Berkshire Concept 70
Страна: США
Год: 1971

Single-seat Standard Class sailplane
M.Hardy. Gliders & Sailplanes of the world

M.Hardy. Gliders & Sailplanes of the world

Concept 70 USA

  Rather surprisingly, in view of the large-scale use of glassfibre in such leisure products as sailing boats and dinghies, the USA was a latecomer in its application to sailplane structures, American manufacturers generally preferring to use metal construction. The first US all-glassfibre sailplane, known as the Concept 70, did not make its first flight until 1970, some 13 years after the Akaflieg Stuttgart FS-24 Phonix had pioneered this material for sailplane structures and the same year in which Bolkow ended production of the balsa wood/glassfibre Phoebus, derived from the Phonix, after over 250 had been built. The single-seater Standard Class Concept 70 was the responsibility of Arthur Zimmerman and Wolfgang Schaer and production by the Berkshire Manufacturing Corporation got under way in 1973, some 16 Concept 70s having been built by the spring of 1974. The cantilever shoulder wings have a constant chord centre section and tapered outer panels, and are of glassfibre/PVC foam sandwich construction, with aluminium flaps lowering to 90°; up to 200lb of water ballast can be carried. The glassfibre monocoque fuselage has a steel tube reinforcing frame connecting the monowheel and wing fittings and continuing into the cockpit for greater strength and rigidity. The pilot sits in a semi-reclining seat, recessed for an American-type parachute, under a one-piece flush Plexiglas canopy which is hinged and jettisonable. The manually-retractable Tost monowheel has a drum brake.

Span: 49 ft 2 1/2 in
Length: 24 ft 0 in
Height: 6 ft 0 in
Wing area: 124 sq ft
Aspect ratio: 20.0
Empty weight: 500 Ib
Max weight: 875 lb
Max speed: 121 mph (in smooth air)
Min sinking speed: 2.03 ft/sec at 50.5 mph
Best glide ratio: 40:1 at 60 mph
A Berkshire Concept 70 glassfibre Standard Class sailplane about to land
Sixth production example of the Berkshire Manufacturing Corporation Concept 70 metal and glassfibre sailplane
Concept 70.