Armstrong Siddeley Sapphire
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The Armstrong Siddeley Sapphire is a British
turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
engine that was produced by
Armstrong Siddeley Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines. The company was created following t ...
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 An axial compressor is a gas compressor that can continuously pressurize gases. It is a rotating, airfoil-based compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. This differs from other ...
design with an annular combustion chamber that developed over . It powered early versions of the
Hawker Hunter The Hawker Hunter is a transonic British jet-powered fighter aircraft that was developed by Hawker Aircraft for the Royal Air Force (RAF) during the late 1940s and early 1950s. It was designed to take advantage of the newly developed Rolls-R ...
and
Handley Page Victor The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final '' V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Avro ...
, and every
Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...
. Production was also started under licence in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
by
Wright Aeronautical Wright Aeronautical (1919–1929) was an American aircraft manufacturer headquartered in Paterson, New Jersey. It was the successor corporation to Wright-Martin. It built aircraft and was a supplier of aircraft engines to other builders in the ...
as the J65, powering a number of US designs. The Sapphire's primary competitor was the
Rolls-Royce Avon The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ...
.


Design and development

Design evolution of the Sapphire started at
Metropolitan-Vickers Metropolitan-Vickers, Metrovick, or Metrovicks, was a British heavy electrical engineering company of the early-to-mid 20th century formerly known as British Westinghouse. Highly diversified, it was particularly well known for its industrial el ...
(Metrovick) in 1943 as an offshoot of the F.2 project. With the F.2 reaching flight quality at about , Metrovick 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 were chosen after a decision to use
gemstone A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, ...
s for future engine names). The Beryl eventually developed 4,000 lbf (18 kN) thrust, but the only project to select it, the Saunders-Roe SR.A/1, was cancelled. The Ministry of Supply (MoS) designated the F.9 as the MVSa.1. In 1948 Metrovick exited the jet engine industry. Armstrong Siddeley, who already had a turbine development of their own, the
ASX Australian Securities Exchange Ltd or ASX, is an Australian public company that operates Australia's primary securities exchange, the Australian Securities Exchange (sometimes referred to outside of Australia as, or confused within Australia as ...
, took over the MVSa.1, now renamed ASSa.1. After a redesign it emerged as the ASSa.2. In December 1949 the ASSa.2 completed an acceptance test at . Its competitor, the Avon Ra.3 had a design thrust of at that time. A number of companies expressed interest in the Sapphire, and it was considered as either the main or backup powerplant for most British designs of the late '40s and early '50s. The ASSa.5 with thrust was used only on the English Electric P.1A, prototype for the Lightning. A simple fixed-nozzle reheat was fitted to extend the performance boundary for stability and control testing from about Mach 1.1 to beyond Mach 1.5. Future versions of the Lightning were powered by the Avon. The ASSa.6, , was used on the
Gloster Javelin FAW Mk.1 The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...
, Hawker Hunter F.Mk.2 and F.Mk.5, and the prototype Sud Ouest SO 4050 Vautour. The higher thrust ASSa.7 at was the first British engine to be rated above and it powered the Gloster Javelin FAW Mk.7, Handley Page Victor B.Mk.1 and a prototype Swiss fighter-bomber, the
FFA P-16 The FFA P-16 was a Swiss prototype ground attack jet fighter designed and produced by aircraft manufacturer Flug- und Fahrzeugwerke Altenrhein (FFA). It was Switzerland's second attempt to develop a domestically designed and manufactured jet f ...
. The Sapphire compressor operated well, free from surging, over its complete RPM range without the need for variable inlet guide vanes (VIGV) or bleed. However, early compressor stages suffered from fatigue due to rotating stall at low RPM and various fixes, such as lacing wire, were incorporated. Curtiss-Wright introduced variable ramps on the
Wright J65 The Wright J65 was an axial-flow turbojet engine produced by Curtiss-Wright under license from Armstrong Siddeley. A development of the Sapphire, the J65 powered a number of US designs. Design and development Curtiss-Wright purchased a license f ...
at the entry to the compressor to prevent the stalling and blade excitation. Armstrong-Siddeley tested a similar solution on the Sapphire but incorporated blade changes instead to reduce the blade response to the stalling. CaygillJavelin From The Cockpit, Peter Caygill, Pen & Sword Books Ltd., states that one of the most serious problems encountered throughout the life of the
Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...
was caused by "centre-line closure" on the Sapphire engine. Flying through thick cloud could cause the compressor case to shrink and rub the blades causing catastrophic engine failures and loss of the aircraft. "Centre-line closure" also caused a Sapphire failure on a
Victor The name Victor or Viktor may refer to: * Victor (name), including a list of people with the given name, mononym, or surname Arts and entertainment Film * ''Victor'' (1951 film), a French drama film * ''Victor'' (1993 film), a French shor ...
B.1. An
afterburner An afterburner (or reheat in British English) is an additional combustion component used on some jet engines, mostly those on military supersonic aircraft. Its purpose is to increase thrust, usually for supersonic flight, takeoff, and comba ...
with limited boost was required for the Javelin's ASSa.7, making it the ASSa.7LR. 12% boost was required at high altitudes to regain the bomber intercept performance that had been lost carrying the new
de Havilland Firestreak The de Havilland Firestreak is a British first-generation, passive infrared homing (heat seeking) air-to-air missile. It was developed by de Havilland Propellers (later Hawker Siddeley) in the early 1950s, entering service in 1957. It was the ...
missiles. Afterburners with a low boost requirement were sometimes known as "wee-heat". Other low-boost reheats have included the "tailpipe augmentation"(TPA) on the F-86H (J73) with +10% at take-off and "Bristol Simplified Reheat"(BSR), with about 16% boost at take-off, tested on Derwent V, Orenda, Olympus and Orpheus engines.


Variants

;MVSa.1: Ministry of Supply designation of the original Metropolitan-Vickers F.9 Sapphire, derived from the Metropolitan-Vickers F.2/4 Beryl. Design work on this much larger engine started in 1943. ;ASSa.3: Completed a 150-hour Service Type Test in November 1951 at a sea level rating of at an s.f.c. of 0.91 ;ASSa.4: ;ASSa.5: Early Armstrong Siddeley developed Sapphire engines. ;ASSa.5R: Reheated engines fitted to the English Electric P.1A. ;ASSa.6:Later engines developed for the
Gloster Javelin FAW Mk.1 The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...
, Hawker Hunter F.Mk.2, F.Mk.5 and the prototype Sud Ouest SO 4050 Vautour ;ASSa.7: Rated at , powering the Gloster Javelin FAW Mk.7, Handley Page Victor B.Mk.1 and the prototype
FFA P-16 The FFA P-16 was a Swiss prototype ground attack jet fighter designed and produced by aircraft manufacturer Flug- und Fahrzeugwerke Altenrhein (FFA). It was Switzerland's second attempt to develop a domestically designed and manufactured jet f ...
. ;ASSa.7LR: Engines with a 12% augmentation reheat system for use above , powering the Gloster Javelin FAW Mk.8. ;
Wright J65 The Wright J65 was an axial-flow turbojet engine produced by Curtiss-Wright under license from Armstrong Siddeley. A development of the Sapphire, the J65 powered a number of US designs. Design and development Curtiss-Wright purchased a license f ...
:Licence production in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
by
Wright Aeronautical Wright Aeronautical (1919–1929) was an American aircraft manufacturer headquartered in Paterson, New Jersey. It was the successor corporation to Wright-Martin. It built aircraft and was a supplier of aircraft engines to other builders in the ...
;ASSa.8: ;ASSa.9: ;ASSa.12: ;Sapphire 101: (ASSa.6) ;Sapphire 104: (ASSa.12) ;Sapphire 202: (ASSa.7)


Uses

*
English Electric Lightning The English Electric Lightning is a British fighter aircraft that served as an interceptor during the 1960s, the 1970s and into the late 1980s. It was capable of a top speed of above Mach 2. The Lightning was designed, developed, and manufa ...
P.1A prototypes, as Avon engines were not ready *
FFA P-16 The FFA P-16 was a Swiss prototype ground attack jet fighter designed and produced by aircraft manufacturer Flug- und Fahrzeugwerke Altenrhein (FFA). It was Switzerland's second attempt to develop a domestically designed and manufactured jet f ...
*
Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...
- Sa.6 and Sa.7 *
Handley Page Victor The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final '' V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Avro ...
B.1, the B.2 variant had RR Conway *
Hawker Hunter The Hawker Hunter is a transonic British jet-powered fighter aircraft that was developed by Hawker Aircraft for the Royal Air Force (RAF) during the late 1940s and early 1950s. It was designed to take advantage of the newly developed Rolls-R ...
F.2 and F.5 * SNCASO SO.4050 Vautour (3rd prototype)


Engines on display

An Armstrong Siddeley Sapphire is on static display at the
Midland Air Museum The Midland Air Museum (MAM) is situated just outside the village of Baginton in Warwickshire, England, and is adjacent to Coventry Airport. The museum includes the ''Sir Frank Whittle Jet Heritage Centre'' (named after the local aviation pionee ...
,
Coventry Airport Coventry Airport is located south-southeast of Coventry city centre, in the village of Baginton, Warwickshire, England. The airport is operated and licensed by Coventry Airport Limited. Its CAA Ordinary Licence (Number P902) allows flights ...
,
Warwickshire Warwickshire (; abbreviated Warks) is a county in the West Midlands region of England. The county town is Warwick, and the largest town is Nuneaton. The county is famous for being the birthplace of William Shakespeare at Stratford-upon-Avon an ...
. Very few Armstrong Siddeley Sapphire engines exist, other known examples are preserved at the
Jet Age Museum The Jet Age Museum is the trading name of the Gloucestershire Aviation Collection, an all-volunteer, charitable organisation dedicated to the preservation of Gloucestershire's aviation heritage. The aviation museum is located on the north side ...
in Gloucester, England, and the
Malta Aviation Museum Malta Aviation Museum is an aircraft museum situated on the site of the former Royal Air Force airfield in the village of Ta'Qali, on the island of Malta. The museum, based in three hangars, covers the history of aviation on the island with exhi ...
at
Ta' Qali Ta' Qali is a wide open space in the limits of Attard and Mosta in central and northern Malta respectively, which contains the national football stadium, the Malta Fairs & Conventions Centre, Ta' Qali National Park, a crafts village, and a natio ...
.


Specifications (ASSa.7)


See also


References


Notes


Bibliography

* Gunston, Bill. ''World Encyclopedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. *


External links


Royal Air Force Museum - Armstrong Siddeley Sapphire


a 1956 ''Flight'' article on the Sapphire

a 1956 ''Flight'' article on the Sapphire 7 {{USAF gas turbine engines
Sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ...
1940s turbojet engines Axial-compressor gas turbine engines