General Aircraft Monospar ST-25 Universal

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.Jackson 1973, pp. 215–220

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.
*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.

Variants

;Monospar ST-25 Jubilee
:(1935-1936) Single fin and rudder. 30 built.
;Monospar ST-25 De Luxe
: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.
;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.
;Monospar ST-25 Universal
:(1936-1939) Twin fin and twin rudder. 29 built, including the conversion of the De Luxe.
;Monospar ST-25 Freighter
:A variant of the Monospar ST-25 Universal, with a large freight door but without the passenger seating.
;GAL.26
:One modified Monospar ST-25 Jubilee, fitted with two Cirrus Minor I engines in 1936.
;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. The GAL.41 flew for the first time 11 May 1939, and was grounded in 1941.

Operators

;
*Adelaide Airways
;
*Eastern Canada Air Lines (five ST-25 Freighters, delivered in 1936)
;
;
*ES-AXY "Vahur", in the service of the Ministry of Transport and Communications
;
*Armée de l'Air (2 ST-25 in Indochine (Vietnam) in November 1945)
;
*Van Melle's Confectionery Works, Breskens (one Jubilee, PH-IPM "Dubbele Arend", delivered in 1935)
;
*New Zealand Aerial Mapping
* Royal New Zealand Air Force
;
*Royal Romanian Air Force
;
* Spanish Republican Air Force
;
* Spanish Air Force
;
* General Command of Mapping (Turkey)
*Turkish Government (two ST-25 Freighters for parachute training delivered in 1937)
;
*Crilly Airways
* Royal Aircraft Establishment (two Jubilees used for radio development)
*Royal Air Force (impressed civil aircraft used during the second world war)

Specifications (Monospar ST-25 Jubilee)

See also

* General Aircraft ST-18 Croydon

References

Citations

Bibliography

*Howson, Gerald. 1990. ''Aircraft of the Spanish Civil War 1936–39''. Putnam
*Jackson, A.J. (1973). ''British Civil Aircraft since 1919'', Volume 2. Putnam. pp. 215–220, 519–521
*Lumsden, Alec; Heffernan, Terry. ''Probe Probare'', Aeroplane Monthly, February 1984
*Ogden, Bob (2009). ''Aviation Museums and Collections of Mainland Europe''. Air-Britain.
*Stroud, John. ''Wings of Peace'', Aeroplane Monthly, April 1988
*

{{GAL aircraft

1930s British civil utility aircraft
ST-25
Low-wing aircraft
Aircraft first flown in 1935
Twin piston-engined tractor aircraft