Bristol Siddeley Gamma

The Gamma was a family of rocket engines used in British rocketry, including the Black Knight and Black Arrow launch vehicles. They burned kerosene fuel and hydrogen peroxide. The family was based around a common combustion chamber design, used either singly or in clusters of up to eight.

They were developed by Armstrong-Siddeley in Coventry, which later became Bristol Siddeley in 1959, and finally Rolls-Royce in 1966. cite web
title=Rolls-Royce Heritage: Coventry
url=http://www.rolls-royce.com/history/heritage/offices/coventry.jsp]

Engine static testing was carried out at High Down, near The Needles on the Isle of Wight (coord|50|39|38.90|N|1|34|38.25|W|). [cite web
title=High Down testing site
url=http://www.spaceuk.org/bk/hd/highdown.htm] [ [http://www.nationaltrust.org.uk/main/w-vh/w-visits/w-findaplace/w-theneedlesoldbattery/w-theneedlesoldbattery-seeanddo.htm Black Knight Testing at The Needles] ] (Spadeadam in Cumbria wasn't used for testing until Blue Streak, after Gamma).

Advantages of kerosene / peroxide engines

Use of kerosene / hydrogen peroxide engines has been a particularly British trait in rocket development, there being few comparable engines (such as the LR-40) from the USA. [cite conference
title=Hydrogen Peroxide - Optimal For Turbomachinery and Power Applications |url=http://www.gkllc.com/AIAA-2007-5537%20Hydrogen%20Peroxide-Optimal%20for%20Turbomachinery%20and%20Power%20Applications.pdf
format=pdf
conference=43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit
date=July 2007
location=Cincinnati, OH
publisher=American Institute of Aeronautics and Astronautics, Inc.
copyright=General Kinetics Inc. ]

The combustion of kerosene with hydrogen peroxide is given by the formula: CH₂ + 3H₂O₂ → CO₂ + 4H₂Owhere CH₂ is the approximate formula of kerosene (see RP-1 for a discussion of kerosene rocket fuels). This compares with the combustion of kerosene and liquid oxygen (LOX) : CH₂ + 1.5O₂ → CO₂ + H₂Oshowing that the exhaust from kerosene / peroxide is predominantly water. This results in a very clean exhaust (second only to cryogenic LO₂/LH₂) and a distinctive clear flame. [cite web
title=Black Arrow
url=http://members.aol.com/nicholashl/ukspace/blackarrow/blackarrow.htm
publisher=Nicholas Hill, The "levitation" picture, showing the R3 / Prospero launch lifting off on Gamma's invisibly transparent exhaust plume.] The low molecular mass of water also helps to increase rocket thrust performance. cite journal
title=High Density Liquid Rocket Boosters for the Space Shuttle
author=Pietrobon, Steven S.
url=http://www.sworld.com.au/steven/pub/lrb.pdf
format=pdf
journal=J. British Interplanetary Society
volume=vol. 52
pages=pp. 163-168,
date=May/June 1999]

The oxidizer used with Gamma was 85% High Test Peroxide (HTP), H₂O₂. Gamma used a silver-plated on nickel-gauze catalyst to first decompose the peroxide.cite journal
journal=J. British Interplanetary Society
author=D. Andrews & H. Sunley
title=The Gamma rocket engines for Black Knight
volume=vol. 43
pages=pp. 301-310
date=July 1990] For higher concentrations of H₂O₂ another catalyst would have been required, such as platinum. No ignition source was required since the very hot decomposed H₂O₂ is hypergolic (will spontaneously combust) with kerosene. Due to the high ratio (8:1) of the mass of H₂O₂ used compared to the kerosene, and also its superior heat characteristics, the H₂O₂ may also be used to regeneratively cool the engine nozzle before combustion. Any pre-combustion chamber used to power the pump turbines needs only to decompose H₂O₂ to provide the energy. This gives the efficiency advantages of closed cycle operation, without its usual major engineering problems.

All of these characteristics lead to kerosene / hydrogen peroxide engines being simpler and more reliable to construct than other liquid propellant chemistries. Gamma had a remarkably reliable service record for a rocket engine. Of the 22 Black Knight and 4 Black Arrow launchers, involving 128 Gamma engines, there were "no" engine failures.

Stentor

The Gamma began as the smaller cruise chamber of the two-chamber Stentor rocket engine produced by Armstrong-Siddeley for the Blue Steel stand-off missile. cite web
title=Avro Blue Steel stand-off missile
url=http://www.skomer.u-net.com/projects/bluesteel.htm]

Gamma 201

infobox rocket engine
name=Gamma 201
type=liquid
country_of_origin =Britain
manufacturer= Bristol Siddeley

predecessor=Armstrong Siddeley Stentor
successor=Gamma 301

purpose = 1st stage booster
oxidizer=Hydrogen peroxide
fuel=kerosene
mixture_ratio= 8:1 (approx.)
combustion_chamber= 4, gimballed in opposed pairs
thrust_at_launch= 17,000 lbf

style=float: left; font-size: 95%; width: 25em; margin: 0 2em 2em 0;

Bristol-Siddeley developed this stand-alone four-chamber engine from 1955 to 1957 for the Black Knight test vehicles. [cite book
title=A Vertical Empire: The History of the UK Rocket and Space Programme, 1950-1971
author=C.N. Hill
date=2001
publisher=Imperial College Press
isbn=1860942687] Gamma 201 was used for the first twelve Black Knight launches (14 in total), Gamma 301 for most of the later flights. cite web
title=Black Knight Flight Data
url=http://www.spaceuk.org/bk/bk2/bk_engines.htm]

The initial Black Knight vehicles were single-stage rockets designed to test prototype re-entry heads for the proposed Blue Streak strategic ballistic missile. Testing of the Black Knight began at Woomera, Australia in 1958, but the Blue Streak project was cancelled in 1960. The rockets continued to be tested until 1965, as part of a planned two-stage space launcher, using the Gamma 201 for the first stage until August 1962, when it was replaced by the more powerful Gamma 301. cite web
title=Gamma 201 rocket engine, c. 1957
url=http://www.sciencemuseum.org.uk/images/I062/10326693.aspx
publisher=Science Museum ] cite web
title=Gamma rocket motor
url=http://www.skomer.u-net.com/projects/gamma.htm] [cite conference
author=Harlow, John
title=Alpha, Beta and RTV-1, The Development of Early British Liquid Propellant Rocket Engines
conference=Congress of the International Astronautical Federation (IAA)
location=Graz, Austria
date=1993 ] [cite conference
author=Harlow, John
title=Hydrogen Peroxide Engines – Early Work on Thermal Ignition at Westcott
conference=International Hydrogen Peroxide Propulsion Conference, Purdue University,
pages=pp. 211-219
date=Nov, 1999] cite journal
journal=J. British Interplanetary Society
volume=Vol. 43, No. 7
location=London
date=July 1990
author=Andrews, D., Sunley, H.
title=The Gamma Rocket Engines for Black Knight
pages=p.p. 301-310] [cite conference
author=Harlow, John
title=Hydrogen Peroxide - A U.K. Perspective
conference=University of Surrey Symposium on Hydrogen Peroxide
date=July 20-24, 1998]

Gamma 301

infobox rocket engine
name=Gamma 301
type=liquid

predecessor=Gamma 201
successor=Gamma 8

purpose = 1st stage booster
oxidizer=Hydrogen peroxide
fuel=kerosene

mixture_ratio= 8:1 (approx.)

combustion_chamber= 4, gimballed in opposed pairs

thrust_at_launch= 19,000 - 21,000 lbf

specific_impulse= 250
burn_time = 120 seconds

style=float: left; font-size: 95%; width: 25em; margin: 0 2em 2em 0;

This was basically the same as the Gamma 201, but had automatic mixture-ratio control for improved thrust. [cite book
title=A Summary of "Black Knight" Flight Data from 1958 to 1962
author=H.W.B. Gordon B.A. and L.W. Parkin MSc
date=February 1964
publisher=UK gov. Original may be found in the Public Record Office, Kew (part of AVIA 6 17362), the on-web link is to a precis by Nicholas Hill.
url=http://members.aol.com/nicholashl/ukspace/bk/tn57.htm] There were 9 initial test firings of the Gamma 301 engine at High Down from 16th April to 31st May 57, all of which were largely successful. Black Knight launches BK16 and BK18 used the Gamma 301. These two were the beginning of the Project Dazzle high-speed re-entry vehicle trials, where a solid fuel Cuckoo was mounted pointing "downwards" in the second stage, so as to increase re-entry speeds. Eight Gamma 301 launches were made in total.

Gamma 2 / Double Gamma

infobox rocket engine
name=Gamma 8
type=liquid
predecessor=Gamma 301

purpose = 2nd stage
oxidizer=Hydrogen peroxide
fuel=kerosene
combustion_chamber= 2, extended

thrust_at_altitude= 0.68 tonnes Black Arrow exhibit, Science Museum, London]
burn_time = 110-120 seconds

style=float: left; font-size: 95%; width: 25em; margin: 0 2em 2em 0;

A two chamber version of Gamma, used for the second stage of the Black Arrow satellite launch vehicle. As the only Gamma not required to operate at sea level, the nozzles were extended to allow better expansion.

cite book
title=Black Arrow Rocket: A History of a Satellite Launch Vehicle and its Engines
author=Douglas Millard
date=2001
publisher=Science Museum |location=London
isbn=1900747413]

Gamma 8

infobox rocket engine
name=Gamma 8
type=liquid
predecessor=Gamma 301

purpose = 1st stage booster
oxidizer=Hydrogen peroxide
fuel=kerosene
combustion_chamber= 8, gimballed in pairs

thrust_at_launch= 22.7 tonnes
burn_time = 125 seconds

style=float: left; font-size: 95%; width: 25em; margin: 0 2em 2em 0;

This was an 8 chamber development of Gamma, used for the first stage of the Black Arrow satellite launch vehicle. Gamma thrust chambers were mounted in pairs radially, each pair on a one-axis tangential gimbal. Collective movement gave roll control, differential movement pitch.

References