With the same basic design characteristics as Marcel Riffard's lightweight all-wood low-wing cantilever monoplane racers, the Caudron C.690 was designed as a trainer for pilots of single-seat fighters. It was similar to the earlier C.720 design, with a large rounded fin and rudder assembly and independent fixed cantilever main landing gear units with wheel spats, but had a 220 hp (164 kW) Renault 6Q-03 engine in place of the 140 hp (104 kW) Bengali Sport and it was also heavier than the C.720. The first prototype flew in early 1936 and was followed by the second on 18 February 1936. This latter aircraft was demonstrated by the Caudron company's flight director Christian Sarton du Jonchay in several foreign countries, including Austria, Hungary, Romania and Yugoslavia. Soon afterwards the first C.690 was demonstrated to Japanese, Soviet and US air missions, resulting in one example of a Caudron single-seater being bought by the Soviet Union and one by Japan, although the exact types are unknown. It is thought they were basically C.690s, but may nave had tailplanes of a more angular type as fitted to the earlier experimental C.580 design.

While undergoing official tests at Villacoublay on 10 May 1937, the first prototype crashed, killing Caudron's chief test pilot René Paulhan. Despite this disaster official interest continued to grow and a production series was ordered for the Armée de l'Air. These aircraft differed from the prototype in having a triangular shaped fin and rudder, longer landing gear legs and fixed leading-edge slots. Production was slow to get under way and the first C.690M aircraft did not begin flight tests until the beginning of April 1939. These military aircraft were unarmed but equipped with an OPL gun camera. Fifteen aircraft had been delivered by the end of May that year, being allocated to CICs (Centres d'Instruction à la Chasse, or Fighter Training Centres) at Salon, Dijon and Etampes, but none remained in flying condition after the French collapse in June 1940. One example (C.690 number 9) was concealed from the occupying forces, and restored to flying condition after the War, taking to the air on 12 April 1945. Repaired later after an accident, all trace of it was subsequently lost.

Variants

Caudron C.690 - Two prototypes and two exported aircraft powered by a 220 hp (164 kW) Renault 6Q-03 6-cylinder inline piston engine. The two aircraft sold to Japan and the Soviet Union are thought to have had a more angular tailplane.

Caudron C.690M - The military production version differing by having the addition of an OPL gun camera, a triangular shaped fin and rudder, longer landing gear legs and fixed leading-edge slots. 15 aircraft were delivered prior to the German invasion.  

Specifications (Caudron C.690M)

Type: Single Seat Advanced Fighter Trainer

Accommodation/Crew: Pilot.

Design: Designer Marcel Riffard of the Société Anonyme des Avions Caudron

Manufacturer: Société Anonyme des Avions Caudron in Issy-les-Moulineaux and Billancourt (Renault engines). In 1933 the Caudron and Renault companies were amalgamated. In 1936 the French aircraft industry was nationalised, but the Société Anonyme des Avions Caudron managed to survive as an independent company.

Powerplant: One 220 hp (164 kW) Renault Bengali 6Q-05 6-cylinder inline piston engine.

Performance: Maximum speed 230 mph (370 km/h) at 6,560 ft (2000 m); economical cruising speed 199 mph (320 km/h); service ceiling 31,825 ft (9700 m); climb to 3,280 ft (1000 m) in 1 minute 30 seconds.

Range: 684 miles (1100 km) on internal fuel.

Weight: Empty equipped 1,482 lbs (672 kg) with a maximum take-off weight of 2,315 lbs (1050 kg).

Dimensions: Span 25 ft 3 1/4 in (7.70 m); length 25 ft 7 3/4 in (7.82 m); height 8 ft 6 1/4 in (2.60 m); wing area 96.88 sq ft (9.0 sq m).

Armament: None.

Variants: C.690, C.690M.

Equipment/Avionics: OPL gun camera and standard communication equipment.

History: First flight (C.690 prototype) early 1936; first flight (second prototype) 18 February 1936; first flight (C.690M) April 1939.