Cunningham-Hall GA-21M

GA-21M
Cunningham-Hall GA-36 tandem seat, military version of GA-21M.
General information
Type	Sports monoplane
National origin	United States
Manufacturer	Cunningham-Hall Aircraft Corporation
Designer	Randolph Hall
Number built	1
History
First flight	1934

The Cunningham-Hall GA-21 was an American two-seat monoplane design to compete for the Guggenheim Safe Aircraft Competition in 1934. Its distinguishing feature was full span flaps which could be manually or automatically adjusted. The GA-36 was a military version of it with tandem, rather than side-by-side seating. ^[1]

Design and development

The GA-21M was all metal aircraft apart from the fabric covering of parts of the wing, otherwise metal-covered, and the control surfaces. The low-set wings were rectangular in plan out to rounded tips and had a high lift section. Both flaps and ailerons filled the whole straight part of the trailing edge, so the latter only opened upwards. ^{[2] [3]}

Apart from its unusual flaps and lateral control the GA-21M was conventional. Powered by a 145 hp (108 kW), seven cylinder Warner Super Scarab radial engine, it had a round-sectioned, metal-skinned, monocoque fuselage. An open cockpit over the forward wing seated two side-by-side. The tailplane was mounted just above the fuselage on the fin and could be trimmed; essentially triangular in plan, it carried rounded elevators. A rounded rudder reached down to the keel. ^[2]

The GA-21Ms had conventional, tailwheel landing gear with the landing wheels ahead of the leading edge within aircraft fairings that also enclosed the legs. ^[2]

The GA-36 was a 1936 military trainer rebuild of the Ga-21M. This included a revised, tandem cockpit and more trouser-like landing gear fairings, making it 15% heavier. ^{[4] [3]}

The automated flaps worked well but were more complicated than, for example, Fowler flaps ^[3] and more expensive to construct. Simpler systems were preferred and the sole GA-21M/36 was sold in 1941, stripped of major components and dumped until the 1980s when it was recovered, fully restored and put on display at the Niagara Aerospace Museum. ^[5]

Specifications (GA-36)

Data from Aero Digest, March 1937 ^[4]

General characteristics

• Crew: 2
• Length: 20 ft 0 in (6.10 m)
• Wingspan: 30 ft 0 in (9.14 m)
• Height: 6 ft 5 in (1.96 m)
• Wing area: 131 sq ft (12.2 m²)
• Empty weight: 1,490 lb (676 kg)
• Gross weight: 2,100 lb (953 kg)
• Fuel capacity: 29 US gal (24 imp gal; 110 L)
• Powerplant: 1 × Warner Super Scarab seven cylinder air-cooled radial piston engine, 145 hp (108 kW) at 2,050 rpm
• Propellers: 2-bladed Hamilton Standard, 8 ft (2.4 m) diameter

Performance

• Maximum speed: 158 mph (254 km/h, 137 kn)
• Cruise speed: 140 mph (230 km/h, 120 kn)
  
• Landing speed with-without flaps: 45–63 mph (72–101 km/h; 39–55 kn)
• Range: 450 mi (720 km, 390 nmi)
• Service ceiling: 14,000 ft (4,300 m)
• Rate of climb: 850 ft/min (4.3 m/s)

References

1. https://airandspace.si.edu/collection-archive/cunningham-hall-collection/sova-nasm-xxxx-0447
2. "Cunningham-Hall Commercial Monoplane". Aero Digest. New York City: Aeronautical Digest Publishing Corp. January 1935. p. 33.
3. "American airplanes - Cu - Cy". www.aerofiles.com. 3 August 2008. Retrieved 2010-01-01.
4. "Cunningham-Hall GA-36". Aero Digest. Vol. 30, no. 3. New York City: Aeronautical Digest Publishing Corp. March 1937. p. 64.
5. Niagara Aircraft Museum - Collection