an aircraft that has not yet been fully proven in flight. Often, this implies that new aerospace technologies are being tested on the aircraft, though the label is more broad....
designed by John Carver Meadows Frost
John Carver Meadows Frost
John Carver Meadows Frost known as "Jack" 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...
in October 1945. The DH 108 featured a tailless
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...
with a single vertical stabilizer
Vertical stabilizer
The vertical stabilizers, vertical stabilisers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip. It is analogical to a skeg on boats and ships.On aircraft, vertical stabilizers generally point upwards...
, similar to the layout of the wartime German Messerschmitt Me 163
Messerschmitt Me 163
The Messerschmitt Me 163 Komet, designed by Alexander Lippisch, was a German rocket-powered fighter aircraft. It is the only rocket-powered fighter aircraft ever to have been operational. Its design was revolutionary, and the Me 163 was capable of performance unrivaled at the time. Messerschmitt...
Komet rocket-powered point-defence interceptor. Initially designed to evaluate swept wing handling characteristics at low and high subsonic speeds for the proposed early tailless design of the Comet
De Havilland Comet
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design...
airliner, three examples of the DH 108 were built to the Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
specifications E.1/45 and E.11/45. With the adoption of a conventional tail for the Comet, the aircraft were used instead to investigate swept wing handling up to supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
speeds. All three prototypes were lost in fatal crashes.
Design and development
Employing the main fuselage section and engine of the de Havilland VampireDe Havilland Vampire
The de Havilland DH.100 Vampire was a British jet-engine fighter commissioned by the Royal Air Force during the Second World War. Following the Gloster Meteor, it was the second jet fighter to enter service with the RAF. Although it arrived too late to see combat during the war, the Vampire served...
mated to a longer fuselage with a single tail fin and swept wings, the de Havilland DH 108 was proposed in 1944 as a test "mule" for the DH 106 Comet which had initially considered a tailless, swept-wing concept. Despite the Comet design taking on more conventional features, the value of testing the unique configuration to provide basic data for the DH.110
De Havilland Sea Vixen
The de Havilland DH.110 Sea Vixen was a twin boom 1950s–1960s British two-seat jet fighter of the Fleet Air Arm designed by de Havilland. Developed from an earlier first generation jet fighter, the Sea Vixen was a capable carrier-based fleet defence fighter that served into the 1970s...
spurred de Havilland to continue development of the DH 108. Selecting two airframes from the English Electric
English Electric
English Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...
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
Ministry of Supply
The Ministry of Supply was a department of the UK Government formed in 1939 to co-ordinate the supply of equipment to all three British armed forces, headed by the Minister of Supply. There was, however, a separate ministry responsible for aircraft production and the Admiralty retained...
named the DH 108 the "Swallow", a name that was never officially adopted by the company.
The new metal wing incorporating a 43˚ sweepback was approximately 15% greater in area than the standard Vampire wing. 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. Although the Vampire fuselage was retained, as development continued, a revised nose and streamlined, reinforced canopy were incorporated.
Testing
The first DH 108 prototypePrototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
, serial number
United Kingdom military aircraft serials
In the United Kingdom to identify individual aircraft, all military aircraft are allocated and display a unique serial number. A unified serial number system, maintained by the Air Ministry , and its successor the Ministry of Defence , is used for aircraft operated by the Royal Air Force , Fleet...
TG283, utilising the Vampire fuselage and a 43° swept wing, flew on 15 May 1946. Designed to investigate low-speed handling, it was capable of only 280 mph (451 km/h). De Havilland Chief Test Pilot Geoffrey de Havilland Jr., son of de Havilland company owner-designer Geoffrey de Havilland
Geoffrey de Havilland
Captain Sir Geoffrey de Havilland, OM, CBE, AFC, RDI, FRAeS, was a British aviation pioneer and aircraft engineer...
, gave a display flight in the DH 108 during the 1946 Society of British Aircraft Constructors
Society of British Aircraft Constructors
The Society of British Aerospace Companies, known as SBAC was the UK's national trade association representing companies supplying civil air transport, aerospace defence, homeland security and space...
(SBAC) airshow at Radlett
Radlett
Radlett is a small town in the county of Hertfordshire between St Albans and Borehamwood on Watling Street with a population of approximately 8,000. It is located in the council district of Hertsmere and is covered by two wards, Aldenham East and Aldenham West...
. 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.
The second, high-speed prototype, TG306, with a 45° swept wing incorporating automatic leading-edge Handley Page slats and powered by a de Havilland Goblin 3 turbojet, flew soon after in June 1946. Modifications to the design included a more streamlined, longer nose and a smaller canopy (framed by a strengthened metal fairing) facilitated by lowering the pilot's seat. While being used to evaluate handling characteristics at high-speed, on 27 September 1946 TG306 suffered a catastrophic structural failure
Structural failure
Structural failure refers to loss of the load-carrying capacity of a component or member within a structure or of the structure itself. Structural failure is initiated when the material is stressed to its strength limit, thus causing fracture or excessive deformations...
that occurred in a dive from 10,000 ft (3,050 m) at Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
0.9 and crashed in the Thames Estuary
Thames Estuary
The Thames Mouth is the estuary in which the River Thames meets the waters of the North Sea.It is not easy to define the limits of the estuary, although physically the head of Sea Reach, near Canvey Island on the Essex shore is probably the western boundary...
. The pilot, Geoffrey de Havilland Jr., was killed in the accident. Early wind tunnel testing had pointed to potentially dangerous flight behaviours, but pitch oscillation at high-speed had been unexpected. The subsequent accident investigation centred on a structural failure that 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
Spar
In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a pole of wood, metal or lightweight materials such as carbon fiber used on a sailing vessel. Spars of all types In sailing, a spar is a...
cracked at the roots with the wings immediately folding backwards.
John Cunningham (RAF officer)
Group Captain John "Cat's Eyes" Cunningham CBE, DSO & Two Bars, DFC & Bar, , was a British Royal Air Force night fighter ace during World War II and a test pilot, both before and after the war...
, the wartime nightfighter ace.
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
Gloster Meteor
The Gloster Meteor was the first British jet fighter and the Allies' first operational jet. It first flew in 1943 and commenced operations on 27 July 1944 with 616 Squadron of the Royal Air Force...
at 616 mph (991 km/h). The second prototype, TG306, was a "back up" for the attempt before it fatally crashed. On 12 April 1948, VW120 established a new World Air Speed Record of 604.98 mph (974.02 km/h) on a 62 mile (100 km) circuit. Then, on 9 September 1948, John Derry
John Derry
John Douglas Derry DFC was a British test pilot, and was the first Briton to exceed the speed of sound...
is thought to have probably exceeded the speed of sound
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
in a shallow dive from 40,000 ft (12,195 m) to 30,000 ft (9,145 m).
In 1949, VW120 put on an aerial display at Farnborough and scored third place in the Society of British Aircraft Constructors
Society of British Aircraft Constructors
The Society of British Aerospace Companies, known as SBAC was the UK's national trade association representing companies supplying civil air transport, aerospace defence, homeland security and space...
Challenge Trophy Air Race before being turned over to the Ministry of Supply
Ministry of Supply
The Ministry of Supply was a department of the UK Government formed in 1939 to co-ordinate the supply of equipment to all three British armed forces, headed by the Minister of Supply. There was, however, a separate ministry responsible for aircraft production and the Admiralty retained...
and test flown at RAE Farnborough. It was destroyed on 15 February 1950 in a fatal crash near Brickhill, Buckinghamshire, killing its test pilot, Squadron Leader
Squadron Leader
Squadron Leader is a commissioned rank in the Royal Air Force and the air forces of many countries which have historical British influence. It is also sometimes used as the English translation of an equivalent rank in countries which have a non-English air force-specific rank structure. In these...
Stuart Muller-Rowland. Accident investigation pointed to a faulty oxygen system that incapacitated the pilot.
Finally, on 1 May 1950 during low-speed sideslip and stall tests the first prototype, TG283, was lost in a crash at Hartley Wintney
Hartley Wintney
Hartley Wintney is a large village and civil parish in the English county of Hampshire.-Location and character:Hartley Wintney is in the Hart district of North-East Hampshire...
killing the pilot Sqn Ldr George E.C. Genders AFC DFM, when, 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.
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; it was the first British aircraft to exceed Mach 1, one of the first jet-poweredJet aircraft
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...
aircraft in the world to achieve this landmark speed.