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de Havilland DH.108 (Swallow)

United Kingdom (1946)
Picture of de Havilland DH.108 (Swallow) Jet-Powered, Swept-Wing Research Aircraft

All three completed and flown DH.108 Swallow test aircraft claimed the lives of three pilots - such was its stained career in the air.


Detailing the development and operational history of the de Havilland DH.108 (Swallow) Jet-Powered, Swept-Wing Research Aircraft.  Entry last updated on 6/5/2018. Authored by Staff Writer. Content ©www.MilitaryFactory.com

The elegant - though highly lethal - de Havilland DH.108 "Swallow" was one of the more important research aircraft for British aviation during the 1940s and early 1950s. Not designed nor developed to any specific military fighter requirement, the aircraft actually existed researching supersonic flight and sweptback wings in regards to the de Havilland DH.106 "Comet" jet passenger airliner program. The Comet became the world's first jet airliner but its own issues limited its overall reach - allowing competitors to claim a large portion of the market share. The research-oriented DH.108 was, itself, a dangerous plane to fly for it claimed the lives of three test pilots in separate aircraft losses, forever staining the Swallow program. Despite the unfortunate setbacks, the DH.108 proved critical in advancing British understanding of swept-back wings, jet-powered flight, and supersonic speeds and control.

The Comet airliner was a program being championed by British authorities in the latter years of World War 2 in an effort provide local aero industry with commitments well after the fighting had ceased. The Comet would be a passenger-minded, turbojet-powered design utilizing a tailless configuration and an advanced sweptback monoplane wing assembly. The charge fell to the storied concern of de Havilland which used its DH.108 platform as the starting point for the finalized research aircraft. The dimensionally smaller, single-seat airframe would mimic many of the qualities to be found in the full-sized Comet and serve to test the various control conditions at supersonic speeds. The Air Ministry requested a pair of prototypes while the name of "Swallow" was only attached to the aircraft by the Ministry of Supply and never official adopted.

The de Havilland DH.108 research aircraft was formed from the body of the existing de Havilland DH.100 "Vampire" (F.Mk 1model), a jet-powered, single-seat fighter-bomber seeing service entry in 1946. The aircraft featured a centralized nacelle housing cockpit and powerplant with a monoplane wing arrangement held to either side of the fuselage. A twin-boom configuration was used to make up the tail section and this produced a twin vertical tail fin arrangement which attached via a single horizontal tailplane assembly between them. When adopted into service, the Vampire became Britain's second jet-powered fighter following the classic Gloster "Meteor".

The choice to modify an existing aircraft expedited the development process. The Vampire F.Mk 1 saw its twin tailbooms deleted which also meant that the vertical tail fins and stabilizer were lost. The cockpit nacelle and engine installation remained as in the original though the nacelle was lengthened some to accommodate a new single vertical tail fin mounted over the jetpipe. The wings were the true addition, specially-designed assemblies which featured 43-degree sweepback and installed in place of the original straight wings of the Vampire. The first aircraft in the Swallow line was known as "TG283" and recorded its first flight on May 15th, 1946 with Geoffrey de Havilland, Jr. - son of the famous company founder - at the controls. Power was from a de Havilland Goblin 2 engine of 3,100lb thrust.

Additional testing revealed a slew of issues under specific conditions, proving the aircraft a handful for even the most veteran of pilots. To help offset difficulties in ground running and landing, the undercarriage of the "Sea Vampire" - the navalized variant of the land-based Vampire - was installed. Its career in the air war short-lived for it was during a stall trial on May 1st, 1950 that the aircraft entered into a spin and was lost, killing the test pilot. During its time aloft, TG283 managed a maximum speed of approximately 350 miles per hour.
TG306 became the second aircraft of the triad and this version introduced retractable slats over the fixed, wooden Handley-Page slats featured on TG283. Power was served through a de Havilland Goblin 4 turbojet of 3,500lbs thrust. Its first flight came during June of 1946 and improved performance led to the aircraft attempting to break the World Air Speed record (held by the competing Gloster Meteor at 616mph). TG283 was met with a few adjustments for the attempt but a trial flight prior ended with the aircraft losing control once more, breaking up in mid-flight, and killing pilot Geoffrey de Havilland, Jr. on September, 27th, 1946. During its time in the air, TG283 recorded a maximum speed of 580 miles per hour - though this achieved in a dive.

The DH.108 program then introduced the final flying machine as VW120 - largely influenced by the TG306 model and its issues. First flight was on July 24th, 1947 and the design now boasted an ejection seat for the pilot and a revised cockpit and forward fuselage. Additional strengthening was added to the structure to help avoid the pitfalls of the previous mark in the series. Power-assisted wing surfaces and controls attempted to take some of the fatigue from the pilot. Power was now from a de Havilland Goblin 5 turbojet engine of 3,600lbs thrust. The aircraft went on to become the first British-designed aircraft to break the sound barrier, this accomplished during a steep dive on September 6th, 1948 and resulting in the official speed of Mach 1.02 being recorded. During the dive, the pilot lost control of the aircraft but was able to reclaim her.

It was during another flight on February 15th, 1950 that VW120 was lost when it disintegrated in-flight. Despite access to an ejection seat, the pilot was lost with the aircraft and such ended the tumultuous DH.108 research program. The aircraft proved just as lethal as it was beautiful by 1940s standards, showcasing clean lines and a certain simplicity about her. While the Dh.106 Comet airliner was eventually brought online, it too suffered a stained record with the in-flight disintegrations of three aircraft. The losses and publicity no doubt damaged sales and companies like Boeing were all to ready to take up the market share. Despite this, the Comet - introduced in 1952 - managed a long service life if only through the 114 total examples completed. These served with a handful of carriers with the final Comet retired in March of 1997. The Comet also made up the basis of the RAF's Hawker Siddeley "Nimrod" maritime patrol platform - which itself was not retired until 2011.

The finalized Comet form was completed with a conventional tail unit fitting a sole vertical tail fin and low-set horizontal planes. It did, however, sport sweptback wing surfaces all the main and tailplane units and its engine intakes were similarly placed as on the Swallow design, well-contoured at the wingroots to appear as part of the wing assembly itself.




General Assessment (BETA)
Firepower  
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Performance  
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Survivability  
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Versatility  
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Impact  
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Rating: 48 (of 100)
The rating is an internal assessment derived from forty factors pertaining to this entry.
Relative Maximum Speed Rating
Hi: 750mph
Lo: 375mph
    This entry's maximum listed speed (677mph).

    Graph average of 562.5 miles-per-hour.
City-to-City Ranges
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Graph showcases the de Havilland VW120's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
Pie graph section
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Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
3
3


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
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National Flag Graphic
Origin: United Kingdom
Year: 1946
Type: Jet-Powered, Swept-Wing Research Aircraft
Manufacturer(s): de Havilland - UK
Production: 3
Status: Retired, Out-of-Service
Global Operators:
United Kingdom (retired)
Historical Commitments / Honors:

Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
Measurements and Weights icon
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the de Havilland VW120 model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
1


Dimension
LENGTH


Feet
31.17 ft


Meters
9.5 m


Dimension
WIDTH


Feet
39.01 ft


Meters
11.89 m


Weight
EMPTY


Pounds
8,940 lb


Kilograms
4,055 kg


Weight
LOADED


Pounds
15,818 lb


Kilograms
7,175 kg

Engine icon
Installed Power - Standard Day Performance:
1 x de Havilland Goblin 5 turbojet engine developing 3,600lb of thrust.

Performance
SPEED


Miles-per-Hour
677 mph


Kilometers-per-Hour
1,090 kph


Knots
589 kts


Performance
RANGE


Miles
730 mi


Kilometers
1,175 km


Nautical Miles
634 nm


Performance
CEILING


Feet
35,433 ft


Meters
10,800 m


Miles
6.71 mi

Armament - Hardpoints (0):

None.
Variants: Series Model Variants
• DH.108 - de Havilland model designation
• "Swallow" - Unofficial nickname
• TG283 - First aircraft; wooden, full-span Handley-Page slats along leading wing edge.
• TG306 - Second aircraft; retractable slats
• VW120 - Third aircraft; ejection seat fitted; various improvements from TG306.