Fiat G.91

The Fiat G.91 is a jet fighter aircraft designed and built by the Italian aircraft manufacturer Fiat Aviazione, which later merged into Aeritalia.

The G.91 has its origins in the NATO-organised NBMR-1 competition started in 1953, which sought a light fighter-bomber (officially, the competition was seeking a "Light Weight Strike Fighter") to be adopted as standard equipment across the air forces of the various NATO nations. The G.91 was specifically designed to fulfil the requirements of this competition, being relatively lightweight and capable of operating from austere airstrips while also being armoured and suitably armed while remaining relatively affordable in comparison to many frontline fighters. On 9 August 1956, the prototype conducted its maiden flight. After reviewing multiple submissions, the G.91 was picked as the winning design of the NBMR-1 competition.

During 1961, the G.91 entered into operational service with the Italian Air Force, 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 Angola and Mozambique. 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. 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.

thumb|alt=An etching representing an Italian G 91R departing from Treviso airport|Etching commemorating the last flight of the G.91R from Treviso airport (April 9,1992)

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 semi-prepared 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. These operational specifications were viewed as not being straightforward to fulfil at that time. Nine of the ten designs to be subsequently submitted for the competition were powered by the Orpheus engine.

In order to evaluate the bids that various aircraft manufacturers submitted in response, a special Advisory Group for Aeronautical Research and Development (AGARD) committee conducted extensive evaluations. 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, during a test flight intended to explore the limits of the aircraft's speed-load envelope, difficulties led to the destruction of the first G.91 prototype. The cause of the prototype's loss was linked to problems encountered with the horizontal control system which had led to structural failure; this led to the tail assembly being subjected to rigorous testing to identify the cause of the failure. Both the third and fourth G.91 prototypes were later sent to France to continue the evaluation flights.

thumb|A preserved G.91 on display at Seattle's [[Museum of Flight. Note the Frecce Tricolori's colors]]

The final selection of the competing designs was planned for late 1957. 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.

Production

By 1957, Fiat Aviazione was in the process of establishing the first production line for the G.91 at their facility at Turin-Aeritalia Airport, Piedmont, Italy. In total, Fiat constructed 174 G.91s of various variants for Italy, along with an additional 144 G.91 R/3 variants for West Germany (including 50 that had been ordered and then cancelled by Greece and Turkey). The first order was for 50 aircraft from Aeritalia, then Dornier and other German firms had an order for 232 machines, which was 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 German order involved a production run of 294 G.91s that were domestically constructed in Germany under a license production arrangement by Flugzeug-Union Süd, a consortium of former competitors Messerschmitt, Heinkel and Dornier; Messerschmitt produced the forward fuselage and tail assembly, Dornier manufactured the center fuselage along with final assembly and flight testing, while Heinkel fabricated the wing. Messier-Bugatti-Dowty produced the aircraft's undercarriage. However, the service subsequently relinquished all fixed-wing aircraft operations to the United States Air Force, and thus the prospective G.91 procurement was not pursued.

Design

thumb|The cockpit of a G.91 R1 in the Istituto Tecnico Industriale Aeronautico A. Malignani, [[Udine, Friuli-Venezia Giulia, Italy]]

The Fiat G.91 is a lightweight tactical ground attack aircraft. It is a subsonic aircraft that was designed for both simplicity and agility. The standard mission of the G.91 was the attack of targets within a 170-mile radius of its base with a typical loiter time of ten minutes, travelling at maximum speed in the combat area and traversing at cruise speeds. The cockpit is positioned directly above the chin-mounted air intake for the engine. It is surrounded on three sides with steel armour plating, the glass windshield is also armoured. The cockpit is furnished with a Martin-Baker Mk.4 ejector seat; it is both pressurised and equipped with manually controlled climate controls.

For the purpose of readily carrying out operations from austere airstrips, Fiat developed purpose-built ground support equipment for the easy and rapid servicing of the aircraft. Specifically, the equipment needed to inspect, maintain, resupply, and repair the G.91 were designed to possess minimal weight and size to facilitate transportation. Fiat also completed a study to add hooks onto the aircraft for the purpose compatibility with arresting gear and aircraft catapult for further increased short field performance; a number of production aircraft in Luftwaffe service were outfitted as such.

Operational history

Italy

thumb|A G.91 R1 in the Istituto Tecnico Industriale Aeronautico A. Malignani, [[Udine, Friuli-Venezia Giulia, Italy, 2007]]

On 20 February 1958, the first pre-production G.91 conducted its maiden flight.

In 1961, the next operational unit to be formed was 14mo Gruppo, Seconda Aerobrigata. 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.

In October 1961, Aufklärungsgeschwader 53 became the first operational G.91 unit to achieve active status; in late May 1962, this same unit proceeded to carry out its first operational training flights.

An additional 45 G.91 T/3 Fiat-built two-seat trainer aircraft were ordered for the Luftwaffe, the first 35 being allocated to Waffenschule 50 with the balance of the order divided between operational units. In early 1961, Waffenschule 50 began its first training courses for pilot instructors. Of these, 22 aircraft were built by Dornier between 1971 and 1973; this variant were used to train Weapons Systems Officers for the F-4 Phantom.

Fifty G.91 R/4 aircraft were taken up from a cancelled Greek/Turkish order but were deemed to be unsuitable for operational use. These were used as training aircraft and were operated solely by Waffenschule 50. When the initial training programme was completed, all R/4 aircraft were retired in 1966 and 40 surviving airframes were sold to Portugal. Other R/4 aircraft remained in Germany and were transferred to ground instructional use or for static displays at recruitment presentations.

It has been claimed that the Luftwaffe had intended to equip a further four wings with the G.91R/3; however, initial operating experience with the type had allegedly 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 has been interpreted as a comment on the aircraft's lacklustre performance. the last G.91 aircraft were officially retired in 1982.

Portugal

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,

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, 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.

thumb|left|Portuguese Air Force G.91 preserved at Sintra Air Base

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. FRELIMO also received Strelas in 1973, although unlike elsewhere, the Portuguese in Mozambique did not lose any aircraft to missiles, 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. The G.91 R/4 variant, of which 25 aircraft were intended to be delivered to both Greece and Turkey, employed the same armament as the G.91 R/1 while using the equipment of the R/3 variant. However, both Greece and Turkey would ultimately not induct any G.91s, these aircraft were instead passed onto Germany's inventory instead.

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.

;G.91: Prototypes and pre-production aircraft.

;G.91A: A single prototype, built to test wing slats and fuel tanks in the wings.

;G.91T/1: Trainer version of G.91R/1 for Italian Air Force. 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.

;G.91YT:A projected two-seat version of the G.91Y, not built.

;G.91YS:Proposed version of the G.91Y for Switzerland, one built.

Operators

thumb|300px|Operators of the G.91 in dark blue, cancelled orders in light blue, evaluations in yellow

;

German Air Force (Luftwaffe)
Aufklärungsgeschwader 53
Aufklärungsgeschwader 54
Erprobungstelle 61
Leichtes Kampfgeschwader 41
Leichtes Kampfgeschwader 42 (Taktisches Luftwaffengeschwader 73)
Leichtes Kampfgeschwader 43
Leichtes Kampfgeschwader 44
Waffenschule 50

;

Hellenic Air Force – G.91R/4, evaluation-only. It was rejected in favor of American designs

;

Italian Air Force – operated 31 Fiat G.91, 97 Fiat G.91R and 103 Fiat G.91T/1 retired in 1995
Frecce Tricolori

;

Portuguese Air Force − 40 G.91/R4s. Purchased from West Germany in 1965, it remained in service until 1993

;

Turkish Air Force − G.91R/4, evaluation-only. It was rejected in favor of American designs

;

United States Army – Evaluated two aircraft (1 G.91R/1, 1 G.91R/3) in 1961.
United States Air Force – 10 G.91R/1 were evaluated in 1961−1962

Aircraft on display

Aeroporto di Arezzo - G.91T/1 2-seat trainer (outdoor) - 32° Stormo (Wing) colours
Luftwaffenmuseum der Bundeswehr, Gatow
Museo Nazionale Scienza e Tecnologia Leonardo da Vinci, Milan, Italy
Istituto Tecnico Industriale Aeronautico, Udine, Friuli-Venezia Giulia, Italy
Sintra Air Base, Portugal
Malta Aviation Museum, Ta'Qali, Malta
Jardim Gil Eanes, Portimão, Portugal

Specifications (G.91R)

thumb|Close up of an Orpheus engine installed on a Fiat G.91 with the rear section removed

thumb|A Matra Type 116M rocket launcher mounted on a G.91 on display at the [[Luftwaffenmuseum der Bundeswehr, Berlin]]

Production

Design

Operational history

Italy

Portugal

Operators

Aircraft on display

Specifications (G.91R)

See also

References

Citations

Bibliography

External links