Svenska Flygmotor RM5
Svenska Flygmotor RM6
The Avon design team was headed by Cyril Lovesey, who had previously been in charge of Merlin development. The engine was intended both as an experiment in axial-flow turbojet engines, as well as (if successful) a replacement for the 5,000 lbf (22 kN) Nene. Originally known as the AJ.65 for Axial Jet, 6,500 lbf which was originally designed by Alan Arnold Griffith, the engine developed as a single-spool design with an eight, later 10 stage compressor, mass flow rate of 150 lb/s (68 kg/s) and a pressure ratio of 7.45. Development started in 1945 and the first prototypes were built in 1947.
Introduction was somewhat slowed by a number of minor problems. The first Avons to fly were two Avon RA.2s in the converted Lancastrian military serial VM732, which flew from Hucknall on August 15, 1948. The prototype RA.2 weighed 2,400 lb and gave 6,000 lb thrust, while the production RA.3 was 125 lb lighter.
Initially a private venture for the company, government backing was forthcoming around the time of the first prototypes.
The engine eventually entered production in 1950, the original RA.3/Mk.101 version providing 6,500 lbf (29 kN) thrust in the English Electric Canberra B.2. Similar versions were used in the Canberra B.6, Hawker Hunter and Supermarine Swift.
Uprated versions soon followed, the RA.7/Mk.114 in 1952, producing 7,350 lbf (32,700 N) in the de Havilland Comet C.2, the RA.14/Mk.201 of 9,500 lbf (42 kN) in the Vickers Valiant and the RA.26 of 10,000 lbf (44 kN) used in the Comet C.3 and Hawker Hunter F.6.
The first of the series with all-weather protection, the RA.7 had a power/weight ratio even better than that of the original production engines, notwithstanding the fact that it had been restressed to accept the loads imposed at transonic speeds. The RA.7R (the suffix "R" denotes that reheat, or afterburning, is fitted) delivers 9,500 lb static thrust at sea level, and an offshoot of the same family is the civil 500 Series, the 503 being the engine of the Comet 2.
The Avon RA.14 first ran in 1952. It has a longer compressor than its forerunners, and it also has a true annular combustion chamber in order to accept the tremendous mass flow without increasing "hoop" diameter. The R.A.14 was intended for installation in the wing (it is known that it powers the Vickers-Armstrongs Valiant B.1), and every effort has been made to reduce depth to a minimum.
A civil counterpart is the RA.16 of 9,000 lb thrust, which was originally intended to power the Comet 3, though that aircraft had later variant, giving 10,000 lb thrust.
An Avon-powered de Havilland Comet 4 flew the first scheduled transatlantic jet service in 1958.
The modifications and improvements introduced to the Avon 200 series were considerable, resulting in a completely different engine with very little in common with the early Marks. Despite this, the name Avon was retained. Differences included a completely new combustion section, a 15 stage compressor based on that of the Armstrong-Siddeley Sapphire, as well as other improvements.
The line eventually topped out with the 12,690 lbf (56,450 N) and 16,360 lbf (72,770 N) in afterburner RA.29 Mk.301/2 (RB.146) used in later versions of the English Electric Lightning. Other aircraft to use the Avon included the de Havilland Sea Vixen, Supermarine Scimitar and Fairey Delta.
The Avon was also produced under license by Svenska Flygmotor as the RA.3/Mk.109 as the RM5, and an uprated RA.29 as the RM6 with 17,110 lbf (76,110 N). The RM5 powered the Saab Lansen, while the RM6 was the main powerplant of the SAAB Draken.
Production was also carried out in Belgium by Fabrique Nationale, including 300 Avon 113s, and a larger number of Avon 203s.
In the US, the Avon was used to power the vertical landing Ryan X-13 Vertijet aircraft (in RA.28-49 form).
In Australia, the Avon was used by Commonwealth Aircraft Corporation to power its heavily modified variant of the F-86 Sabre, known as the CA-27 Avon-Sabre.
The Avon continued in aero engine production, mostly for the use in the Sud Aviation Caravelle and English Electric (BAC) Lightning, until 1974, by which time over 11,000 had been built. The engine garnered an impressive safety record over that time. The Avon remained in operational service with the RAF, powering the English Electric Canberra PR.9, until 23 June 2006.
The Avon 200 is an industrial gas generator that is rated at 21-22,000shp. As of 2011, 1,200 Industrial Avons have been sold, and the type has established a 60,000,000 hour class record for its class.
Svenska Flygmotor RM5
Svenska Flygmotor RM6
As a compact electrical generator, the type EAS1 Avon based generator can generate a continuous output of 14.9 MW.