Armstrong Siddeley Python

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).

Design and development

The design started as an experimental pure-turbojet known as the ASX, which commenced testing in 1943. By this point other engine designs were already entering pre-production, and it seemed there was little need for the ASX in its existing form. The design was then modified into the turboprop layout with the addition of a second turbine stage, which was geared to the propeller and was named ASP at that stage.^[1]

Flight testing

Early flight-testing of the Python was carried out using the Lancaster B.1 (FE) TW911 and the Lincoln B.2 RE339/G, each aircraft having the two outboard Rolls-Royce Merlins replaced by Pythons. Lincoln B.2 RF403 also had two Pythons similarly installed and was used for high-altitude bombing trials at Woomera, South Australia, the Pythons being used to increase the height from which tests could be carried out. These trials were principally of the ballistic casings for the Blue Danube atomic weapon, there being at the time no other suitable aircraft available that could accommodate the large weapon casing measuring 62 inches diameter x Vorlage:Convert in length, and carry it to the height required. Maximum release height and speed for the first eleven tests was 275 mph and Vorlage:Convert with a bombing error of 61 ft.^[2]