General Aircraft Monospar ST-25

Monospar ST-25
Monospar ST-25 Jubilee of Eloy Fernández Navamuel during the Spanish Civil War[1]
Role
National origin	United Kingdom
Manufacturer	General Aircraft Ltd, Hanworth
First flight	19 June 1935
Produced	1935-1939
Number built	60
Developed from	General Aircraft Monospar ST-10

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 earlier GAL Monospar ST-10, with the addition of folding seat for a fifth passenger and the addition of a radio receiver. First flying on 19 June 1935, the type was named Jubilee, and also numbered 25, in honour of 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's New Zealand Aerial Mapping Ltd was lost in 1986 as a result of a hangar fire.^[3]
• The last surviving Monospar ST-25 (OY-DAZ), an ST-25 Ambulance, was fully restored during 1989-1999, and now displayed in Egeskov Veteranmuseum at Egeskov Castle, Denmark.^[4]

Variants

Monospar ST-25 Jubilee

(1935-1936) Single fin and rudder. 30 built.^[2]

Monospar ST-25 De Luxe

One Monospar ST-25 Jubilee with 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 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. The GAL.41 flew for the first time 11 May 1939, and was grounded in 1941.^[5]

Operators

 Australia

• Adelaide Airways

 Canada

• Eastern Canada Air Lines (5 × ST-25 Freighters, delivered in 1936)

 Denmark

 France

 New Zealand

• New Zealand Aerial Mapping
• Royal New Zealand Air Force

 Romania

• Royal Romanian Air Force

 Spain

• Spanish Republican Air Force

 Spain

• Spanish Air Force

 Turkey

• Turkish Government (2 × ST-25 Freighters for parachute training delivered in 1937)
• Turkish Mapping Aviation

 United Kingdom

• Crilly Airways
• Royal Aircraft Establishment (2 × Jubilees used for radio development)
• Royal Air Force (impressed civil aircraft used during the second world war)

Specifications (Monospar ST-25 Jubilee)

Data from Jackson, 1973

General characteristics

• Crew: 1
• Length: 26 ft 4 in (8.03 m)
• Wingspan: 40 ft 2 in (12.24 m)
• Height: 7 ft 10 in (2.39 m)
• Wing area: 217 sq ft (20.16 m2)
• Empty weight: 1,680 lb (762 kg)
• Loaded weight: 2,875 lb (1,304 kg)
• Powerplant: 2 × Pobjoy Niagara II radial engine, 90 hp (67 kW) each

Performance

• Maximum speed: 142 mph (228.5 km/h)
• Range: 585 miles (941 km)
• Service ceiling: 16,000 ft (4,877 m)
• Rate of climb: 800 ft/min (4.06 m/s)

See also

General Aircraft ST-18 Croydon

Notes

1. ^ Howson, 1990
2. ^ ^{a b c d e f g} Jackson 1973, pp. 215-220
3. ^ NZ Aerial Mapping
4. ^ Ogden (2009)
5. ^ British Aircraft of WW2 accessed 13 July 2007

Bibliography

• Howson, Gerald. 1990. Aircraft of the Spanish Civil War 1936-39. Putnam ISBN 978-0851778426
• Jackson, A.J. (1973). British Civil Aircraft since 1919, Volume 2. Putnam. pp. 215-220, 519-521 ISBN 0 370 10010 7
• Lumsden, Alec; Heffernan, Terry. Probe Probare, Aeroplane Monthly, February 1984
• Ogden, Bob (2009). Aviation Museums and Collections of Mainland Europe. Air-Britain. ISBN 9780851304182
• Stroud, John. Wings of Peace, Aeroplane Monthly, April 1988

External links

• British Aircraft Directory accessed 13 July 2007