General Aircraft Monospar

https://en.wikipedia.org/wiki/General_Aircraft_Monospar

The General Aircraft Monospar was a 1930s British family of touring and utility
aircraft built by General Aircraft Ltd (GAL).

In 1929, the Monospar Company Ltd was formed to pursue new techniques of
designing cantilever wings, based on the work of Swiss engineer Helmuth J.
Stieger, who headed the company. Helmuth John Stieger was born in Zurich in 1902
and educated at the Swiss Federal Polytechnic then the Imperial College of
Science in London. While working as a designer for William Beardmore and
Company, he formed his own ideas about wing design and evolved an improved
method of building and stressing wings for which he was later granted a British
Patent in December 1927. The principle behind this Patent No. 306,220 was that
the wing needed only one spar with torsion loads resisted by an efficient system
of strong compression struts with triangulated bracing in the form of thin
wires. The design was revolutionary and very light for its strength.

Based on this design, The Monospar Company designed a twin-engined low-wing
aircraft designated the Monospar ST-3, that was built and flown in 1931 by the
Gloster Aircraft Company at Brockworth, Gloucestershire. After successful
testing of the Monospar ST-3, a new company General Aircraft Ltd was formed to
produce aircraft that used the new Monospar wing designs.

The first production design was the Monospar ST-4, a twin-engined low-wing
monoplane with a fixed tailwheel landing gear and folding wings for ground
storage. Powered by two Pobjoy R radial engines, the first aircraft (G-ABUZ)
first flew in May 1932, and was followed by five production aircraft. The
Monospar ST-4 Mk.II, an improved variant with minor differences, followed with a
production run of 30. In 1933, the Monospar ST-6 appeared, a similar aircraft to
the ST-4 with manually retractable landing gear and room for an extra passenger.
The Monospar ST-6 was only the second British aircraft to fly with retractable
landing gear (the first, the Airspeed Courier, was flown a few weeks earlier).
Another Monospar ST-6 was built, and two ST-4 Mk.IIs were converted. GAL then
produced a developed version, the Monospar ST-10, externally the same but
powered by two Pobjoy Niagara engines, an improved fuel system, and aerodynamic
refinements.

The Croydon factory closed down in 1934, and a larger factory was opened in 1935
at London Air Park, Hanworth.


Role
Cabin monoplane

Manufacturer
General Aircraft Ltd

First flight
1932

Number built
45

Variants
Monospar ST-25

The Monospar ST-10 prototype (G-ACTS) won the 1934 King's Cup Air Race with an
average speed of 134.16 mph. Only one other ST-10 was built, along with two
similar ST-11s with de Havilland Gipsy Major engines for export to Australia. A
production batch of ten Monospar ST-12 aircraft was based on the ST-11 with
fixed landing gear.

Specifications (Monospar ST-12)

General characteristics
Capacity: four
Length: 26 ft 4 in (8.03 m)
Wingspan: 40 ft 2 in (12.24 m)
Height: 7 ft 10 in (2.30 m)
Wing area: 217 ft2 (20.16 m2)
Empty weight: 1,840 lb (835 kg)
Gross weight: 2,875 lb (1,304 kg)
Powerplant: 2 × de Havilland Gipsy Major 4-cylinder inverted inline piston
engine, 130 hp (97 kW) each

Performance
Maximum speed: 158 mph (254 km/h)
Range: 410 miles (660 km)
Service ceiling: 21,000 ft (6,400 m)





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