| Gnat | |
|---|---|
.jpg) A Folland Gnat overRIAT, 2018 | |
| General information | |
| Type | Fighter, light tactical bomber andtrainer |
| Manufacturer | Folland Aircraft |
| Designer | |
| Status | Retired |
| Primary users | Royal Air Force |
| Number built | 449 (including HAL Ajeet) |
| History | |
| Introduction date | 1959 (RAF) |
| First flight | 18 July 1955 |
| Retired | 1979 (RAF) |
| Developed from | Folland Midge |
| Variant | HAL Ajeet |
TheFolland Gnat is a British compactswept-wingsubsonicfighter aircraft that was developed and produced byFolland Aircraft. Envisioned as an affordable light fighter in contrast to the rising cost and size of typical combat aircraft, it was procured as atrainer aircraft for theRoyal Air Force (RAF) as well as by export customers, who used the Gnat in both combat and training capacities.
Designed byW. E. W. Petter, the Gnat has its origins in the preceding private ventureFolland Midge. The issuing ofOperational RequirementOR.303 by the BritishAir Ministry served to motivate the type's development; the Gnat was later submitted to meet this requirement. Its design allowed for its construction and maintenance tasks to be carried out without specialised tools, making it suitable for use in countries that had not yet become highlyindustrialised.[1][2] The Gnat has been viewed as a major motivating factor towards the issuing of theNATONBMR-1 requirement, which sought to make available a common strike/attacklight fighter with which to equip the air forces of the various NATO members.
Although never used as a fighter by the Royal Air Force (RAF), theGnat T.1 jet trainer variant was adopted and operated for some time. In the United Kingdom, the Gnat became well known due to its prominent use as the display aircraft of the RAF'sRed Arrows aerobatic team. TheGnat F.1 was exported to Finland, Yugoslavia and India. TheIndian Air Force became the largest operator and eventually manufactured the aircraftunder licence. Impressed by its performance during combat, India proceeded to develop the improvedHAL Ajeet, a modified variant of the Gnat. In British service, the Gnat was replaced by theHawker Siddeley Hawk.
In October 1950,W. E. W. "Teddy" Petter, a British aircraft designer formerly ofWestland Aircraft andEnglish Electric, joinedFolland Aircraft as its managing director and chief engineer.[3][4] Almost immediately upon joining the firm, Petter conducted a study into the economics behind modern fighter manufacturing, and concluded that many combat aircraft entailed far too great a cost in terms ofman-hours and material to be readilymass-produced during a major conflict.[4] While the BritishAir Staff emphasised quality over quantity, the economics involved in the anticipated vast wartime production of many of the RAF's aircraft of the time, such as theHawker Hunter and theGloster Javelininterceptors, were viewed as questionable.[4]
Petter examined the prospects for producing a more affordable but capable "light fighter", including a survey of available modern engines to power the type.[4] Having identified suitable powerplant arrangements along with methods of making multiple key design aspects, such as the manufacturing of the fuselage and wings, more affordable, Folland promptly commenced work upon this lightweight fighter concept, financing the project using existing company funds.[4] The light fighter project soon received the Fo-141 designation along with the name Gnat.[3] Development of the Gnat and the specifics of its design were heavily influenced by the issuing ofOperational RequirementOR.303, which sought a capable lightweight fighter aircraft. Work to develop the Gnat went ahead, irrespective of any external orders or financing; there was no funding provided to support the type's early development from any British government department, such as theMinistry of Supply.[3][5]
Petter believed that a compact and simplified fighter would offer the advantages of low purchase and operational costs, and that the Gnat should be capable of being manufactured both cheaply and easily.[3] The emergence of new lightweightturbojet engines, several of which were well advanced in their own development process, also enabled the envisioned light fighter concept to be realised.[1] The Gnat was initially intended to be powered by aBristol BE-22 Saturn turbojet engine, capable of generating 3,800 lbf (16.9 kN 1,724 kgp) of thrust. However, development of the Saturn was cancelled; in its place, the more capable but not immediately availableBristol Orpheus turbojet engine was adopted instead.[3]
In order that the project would not be delayed before reaching the prototype stage, Petter's unarmed proof-of-concept demonstrator for the Gnat was instead powered by the less powerfulArmstrong Siddeley Viper 101turbojet engine, capable of generating 1,640 lbf (7.3 kN / 744 kgp) of thrust.[3] While using a different powerplant from later-built prototypes and production aircraft, the demonstrator still used a nearly identical airframe along with similar onboard systems so that these could be proved in advance of the Gnat itself being built.[3] This demonstrator was designatedFo-139 Midge. On 11 August 1954, the Midge performed itsmaiden flight, piloted by Folland's chief test pilotEdward Tennant.[6] Despite the low-powered engine, the compact jet was able to break Mach 1 while in a dive and proved to be very agile during its flying trials. On 26 September 1955, the Midge was destroyed in a crash, which had possibly been due to human error by a pilot from a potential overseas purchaser.[7]
The Midge, partly due to its nature as a private venture, had only a short lifespan, however had served as a proof-of-concept demonstrator for the subsequent aircraft. It had failed to interest the RAF as a combat aircraft at that time, but officers did issue encouragement of the development of a similar aircraft for training purposes.[8] The larger Gnat, which was being developed in parallel with the Midge, was an improved version of the original fighter design; it was differentiated by larger air intakes to suit the Orpheus engine, a slightly larger wing, and provision for the installation of a 30 mmADEN cannon in each intake lip.[8][9] The first prototype Gnat was built as a private venture by Folland. Subsequently, six further aircraft were ordered by the BritishMinistry of Supply for evaluation purposes.[8] On 18 July 1955, the Folland prototype,serial numberG-39-2, first flew fromRAF Boscombe Down,Wiltshire.[a][10]
Although the evaluation by the British brought no orders for the lightweight fighter, orders were placed by Finland and Yugoslavia. India placed a large order for the type, which included alicence for production byHindustan Aeronautics Limited (HAL).[11] Although the Gnat's development is considered a factor which motivated theMutual Weapons Development Team to issue theNATONBMR-1 requirement for a low level strike/attacklight fighter, the Gnat itself was not evaluated in the competition, which was won by theFiat G.91.[12] However, the Gnat was evaluated in 1958 by the RAF as a replacement for thede Havilland Venom, as well as other light aircraft such as theBAC Jet Provost.[13] TheHawker Hunter was selected as the eventual winner of the fly-off competition.
Although RAF interest in the possibilities for using the Gnat as a fighter had waned, Folland identified a potential use for the type as a trainer aircraft. Accordingly, the aircraft was modified to conform with the requirements of Specification T.185D, which had called for an advanced two-seat trainer aircraft that could transition pilots between the currentde Havilland Vampire T 11 and operational fighters, such as thesupersonicEnglish Electric Lightning.[8]
Folland proposed the two-seat Fo. 144 Gnat Trainer. The trainer model featured several changes, including the adoption of a new wing with additional fuel capacity, which in turn allowed for more internal space within the fuselage to be allocated for additional equipment. A more powerful variant of the Orpheus engine was also used, while the length of the forward fuselage area was increased, and the tail surfaces were enlarged. The inboard ailerons of the fighter variant were reconfigured to an arrangement of outboard ailerons and conventional flaps. On 7 January 1958, an initial contract for 14 pre-production Gnat trainers was issued.[14]
On 31 August 1959, the prototype Gnat Trainer conducted its maiden flight fromChilbolton airfield,Hampshire.[15] 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 byHawker Siddeley Aviation (becoming the Hamble division), further orders for 30, 20 and 41 trainers were placed between February 1960 and March 1962, receiving thedesignationGnat T Mk. 1.[16] The final Gnat T.1 for the RAF was delivered in May 1965.
Folland sought to develop more capable versions of the Gnat; one of the more substantial of these proposals was tentatively designated as the Gnat Mk.5.[17] This model was to be capable of supersonic speeds and was intended to be made available in both single-seat and twin-seat configurations, enabling its use in the trainer andinterceptor role. The Gnat 5 was to be powered by either a pair ofRolls-Royce RB153R engines or two Viper 20 engines; in the interceptor role, it would be also equipped with aFerrantiAI.23 Airpassradar and armed with a pair ofde Havilland Firestreakair-to-air missiles.[17] Featuring an estimated maximum speed aroundMach 2 (2,500 km/h; 1,500 mph) and a time to 50,000 ft (15,000 m) of 3 minutes, Folland estimated that a prototype could be flown as early as the end of 1962 and that the Gnat 5 could be readied for operational service within four or five years.[17]
In 1960,Maurice Brennan joined Folland as its chief engineer and director. Hawker Siddeley wanted to use his knowledge ofvariable-geometry wings in future designs.[11] Under his direction, a variable geometry wing was applied to the basic Gnat 5 design to produce two different configurations – onetailless and one with a conventional tail – for a multipurpose fighter/strike/trainer, designated the Fo.147. The design used a unique mechanism to sweep the wings; this mechanism used a combination of tracks positioned on the fuselage sides, the centerline, and on the underside of the wings, and was actuated byhydraulically-drivenball screws positioned at the inner ends of the wings.[17] The wings could be swept from 20 degrees to 70 degrees; at the 70-degree position,longitudinal control was maintained by wing tip-mountedelevons, and at the 20-degree position by a retractablecanard arrangement. Auto-stabilisation was also to be used. By providingtrimming with the canard, a large tailplane was not needed, as would have been on designs without a canard configuration.[18]
The Fo.147 was to have been capable of speeds in excess of Mach 2, with the speed limit set by the temperature of the structure as a result of kinetic heating.[19] It had a maximum all-up weight of 18,500 lb (8,400 kg), comparing well with the Gnat 5's more restrictive 11,100 lb (5,000 kg) maximum. According to aviation author Derek Wood, the Fo.147: "would have provided a first-class flying test-bed for variable geometry theories...even a VG conversion of the standard Gnat Mk 2 fighter would have been an invaluable research tool".[19] However, neither the Fo.147 nor its successor, the Fo.148, would be developed to the prototype stage; the RAF showed little interest in the need for a variable-geometry trainer, although it intended to procure theGeneral Dynamics F-111K strike aircraft.[19]
The Folland Gnat was a purpose-built light fighter aircraft, suitable as both atrainer and a combat aircraft inground-attack andday-fighter roles.[20] The cockpit offered many features expected in standard fighter aircraft: fullpressurisation,climate control, and anejection seat.[4]
_Karhulan_ilmailukerhon_lentomuseo_16.JPG)
According to Folland, the Gnat offered advantages over conventional fighter aircraft in terms of cost, man-hours, handling, serviceability, and portability.[21] Itstricycle landing gear let it operate from austere grass airstrips, thanks to the aircraft's low weight.[4]
The Gnat design used a conventional metal stressed-skin structure, with extensive flush-rivetting.[4] To reduce workload and cost, intensive fabrication methods such asmachining,forging, andcasting were minimised. The airframe could be constructed using simplejigs without any specialised skills or tooling.[4] The wing (for example) could be produced at a quarter of the cost, with less than one-fifth the labour, required for the wings of other contemporary fighter aircraft.[4] Similarly, the layout and construction techniques used allow the airframe to be rapidly disassembled into its major subsections, without the use ofcranes or ladders; the Gnat was vastly easier to service than most other aircraft.[5]
_Keski-Suomen_ilmailumuseo_6.JPG)
TheFinnish 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 alicence agreement was reached to allowValmet to build the Gnat at Tampere in Finland,[22] although, in the end, none were built. On 31 July 1958, Finnish Air Force MajorLauri Pekuri, afighter ace of theSecond World War, became the first Finnish pilot to break thesound barrier while flying a Gnat atLake Luonetjärvi.[23]
Gnat F.1 proved initially problematic in the harsh Finnish conditions. Finland was the first operational user of Gnat F.1, and the plane still had many issues yet to be resolved. All Gnats were grounded for half a year on 26 August 1958 after the destruction of GN-102 due to a technical design error in its hydraulic system, and the aircraft soon became the subject of severe criticism. Three other aircraft were also destroyed in other accidents, with two pilotsejecting and one being killed. Once the initial problems were ironed out, the plane proved to be extremely manoeuvrable and had 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 theHäme Wing moved toRovaniemi, and when the newSaab 35 Drakens were brought into use.[8]
In September 1956 the Indian government signed a contract for the production of the aircraft and Orpheus engine in India.[24] The first 13 aircraft for theIndian Air Force (IAF) were assembled atHamble-le-Rice, they were followed by partly completed aircraft and then sub-assemblies as Hindustan Aircraft slowly took over first assembly, and then production of the aircraft. The first flight of an Indian Air Force Gnat was in the United Kingdom on 11 January 1958; it was delivered to India in the hold of aC-119, and accepted by the Air Force on 30 January 1958. The first Gnat squadron was theNo. 23 (Cheetah), which converted fromVampire FB.52 on 18 March 1960 using six Folland-built Gnats. The first aircraft built from Indian-built parts first flew in May 1962. The last Indian-built Gnat F.1 was delivered on 31 January 1974.
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Unlike the RAF, the IAF did not operate trainer variants of the Gnat.[25] The Gnat had a tendency to pitch up sharply on raising the undercarriage; almost all new pilots would find it difficult to control the anticipated pitch up.[25] Consequently, the Gnat was an extremely difficult aircraft to handle in the early stages of training, so IAF pilots generally qualified first on Hawker Hunter trainers, which gave them experience on powered controls. A pilot would then do a brief full throttle run on the runway in the Gnat, before flying solo. With sufficient experience, pilots would exploit the nimble mini-sized aircraft to its limits.
The Gnat proved to be a frustrating opponent for the larger and heavierCanadair Sabre operated by Pakistan.[26][27][28] The Gnat's success during the 1965 and 1971 Indo-Pakistani Wars was dependent on tactics, pilot skill, and sortie context.[29] Tactics utilised by IAF Gnat pilots included drawing Sabre pilots into vertical contests, where the Sabres were at a disadvantage. As the Gnat was lightweight and compact in shape, it was hard to see, especially at the low levels where most dogfights took place.[30]is credited by many independent and Indian sources as having shot down sevenPakistaniNorth American F-86 Sabres in theIndo-Pakistani War of 1965.[31][30] One Gnat was captured by Pakistani forces, following a forced landing, during the initial phase of the 1965 war. IAFSquadron Leader Brij Pal Singh Sikand later reported that he had experienced a complete electrical failure on his Gnat, after separating from his formation to fight a lone Sabre; Sikand landed at an abandoned Pakistaniairstrip atPasrur. Two PAFLockheed F-104 Starfighter pilots subsequently claimed a role in forcing down Sikand's Gnat.[32][33][34] (This Gnat has since been displayed at thePakistan Air Force Museum, Karachi.) On 16 December 1965, after a ceasefire was agreed, a PakistaniCessna O-1 was also shot down by a Gnat pilot.[31]
Gnats were used again by India in theIndo-Pakistani War of 1971.[35][36] Apart fromair defence operations, in theBangladesh Liberation War, Gnats flew anti-shipping operations,ground attack, bomber/transport escort andclose air support operations.[35][36] During theBattle of Boyra the firstdogfights overEast Pakistan (Bangladesh) took place. IAF Gnats shot down two PAF Canadair Sabres and badly damaged one. Another dogfight involving a Gnat was overSrinagar airfield where a lone Indian pilot held out against six Sabres, shooting two in the process, before being shot down.[37][38][39] Gnat pilotNirmal Jit Singh Sekhon wasposthumously honoured with theParam Vir Chakra (India's highest gallantry award), becoming the only member of the IAF to be given the award.
The Gnat was nicknamed "Sabre Slayer" within the IAF, since most of its combat kills during the two wars were against PAF Sabres – despite the Canadair Sabre Mk 6 being widely regarded as the best dogfighter of its era.[40][41][42] Tactics called for Gnats taking on the Sabres in the vertical, where the Sabres were at a disadvantage. As the Gnat was lightweight and compact in shape, it was hard to see, especially at the low levels where most dogfights took place.[30] While the IAF was impressed by the Gnat's performance in the two wars, the aircraft had many technical problems including hydraulics, a temperamental pair of Aden 30 mm cannons which often failed in-flight, significant "bent thrust" on take-off, leading to many aborted take-offs[43] and an unreliable control system. To address these failings, the IAF issued a requirement for an improved "Gnat II" in 1972, at first specifying that the new version was to be optimised as an interceptor but then expanding the specification to include ground attack. Over 175 of anHindustan Aeronautics Limited licence-built variant, theHAL Ajeet (ajeet meaning "unconquerable"), were produced inBangalore. The Ajeet, in effect, expanded the IAF's Gnat fleet, and the two types were reportedly phased out in tandem, with their final retirement occurring in 1991.[citation needed]
Several ex-IAF Folland Gnats have survived, in private hands. Some Gnats, including one that had participated in the 1971 war in East Pakistan, were presented to theBangladesh Air Force.[44]
The first production Gnat T.1s for theRoyal Air Force were delivered in February 1962 to theCentral Flying School atRAF Little Rissington. The major operator of the type was4 Flying Training School atRAF Valley, the first aircraft being delivered in November 1962. In 1964 4 FTS formed theYellowjacks aerobatic team with all-yellow painted Gnats. The team reformed in 1965 as part of the Central Flying School as theRed Arrows which operated the Gnat until 1979 as the RAF aerobatic demonstration team.[8] On 14 May 1965 the last Royal Air Force Gnat T.1 to be built was delivered to the Red Arrows.
Once pilots graduated from basic training on theBAC Jet Provost and gained their wings they were selected for one of three streams: fast jet, multi-engined, or helicopter. Those selected for fast jets were posted to RAF Valley for advanced training on the Gnat T.1, typically 70 hours of flying. Students would then move on to operational training using theHawker Hunter, followed by a posting to an operational conversion unit for the type of aircraft to be flown.
Following the introduction of theHawker Siddeley Hawk into the training role as a replacement the Gnats were withdrawn from service.[8] The largest operator 4 FTS retired its last Gnat in November 1978. Most of the retired Gnats were delivered toNo. 1 School of Technical Training atRAF Halton and other training establishments to be used as ground training airframes. When the RAF had no need for the Gnats as training airframes they were sold off. Many were bought by private operators and some are still flying today.[45] The final RAF operator of the Gnat was the Red Arrows, which retained their aircraft through the 1979 display season.[46] The team received its first Hawk in August 1979 and converted fully from the Gnat for the 1980 display season.[47]
Yugoslavia ordered two Gnat F.1s for evaluation; the first aircraft flew on 7 June 1958 and both were delivered to Yugoslavia by rail. The aircraft were flown by the flight test centre but no further aircraft were ordered. One aircraft was destroyed in a crash in October 1958 while the other is preserved and on display in Serbia.
_K-SIM_01.jpg)
Several Gnats survive including some airworthy examples (particularly in the United States and the United Kingdom) and others on public display.
Data fromJane's All the World's Aircraft 1958-59,[56]The Great Book of Fighters[57]
General characteristics
Performance
Armament
Avionics
Four privately owned Gnat T.1s together with an Ajeet portrayed the fictional carrier-based "Oscar EW-5894 Phallus" tactical fighter bombers flown by US Navy pilots in the 1991 comedyHot Shots!.[59]
Related development
Aircraft of comparable role, configuration, and era
Related lists
The initial version of this article was based on apublic domain article fromGreg Goebel's Vectorsite.
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