Breguet 904 Nymphale
The Breguet 901 high-performance single-seat sailplane was developed in 1953 from the Type 900, Breguet's first sailplane which, on its maiden flight on 13 May 1949, covered a distance of 292 miles at an average speed of 56mph which, had it been observed, would have set up a new French goal flight record.
The Type 900 was of all-wood construction with fabric covered wings of 46 ft 11 in span with slotted ailerons, slotted flaps and metal dive brakes, and a plywood-covered fuselage. The Type 901, designed by J. Cayla, incorporated several advanced features for its time and took first place in the single-seater class at the 1954 World Gliding Championships at Camphill, going onto repeat this success at the 1956 World Championships in France, by which time a production batch of 60 had been put in hand.
The 901 differed from the 900 chiefly in having a longer span (56ft 10in) wing of higher aspect ratio and a more streamlined fuselage, with the large blown Plexiglas cockpit canopy flush with the fuselage top line, a practice since adopted by many other sailplane designers. Another unusual feature was the carriage of 165 lb of water ballast in the wings, which could be discharged through openings just beneath the wings in each side of the fuselage.
Construction was very similar to the Type 900 with slotted ailerons and multi-hinged slotted Fowler flaps on the laminar-flow wing, and metal dive brakes on the upper and lower surfaces. The leading edge torsion box is a sandwich of plywood and Klegecel, an expanded plastic pre-formed under heat to the required shape, giving very strong and light structure. The single spar is of spruce and plywood and wing covering is of plywood and fabric.
The tail unit is of very similar construction, and the tailplane and elevators can be folded horizontally for transport. The fuselage is a plywood-covered monocoque with a single retractable monowheel with hydraulic brake for landing; a landing can be made with the wheel retracted without serious damage to the structure. The pilot is provided with radio, blind-flying equipment and oxygen.
The Type 901-S1, which first flew in 1956, differed from the 901 in having modified flaps, a slightly longer fuselage and larger tailplane. The Breguet 904 Nymphale is a two-seater version of the 901, the first of two prototypes making its maiden flight on 26 May 1956.
This featured a laminar-flow wing of 20m (65ft 7in) span and end-plate fairings called 'salmons' on the wing tips; the second seat increased the length to 29ft 6in.
Span: 56ft 10in
Length: 24ft 10in
Wing area: 161.5sqft
Aspect ratio: 20
Empty weight: 584lb
Max weight: 948lb
Max speed: 136mph
Min sinking speed: 2.0ft/sec at 45mph
Best glide ratio: 36:1 at 53mph