|A Fiat G.91 at the Luftwaffe Museum in Gatow|
|First flight||9 August 1956|
|Status||Several in museums|
|Primary users||Italian Air Force
German Air Force
Portuguese Air Force
|Number built||770|
The Fiat G.91 was an Italian jet fighter aircraft designed and built by Fiat Aviazione, which later merged into Aeritalia. The G.91 has its origins in the NATO-organised NBMR-1 competition in 1953, which sought a light fighter-bomber "Light Weight Strike Fighter" to be adopted as standard equipment across the air forces of the various NATO nations. After reviewing multiple submissions, the G.91 was picked as the winning design of the NBMR-1 competition.
The G.91 entered into operational service with the Italian Air Force in 1961, and with the West German Luftwaffe in the following year. Various other nations adopted it, such as the Portuguese Air Force, who made extensive use of the type during the Portuguese Colonial War in Africa. The G.91 enjoyed a long service life that extended over 35 years.
The G.91 remained in production for 19 years, during which a total of 756 aircraft were completed, including the prototypes and pre-production models. The assembly lines were finally closed in 1977. The G.91 was also used as a basis for an twin-engined development - the Fiat/Aeritalia G.91Y.
As a result of experiences from the Korean War alongside newly developed concepts of aerial cooperation, the members of NATO recognised a need to reequip their inventories with a suitable jet-powered ground attack aircraft. In December 1953, NATO Supreme Command issued specifications for a new light tactical support aircraft. European manufacturers were invited to submit their designs for this requested Light Weight Strike Fighter role. The G.91 was designed to this specification by the Italian engineer Giuseppe Gabrielli, hence the "G" designation. The competition was intended to produce an aircraft that was light, small, expendable, equipped with basic weapons and avionics and capable of operating with minimal ground support. These specifications were developed for two reasons: the first was the nuclear threat to large air bases, many cheaper aircraft could be better dispersed, and the other was to counter the trend towards larger and more expensive aircraft.
The specified technical requirements included a 1,100 m (3,610 ft) takeoff distance over a 15 m (49 ft) obstacle, the capability to operate from grass airstrips and roads, a maximum speed of Mach 0.95, a range of 280 km (170 mi) with 10 minutes over the target while possessing a maximum of 2,200 kg (4,850 lb) empty weight and 4,700 kg (10,360 lb) max weight. Equipment requirements were the presence of armoured protection for the pilot and the fuel tanks along with alternative arrangements of 4 × 12.7 mm (.5 in) guns or 2 × 20 mm or 30 mm cannons.
The challenge of providing an engine that matched the requirements of lightness and power, reliability and ease of maintenance was solved by using the Bristol Siddeley Orpheus turbojet then at the start of development in the UK. Development of this engine was aided by substantial contribution from the US Mutual Weapons Development Programme. Nine of the ten designs to be subsequently submitted for the competition were powered by the Orpheus engine.
The designs were required within two months of the competition. The special committee had to choose from eight projects. Besides the G.91, these included the Northrop N-156, Dassault Mystère XXVI, Sud-Est Baroudeur, Aerfer Sagittario 2 and the Breguet Br.1001 Taon . These designs were assessed starting on 18 March 1953 by NATO's Advisory Group for Aeronautical Research and Development (AGARD) under the chairmanship of Theodore von Kármán. The initial project selection process took 18 months to complete.
Fly-off and selection
On 30 June 1955, the first result was announced: the two winning projects were, in order: the Breguet Br. 1001 Taon and the Fiat G.91. A third design was subsequently added: the Dassault Mystère XXVI, and three prototypes of this design were also ordered. On 9 August 1956, the prototype G.91 conducted its maiden flight at the Caselle airfield airfield, Turin, Italy]]; it was flown by Chief Test Pilot Riccardo Bignamini. Accordingly, the G.91 had achieved a seven-month head start over the Dassault prototype and almost a year ahead of the Breguet Taon.
An intensive series of test flights followed the type's maiden flight, these were not without setbacks. The most serious problem discovered during these was the presence of aeroelastic vibrations, leading to a series of investigative flights to resolve this condition. On 20 February 1957, one such flight led to the destruction of the first G.91 prototype. The re-engineering work that had been performed to cure the vibration problem was very extensive and resulted in the second prototype being fitted with a larger tail, a 6 cm (2 in) higher canopy, a ventral fin and some other modifications. In July 1957, the second prototype performed its first flight, but it was not immediately sent to participate in the final evaluation process. The third and fourth G.91 prototypes were sent to France, for the competition.
The final selection of the competing designs was planned for late 1957. In September 1957, at the Centre d'Essais en Vol at Brétigny-sur-Orge, in France, the three rival aircraft types met for evaluation trials. During these trials, the Italian aircraft is claimed to have delivered an impressive performance. In January 1958, the Fiat G.91 was officially declared the winner of the competition.
In April 1958, following a meeting of NATO defence ministers, an agreement was formed that the G.91 would be the first NATO lightweight strike fighter, and that it was to be followed in 1961 by "a developed version" of the Breguet Taon. In May 1958, a production meeting was scheduled to discuss the production of the aircraft with financial support from the United States; the Americans would provide some of the finance for the French, German and Italian aircraft, in addition to paying for the Turkish aircraft. The defence ministers reached an agreement to order 50 aircraft for each country.
Given the large economic and commercial interests at stake, there was a certain amount of controversy surrounding this decision. After the loss of the first G.91 prototype, the French government preferred to pursue development of the locally designed Étendard instead. The British government similarly ignored the competition to concentrate on Hawker Hunter production for the same role. The Italian government had elected to order the G.91 for the Italian Air Force prior to the results of the competition being known. These pre-production machines would later go on to serve for many years with the Italian aerobatic team, the Frecce Tricolori, designated as the G.91 PAN.
The type was also considered by Austria, Norway, Switzerland, and even the United States Army, which briefly evaluated the type as a possible Forward Air Control aircraft prior to the service relinquishing all fixed-wing aircraft operations to the United States Air Force.
Aeritalia built 174 G.91s for Italy, plus 144 R/3 variants for West Germany (including 50 that had been ordered and then cancelled by Greece and Turkey). The German order involved a production run of 294 G.91s built in Germany by Flugzeug-Union Süd (a consortium of former competitors Messerschmitt, Heinkel and Dornier). These were the first combat aircraft built in Germany since World War II. The first order was for 50 machines from Aeritalia, then Dornier and other German firms had an order for 232 machines, later increased to 294.
The Luftwaffe (German Air Force) also bought 44 G-91T/3 two-seat trainers and another 22 were produced in Germany, ending production in 1972. The Luftwaffe had intended to equip a further four wings with the G.91R/3 but initial operating experience with the type left the Luftwaffe disappointed with the aircraft's performance and thus the intended further orders for the type were cut. A number of Luftwaffe G.91s were emblazoned with a "pig" emblem, this as been interpreted as a comment on the aircraft's lacklustre performance.
The first G.91s entered service with the Italian Air Force in August 1958, with 103mo Gruppo, 5a Aerobrigata, called "Caccia Tattici Leggeri (CTL)", based at Pratica di Mare Air Force Base, the same with Reparto Sperimentale di Volo. The next operational unit was 14mo Gruppo, Seconda Aerobrigata in 1961. This unit had its role shifted to tactical support, because its groups were 14mo, 103mo (dispatched from 5 A/B to this Aerobrigade) and 13mo (only in reserve). All of them were based at Treviso-Sant'Angelo.
The last G.91 was phased out and retired by Italy in 1995.
Forty-five G.91 T/3 Fiat built two-seat trainer aircraft were ordered for the Luftwaffe, the first 35 being allocated to Waffenschule 50 (Weapon School 50) with the balance of the order divided between operational units. 22 aircraft were built by Dornier between 1971 and 1973, these aircraft were used to train Weapons Systems Officers for the F-4 Phantom.
Five Fiat built G.91R/3 aircraft were delivered to Erprobungstelle 61 for trials with subsequent deliveries being allocated to Aufklarungsgeschwader 53 based at Erding, near Munich along with Waffenschule 50. The first Dornier-built example of this variant was flight tested on 20 July 1961. The G.91R/3 equipped four newly formed Leichte Kampfgeschwader (light attack wings), often replacing former F-84 Thunderstreak units.
Fifty G.91 R/4 aircraft were taken up from a cancelled Greek/Turkish order but being unsuitable for operational use were used as training aircraft and were operated solely by Waffenschule 50. When the initial training programme was completed the R4 was retired in 1966, 40 surviving airframes were sold to Portugal. Other R/4 aircraft remained in Germany and were transferred to ground instructional use or displayed at recruitment presentations.
On 1 January 1970, the Luftwaffe fleet consisted of 310 G.91 R/3 and 40 G.91T aircraft, and by 1976 only 20 of the R/3s had been lost to accidents, a loss rate of 6%. The G.91 R/3 was to be replaced in the early 1980s by the Dassault/Dornier Alpha Jet which operated in the same role, with the last G.91s being retired in 1982.
From 1961, Portugal became involved in fighting against nationalist movements in its African overseas territories, the series of conflicts becoming known as the Portuguese Colonial War. Portugal had deployed a detachment of F-86 Sabres to Portuguese Guinea in August 1961, prior to the outbreak of major fighting, but was forced to withdraw the jet fighters back to Europe owing to pressure from the United States and the United Nations, who imposed an arms embargo. This left a gap in air cover for Portugal's African colonies, both in the close air support role, and in the air defence role.
In 1965, as the scale of fighting increased, Portugal attempted to purchase 100 surplus Canadian built Sabre Mk 6s from West Germany, but instead, it was offered 40 G.91R/4s, which had originally been built for Greece and Turkey and which differed from the rest of the Luftwaffe G.91s sufficiently to create maintenance problems in exchange for allowing Germany to build and use an airbase at Beja in Portugal for training.
G.91s arrived in Portuguese Guinea in 1966, equipping Esquadra 121 Tigres based at Bissau, and being used for reconnaissance and close support with rockets, napalm and bombs against PAIGC rebels. When the PAIGC started to be supplied with Soviet-made Strela 2 (NATO designation SA-7 Grail) MANPADS in early 1973, these immediately became a threat to Portuguese air superiority. On 25 March 1973, and 28 March, two FAP G.91s were shot down by missiles within three days, with a further two lost to conventional ground fire later in the year. (By comparison, only two G.91s had been lost in Guinea from 1966 to 1973.) A final G.91 was lost to a missile on 31 January 1974, while Strelas were also responsible for the loss of a T-6 Texan and two Do.27K-2s.
G.91s deployed to Mozambique at the end of 1968, equipping Esquadra 502 Jaguares ininitally at Beira, later moving to Nacala, with a second squadron Esquadra 702 Escorpiões (Scorpions) forming in September 1970 at Tete, flying against FRELIMO forces. Fremilo also received Strelas in 1973, although unlike elsewhere, the Portuguese in Mozambique did not lose any aircraft to missiles with Chinese support, even if it forced Portuguese pilots to change their tactics. The only G.91 destroyed in combat in Mozambique was the serial number 5429, flown by Lt. Emilio Lourenço: his plane was destroyed and Lourenço killed by a premature detonation of its bombs while flying a strike against rebel positions on 15 March 1973.
In 1973, with the United Nations weapons embargo against Portugal, the Air Force faced problems purchasing further numbers of close air support aircraft. An attempt was then made to acquire more Fiat G.91s from Germany by having Dornier disassembling the aircraft and then selling them as spare parts to Switzerland and Spain. These spare parts would be later sold to Portugal and assembled locally with different serial numbers. However, the deal did not follow through as the German government vetoed it.
In April 1974, the Portuguese government fell in the Carnation Revolution, with the new government seeking to grant its colonies independence. Portugal withdrew its G.91s from Guinea when it was granted independence in 1974, with its forces also leaving Mozambique. One of the G.91 squadrons was briefly deployed to Angola in late 1974, in order to try to prevent fighting between rival National Liberation Front of Angola (FNLA) and National Union for the Total Independence of Angola (UNITA) forces, being finally withdrawn back to Portugal in January 1975.
In 1976, a second purchase of 14 G.91 R/3s and 7 G.91 T/3 trainers was made from Germany, which were followed by further aircraft when the G.91 was withdrawn from Luftwaffe service in from 1980 to 1982, giving a total of 70 R/3s and 26 T/3s, although not all of these entered service, with many being broken up for spare parts. Portugal finally phased out the last of its G.91s in 1993.
Data from: Warpaint No.49:Fiat G.91
Trainer and reconnaissance variants were produced right from the start of G.91 production, but the basic design of the aircraft remained virtually unchanged throughout almost the entire production run of the aircraft. The one major difference is that the R series aircraft were single-seaters, while the T series aircraft had two seats. To accommodate the extra seat, the T series aircraft had a slightly longer fuselage.
- Prototypes and pre-production aircraft.
- A single prototype, built to test wing slats and fuel tanks in the wings.
- (BS - Battle Surveillance) Derived from the G.91T with improved avionics and photographic equipment, not built.
- Two-seat version of the BS/1, not built
- Proposed version of the G.91Y for the AMI, not built.
- A single aircraft modified from a pre-production aircraft with extra navigation equipment such as Decca Navigator and Rho-Theta.
- Light attack/reconnaissance aircraft, fitted with modified nose housing three cameras.
- Revised instrumentation.
- Strengthened airframe.
- Single-seat ground-attack, reconnaissance version for the Luftwaffe. Powered by a Bristol-Siddeley Orpheus turbojet engine. Armed with two 30 mm (1.181 in) DEFA cannons.
- a single R/3 modified with JATO rockets and arrestor hook for the Luftwaffe:
- Similar to the G.91R/3, but armed with four 12.7 mm (0.5 in) Colt-Browning machine guns. Powered by a Bristol-Siddeley Orpheus turbojet engine.
- A projected long-range version for Norway
- A projected version with improved undercarriage, revised avionics, increased tankage and weapon load, for Italy
- G.91RS or G.91S
- Projected variant with revised wing and 31.4 kN (7,050 lbf) B.Or.12 Orpheus or Fiat 4032 engine, not built.
- Trainer version of G.91R/1 for Italian Air Force.
- Trainer version for Luftwaffe.
- G.91T/3 Logair
- A single conversion of a Luftwaffe T/3 with a data acquisition probe.
- Projected supersonic version of the G.91T, not built
- Aerobatic display aircraft for Frecce Tricolori, converted from pre-production G.91s.
- G.91 target tug
- A target tug variant was developed with an under-wing pylon mounted winch and target drogue. The drogue being attached to an extension of the winch around the trailing edge , above the wing. Other modifications included a large blade aerial above the centre fuselage and an anti-collision light at the forward end of the dorsal fin.
Main article: Fiat G.91YAn additional 67 aircraft built by Aeritalia were significantly different from earlier versions. These single-seat aircraft, based on the trainer, designated G.91Y and nicknamed "Yankee", replaced the original Bristol Siddeley Orpheus engine with two General Electric J85 units in a "completely re-engineered structure" giving 60% more power and doubling range with 75% more payload.  The G.91Y first flew on 12 December 1966 and displayed an improvement in speed, range, payload, and manoeuvrability. The maximum speed was increased to 1,110 km/h (690 mph, 600 kn, Mach 0.91). The machine guns were replaced by a pair of DEFA 552 30 mm cannon with 125 rounds per gun. All the aircraft built served with the Italian Air Force.
- A projected two-seat version of the G.91Y, not built.
- Proposed version of the G.91Y for Switzerland, one built.
- German Air Force (Luftwaffe)
- Hellenic Air Force Evaluation operator, four aircraft in service, but retired.
- Italian Air Force operated 31 Fiat G.91, 97 Fiat G.91R and 103 Fiat G.91T/1 retired in 1995
- Portuguese Air Force (1966–1993)
- United States Army – Evaluated two aircraft (1 G.91R/1, 1 G.91R/3) in 1961.
- United States Air Force – Also an evaluation operator with two aircraft.
Aircraft on display
There are numerous examples preserved in museums around the world.
- Crew: 1
- Length: 10.3 m (33 ft 9 in)
- Wingspan: 8.56 m (28 ft 1 in)
- Height: 4.0 m (13 ft 1 in)
- Wing area: 16.4 m² (177 ft²)
- Empty weight: 3,100 kg (6,830 lb)
- Loaded weight: 5,440 kg (11,990 lb)
- Max. takeoff weight: 5,500 kg (12,100 lb)
- Powerplant: 1 × Bristol Siddeley Orpheus 803 turbojet, 22.2 kN (5,000 lbf)
- Maximum speed: 1,075 km/h (580 kn, 668 mph)
- Range: 1,150 km (621 nmi, 715 mi)
- Service ceiling: 13,100 m (43,000 ft)
- Rate of climb: 30 m/s (6,000 ft/min)
- Wing loading: 331 kg/m² (67.8 lb/ft²)
- Thrust/weight: 0.42
4× 12.7 mm (0.50 in) M2 Browning machine guns; or
2× 30 mm (1.18 in) DEFA cannons (Luftwaffe G.91R/3 only)
- Hardpoints: 4× under-wing pylon stations with a capacity of 680 kg (1,500 lb) for G.91R/3 & R/4 and 500 kg (1,100 lb) for G.91R/1 and provisions to carry combinations of:
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
- Angelucci and Matricardi 1980, p. 272.
- Apostolo 1966, p. 3.
- Angelucci and Matricardi 1980, p. 273.
- Ferrari 1992, p. 83.
- Hooker, Stanley (2002) . Not much of an engineer. An autobiography. Shrewsbury: Airlife Publishing. p. 164. ISBN 1-85310-285-7.
- "NATO Choice Highlights Orpheus Success." Flight, No. 2618 Volume 75, 27 March 1959. p. 22.
- Niccoli 2002, p. 168.
- Angelucci and Matricardi 1980, p. 274.
- Ferrari 1992, p. 85.
- "NATO's Strike Fighter". Flight International: 556. 25 April 1958.
- Crosby 2002, p. 183.
- Green 1964, p. 35.
- Apostolo 1966, p. 2.
- Doll and Dorner 1974, p. 19.
- Lambert 1957, p. 114.
- Jackson 1974, p. 24.
- Jackson 1976, p. 33.
- Jackson 1976, p. 96.
- Jackson 1974, p. 25.
- Jackson 1974, p. 84.
- Jackson 1976, p. 35.
- Fiat G.91 – Luftwaffe history www.geschichte.luftwaffe.de Retrieved: 30 November 2010 (German)
- Nicolli 2002, p. 174.
- Lopes 1988, p. 64.
- Nicolli 2002, p. 181.
- Lopes 1988, pp. 66–67.
- Lopes 1988, p. 68.
- Lopes 1988, pp. 67–68.
- Cooper, Tom and Pedro Alvin. "Guiné (Portuguese Guinea), 1959–1974". AICG.org. 12 May 2009. Retrieved 3 February 2010.
- Lopes 1988, pp. 68–69.
- Lopes 1988, p. 70.
- Cooper, Tom. "Mozambique, 1962–1992". AICG.org. 10 February 2008. Retrieved: 3 February 2010.
- Lopes 1988, pp. 70–71.
- Lopes 1988, p. 71.
- Caruana, Richard J. (2004). Warpaint No.49:Fiat G.91. Warpaint Books Ltd / Hall Park Books. Retrieved 31 December 2015.
- Niccoli 2002, p. 169.
- "Italy: Fighters and Fighter-bombers"Flight 20 June 1958. p857 gives 6,800lbf
- Taylor 1969, p. 216.
- Fiat G.91Y Flight International, 20 June 1968 p 931
- Niccoli 2002, p. 178.
- "Italian Air Force Aircraft Types".
- Harding, p.128.
- Hispano Suiza (30 August 1962), "Hispano Suiza Aircraft Rockets Type R 80 SURA", Flight International: 159 accessed: 23 October 2008.
- Angelucci, Enzo and Paolo Matricardi. Combat Aircraft 1945–1960. Maidenhead, Berkshire, UK: Sampson Low Guides, 1980. ISBN 0-562-00136-0.
- Apostolo, Giorgio. The Fiat G.91. Leatherhead, Surrey, UK: Profile Publications Ltd., 1966.
- Crosby, Francis. "Fiat/Aeritalia G91." Fighter Aircraft. London: Lorenz Books, 2002. ISBN 0-7548-0990-0.
- Doll, Peter and Herman Dorner. The New Luftwaffe in Action (In Action No.1013). Carrollton, Texas: Squadron/Signal Publications, 1974.
- Ferrari, Massimo. "Addio G.91R" (in Italian). RID magazine, August 1992.
- Green, William. The World's Fighting Planes. London: Macdonald, 1964.
- Harding, Stephen (1997). U.S. Army Aircraft Since 1947. Atglen, Pennsylvania, USA: Schiffer Publishing Ltd. LCCN 96-69996.
- Jackson, Paul A. German Military Aviation 1956–1976. Hinckley, Leicestershire, UK: Midland Counties Publications, 1976. ISBN 0-904597-03-2.
- Lambert, C. M. "Fiat Aviazione." Flight International, 25 January 1957. pp. 111-114.
- Lopes, Mario Canongia. "Portugal's Ginas". Air Enthusiast, Thirty-six, May–August 1988, pp. 61–72. ISSN 0143-5450.
- Niccoli, Riccado. "Fiat G.91, NATO's Lightweight Fighter." International Air Power Review. Volume 7, Winter 2002.
- Taylor, John W. R. "Fiat G.91". Combat Aircraft of the World from 1909 to the Present. New York: G.P. Putnam's Sons, 1969. ISBN 0-425-03633-2.
- "Fiat G.91", Flight: 696, 23 May 1958
- "Mobile and Agile: the Fiat G.91", Flight: 461, 3 April 1959
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