High Quality Content by WIKIPEDIA articles! The Armstrong Siddeley Python was an early British turboprop engine designed and built by the Armstrong Siddeley company in the mid 1940s. Its main use was in the Westland Wyvern carrier-based heavy fighter, the turboprop engine replacing the Wyvern prototype`s original Rolls-Royce Eagle piston engine in production aircraft. In this application, the Python was rated at 4,110 EHP (Effective Horsepower).