This single-seater first flew in 1950 and was intended for training in performance and distance flying, and for pilots who aimed to qualify for the French ‘D’ licence.

It is a semi-cantilever high wing monoplane with a small bracing strut each side for the singlespar wooden wing, which is covered partly with plywood and partly with fabric. The air brakes consist of two staggered rows of three semi-circular metal plates on each side of the wing just outboard of the bracing strut; these rotate on their axes to protrude above and below the wing surface or to be withdrawn into the wing section. No flaps are fitted, And the oval-section fuselage is of all-wood construction with the pilot sitting under a small canopy. The landing gear consists of a fixed monowheel with a sprung nose-skid and a tailskid, and the tail unit is also of wooden construction.

There were still about seven examples of the C 311P on the French register in 1979.

Castel C311P
Span: 45 ft 11 in
Wing area: 158 sq ft
Aspect ratio: 13.3
Empty weight: 345 lb
Max weight: 537 lb
Speed at best gliding angle: 40.3 mph
Min sinking speed: 2.1 ft/sec