In 1945, Rolls-Royce started the development of the AJ.65 (axial jet, 28,912 N (6,500 lb) thrust) Avon to replace the Nene, going through several design and test iterations. The first 100-series (RA.3) production engines were delivered in June 1950. For the Comet and Caravelle, the civil RA.29 was produced at 45,592 N (10,250 lb) thrust. The RB.146 300-series was later produced at 76,105 N (17,110 lb) thrust with afterburning.
The Avon powered a variety of military and commercial aircraft: English Electric Canberra, Hawker Hunter, and Vickers-Armstrong Valiant, de Havilland Comet and S.N.C.A.S.E. Caravelle.
This engine, a 44,480 N (10,000 lb) thrust RA.28-49, was manufactured in June 1955 specifically for the Ryan Aeronautical Company in San Diego, California. It powered the Ryan X-13 VTOL Vertijet between 1955 and 1957. In November 1956, the Vertijet, now in the museum's collection, was the first jet-powered VTOL aircraft to demonstrate transition from horizontal to vertical flight and return to horizontal flight.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.