The Gloster Guan was a single-engined single-seat experimental biplane fighter built in the United Kingdom

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...

 to test the performance of fighters using supercharged engines at high altitudes. Three were planned but only two constructed.

Development

The power output of piston engines falls with altitude because of the falling oxygen density. As a result performance falls away and the operational ceiling is limited. Gloster had, with the Gorcock produced an aircraft much faster than its contemporaries and the Guan was designed to use supercharging to maintain this performance at height and raise the service ceiling above its competition.

Three Guans were ordered by 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...

 in 1925. As in the Gorcock, power came from variants of the Napier Lion

Napier Lion

The Napier Lion was a 12-cylinder broad arrow configuration aircraft engine built by Napier & Son starting in 1917, and ending in the 1930s. A number of advanced features made it the most powerful engine of its day, and kept it in production long after contemporary designs had stopped production...

 broad arrow

Broad arrow

A broad arrow or pheon is a type of arrow with a typically flat barbed head. It is a symbol used traditionally in heraldry, most notably in England, and later the United Kingdom to mark government property.-Use in heraldry:...

 12-cylinder engine. The first Guan had the 450 hp (335 kW) geared Lion IV; the second the ungeared 525 hp (475 kW) Lion VI. A projected third aircraft would have had an inverted Lion, known as the Lioness, but this machine was not built. These engines had their exhaust-driven supercharger (a concept nowadays known as turbocharger

Turbocharger

A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...

) mounted on the nose under the propeller, with much exposed pipework. The radiator was mounted under the fuselage and between the undercarriage legs. Initially these engines drove two-blade fixed-pitch airscrews, but the first aircraft was later fitted with a metal variable-pitch constant-speed propeller.

The Guan was a single-bay biplane with wooden, fabric-covered wings of unequal span and marked stagger. All Folland

Henry Folland

Henry Philip Folland was an English aviation engineer and aircraft designer.-Life:Folland was born to Frederick and Mary Folland at 2 King Street, Holy Trinity, Cambridge. His father was listed as a Stonemason....

's Gloster fighters from the Grebe

Gloster Grebe

-See also:-References:NotesBibliography* James, Derek N. Gloster Aircraft since 1917. London: Putnam and Company Ltd., 1987. ISBN 0-85177-807-0.* Thetford, Owen. Aircraft of the Royal Air Force 1918-57. London:Putnam, First edition 1957....

 onwards had used a thick upper wing in combination with a fairly thin lower wing and the Guan followed this pattern, chosen to provide low drag at high speed with good lift at low, take-off speeds. It had parallel interplane struts and ailerons on all wings.

The fuselage was all-metal and fabric covered. The rear fuselage was closer in design to that of the Gamecock

Gloster Gamecock

|-See also:-Bibliography:* Green, William and Swanborough, Gordon. "The Era-Ending Gamecock". Air Enthusiast, Number 21, April-July 1983.Bromley, Kent:Pilot Press. p. 1-8, 58-62. ISSN 0143-5450....

 than the Grebe or Gorcock, and the empennage was almost identical to that of the Gamecock.

The first aircraft went to RAE Farnborough in August 1926 and the second followed early in the next year. Supercharging delivered the anticipated performance enhancements, with full power and a top speed of 175 mph (280 km/h) at 15,000 ft (4,570 m). Service ceiling was 31,000 ft (9,450 m) compared with 24,000 ft (7,315 m) for the similarly-powered but slightly smaller-span Gorcock. The fast-spinning turbo-superchargers gave continual trouble. This led to the cancellation of the third Guan and the whole development programme.

The name

Gloster's search for alliterative bird names took them far and wide. Guan

Guan (bird)

The guans are a number of bird genera which make up the largest group in the family Cracidae. They are found mainly in northern South America, southern Central America, and a few adjacent Caribbean islands...

 is the local name for one of several genera of game-birds of the family Cracidae, which live in tropical America.

Specifications (second Guan)