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Folland Fo.141 Gnat
Developed from the Fo 139 Midge, the Fo 141 Gnat was designed as a light fighter. The shoulder wing is swept back at 40 degrees. All tail surfaces are swept with a one-piece tailplane low-set on the fuselage. Ailerons are on the inner wings and can be drooped to act as flaps. The wheel fairing doors act as air-brakes when the undercarriage is partially lowered in flight. The tricycle undercarriage has single main wheels and twin nose wheels, all retracting rearwards into the fuselage.
The private-venture prototype Gnat G-39-2, piloted by Folland's chief test pilot, Squadron Leader E. A. Tennant, first flew at the Airplane & Armament Experimental Establishment at Boscombe Down on 18 July 1955. The aircraft was powered by a newly developed 1490kg thrust Bristol Orpheus turbojet.
 Folland Gnat Prototype G-39-2 on take off run in 1955
The Gnat, being developed in parallel with the Midge, was an improved version of the original fighter design, differentiated by larger air intakes for the Bristol Orpheus engine (the Midge had an Armstrong Siddeley Viper engine), a slightly larger wing, and provision for a 30 mm ADEN cannon in each intake lip.
Although the Royal Air Force had lost interest in the Gnat as a fighter, the Finnish air force took delivery of 13 aircraft in 1958-59. The Finnish Air Force received the first of its 13 Gnats (11 fighters and 2 photo-reconnaissance planes) on 30 July 1958. It was soon found to be a problematic aircraft in service and required a lot of ground maintenance. In early 1957 a licence agreement was reached to allow Valmet to build the Gnat at Tampere in Finland, although in the end none was built.
On 31 July 1958, the Finnish Air Force Major Lauri Pekuri, a World War II fighter ace, broke the sound barrier for the first time in Finland at Lake Luonetjärvi with a Folland Gnat.
 Folland Gnat Finnish Air Force
Gnat F.1 proved initially problematic in the Finnish harsh conditions. Finland was the first operational user of Gnat F.1, and the plane had still many issues yet unresolved. All Gnats were grounded for half a year on 26 August 1958 after the destruction of GN-102 due to a technical design error on hydraulic system, and the aircraft soon became the subject of severe criticism. Three other aircraft were also destroyed in other accidents, with two pilots ejecting and one being killed. Once the initial problems were ironed out, the plane proved to be extremely manouevreable and have good performance in the air, but also to be very maintenance intensive. The availability of spare parts was always an issue, and its maintenance a challenge to the conscript mechanics. The Gnats were removed from active service in 1972 when the Häme Wing moved to Rovaniemi, and when the new Saab 35 Drakens were brought into use.
 Two Finnish Gnats on the ground
The Finnish Air Force serial codes for Folland Gnat were GN-100 to GN-113 and its usual nickname Nutikka (“Stubby”). Several Finnish Gnat F.1s still survive either as museum pieces or memorials. One airframe, GN-113, is in private ownership.
 Folland Gnat Mk.1 (GN-101) K-SIM 04
The Yugoslav government also bought two but the major export order was from India: 40 airframes in various stages of completion were supplied from the UK, and licence-production was undertaken by Hindustan Aeronautics Ltd at Bangalore, local production accounting for 175 aircraft. The Gnat entered Indian Air Force service in the spring of 1958, when the Gnat Handling Flight was first formed, and ultimately eight squadrons were equipped.
The Indian Air Force (IAF) operated the Folland Gnat jet fighter from 1958, with over 200 aircraft being license built by Hindustan Aeronautics Limited (HAL). The aircraft proved successful in combat in both the 1965 and the 1971 War with Pakistan, both in the low-level air superiority role and for short range ground attack missions, while being inexpensive to build and operate, came to be called the Gnat Mk 2.
In the words of Late Air Cmde Jasjit Singh, "The Gnat was a very unforgiving aircraft and had the poorest safety track record in the IAF, despite having only Average plus pilots posted to it." In his book, Indian Air Force: The Case for Indigenisation, Air Cmde Singh said, "It is not surprising the RAF never used it.”
The Gnat aircraft had a peculiar design with the ailerons also doubling as flaps, drooping 15 degrees from a normal aileron position with undercarriage in down position. The raising and lowering of the undercarriage made the ailerons (flaps) go up and down from their normal position. This involved excessive change in attitude and required proper handling by the pilot. All the pilots were briefed repeatedly on this aspect to control the excessive pitch-up after raising of the undercarriage after take-off. Not surprisingly, there were a few incidents because of this peculiar nature of the aircraft.
Although the RAF had not selected the Gnat for service in a front-line role, it did have a requirement for an unarmed, two-seat advanced trainer to replace the de Havilland Vampire T.Mk 11 and to follow the Hunting Jet Provost sections of the all-through jet training programme. Folland undertook a private-venture investigation of the changes necessary to install a second seat and to bring the landing speed down to less than 185km/h. The most significant of these changes was a new wing, increased in area by 3.72sq.m and with additional fuel capacity, which reduced the fuel storage requirement in the fuselage, making room for additional equipment. This became the Folland Fo 144 Gnat
Fo 141
Engine: Bristol Siddeley Orpheus 701, 4520 lb
Wing span: 22 ft 2 in
Wing area: 135.5 sq.ft
Length: 29 ft 9 in
Height: 8 ft 10 in
MTOW: 8885 lb
Fuel capacity: 300 gal
External fuel: 2 x 66 gal drop tanks
Wheel track: 4 ft 1 in
Wheelbase: 7 ft 9 in
Max speed: 695 mph / M0.98 at 20,000 ft
Max ROC: 20,000 fpm
Service ceiling: 50,000 ft +
Max endurance: 2 hr 30 min
Armament: 2 x 30mm Aden cannon
Bombload: 2 x 500 lb bomb or 12 air-ground rockets
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