EFF (Entwicklungsgemeinschaft for Flugzugbau der Akademischen Fluggruppe)
Le Prometheus I est issu d?un programme lancé en 1970 par des membres de l’Akademische Fluggruppe (AFG) de Zurich. Parmi eux on trouve T. Bircher, un des principaux constructeurs du planeur Diamant, A.Schiller, qui a entièrement conçu et réalisé le FS-1, P. Senn, qui a construit un Weihe et réparé de nombreux planeurs et D. Favarger, responsable de la Technische Abteilung de l’AFG. Afin de mener à bien ce projet, ils ont fondé EFF (Entwicklungsgemeinschaft fur Flugzeugbau : Groupe d’étude et de construction aéronautique)
The Prometheus 1 was an experimental powered sailplane, based on the airframe of the FFA Diamant 18. Design and construction began in late 1970, and the aircraft flew for the first time on 21 June 1971, powered by a 176 lb (80 kg) Microturbo Eclair II turbojet engine. This had been later replaced by a more powerful TRS 25 engine.
Caractéristiques du Prometheus I
| Manufacturer | FFA |
| Modified by | EFF |
| Type | Jet glider |
| First flight | 21 june 1971 |
| Nb. built | 1 with Eclair II |
| Crew | 1 |
Power plant
| Engine | Microturbo | Eclair II |
| Count | 1 | |
| Type | Turbojet | |
| Max ratings | 80 kg | 225 lbs |
Dimensions
| Span | 18,00 m | 59.05 ft |
| Length | 7,56 m | 24.80 ft |
| Height | 1,35 m | 4.43 ft |
| Areas | m² | ft² |
| Aspect ratio | 22,5 |
Weights
| Empty | 290 kg | 639 lb |
| Crew | kg | lb |
| Fuel | 81,8 l | lb |
| Engine | kg | lb |
| Waterballast | Kg | lb |
| Max. permissible | 500 kg | 1102 lb |
Performances
| Vne – Max. speed | 270 km/h | 168 mph |
| Max crusing speed at S/L | 210 km/h | 130 mph |
| Max eco. speed at S/L | 170 km/h | 106 mph |
| Vs – Stall speed flaps up | 80 km/h | 50 mph |
| Vs – Stall speed flaps down | 68 km/h | 42.5 mph |
| Max. rate of climb at S/L | 180 m/mn | 591 ft/min |
| Service ceiling | 11 000 m | 36,100 ft |
| Range | > 250 km | > 155 miles |
| Best gliding ratio | 28:1 | |
| Landing distance from 50 ft | 50 m | 164 ft |
| Take off distance to 50 ft | 150 m | 492 ft |
| G limits | + | – |
General description
Wings, Fuselage, tail units and landing gear are coming from an original Diamant 18.
Power Plant
One 264 lb (120 kg) st Microturbo TRS 25 turbojet, mounted on a pylon above the wing center-section.
Total fuel capacity
Fuel in two 8-75 Imp gallon (40 litre) wing tanks and one 0.4 Imp gallon (1.8 litre) fuselage tank.
Total : 17.9 Imp gallons (81.8 litres).
Oil capacity
0.11 Imp gallons (0.5 litres).
English 
Français