Bristol Siddeley Gamma
Encyclopedia
The Armstrong Siddeley, later Bristol Siddeley 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.
Engine static testing was carried out at High Down, near The Needles
on the Isle of Wight
(50°39′38.90"N 1°34′38.25"W). (Spadeadam
in Cumbria
wasn't used for testing until Blue Streak
, after Gamma).
The combustion of kerosene with hydrogen peroxide is given by the formula
where 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)
showing 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. The low molecular mass of water also helps to increase rocket thrust performance.
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. 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.
Bristol-Siddeley developed this stand-alone four-chamber engine from 1955 to 1957 for the Black Knight
test vehicles. Gamma 201 was used for the first twelve Black Knight launches (14 in total), Gamma 301 for most of the later flights.
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.
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.
satellite launch vehicle. As the only Gamma not required to operate at sea level, the nozzles were extended to allow better expansion.
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.
Black Knight (rocket)
Black Knight was a British launch vehicle to test and verify the design of a re-entry vehicle for the Blue Streak missile.The United Kingdom's first indigenous rocketry project, Black Knight was manufactured by Saunders-Roe on the Isle of Wight, had its engines tested at The Needles and was...
and Black Arrow
Black Arrow
Black Arrow, officially capitalised BLACK ARROW, was a British satellite carrier rocket. Developed during the 1960s, it was used for four launches between 1969 and 1971...
launch vehicles. They burned kerosene fuel and hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
. 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
Coventry
Coventry is a city and metropolitan borough in the county of West Midlands in England. Coventry is the 9th largest city in England and the 11th largest in the United Kingdom. It is also the second largest city in the English Midlands, after Birmingham, with a population of 300,848, although...
, which later became Bristol Siddeley
Bristol Siddeley
Bristol Siddeley Engines Ltd was a British aero engine manufacturer. The company was formed in 1959 by a merger of Bristol Aero-Engines Limited and Armstrong Siddeley Motors Limited. In 1961 the company was expanded by the purchase of the de Havilland Engine Company and the engine division of...
in 1959, and finally Rolls-Royce
Rolls-Royce Limited
Rolls-Royce Limited was a renowned British car and, from 1914 on, aero-engine manufacturing company founded by Charles Stewart Rolls and Henry Royce on 15 March 1906 as the result of a partnership formed in 1904....
in 1966.
Engine static testing was carried out at High Down, near The Needles
The Needles
The Needles is a row of three distinctive stacks of chalk that rise out of the sea off the western extremity of the Isle of Wight, England, close to Alum Bay. The Needles lighthouse stands at the end of the formation...
on the Isle of Wight
Isle of Wight
The Isle of Wight is a county and the largest island of England, located in the English Channel, on average about 2–4 miles off the south coast of the county of Hampshire, separated from the mainland by a strait called the Solent...
(50°39′38.90"N 1°34′38.25"W). (Spadeadam
RAF Spadeadam
RAF Spadeadam is a Royal Air Force station in Cumbria, England close to the border with Northumberland. It is the home of the 9000 acre Electronic Warfare Tactics Range, making it the largest RAF base in the United Kingdom.-History:...
in Cumbria
Cumbria
Cumbria , is a non-metropolitan county in North West England. The county and Cumbria County Council, its local authority, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbria's largest settlement and county town is Carlisle. It consists of six districts, and in...
wasn't used for testing until Blue Streak
Blue Streak missile
The Blue Streak missile was a British medium range ballistic missile . The Operational Requirement for the missile was issued in 1955 and the design was complete by 1957...
, 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.The combustion of kerosene with hydrogen peroxide is given by the formula
- CH2 + 3H2O2 → CO2 + 4H2O
where CH2 is the approximate formula of kerosene (see RP-1
RP-1
RP-1 is a highly refined form of kerosene outwardly similar to jet fuel, used as a rocket fuel. Although having a lower specific impulse than liquid hydrogen , RP-1 is cheaper, can be stored at room temperature, is far less of an explosive hazard and is far denser...
for a discussion of kerosene rocket fuels). This compares with the combustion of kerosene and liquid oxygen (LOX)
- CH2 + 1.5O2 → CO2 + H2O
showing 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. The low molecular mass of water also helps to increase rocket thrust performance.
The oxidizer used with Gamma was 85% High Test Peroxide
High test peroxide
High-test peroxide or HTP is a high -concentration solution of hydrogen peroxide, with the remainder predominantly made up of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with no remaining liquid water...
(HTP), H2O2. Gamma used a silver-plated on nickel-gauze catalyst to first decompose the peroxide. 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
Staged combustion cycle (rocket)
The staged combustion cycle, also called topping cycle or pre-burner cycle, is a thermodynamic cycle of bipropellant rocket engines. Some of the propellant is burned in a pre-burner and the resulting hot gas is used to power the engine's turbines and pumps...
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.Gamma 201
Black Knight (rocket)
Black Knight was a British launch vehicle to test and verify the design of a re-entry vehicle for the Blue Streak missile.The United Kingdom's first indigenous rocketry project, Black Knight was manufactured by Saunders-Roe on the Isle of Wight, had its engines tested at The Needles and was...
test vehicles. Gamma 201 was used for the first twelve Black Knight launches (14 in total), Gamma 301 for most of the later flights.
The initial Black Knight vehicles were single-stage rockets designed to test prototype re-entry heads for the proposed Blue Streak
Blue Streak missile
The Blue Streak missile was a British medium range ballistic missile . The Operational Requirement for the missile was issued in 1955 and the design was complete by 1957...
strategic ballistic missile
Ballistic missile
A ballistic missile is a missile that follows a sub-orbital ballistic flightpath with the objective of delivering one or more warheads to a predetermined target. The missile is only guided during the relatively brief initial powered phase of flight and its course is subsequently governed by the...
. Testing of the Black Knight began at Woomera
Woomera Test Range
The RAAF Woomera Test Range is a weapons testing range operated by the Royal Australian Air Force Aerospace Operational Support Group...
, 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.
Gamma 301
This was basically the same as the Gamma 201, but had automatic mixture-ratio control for improved thrust. There were 9 initial test firings of the Gamma 301 engine at High Down from 16 April to 31 May 57, all of which were largely successful. Black KnightBlack Knight (rocket)
Black Knight was a British launch vehicle to test and verify the design of a re-entry vehicle for the Blue Streak missile.The United Kingdom's first indigenous rocketry project, Black Knight was manufactured by Saunders-Roe on the Isle of Wight, had its engines tested at The Needles and was...
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
A two chamber version of Gamma, used for the second stage of the Black ArrowBlack Arrow
Black Arrow, officially capitalised BLACK ARROW, was a British satellite carrier rocket. Developed during the 1960s, it was used for four launches between 1969 and 1971...
satellite launch vehicle. As the only Gamma not required to operate at sea level, the nozzles were extended to allow better expansion.
Gamma 8
Black Arrow
Black Arrow, officially capitalised BLACK ARROW, was a British satellite carrier rocket. Developed during the 1960s, it was used for four launches between 1969 and 1971...
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.