The EFW N-20 Aiguillon (Stinger) was Switzerland's first indigenous jet fighter aircraft with the Armstrong Siddeley Mamba turboprop chosen as the basis for the N-20's engines. The converted powerplant was named Swiss Mamba SM-1 but only six engines were built (four fitted to the N-20 with two spares). The prototype was completed in 1952 and flew briefly during a taxi test in April 1952 but development of the engine and the N-20 aircraft was cancelled soon afterwards. The prototype is now on display at this museum with the port side engines having their intake cowlings removed.