The Leduc 0.21 was an experimental ram jet aeroplanes flown in France in the 1950s. Tests of this aeroplane demonstrated the potential of ramjets and led to design of a more advanced high speed, high altitude interceptor.

The Leduc 0.21 was a ram jet (athodyd), a jet engine which depends on intake design and forward speed (rather than a compressor stage) to force air into the engine at sufficient compression to ignite when mixed with fuel.

René Leduc began experimenting with ram jet engines in 1935 but World War II meant his first test aeroplane, the Leduc 0.10, was not completed until 1945.

After it flew successfully a more advanced version, the Leduc 0.21, was designed and two built to further test the capabilities of ram jets.

Lacking any power source to achieve ignition speed, the Leduc 0.21 had to be launched from a mother-ship.

The first one made its initial flight on 7 August 1953 and both made a total of 284 flights before the test program was completed in 1956.

This model represents the first Leduc 0.21 in late 1953.

Mach 2 1:72 kit completed by Leigh Edmonds in August 2015.