Country of origin:

United Kingdom

Description:

Light twin-engine low-wing cabin monoplane

Power Plant:

Two 71 kw (95 hp) Pobjoy Niagara II seven-cylinder air-cooled radial engines

Specifications:

History:

In about 1930 the Monospar Wing Company Ltd was set up to build a new design of wing for the British Air Ministry, the new wing being fitted to a three-seat low-wing monoplane named the Monospar ST.3. Powered by two 37 kw (50 hp) Salmson radial engines, this aircraft undertook much testing to prove the strength of the new design. Success led to the formation of a new company, General Aircraft Ltd, to build aircraft utilising the new method of construction and this ultimately led to the development of the Monospar series of monoplanes.

Initially a batch of five aircraft, known as the ST.4, was built, the prototype G-ABUZ (c/n 1) flying for the first time in May 1932. One G-ABVN (c/n 2), the first production aircraft, served with Portsmouth Southsea & Isle of Wight Aviation before being flown to Australia in December 1936 / January 1937 by C D and M M Kelman, his wife. It was used by the Royal Australian Air Force (RAAF) as an Instructional Airframe during World War II but its subsequent history in Australia is not known. The fuselage was noted at Bankstown, NSW amongst derelict aircraft in 1954. Its ultimate fate is not known.

The Monospar developed through a series of models in the 1930s with the ST.4 Mk II and the ST.6, of which only three were completed. In 1933 the manufacturer’s Croydon plant was closed and the company re-organised, production re-commencing at a facility at Hanworth in Middlesex. A new model, the ST.10, later appeared, fitted with 67 kw (90 hp) Pobjoy Niagara radial engines. However, it did not go into production and only two examples were completed. Of these one, VH-UST (c/n ST10/34), was operated by Robert Bryce & Company of Melbourne, VIC; WASP Airlines of Sydney, NSW; and J J Larkins and J N Jackson of Mascot, NSW, but was destroyed when it collided with de Havilland DH.60G VH-UFV (c/n 1A) at Mascot on 19 November 1939.

Two similar aircraft were built fitted with 60 kw (80 hp) Pobjoy Niagara engines and retractable undercarriages as the ST.11, both being imported to Australia. The first VH-UAZ (c/n ST11/33) was registered to the Department of Civil Aviation (DCA) in October 1934 and remained with the Department until it was damaged on take-off at Archerfield, QLD on 1 February 1937. It was repaired and went to K R M Farmer at Coode Island, VIC in February 1941, and later Airlines (WA) Ltd on 29 May 1942. It was damaged by wind after landing at Rockwell, NSW on 25 November 1942. It crashed on take-off at Maylands, WA on 16 June 1944 and the Certificate of Airworthiness lapsed in October 1945. The fuselage at one stage was reported to be in the collection of the Bull Creek Air Force Museum in Perth, WA.

The second ST.11, VH-USN (c/n ST11/37), was delivered by air from the United Kingdom in January 1935 and was first registered to Eastern Air Transport in February 1935; then Kingsford Smith Air Service Ltd in June 1938. It was taken over by Airflight Ltd at Mascot in September 1940. It was finally struck off the register in July 1947 and broken up.

In 1936 an improved variant known as the ST.25 appeared, powered by Pobjoy Niagara III engines with Rotax electric starters and other minor modifications, but only two were built. Up to this stage General Aircraft had not been particularly happy with directional control when an engine was lost, and some testing was carried out on an ST.10 fitted with twin rudders in place of the single rudder. This led to the ST.25 Universal, 29 examples of which were built.

One ST.25 Monospar was imported to New Zealand in 1936 for NZ Aerial Mapping Company of Hastings for aerial photographic work, becoming ZK-AFF (c/n ST25/84). It operated from 1936 to 1943, when it was placed in storage as the operator used a Beech AT.11 Kansan in that period. It was overhauled in 1968 and resumed work but was destroyed in a hangar fire on 26 June 1986.

In 1935 a new model appeared, this being basically the ST.10 with additional windows and a folding seat for a fifth passenger. Known as the ST.25 Jubilee, 30 examples were built. Three came to Australasia: VH-UUV (c/n ST25/48 – ex HB-AIR) was operated by Adelaide Airways Ltd from 25 October 1935, later Australian National Airways Pty Ltd (named ‘Boyana’) from 1 November 1936. On 8 October 1938 it was damaged at Somerton, VIC and lay inactive until struck off the register on 14 June 1940.

VH-UVJ (c/n ST25/60) was first registered in December 1935 to Airlines (WA) Ltd, having first flown on 9 October 1935. It was shipped to Fremantle, WA and named ‘Miss Wiluna’, initially operating on the Perth – Wiluna – Kalgoorlie route in Western Australia. It suffered an engine failure on 22 December 1936 near Meekathara, WA, and made a forced landing. It was substantially damaged, was not rebuilt, and was struck off the register in December 1936.

The third aircraft VH-UVM (c/n ST25/69) was registered to Robert Bryce & Company on 14 February 1936. It was sold to the Canterbury Aero Club at Christchurch in New Zealand in October that year as ZK-AET. It was impressed by the Royal New Zealand Air Force (RNZAF) as NZ584 on 13 October 1939 and was operated by the Communications Flight at Rongotai. It became Instructional Airframe 32 in January 1941 and was later broken up.