The Folland Gnat was a small, swept-wing British subsonic jet trainer and light fighter aircraft developed by Folland Aircraft for the Royal Air Force, and flown extensively by the Indian Air Force.
The Gnat was designed by W.E.W. Petter as a development of the private venture Folland Midge and first flew in 1955. Its design allowed its construction without specialised tools by countries not highly industrialised. Although never used as a fighter by the Royal Air Force (RAF), the Gnat T.1 trainer variant was widely used. The Gnat became well known as the aircraft of the RAF's Red Arrows aerobatic team.
The Gnat was exported to Finland, Yugoslavia and India. The Indian Air Force became the largest operator and eventually manufactured the aircraft under licence. India then developed the HAL Ajeet, a modified and improved variant.
Design and development
The Gnat was the creation of W.E.W. "Teddy" Petter, a British aircraft designer formerly of Westland Aircraft and English Electric. Designed to meet the 1952 Operational Requirement OR.303 calling for a lightweight fighter, Petter believed that a small, simple fighter would offer the advantages of low purchase and operational costs. New lightweight turbojet engines that were being developed enabled the concept to take shape. Petter's first design resulted in the private venture Folland Midge which had a short lifespan, but served as a proof-of-concept design. It failed to interest the RAF as a combat aircraft, but they encouraged the development of a similar aircraft for training purposes.
Gnat F.1 single seat fighter variant at the 1957 Paris Air Salon
The Midge first flew on 11 August 1954 but was destroyed in a crash on 20 September 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 a Armstrong Siddeley Viper engine), a slightly larger wing, and provision for a 30 mm ADEN cannon in each intake lip.
The first prototype Gnat was built as a private venture project by Folland but subsequently six further aircraft were ordered by the British Ministry of Supply for evaluation. The Folland prototype, serial number G-39-2, first flew on 18 July 1955 from Boscombe Down.
Although the evaluation by the British did not end up in an order for the lightweight fighter orders were placed by Finland, Yugoslavia and a large order from India which included licence production by Hindustan Aeronautics Limited. Although the Gnat's development was attributed as motivating the Mutual Weapons Development Team to issue a NATO requirement for a low level light fighter, the Gnat was not evaluated in the competition, won by the Fiat G.91. The Gnat was evaluated in 1958 by the Royal Air Force as a de Havilland Venom replacement, as well as other light fighters such as the BAC Jet Provost, the Hawker Hunter was the eventual winner of the fly-off competition.
Gnat T.1 on display in 2009
Although RAF interest waned in its possible use as a fighter, the Gnat was modified to meet the 1957 Trainer Specification T.185D that called for an advanced two-seat trainer that could transition pilots between the current DH Vampire T 11 and operational fighters such as the English Electric Lightning. Folland proposed the two-seat Fo. 144 Gnat Trainer, it had a new wing with additional fuel capacity, this allowed more room in the fuselage for additional equipment. A more powerful variant of the Orpheus engine was used, the front fuselage length was increased and had larger tail surfaces. The inboard ailerons of the fighter variant were changed to outbound ailerons and conventional flaps.
An initial contract for 14 pre-production Gnat trainers was issued in 7 January 1958. The prototype Gnat Trainer first flew on 31 August 1959 from Chilbolton airfield, The Ministry did not at first place a production order as they were concerned about the size and ability of the company to take on a large order. Following the take over of Folland by Hawker Siddeley Aviation (becoming the Hamble division) further orders for 30, 20 and 41 trainers were placed between February 1960 and March 1962 with the designation Gnat T Mk 1.