Schweizer SGM 2 37

Development

Schweizer had flown a Schweizer SGU 1–19 as a motor glider in 1946 without putting the design into production. Later in 1958 the company carried out a design study of a powered aircraft based on the 1–26 designated as the Schweizer SA 1-30, but after some test flying and modification it was not put into production. A single motorglider prototype, the Schweizer 2–31 was completed, but no further motorgliders were built by the company until 1982.

The SGM 2–37 was designed at the request of the USAF for use at USAFA, in both the powered and glider trainer role.

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

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

Tail from the Schweizer SGS 2-32

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.

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.

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.

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 28:1 with the propeller feathered, and a minimum sink speed of 3.16 feet/sec (0.96 m/s). The USAF Technical Orders indicate a glide ratio of between 19.3:1 and 19.7:1.

The SGS 2–37 was marketed by the company as being suitable for the following roles:

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 Schweizer RU-38 Twin Condor.

Certification

The SGM 2–37 was certified by the Federal Aviation Administration under type certificate G1NE on 22 March 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.

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 United States Dollar70,000 base price did not include a feathering propeller, gyro instruments, wheel fairings, long range fuel tanks or other optional extras.

Operational history

Examples of the TG-7 were used by the US Army from 1985 on covert surveillance duties under the Grisly Hunter project. The two aircraft were then transferred to the US Coast Guard by mid 1989, were modified and were re-designated RG-8A. The aircraft were used on coastal patrols from the US Coast Guard base at Miami wearing a grey low visibility color scheme, as shown in the adjacent image taken in 1989.

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.

Variants

SGM 2–37

Motor glider for USAF and civil use, 12 completed.

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 235 hp (175kW) and first flown in 1982 and eight. 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.

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 lb (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 lb (1950 kg). The US aircraft registry records four SA 2-37Bs, all owned by Schweizer Aircraft. All are in the experimental Research and Development category.

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.

Operators

 United States

United States Air Force

United States Army

United States Coast Guard

 Colombia

Colombian Air Force

 Mexico

Mexican Air Force

Specifications (SGM 2–37)

Data from Sailplane Directory, USAFA, Soaring magazine November 1983 & FAA Aircraft Type Certificate G1NE

General characteristics

Crew: two in side-by-side seating

Length: 27 ft 6 in (8.5 m)

Wingspan: 59 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)

Useful load: 650 lb (295 kg)

Loaded weight: 1850 lb (839 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)