The Castel C.25S, sometimes known as the Aire, is a French training glider, the design, by Robert Castello, began soon after the Franco-German Armistice of June 1940. The C.25S was intended to increase the number of machines available for recreational gliding in the southern, unoccupied region of France.
The C.25S is an all wood aircraft with a monocoque fuselage skinned with plywood and fabric covered, wooden framed wings. The cantilever, high mounted, constant dihedral wings have a constant chord inner section, occupying about 40% of the span, and outer, straight tapered panels with rounded wing tips and ailerons filling their trailing edges. Airbrakes are mounted at mid-chord on the inner-outer panel junction, opening above the wings.
Castel C 25 S 192 F-CRQF
The fuselage has parallel, flat sides and is polygonal in cross-section, tapering to the tail. The crew are seated beneath the leading edge of the wing in side-by-side seating equipped with dual control, enclosed by a canopy which is hinged at the leading edge of the wing. The C.23S has a narrow fin with a shallow forward extension that mounts the tapered tailplane clear of the fuselage. Its rudder is horn balanced, has a curved trailing edge and extends down to the keel, requiring a cut-out between the separate elevators for its movement. The C.25S has a fixed monowheel undercarriage, assisted by a forward mounted main skid and small tailskid.
The first two prototypes of the C.25S both flew in 1942. 100 C.25S were ordered by the French Air Ministry to assist the post-war revival of aviation in France. These were built in Fouga's factory at Aire-sur-Adour between 1945 and 1948 and delivered to French gliding clubs.
Significantly more may have been built; some sources say that another 30 were built during the war and others asserts a total of 200 were built. The C.25Ss with the Caudron C.800s provided the backbone of the French glider basic training fleet until the arrival of the Wassmer WA 30 Bijave in the early 1960s.
The C.25S proved to be a successful long distance flyer, setting several records in the early 1950s.
- 05/09/1953, France record away with fixed goal, La Ferte - Cognac or 370 km, crew and LEPANSE ROBOAM,
- 05/12/1953, France record away and return with goal set La Ferte - Blois is 250 km, and crew LEPANSE DICICO,
- 04/16/1954, record feminine France free distance, La Ferte - Niort is 322 km, crew ABADIE and CARPENTER,
- 18/04/1954, women's world record away and go back to La Ferte - Blois 251 km, crew ABADIE and CARPENTER,
- 04/17/1955, women's record away free, Beynes - Mirambeau 445 km per crew and Marcelle CHOISNET Nadette of Abelenda (to ... 3 km world record).
A pair of C.25S had a role in one of the most commercially successful French films, the 1966 comedy La Grande Vadrouille.
Castel C 25 S 192 F-CRQF
About a dozen examples of the C 25S were still on the French civil register in 1979. Five remained on the French civil aircraft register in 2010.
Length: 7.23 m (23 ft 9 in)
Wingspan: 16.0 m (52 ft 6 in)
Height: 2.22 m (7 ft 3 in)
Wing area: 20.0 sq.m (215 sq ft)
Aspect ratio: 12.8
Profile at the root: Gö 535
Profile at the end: NACA 23010
Dihedral: 1 ° 30
Empty weight: 261 kg (575 lb)
Gross weight: 441 kg (972 lb)
Never exceed speed: 140 km/h (87 mph; 76 kn)
Rough air speed max: 90 km/h (55.9 mph; 48.6 kn)
Aerotow speed: 100 km/h (62.1 mph; 54.0 kn)
Maximum glide ratio: about 25 at 67–69 km/h (41.6–42.9 mph; 36.2–37.3 kn)
Rate of sink: 0.73 m/s (144 ft/min) minimum, at 62 km/h (38.5 mph; 33.5 kn)
Rate of sink: 2 m / s at 65 - 100 km / h
Wing loading: 22.0 kg/sq.m (4.5 lb/sq ft)