The General Aircraft Monospar ST-25 was a British 1930s light twin-engined utility aircraft.
Design and development
The Monospar ST-25 was a low-wing cantilever monoplane with a fabric-covered metal structure. The monospar name came from the use of a single
spar in the wing structure, that had been developed by H J Stieger. The cabin was enclosed with five seats. It was based on the GAL
Monospar ST-10, with the addition of a folding seat for a fifth passenger, extra side windows, and the addition of a radio receiver. On 19 June 1935, the prototype (G-ADIV) made its first flight at
Hanworth Air Park. It was designated Monospar ST-25 Jubilee, to honour the 25th anniversary of the reign of King George V.[2]
Operational history
The last flying Monospar ST-25 (ZK-AFF), of
Piet Van Asch, the owner of New Zealand Aerial Mapping Ltd, was lost in 1986 in a hangar fire.[3]
The last surviving Monospar ST-25 (OY-DAZ), an ST-25 Ambulance, was fully restored during 1989–1999, and is now displayed in Egeskov Veteranmuseum at
Egeskov Castle, Denmark.[4]
Variants
Monospar ST-25 Universal, after conversion from ST-25 De LuxeMonospar ST-25 Universal
One Monospar ST-25 Jubilee with a large single fin and two
Niagara II engines, later converted to the prototype Monospar ST-25 Universal, with twin fins.[2]
Monospar ST-25 Ambulance
Variants of both Monospar ST-25 Jubilee and ST-25 Universal, with a large door on the starboard side to allow a stretcher to be loaded.[2]
Monospar ST-25 Universal
(1936-1939) Twin fin and twin rudder. 29 built, including the conversion of the De Luxe.[2]
Monospar ST-25 Freighter
A variant of the Monospar ST-25 Universal, with a large freight door but without the passenger seating.[2]
GAL.26
One modified Monospar ST-25 Jubilee, fitted with two
Cirrus Minor I engines in 1936.[2]
GAL.41
One experimental aircraft based on the Monospar ST-25 Universal. A new fuselage was built containing a pressurized section with two seats. Its purpose was to test possible pressurization systems for a proposed airliner, the GAL.40.[5][a] The GAL.41 flew for the first time on 11 May 1939,[7] and was grounded in 1941.[8]