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Schweizer SGM 2-37 / TG-7A / RG-8A

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The SGM 2-37 self-launching two-place, side-by-side, fixed gear, motorglider designed by Leslie Schweizer at the request of the USAF for use at USAFA.

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 (112 kW) or a Lycoming O-360 of 180 hp (134 kW).

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, and has the capacity to operate as a towplane for other gliders.

First flying in 1982, 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.

USAFA TG-7A

The SGM 2–37 was certified by the Federal Aviation Administration under type certificate G1NE on 22 March 1983. The 2–37 type certificate was later held by K & L Soaring of Cayuta, New York. K & L Soaring provided all parts and support for the Schweizer line of sailplanes.

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 $70,000 base price did not include a feathering propeller, gyro instruments, wheel fairings, long range fuel tanks or other optional extras.

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 in 1989.

RG-8A surveillance aircraft of the US Coast Guard at Opa Locka, Miami, in 1989.

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

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.

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.

Operators also included the Colombian Air Force and Mexican Air Force.

SA2-37B of the Aerial Surveillance Squadron, 3rd Air Group, Mexican Air Force at Santa Lucia Air Force Base

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

SGM 2–37 / TG-7A
Engine: 1 × Lycoming O-235-L2C, 112 hp (84 kW)
Prop: aluminum fixed pitch
Wingspan: 59 ft 6 in (18.14 m)
Wing area: 195.7 ft2 (18.18 m2)
Airfoil: Wortmann Fx 61–163
Aspect ratio: 17.9
Length: 27 ft 6 in (8.5 m)
Height: 7 ft 8 in (2.4 m)
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)
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)
L/DMax: 28
MinSink: 0.96 m/s / 3.16 fps / 1.87 kt
Glide ratio: 19.3:1 – 19.7:1
Wing loading: 9.45 lb/ft2 (46.15 kg/m2)
Power/mass: 16.51 lb/hp (0.100 kW/kg)
Baggage compartment: 27 cu.ft / 760 lt
Crew: two side-by-side

SA 2-37A
Engine: 1 × Lycoming TIO-540-B, 235 hp (175kW)
Crew: two side-by-side

SA 2-37B
Engine: 1 × Lycoming TIO-540-AB1AD, 250 hp
Gross weight: 4300 lb (1950 kg)
Fuselage bay: 70-cubic-foot (2,000 L)
Sensor payload: 500 lb (231 kg)
Fuel capacity: 99 US gallons (370 lt)
Time on station: 12 hr

Schwarz No.1 / No.2

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In 1895 Austrian timber merchant David Schwarz produced plans for a rigid-framed airship. It was built in St Petersburg for the Russian government but, although completed, never flew due to political complications; the Russians constantly regarding Schwartz as a spy. Schwartz was forced to leave Russia in secrecy, retuning to Germany where he built a second airship of similar design for the Prussian Airship Division in Berlin.

Schwarz died before the constuction was complete. The work was taken over by his able and practable widow until completed. The airship was a bottle-shaped craft of cylindrical form with a conical nose and shallow rounded stern, an internal framework constructed of tubular aluminium members and girders was covered by a skin of sheet aluminium .008in in thickness. The hull contained a single gas cell.

The filling of the envelope was accomplished by introducing a series of paper bags within the framework to be filled with hydrogen gas, which at the same time expelled an equal volume of air contained within the metal hull. A two-cylinder Daimeter petrol motor of 12 hp provided power, driving three airscrews through fabric transmission belts.

Two wing screws mounted above the car were assigned to drive the craft through the air, while a third larger diameter propeller mounted on the centre line, able to move through 90˚ vertically and horizontally, was supposed to control direction.

Schwarz No.2 crashed on its initial flight at Tempelhof on 4 November 1897. With the engines running, the ground crew released the ropes and the airship rose to approximately 100 ft. Maintaining its position against the breeze for some minutes, the airship was beginning to make headway against the wind when the left-hand driving belt jumped off its sheaves.

The airship continued to rise to 1300 ft as the pilot, a soldier named Ernst Jagels, struggled to maintain control, adjusting the angle of the central propeller to counter the wind. Just as he was turning into wind the right-hand driving belt also slipped off. Jagels valved gas to bring the craft down near the Tempelhof Field but the descent was too rapid, causing it to crash heavily on the ground, completely wrecking the airship. Jagels escaped unharmed but without further funding the project was abandoned.

Envelope capacity: 131,000 cu.ft
Length: 154 ft
Diameter: 46 ft
Height: 60 ft
Engine: Diamler 2 cyl, 12 hp
Speed: 17 mph
Crew: 1

Sclaves 1910 Biplane

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This tractor French biplane, constructed of metal pipes and an abundance of wire bracing, powered by an acetylene motor was tested at Amberieu in 1910 by a man from Lyon named Sclaves. At least one photo shows a 50 hp Prini-Berthaud engine. The rectangular wings were braced entirely by one pair of outboard struts on each side and wires from double kingposts on top. The heavy forward box structure seemed made of pipes; the rear fuselage was uncovered. The two wheels were castering.

Schüler 1909 Eindecker

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This high-wing monoplane was tested in late spring and summer of 1909 at the parade ground in Chemnitz, Saxony, after a public exhibition in April 1909. Schüler had completed his engineering studies there. It was probably inspired by the Demoiselle and was completed before Hans Grade had built his first similar “Libelle” in June 1909. The machine was not a great success and thus Schüler didn’t appear at the first German aeronautical exhibition (ILA) in Frankfurt or the first meeting at Johannisthal in September/October 1909, but he was among the first who rented a shed at this newly built airfield. At the beginning of 1910 Schüler was busy working on a monoplane for Leo Lendner and building engines for Hanuschke and others in his “Max Schüler Aeroplan-Fabrik”, which he had founded in his hometown Berlin in late 1909.