Armstrong Siddeley Sapphire

This article is about the jet aero-engine, for the vehicle see Armstrong Siddeley Sapphire (motor car)

Sapphire
Preserved Armstrong Siddeley Sapphire at the Midland Air Museum
Type	Turbojet
Manufacturer	Armstrong Siddeley
First run	1 October 1948
Major applications	Gloster Javelin Handley Page Victor Hawker Hunter
Variants	Wright J65

The Armstrong Siddeley Sapphire was a British turbojet engine produced by Armstrong Siddeley in the 1950s. It was the ultimate development of work that had started as the Metrovick F.2 in 1940, evolving into an advanced axial flow design with an annular combustion chamber that developed over 11,000 lbf (49 kN). It powered early versions of the Hawker Hunter and Handley Page Victor, and every Gloster Javelin. Production was also started under license in the United States by Curtiss-Wright as the J65, powering a number of US designs.

Design and development

Design of the Sapphire started at Metropolitan-Vickers (Metrovick) in 1943. With the F.2 reaching flight quality at about 1,600 lbf (7,100 N), the Metrovick engineers turned to producing larger designs, both an enlarged F.2 known as the Beryl, as well as the much larger F.9 Sapphire, the names being chosen after they decided to use gemstones for future engine names. The Beryl was soon running and eventually developed 4,000 lbf (18 kN) thrust, but the only project to select it, the Saunders-Roe SR.A/1, was cancelled. By this point the F.9 was developing about 7,500 lbf (33 kN), somewhat more than its competitor from Rolls-Royce, the Avon. A number of companies expressed interest in the F.9, and it was considered as either the main or backup powerplant for most late-40s/early-50s British designs.

At about the same time Metrovick exited the jet engine industry,^[1][2] with their design team being quickly acquired by Armstrong Siddeley. Although Armstrong Siddeley already had a turbine development of their own, the ASX, they were primarily focused on turboprops and the Metrovick team was a welcome addition.^{[citation needed]}

Work on the F.9 continued, now renamed the ASSa.5, and was delivered at 7,500 lbf (33,000 N) ratings. This early engine was used only on the EE P.1.A, prototype for the famed Lightning. The fit was not entirely a happy one, and the afterburning ASSa.5R did little to address this, delivering an improved 9,200 lbf (41,000 N) "wet", but doing so in an unreliable fashion that demanded a short period of "no use" while the problems were addressed.^[3] Future versions of the Lightning would be powered by the Avon instead.

The engine was soon passing tests at ever-increasing power settings. The ASSa.6 increased power to 8,300 lbf (37,000 N), and powered the Javelin FAW Mk.1, Hawker Hunter F.Mk.2 and F.Mk.5, and the prototype Sud Ouest SO 4050 Vautour. The dramatically more powerful ASSa.7 at 11,000 lbf (49 kN) was the first British engine to be rated above 10,000 lbf (44 kN), powering the Javelin FAW Mk.7, Handley Page Victor B.Mk.1 and a prototype Swiss fighter-bomber, the FFA P-16. Afterburners of limited quality were also added to the ASSa.7, producing the 12,390 lbf (55,100 N) wet ASSa.7LR, used on some Javelin FAW Mk.8's. An improved model produced 15,000 lbf (67 kN) above 20,000 ft (6,100 m), appearing on other FAW Mk.8's and all FAW Mk.9's.^[4]

Applications

Note:^[5]

• English Electric P.1.A
• FFA P-16
• Gloster Javelin
• Handley Page Victor
• Hawker Hunter
• Sud Aviation Vautour

Engines on display

An Armstrong Siddeley Sapphire is on static display at the Midland Air Museum, Coventry Airport, Warwickshire.

Specifications (ASSa.6)

Data from Flight:^[6]

General characteristics

• Type: Turbojet
• Length: 134 in (3404 mm)
• Diameter: 37.4 in (950 mm)
• Dry weight: 2,600 lb (1179 kg)

Components

• Compressor: 13 stage axial
• Combustors: Annular
• Turbine: Two stage

Performance

• Maximum thrust: 8,300 lbf (3,765 kgf), sea level at 8,600 rpm
• Specific fuel consumption: 0.85 lb/hr/lb
• Thrust-to-weight ratio: 3.2:1

See also

Related development

• Wright J65
  

Comparable engines

• Rolls-Royce Avon
  

Related lists

• List of aircraft engines
  

References

Notes

1. ^ Depending on the sources, Metrovick either left the engine business on their own to concentrate on steam turbines, or were forced from the market by the Ministry of Supply in order to reduce the number of companies they had to deal with.
2. ^ Gunston 1989, p.102. Note: "...the firm had decided in 1947, under Ministry pressure, to get out of aviation"
3. ^ English Electric Lightning
4. ^ Armstrong Siddeley Sapphire
5. ^ In many cases the Sapphire was used on early prototypes of these aircraft and was often later replaced by the Rolls-Royce Avon, only the generic aircraft types are given.
6. ^ Flight Global Archive -September 1954 www.flightglobal.com. Retrieved: 3 November 2008

Bibliography

• Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9

External links

• Royal Air Force Museum - Armstrong Siddeley Sapphire
• A 1952 advert for the Sapphire/J 65