Schweizer SGM 2-37

The Schweizer SGM 2-37 is a two-place, side-by-side, fixed gear, low wing motor glider.^[1][3]

A total of twelve were produced between 1982 and 1988, including nine for the United States Air Force Academy, which designated it the TG-7A. The TG-7A was retired from USAFA service in April 2003.^[1][2][4]

The basic airframe was later developed into the SA 2-37A and B covert surveillance aircraft.^[5]

Development

Schweizer had flown a Schweizer SGU 1-19 as a motor glider in 1946 without putting the design into production. Later the company carried out a design study of a motorglider designated as the Schweizer 1-30, but no examples were built. A single motorglider prototype, the Schweizer 2-31 was completed, but no further motorgliders were built by the company until 1982.^[6][7][8][9]

The SGM 2-37 was designed at the request of the USAF for use at USAFA, in both the powered and glider trainer role.^[3]

To save both money and development time the aircraft used a number of existing aircraft components:

• Nose, cowling and engine installation adapted from the Piper PA-38 Tomahawk^[2]
• Wings adapted from the Schweizer SGS 1-36 Sprite, including extensions to bring it from the Sprite's 46.2 feet (14.1 m) to 59.5 feet (18.1 m) and leading edge cuffs to improve stall characteristics^[2]
• Tail from the Schweizer SGS 2-32^[2]

The design was intended to be available as a civil aircraft as well as a military aircraft. The USAF version was delivered with a Lycoming O-235-L2C 4 cylinder aircraft engine of 112 hp (84 kW). The civil version offered the same engine or an option of a Lycoming O-320 of 150 hp or a Lycoming O-360 of 180 hp.^[2][3]

The aircraft is of all metal aluminum monocoque construction. The engine cowling is made from fiberglass and plastics are employed in some of the nonstructural components.^[2]

The 2-37 features a 27 cu ft (760 L) baggage compartment behind the side-by-side seating. The aircraft does not have flaps, but instead has top-and-bottom wing-mounted balanced divebrakes, similar to other Schweizer glider designs.^[3]

Performance includes a cruise speed of 114 mph while burning 4 US gal per hour with the O-235 engine. The 17.9 aspect ratio wing provides a glide ratio of 29:1 and a minimum sink speed of 3.16 feet/sec (0.96 m/s). The SGS 2-37 was marketed by the company as being suitable for the following roles:^[1][3]

• Sailplane trainer
• Powered aircraft trainer
• Glider towplane (with larger horsepower engine option)
• Private touring aircraft
• Surveillance
• Aerial Inspection

The 2-37 was later developed into the SA 3-38, known in military service as the RU-38 Twin Condor.

Certification

The SGM 2-37 was certified by the Federal Aviation Administration under type certificate G1NE on March 22, 1983. The 2-37 type certificate is currently held by K & L Soaring of Cayuta, New York. K & L Soaring now provides all parts and support for the Schweizer line of sailplanes.^[10][11]

Reception

Soaring, the journal of the Soaring Society of America, described the SGM 2-37 as: "Very versatile, very promising, very expensive". The publication's review noted that the USD$70,000 base price did not include a feathering propeller, gyro instruments, wheel fairings, long range fuel tanks or other optional extras.^[3]

Operational history

There were nine aircraft still registered in the USA in April 2008. Current owners include the Tuskegee Airmen National Historical Museum and designer Leslie E. Schweizer.^[12]

Variants

SGM 2-37

Motor glider for USAF and civil use, 12 completed.^[1][3]

SA 2-37A

The SA 2-37A is a two seat special mission surveillance aircraft built for the Central Intelligence Agency and US Army and equipped with a Lycoming O-540-B powerplant of 235hp (175kW) and first flown in 1982 and eight.^[13] The US aircraft register records six SA-2-37As, including four belonging to Vantage Aircraft Leasing with serial numbers as high as 8. All are in the experimental exhibition category.^[14]

SA 2-37B

The SA 2-37B is a development of the 2-37A equipped with a Lycoming TIO-540-AB1AD powerplant of 250 hp. The aircraft is optimized for covert surveillance missions and carries FLIR and electronic sensors. It has a 500 pound (231 kg) sensor payload in a 70-cubic-foot (2,000 L) fuselage bay. With a fuel capacity of 99 US gallons (370 L) it can remain on station for up to 12 hours. Gross weight is 4300 lbs (1950 kg).^[5] The US aircraft registry records four SA 2-37Bs, all owned by Schweizer Aircraft. All are in the experimental Research and Development category.^[15]

TG-7A

United States Air Force designation for the SGM 2-37.

RG-8A

In US Coast Guard service the SA 2-37 is designated RG-8A, indicating Glider, Reconnaissance.^[16]

Operators

 United States

• United States Air Force
• United States Coast Guard

 Colombia

• Colombian Air Force^[17]

 Mexico

• Mexican Air Force^[18]

Specifications (SGM 2-37)

Data from Sailplane Directory,^[1] USAFA,^[2] Soaring magazine November, 1983^[3] & FAA Aircraft Type Certificate G1NE^[10]

General characteristics

• Crew: two in side-by-side seating
• Length: 27 ft 6 in (8.5 m)
• Wingspan: 56 ft 6 in (18.14 m)
• Height: 7 ft 8 in (2.4 m)
• Wing area: 195.7 ft² (18.18 m²)
• Airfoil: Wortmann Fx 61-163
• Empty weight: 1200 lb (544 kg)
• Loaded weight: 1850 lb (839 kg)
• Useful load: 650 lb (295 kg)
• Max takeoff weight: 1850 lb (839 kg)
• Powerplant: 1 × Lycoming O-235-L2C aluminum fixed pitch, 112 hp (84 kW)

Performance

• Never exceed speed: 135 mph (219 km/h)
• Maximum speed: 135 mph (181 km/h)
• Cruise speed: 112 mph (181 km/h)
• Stall speed: 48 mph with divebrakes closed (78 km/h)
• Range: 230 mi (372 km)
• Service ceiling: 14,000 ft (4300 m)
• Rate of climb: ft/min (m/s)
• Wing loading: 9.45 lb/ft² (46.15 kg/m²)
• Power/mass: 16.51 lb/hp (0.100 kW/kg)

See also

• List of gliders
  

Aircraft of comparable role, configuration and era

• Diamond HK36 Super Dimona
• Grob G 109
• Pipistrel Sinus
• Valentin Taifun
  

References