When it was issued, Air Ministry Specification 5/24 sought an advanced trainer for Royal Air Force use, alongside being suitable for the Fleet Air Arm for practice deck-landings and general seaplane operations. This resulted in primary characteristics which included good low-speed handling and good acceleration on take-off.
Contracts were placed for three prototypes; Blackburn TR1 Sprat (N207), Vickers Vendace I (N208) and the Parnall Perch (N217). Power in each case was provided by a 275 hp Rolls-Royce Falcon III engine although the Sprat could also accommodate the Siddeley Puma or ADC Nimbus engines.
The Blackburn Aircraft Company Sprat was a single-bay biplane with folding wings and a wide-track divided undercarriage. Unusually, the centre section struts were in an 'X-configuration' splayed out from the fuselage top longerons, reminiscent of the earlier Blackburn Dart and Blackburn Velos. The air crew were provided with triangular windshields, with flight instruments arranged along the trailing edge of the upper wing centre section.
Twin floats were fitted for seaplane operations and water handling was said to be excellent. Correctly trimmed, the aircraft would fly cleanly off the water surface, even with the pilot’s hands off the controls.
The prototype Blackburn Sprat (N207) was flown for the first time on 24th April 1926, being subsequently tested at Martlesham Heath (on wheels), as well as Felixstowe (on floats), during June 1926.
By 3rd July 1926, the prototype (N207) had been restored to its landplane configuration and it was shown in the New Types Park at the annual RAF Display at Hendon. It gave a well-received, and spirited flying display at the show, although sadly it did not receive any order nor a production contract.
The winning design was judged to be the Vickers Vendace 1 although that also failed to receive a production contract because the requirement was later cancelled on economic grounds.
Variants & Number Built
One prototype (N207)
|Powerplant||One 275 hp Rolls-Royce Falcon III|
|Span||34 ft 9 in|
|Maximum Weight||3,220 lb||3,550 lb|
|Capacity & Armament||Instructor and student; no armament|
|Speed (sea level)||115 mph||112 mph|
|Speed (5,000 ft)||112 mph||109 mph|