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FFA Diamant Switzerland

  This Swiss high performance single-seater is notable in being a true all-glassfibre sailplane in which the whole structure is made of that material, differing from most other glassfibre designs which use such materials ДальшеMore>>> as plywood or balsa quite extensively; only the flying control systems and fittings of the Diamant are of other materials. The ideal of an all-glassfibre sailplane was achieved in several stages, the first being development of the fuselage and tail unit at the Swiss Federal Institute of Technology in Zurich under the direction of Professor Rauscher. A prototype fuselage was built in 1962 and was flown with the plywood and fabric wings of a Schleicher Ka 6CR, the resulting aircraft being designated Ka-Bi-Vo. The Diamant's development was now gradually taken over by Flug- und Fahrzeugwerke AG FFA, and the next stage was the HBV-Diamant 15 which used the 15m span wings of the Glasflugel H 301 Libelle. This first flew on 5 September 1964 and 13 of this variant were subsequently built; the Libelle's wings being glassfibre balsa sandwich shells without ribs, featuring ailerons that gave partial downward movement when the flaps were lowered, and there were glassfibre dive brakes forward of the flaps. The HBV-Diamant 15 was followed by the generally similar Diamant 16.5, with wings of increased span (16.5m) designed and built by FFA; a total of 41 of this variant were built. Latest version is the Diamant 18, which first flew in February 1968, very similar to the 16.5 but with the span increased to 18m (59 ft 0 1/2 in); like the Diamant 16.5, water ballast an be carried in the wing roots. The monocoque fuselage is an epoxy-glassfibre sandwich with foam inserts, and the tail unit is of the same construction, the all-moving one-piece tailplane being mounted on top of the fin. As well as a small tailwheel (a tailskid is optional) there is a manually-retractable monowheel with a brake, and another feature is a glassfibre ring spring shock absorber; the tow release retracts with the landing gear. The pilot sits in a semi-reclining position under a long forward-sliding one-piece canopy, and there is provision for radio and oxygen.
  A powered version of the Diamant 18 known as the EFF Prometheus 1 made its first flight on 21 June 1971, powered by a 176lb st Microturbo Eclair II turbojet mounted behind the cockpit. The Prometheus was developed by EFF - Entwicklungsgemeinschaft fur Flugzeugbau der Akademischen
Fluggruppe, and it was later converted back to a standard Diamant 18.


Data: Diamant 18
Span: 59 ft 0 1/2 in
Length: 25 ft 4 in
Height: 4 ft 5 in
Wing area: 186 sqft
Aspect Ratio: 22.7
Empty weight: 617 lb
Max weight: 970 lb
Max speed: 149 mph
Min sinking speed: 1.71 ft/sec at 45 mph
Best glide ratio: 45:1 at 62 mph