Wibault 260

The French R.2 specification of 1928 called for an all-metal two seat reconnaissance aircraft, fast and with a rapid climb rate and large radius of action. It led to prototypes from eight manufacturers, the Amiot 130, Breguet 33, Latécoère 490, Les Mureaux 111, Nieuport-Delage Ni-D 580, Potez 37, Weymann WEL-80 and the Wibault 260. One of the terms of the specification required the manufacturers to use a Hispano-Suiza 12Nb water-cooled V-12 engine.[1][2]

The Wibault 260 was an all-metal monoplane with a parasol, cantilever wing. In plan the wing was largely trapezoidal out to blunt tips, with most of the sweep on the trailing edges, though it had a short span centre-section with an unswept leading edge and a deep cut-out in the trailing edge to improve the field of view from the cockpit. The thickness/chord ratio of the outer panels decreased progressively towards the tips. There was no dihedral. High aspect ratio ailerons filled the entire trailing edges. Wing and fuselage were joined by a pair of outward leaning, approximately N-form cabane struts between the outer ends of the centre-section and the upper fuselage. The wings were built around two spars and dural skinned.[3]

Its fuselage was constructed entirely in duralumin, with four longerons which defined its rectangular cross-section. Its water-cooled 480 kW (650 hp) Hispano-Suiza 12Nb upright V-12 engine was in the nose within a pointed engine cowling with bulges around the two cylinder blocks. Its shallow radiator curved around the underside of the forward fuselage at the rear of the engine. A 500 L (110 imp gal; 130 US gal) fuel tank was behind the fire wall. Aft, the pilot's cockpit was under the wing cut-out with a forward view under the wing and equipped with two fixed machine guns firing through the propeller disk. The observer/gunner's position was immediately behind the pilot and was equipped with photographic and radio equipment, together with two flexibly mounted machine guns.[3]

The empennage was conventional, with a triangular plan tailplane mounted near the top of the fuselage and braced on each side with a strut to the lower fuselage. Its angle of incidence could be adjusted in flight by the pilot. The elevators were narrow and rectangular apart from central cut-outs to allow operation of the trapezoidal rudder, which extended down to the keel and was mounted on a triangular fin.[3]

The Wibault 260 had fixed, conventional steel landing gear with a track of 2.60 m (8 ft 6 in), its wheels fitted with brakes. Upward sloping half-axles met centrally under the fuselage at the vertex of a transverse V-strut and, on each side, a faired, long displacement oleo leg and a faired drag strut, both from the lower fuselage longeron, carried the outer end of the axle. The tailskid also had an oleo strut.[3]

The date of the Wibault 260's first flight is not known but it was flying by mid-1930.[4] In early November 1930 Ribière gave a "trés belle" (very fine) demonstration of it at Villacoublay.[5]

The S.T.I.Aé Concours des avions de grande reconnaissance (Long range reconnaissance aircraft competition) at Villacoublay began in April 1931[2] and, unusually, lasted about a year.[6] The French government had paid in March 1930 for two Wibault 260s to be built for the contest[7] but the winner was the ANF Les Mureaux 111,[6] so the Wibault did not go into production.

Data from Les Ailes August 1930[3]

General characteristics

• Crew: Two
• Length: 10.38 m (34 ft 1 in)
• Wingspan: 14.939 m (49 ft 0 in)
• Height: 3.619 m (11 ft 10 in)
• Wing area: 30.345 m² (326.63 sq ft)
• Empty weight: 1,800 kg (3,968 lb)
• Gross weight: 2,570 kg (5,666 lb)
• Fuel capacity: 500 L (110 imp gal; 130 US gal)
• Powerplant: 1 × Hispano-Suiza 12Nb water-cooled, upright V-12, 532 kW (713 hp) notional power 480 kW (650 hp)
• Propellers: 2-bladed

Performance

• Range: 900 km (560 mi, 490 nmi)
• Service ceiling: 5,000 m (16,000 ft) operational

Armament

• Two fixed, forward firing machine guns and two flexibly mounted machine guns