The C.710 were a series of light fighter aircraft developed by Caudron-Renault for the French Armée de l'Air just prior to the start of World War II. One version, the C.714, saw limited production, and were assigned to Polish pilots flying in France after the fall of Poland in 1939. A small number were also supplied to Finland.
Design and development
The original specification that led to the C.710 series was offered in 1936 in order to quickly raise the number of modern aircraft in French service, by supplying a "light fighter" of wooden construction that could be built rapidly in large numbers without upsetting the production of existing types. The contract resulted in three designs, the Arsenal VG-30, the Bloch MB-700, and the C.710. Prototypes of all three were ordered.
The original C.710 model was an angular design developed from an earlier series of air racers. One common feature of the Caudron line was an extremely long nose that set the cockpit far back on the fuselage. The profile was the result of using the 336 kW (450 hp) Renault 12R-01 12-cylinder inline engine, which had a small cross-section and was fairly easy to streamline, but very long. The landing gear was fixed and spatted, and the vertical stabilizer was a seemingly World War I-era semicircle instead of a more common trapezoidal or triangular design. Armament consisted of a 20 mm Hispano-Suiza HS.9 cannon under each wing in a small pod.
The C.710 prototype first flew on 18 July 1936. Despite its small size, it showed good potential and was able to reach a level speed of 470 km/h (292 mph) during flight testing. Further development continued with the C.711 and C.712 with more powerful engines, while the C.713 which flew on 15 December 1937 introduced retractable landing gear and a more conventional triangular vertical stabilizer.
The final evolution of the 710 series was the C.714 Cyclone, a variation on the C.713 which first flew in April 1938 as the C.714.01 prototype. The primary changes were a new wing airfoil profile, a strengthened fuselage, and instead of two cannons, the fighter had four 7.5 mm MAC 1934 machine guns in the wing gondolas. It was powered by the newer 12R-03 version of the engine, which introduced a new carburettor that could operate in negative G.
The Armée de l'Air ordered 20 C.714s on 5 November 1938, with options for a further 180. Production started at a Renault factory in the Paris suburbs in summer 1939.
Other projected versions were the C.720 trainer with a 75 or 164 kW (100 or 220 hp) engine, the C.760 fighter with a 559 kW (750 hp) Isotta-Fraschini Delta engine, and the C.770 fighter with an 597 kW (800 hp) Renault V-engine. None of these reached production.