| T-37 Tweet | |
|---|---|
 A T-37 Tweet from the 85th Flying Training Squadron, Laughlin Air Force Base, Texas, flies overAmistad Reservoir during a training mission. | |
| General information | |
| Type | Military trainer aircraft |
| National origin | United States |
| Manufacturer | Cessna |
| Status | Retired from American service in 2009, In limited service with the Pakistan Air Force |
| Primary users | United States Air Force (historical) |
| Number built | 1,269 |
| History | |
| Manufactured | 1955–1975 |
| Introduction date | 1957 |
| First flight | 12 October 1954 |
| Retired | 2009 (USAF) |
| Variant | Cessna A-37 Dragonfly |
TheCessna T-37 Tweet (designatedModel 318 byCessna) is a small, economical twin-enginejet trainer aircraft. It was flown for decades as a primary trainer of theUnited States Air Force (USAF) as well as in the air forces of several other nations.
The T-37 was developed in response to the launch of the "Trainer Experimental (TX)" program for theUnited States Air Force (USAF) in early 1952. On 12 October 1954, the prototype XT-37 performed itsmaiden flight. While the first prototype was lost duringspin tests, features to improve handling were installed upon subsequent prototypes, such as nose-mountedstrakes and a heavily redesigned largetail unit, after which the USAF chose to order the aircraft into production as theT-37A. The service received the first production aircraft during June 1956.
In response to the T-37A being underpowered, the USAF ordered an improved version, theT-37B, that was powered by uprated J-69-T-25 engines and was also equipped with improved avionics. A total of 552 new-built T-37Bs were constructed through 1973; all surviving T-37As were eventually upgraded to the T-37B standard as well. The T-37 served as the USAF's primary pilot training vehicle for over 50 years after its first flight. After completing initial training in the T-37, students progressed on to other advanced Air Force, Navy,Marine Corps or Allied trainers. A total of 1,269 T-37s were constructed prior to production ending in 1975. In 2009, the USAF withdrew its final T-37, having replaced the type with the newerturboprop-poweredBeechcraft T-6 Texan II.
In addition to its use as a trainer, an armed T-37C variant was developed as a weapons trainer. A dedicated attack variant, theA-37 Dragonfly, was also developed by Cessna during the 1960s in response to a need forcounter-insurgency aircraft (COIN) aircraft for theVietnam War. Both the A-37 and T-37C were exported to various other countries, leading to their adoption by the air forces of several South American nations.
The T-37 can be traced back to the spring of 1952 and the issuing of a request for proposals by theUnited States Air Force (USAF) for what would become the "Trainer Experimental (TX)" program. The request called for a lightweight twin-seat basic trainer that would be suitable for introducing USAF cadets to jet aircraft. More specifically, the aircraft had to be simple to operate, easy to maintain, structurally strong, possess favourable low-speed handling qualities, be relatively safe while performing high altitude maneuvers, adequate fuel capacity for at least two flight hours, a service ceiling of 30,000 feet, a maximum approach speed of 113 knots, a maximum all-up weight of 4,000 lbs, and the ability to land and take off in less than 4,000 feet.[1]
Cessna was one of eight aircraft manufacturers to respond to the TX request, the company designed a twin-jet aircraft withside-by-side seating that it internally designated as theModel 318.[1] The USAF favorably received Cessna's submission, particularly the use of the side-by-side seating configuration as it let the student and instructor interact more closely than would be possible withtandem seating. In the spring of 1954, the USAF issued a contract to Cessna for the production of threeprototypes of the Model 318 along with a separate contract for a single static test aircraft. The aircraft was designatedXT-37 by the USAF. According to aviation author Kev Darling, the selection of Cessna was a surprising result as the company was only experienced with piston-engined aircraft at the time.[1]
The XT-37 was an all-metal aircraft with a semi-monocoque fuselage.[1] It was an aerodynamically clean aircraft, so much so that aspeedbrake was fitted behind the nosewheel doors that would be deployed to increasedrag when the aircraft was landing as well as in other phases of flight. Since the relatively shortlanding gear placed the engine's air intakes close to the ground, screens pivoted over the intakes from underneath when the landing gear was extended to preventforeign object damage. The wide track and a steerable nosewheel enabled it to be relatively easy to handle on the ground while the short landing gear avoided the need for access ladders and service stands. For simplicity of maintenance, the fuselage featured in excess of 100 access panels and doors; an experienced ground crew could change an engine in about half an hour.[2]
The XT-37 was fitted with a pair ofContinental-Teledyne J69-T-9turbojet engines, which wereFrenchTurbomeca Marboré engines produced underlicense, each being capable of generating up to 920 lbf (4.1 kN) ofthrust.[1] These engines were equipped withthrust attenuators that permitted them to remain spooled-up (i.e. rotating at speeds above idle) during landing approach, permitting shorter landings while still allowing the aircraft to easily make another go-around in case something went wrong. The empty weight of the XT-37 was 5,000 lb (2,300 kg).
The XT-37 had a low, straight wing while the engines buried in thewing roots, aclamshell-typecanopy hinged to open vertically to the rear, a control layout similar to that of contemporary operational USAF aircraft,ejection seats, andtricycle landing gear with a wide track of 14 ft (4.3 m).[3] Many of the aircraft's components were designed and built internally by Cessna; relatively few externalcontractors were involved in the production.[4]
On 12 October 1954, the XT-37 performed itsmaiden flight.[5][1] Flight testing revealed the XT-37 to have a maximum speed of 390 mph (630 km/h) at altitude and a range of 935 mi (1,505 km). Furthermore, it possessed aservice ceiling of 35,000 feet (10,700 m);[6] however, due to the cockpit beingunpressurized, it was limited to an operational ceiling of 25,000 feet (7,600 m) by USAF regulations.
The initial prototype crashed duringspin tests.[7] To improve handling, subsequent prototypes were equipped with new aerodynamic features, such as lengthystrakes along the nose and an extensively redesigned and enlargedtail. On 3 May 1955, the third and final prototype took flight for the first time.[7] After these modifications were implemented, the USAF found the aircraft to be acceptable to their needs and ordered it into production as theT-37A. Despite the changes, production aircraft remained tricky to correctly recover from a spin; it had a relatively complex recovery procedure in comparison to most aircraft. If fuel distribution was not managed correctly, a weight imbalance situation could be created that may lead to an unrecoverable stall.[4]
The production T-37A was similar to the XT-37 prototypes, differing only in only minor ways as to address problems revealed by flight testing.[8] During September 1955, the first T-37A was completed, it made its first flight later that year. The USAF ultimately ordered 444 T-37As, the last of which was produced in 1959.[9] During 1957, the US Army evaluated three T-37As for battlefield observation and other combat support roles, but eventually procured theGrumman OV-1 Mohawk for this purpose instead.[10] Darling alleges that this outcome had been largely due to political factors, including the opposition of the USAF.[11]
USAF officials reportedly liked the T-37A but often considered it to be underpowered; consequently, the service ordered an improved version, theT-37B. It was outfitted with uprated J-69-T-25 engines that provided roughly 10 percent more thrust as well as being more reliable. The new variant also featured improvedavionics, fuel flow improvements, as well as various changes to reduce maintenance requirements.[9] A total of 552 newly built T-37Bs was constructed through 1973. All surviving T-37As were progressively upgraded to the T-37B configuration as well, the rebuilding program being completed by July 1960.[12]
Following a series of accidents caused bybird strikes between 1965 and 1970, all T-37s were later retrofitted with a new windshield made ofLexan polycarbonate plastic 0.5 in (12.7 mm) thick; this had sufficient strength to reliably withstand the impact of a 4 lb (1.8 kg) bird at a relative speed of 288 mph (463 km/h). While early examples of this new windshield suffered from distortion, this was rectified via production changes.[13]
In 1962, Cessna suggested the T-37B as a replacement for theNorth American F-100 Super Sabre as the primary aircraft for the USAF aerobatic demonstration team, theThunderbirds, but the USAF was satisfied with the F-100.
The T-37A and T-37B had no built-in armament and lacked anystores pylons for external armament. During 1961, Cessna began developing a modest enhancement of the T-37 for use as a weapons trainer. The new variant, the designatedT-37C, was intended forexport and could be used for light attack duties if required.[14] The prototype T-37C was a modified T-37B; the principal changes made included strengthened wings and the addition of a stores pylon under each wing outboard of the main landing gear well. The T-37C could also be fitted with areconnaissancecamera mounted inside thefuselage. It could also be fitted with wingtip fuel tanks, each with a capacity of 65 US gal (245 L), that could be dropped in an emergency.
The primary armament of the T-37C was theGeneral Electric "multipurpose pod" with a .50 caliber (12.7 mm)machine gun with 200 rounds, two 70 mm (2.75 in) folding-finrocket pods, and four practicebombs. Other stores, such as folding-fin rocket pods orSidewinder air-to-air missiles, could be carried. A computinggunsight andgun camera were also added. The changes increased the weight of the T-37C by 1,430 lb (650 kg). As the engines were not upgraded, the changes caused a reduction in the aircraft's top speed to 595 km/h (370 mph), though the wingtip tanks increased its maximum range to 1,770 km (1,100 mi).
Production of the T-37 slowed considerably during the early 1960s, although there was an uptake during the latter half of the decade, both to address attrition and an uptick in demand as theVietnam War intensified.[15] Around this time, the aircraft was authorised for supply to friendly overseas operators under theMilitary Aid for Assistance programme.[16] Production of the T-37 was terminated in 1975. By this point, export sales of the type included 273 T-37Cs.[14] This was on top of the 444 T-37As and 552 T-37Bs produced for both domestic and export customers for a total of 1,269 aircraft built.
A dedicated attack variant of the T-37, referred to as theA-37 Dragonfly, was developed during the 1960s. This was largely in response to theVietnam War, for which the USAF came to recognize the need for dedicatedcounter-insurgency aircraft (COIN) aircraft to engage with the ground forces ofNorth Vietnam.[17] Being derived from the T-37, the USAF had determined that an prospective COIN model would need to be able to carry a far greater payload, have moreendurance, and possess better short-field performance.[18] Specific alterations made included the adoption of strengthened wings, the use of larger wingtip fuel tanks of 360 litres (95 US gal) capacity, additional avionics suitable for battlefield communications, navigation, and targeting, toughenedlanding gear that were suitable for rough-field operation, and the fitting of aGeneral Electric-suppliedGAU-2B/A 7.62 mm (0.300 in) "Minigun" Gatling-style machine gun capable of a rate of fire of 3,000 rounds/minute and 1,500 rounds of ammunition that was installed in the aircraft's nose along with an accompanyinggunsight andgun camera. Threestores pylons were installed on each wing that were compatible with various munitions.[19][20] This A-37 would not only be used in frontline combat in Vietnam, but was also exported to various other air forces, including several South American nations.[21][22]
Cessna proposed a number of innovative variants of the T-37 that never went into production. In 1959, Cessna built a prototype of a light jet transport version of the T-37, designated the CessnaModel 407, which was stretched 2 ft (61 cm) to accommodate a four-place pressurized cockpit with an automobile-type configuration. Only a wooden mockup of the Model 407 was constructed. The project was cancelled due to insufficient customer interest.[23]
The company also proposed a similar four-place military light transport, theModel 405, with a large clamshell canopy, but it was never built.
In response to aUnited States Navy "Tandem Navy Trainer" (TNT) requirement, Cessna proposed a T-37 with a modified fuselage featuring a tandem cockpit. The Navy selected theNorth American T-2 Buckeye, instead.
Cessna proposed various other trainer derivatives for the US Navy and USAF, including avertical takeoff version based on the TNT configuration and incorporating lift-jet pods in the wings, but none of them reached the prototype stage.
During June 1956, deliveries of the T-37A commenced to the USAF; the service began both Aviation Cadet and commissioned officer pilot training using the type during the following year. The first T-37B was delivered in 1959. Instructors and students typically considered the T-37A to be a pleasant aircraft to fly, handling relatively well, being agile and responsive, though it was definitely not overpowered. It was capable of all traditionalaerobatic maneuvers. Students intentionally placed the aircraft into a spin as part of their pilot training.
The T-37A was very noisy even by the standards of jet aircraft. The intake of air into its small turbojets emitted a high-pitched shriek that led some to describe the trainer as the "Screaming Mimi",[24] the "6,000 pound dog whistle"[25] or "Converter" (converts fuel and air into noise and smoke).[26] The piercing whistle gave rise to the T-37's nickname of "Tweety Bird", which was regularly shortened to "Tweet".[19] The USAF expended a considerable amount of time and money onsoundproofing buildings at bases where the T-37 was stationed whileear protection were mandatory for all personnel when near an operating aircraft.
By 1996, a total of 132 aircraft had been lost in Class A accidents and 75 fatalities had been incurred, the majority of which were attributed to pilot error. Common errors included inadvertently shutting down the engines via throttle mismanagement, use of the aircraft in cold weather conditions, and oil system issues.[27]
During the late 1970s, amid rising tensions betweenArgentina andChile over conflicting territorial claims, commonly referred to be as theBeagle conflict, theChilean Air Force retrofitted their T-37s into an armed configuration near identical to that of the A-37.[28] Similarly, theColombian Air Force decided to reorient its T-37Cs from training to light attack duties during the early 1980s.[29]
Over the decades, the USAF made several attempts to replace the T-37, such as the abortiveFairchild T-46, however it remained in service with the USAF into the twenty-first century. The T-37 was ultimately phased out in favor of theBeechcraft T-6 Texan II between 2001 and 2009. The T-6 is aturboprop aircraft that possesses more power, betterfuel efficiency, and more modernavionics than the T-37. The final USAF student training sortie by a T-37B in theAir Education and Training Command took place on 17 June 2009. The last USAF operator of the T-37B, the80th Flying Training Wing, flew the sortie from its home station atSheppard Air Force Base, Texas. The last T-37B was officially retired from active USAF service on 31 July 2009.[30]
Ecuador
Pakistan
.jpg)
T-37s, including both new-build and ex-USAF aircraft, were supplied to a number of countries, including:
Bangladesh
Brazil
Burma
Chile
Colombia
Germany
Greece
Jordan
Khmer Republic
Portugal
Peru Pakistan
South Korea
South Vietnam
Thailand
Turkey
United States
Vietnam
Morocco
Data fromJane's All the World's Aircraft 1965–66,[5]A-37/T-37 Dragonfly in Action[41]
General characteristics
Performance
Armament
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.
| National | |
|---|---|
| Other | |
