Armstrong Siddeley Sapphire

Design evolution of the Sapphire started at Metropolitan-Vickers (Metrovick) in 1943 as an offshoot of the F.2 project. With the F.2 reaching flight quality at about {{convert|1600|lbf|abbr=on}}, 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 gemstones 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{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200017.html |title=armstrong siddeley {{!}} gloster javelin {{!}} 1956 {{!}} 0017 {{!}} Flight Archive |website=www.flightglobal.com |url-status=dead |archive-url=https://web.archive.org/web/20111119064414/http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200017.html |archive-date=2011-11-19}} Metrovick exited the jet engine industry.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.Gunston 1989, p.102. Note: "...the firm had decided in 1947, under Ministry pressure, to get out of aviation" Armstrong Siddeley, who already had a turbine development of their own, the ASX, 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 {{convert|7380|lbf|abbr=on}}. Its competitor, the Avon RA.3 had a design thrust of {{convert|6500|lbf|abbr=on}} at that time.{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1955/1955%20-%201780.html |title=electric company {{!}} english electric {{!}} 1955 {{!}} 1780 {{!}} Flight Archive |website=www.flightglobal.com |url-status=dead |archive-url=https://web.archive.org/web/20160425115057/https://www.flightglobal.com/pdfarchive/view/1955/1955%20-%201780.html |archive-date=2016-04-25}} 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 {{convert|7500|lbf|abbr=on}} 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."Testing Years" Roland Beamont, Ian Allan Ltd. Londondon, {{ISBN|0 7110 1072 2}}, p.93 Future versions of the Lightning were powered by the Avon.

The ASSa.6, {{convert|8300|lbf|abbr=on}}, was used on the Gloster Javelin FAW Mk.1, Hawker Hunter F.Mk.2 and F.Mk.5, and the prototype Sud Ouest SO 4050 Vautour. The higher thrust ASSa.7 at {{convert|11000|lbf|kN|abbr=on}} was the first British engine to be rated above {{convert|10000|lbf|kN|abbr=on}} 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 Sapphire compressor operated well, free from surging,{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200018.html |url-status=dead |archive-url=https://web.archive.org/web/20130522060649/http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200018.html |archive-date=22 May 2013 |title=armstrong siddeley {{!}} 1956 {{!}} 0018 {{!}} Flight Archive}} 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 at the entry to the compressor{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200022.html |url-status=dead |archive-url=https://web.archive.org/web/20150424151652/http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200022.html |archive-date=24 April 2015 |title=armstrong siddeley {{!}} 1956 {{!}} 0022 {{!}} Flight Archive}} 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.{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201599.html |url-status=dead |archive-url=https://web.archive.org/web/20160426015350/https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201599.html |archive-date=26 April 2016 |title=1956 {{!}} 1599 {{!}} Flight Archive}}

CaygillJavelin From The Cockpit, Peter Caygill, Pen & Sword Books Ltd., {{ISBN|978-1-84884-656-2}} states that one of the most serious problems encountered throughout the life of the Gloster Javelin 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 B.1.The Handley Page Victor Volume 1, Roger R Brooks, Pen & Sword Aviation 2007, {{ISBN|978 1 84415 411 1}}, p.195

An afterburner 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 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"seven decades of progress" General Electric, Aero Publishers Inc. 1979, Fallbrook, {{ISBN|0-8168-8355-6}}, p. 83 and "Bristol Simplified Reheat"(BSR), with about 16% boost at take-off, tested on Derwent V, Orenda, Olympus"Olympus-the first forty years" Alan Baxter, Rolls-Royce Heritage Trust, 1990, {{ISBN|9780951171097}}, p.26 and Orpheus engines.{{cite web |url=https://www.flightglobal.com/pdfarchive/view/1959/1959%20-%202122.html |url-status=dead |archive-url=https://web.archive.org/web/20111119073150/http://www.flightglobal.com/pdfarchive/view/1959/1959%20-%202122.html |archive-date=19 November 2011 |title=1959 {{!}} 2122 {{!}} Flight Archive}}

;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 {{convert|7500|lbf|kN|abbr=on|2}} at an s.f.c. of 0.91

;ASSa.4:{{cite book|last=Taylor|first=John W.R. FRHistS. ARAeS|title=Jane's All the World's Aircraft 1955-56|year=1955|publisher=Sampson, Low, Marston & Co Ltd|location=London}}

;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, Hawker Hunter F.Mk.2, F.Mk.5 and the prototype Sud Ouest SO 4050 Vautour

;ASSa.7: Rated at {{convert|11000|lbf|kN|abbr=on}}, powering the Gloster Javelin FAW Mk.7, Handley Page Victor B.Mk.1 and the prototype FFA P-16.

;ASSa.7LR: Engines with a 12% augmentation reheat system for use above {{convert|20000|ft|m|abbr=on}}, powering the Gloster Javelin FAW Mk.8.

;Wright J65:Licence production in the United States by Wright Aeronautical

;ASSa.8:

;ASSa.9:

;ASSa.12:

;Sapphire 101: (ASSa.6)

;Sapphire 104: (ASSa.12)

;Sapphire 202: (ASSa.7)

• English Electric Lightning P.1A prototypes, as Avon engines were not ready
• FFA P-16
• Gloster Javelin - Sa.6 and Sa.7
• Handley Page Victor B.1, the B.2 variant had RR Conway
• Hawker Hunter F.2 and F.5
• SNCASO SO.4050 Vautour (3rd prototype)

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

Very few Armstrong Siddeley Sapphire engines exist, other known examples are preserved at the Jet Age Museum in Gloucester, England, and the Malta Aviation Museum at Ta' Qali.

{{jetspecs

|

|ref=Jane's.{{cite book|last=Taylor|first=John W.R. FRHistS. ARAeS|title=Jane's All the World's Aircraft 1962-63|year=1962|publisher=Sampson, Low, Marston & Co Ltd|location=London}}

|type=Turbojet

|length={{convert|125.2|in| mm|abbr=on|0}}

|diameter={{convert|37.55|in| mm|abbr=on|0}}

|weight={{convert|3,050|lb|kg|abbr=on|0}}

|compressor=13-stage axial flow

|combustion=Annular with 24 hockey-stick vaporisers

|turbine=Two-stage

|fueltype=Aviation kerosene

|oilsystem=Flood feed, minimum oil pressure {{convert|12|psi|kPa|abbr=on|0}}, tank capacity {{convert|18|imppt|L|abbr=on|0}}

|power=

|thrust={{convert|11,000|lbf|kN|abbr=on|0}} at sea level at 8,000 rpm

|compression=

|aircon=

|turbinetemp=

|fuelcon=

|specfuelcon=0.885 lb/hr/lb (90.214 kg/kN/hr) at take-off rating

|power/weight=

|thrust/weight=3.607

}}

{{Aircontent

|related=

• Wright J65

|similar engines=

• General Electric J73
• Ishikawajima-Harima J3
• Rolls-Royce Avon
• SNECMA Atar
• Tumansky R-13
• Tumansky R-25

|lists=

• List of aircraft engines

|see also=

}}

{{Reflist}}

{{refbegin}}

• Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. {{ISBN|1-85260-163-9}}
• {{cite book|last=Kay|first=Anthony L.|title=Turbojet History and Development 1930-1960 |publisher=The Crowood Press|location=Ramsbury|date=2007|edition=1st|volume=1|isbn=978-1-86126-912-6}}

{{refend}}

{{Commons category|Armstrong Siddeley Sapphire}}

• [http://www.rafmuseum.org.uk/research/collections/engine-armstrong-siddeley-sapphire-200/ Royal Air Force Museum - Armstrong Siddeley Sapphire]
• [http://www.aviationancestry.com/Engines/ArmstrongSiddeley/ArmstrongSiddeley-Sapphire-1952-1.html A 1952 advert for the Sapphire/J 65]
• [http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%200017.html "Armstrong Siddeley Sapphire"] a 1956 Flight article on the Sapphire
• [https://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201598.html "Sapphire 7"] a 1956 Flight article on the Sapphire 7

{{ASaeroengines}}

{{USAF gas turbine engines}}

Sapphire

Category:1940s turbojet engines

Category:Axial-compressor gas turbine engines