This Standard Class single-seater was designed by John Sellers, who was also responsible for the Slingsby T53, for Torva Sailplanes Ltd of Scarborough, Yorkshire, which company he had formed in September 1969 with Chris Riddell, and it was intended to be a moderately priced type with good performance suitable both for clubs and the private owner and competition pilot, for whom two production versions were to have been marketed.
These were the Torva 15 Standard for club use and the Torva 15 Sport for the private owner and contest flying, the latter being fitted with flaps and having a retractable monowheel, while the Standard had provision for up to 130lb of water ballast. The Torva 15 was noteworthy as being the first British designed sailplane to be constructed largely of glass-reinforced plastics (GRP), although the wings have plywood ribs and the fuselage has plywood and foam sandwich frames to support its GRP shell and side longerons. Design work began on 6 October 1969 and construction of the Torva 15 Sport prototype (also known as the Torva TA 1) commenced on 16 March 1970; this first flew on 8 May 1971 in the hands of Chris Riddell. A modified Wortmann aerofoil section was chosen for the cantilever shoulder wings to give a very high lift coefficent for achieving a good rate of climb in weak British thermals, and also to give a low stalling speed for short-field landings. The wings have a GRP spar with ply webs and GRP/balsa shell; both the ailerons and flaps are of GRP with a foam core, the ailerons having variable differential and drooping with the flaps, but being isolated from the latter at the flap full-down position. Light alloy Schempp-Hirth air brakes are also fitted. The fuselage and canopy shape were computer calculated to achieve a good aerodynamic shape and roomy cockpit; the pilot sits under a Suntex lift-off transparent one-piece canopy and has a GQ five-point seat harness. The tail surfaces have GRP/balsa shells and plywood webs, the tailplane being an all-moving surface with a geared anti-balance tab. The retractable rubber-sprung monowheel is located forward of the eg and is manually retracted, with an internal expanding brake; there is also a GRP sprung tailskid with a small wheel.
Only three more Torva 15s were built after the prototype, as the company was forced to close down; these were also known as TA 2 Sprites.
Torva 15 Standard
Span: 15.0 m / 49 ft 2.5 in
Length: 7.11 m / 23 ft 3.25 in
Height: 5 ft 0 in
Wing area: 11.3 sq,m / 121.5 sq.ft
Aspect ratio: 20.0
Empty weight: 238 kg / 525 lb
Max weight: 408 kg / 900 lb
Water ballast: 59 kg / 130 lb
Max speed: 134 mph / 116 kt / 216 km/h (in smooth air)
Max rough air speed: 80 kt / 148 km/h
Stall speed: 35 kt / 65 km/h
Min sinking speed: 0.62 m/sec / 2.03 ft/sec at 50 mph / 43.5 kt / 81 km/h
Best glide ratio: 37:1 at 51 mph / 44 kt / 82 km/h
