Leduc RL.21

The Leduc RL.21 was a single engine, single seat light aircraft built in the late 1950s in France. Designed to achieve high speeds from modest engine power, it set seven class records in the early 1960s.

Design and development
Between 1939 and 1975 the amateur aircraft designer and builder René Leduc (not the ramjet designer of the same name) completed and flew five different lightplanes, two of which set records in their class. The RL.21 was a low wing monoplane with its wings braced to the upper fuselage by a pair of inverted-V struts. It was powered by a 135 hp SNECMA-Régnier 4L-00 four cylinder inverted air-cooled inline engine driving a two blade propeller. A low, smoothly streamlined canopy covered the single seat cockpit and merged aft into a raised rear fuselage. The empennage was conventional. The RL.21 had a tailwheel undercarriage with spatted main wheels on cantilever legs, mounted on the wings approximately below the ends of the wing struts.

Leduc built the RL.21 over a period of six years with assistance from Sud Aviation and from the Nantes Technical School. It flew for the first time in August 1960. Between late 1960 and early 1967 it set seven records in its C1a and C1b categories, respectively for aircraft with maximum take-off weights below 500 kg and between 500-1000 kg. The earliest were for speeds of 313.5 km/h and 316.2 km/h for the two classes around a 100 km closed circuit and the last at 217 mph and 208 mph over a 500 km closed circuit. Throughout these flights the pilot was Raymond Davy.