De Havilland Sprite
Encyclopedia
The Sprite was a British rocket engine built by de Havilland
for use in RATO applications. For RATO use only a short burn time is required, with simplicity and light weight as major virtues. The intended market was for assisting take-off of de Havilland Comet
1 airliners (as hot and high
operations in the British Empire
were considered important) and also for V-bombers carrying heavy nuclear weapons. 30 successful test flights were carried out by Comets, from May 1951, but gas turbine performance improved rapidly, and so RATO was not required in service.
A hydrogen peroxide
monopropellant
was used, decomposed into oxygen and steam over a metallic calcium
catalyst. The maximum thrust was 5000 lbf (22.2 kN), varying over the 16 second burn time for a total impulse of 55000 lbf (244.7 kN) seconds.
A technology update then took place with the proving of silver plated nickel gauze packs as catalysts with the establishment of optimum loadings and flows. This practice was replicated in all future applications with the catalyst no longer consumed.
In April 1952 the DSpr.2 proved this modification impressively in Comet demonstration with clean exhaust. The next stage was pursued with the Super Sprite (DSpr.4) following the ATO development precedent with 'hot' operation but now enhanced in simplicity by ability to inject kerosene fuel once chamber pressure was established by the catalysed peroxide flow. The units, flight approved in August 1953, reverted to the practice of being parachuted after firing for routine re-use in service
operations with the Vickers Valiant
V bomber.
For simplicity, there were no fuel pumps and the tanks were pressurised by nitrogen from nine cylinders wrapped around the combustion chamber.
The Super Sprite was packaged as a self-contained engine in its own nacelle, jettisoned after take-off and retrieved by parachute. Inflatable air bags cushioned its impact with the ground. To obtain a clean separation from the carrier aircraft, the production engines fitted to the Vickers Valiant
had a small canard vane at the nose, pitching the nacelle downwards on separation.
De Havilland regarded the 166 units manufactured as a standard production item, supported by their Service Department alongside piston and turbojet engines. It was the first rocket engine to gain formal type approval
.
The Super Sprite project was cancelled in October 1960, at a reported total cost of £ 850,000.
De Havilland
The de Havilland Aircraft Company was a British aviation manufacturer founded in 1920 when Airco, of which Geoffrey de Havilland had been chief designer, was sold to BSA by the owner George Holt Thomas. De Havilland then set up a company under his name in September of that year at Stag Lane...
for use in RATO applications. For RATO use only a short burn time is required, with simplicity and light weight as major virtues. The intended market was for assisting take-off of de Havilland Comet
De Havilland Comet
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design...
1 airliners (as hot and high
Hot and high
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. Lower air density reduces the amount of lift generated by the wings or the rotors of an aircraft, which may hamper...
operations in the British Empire
British Empire
The British Empire comprised the dominions, colonies, protectorates, mandates and other territories ruled or administered by the United Kingdom. It originated with the overseas colonies and trading posts established by England in the late 16th and early 17th centuries. At its height, it was the...
were considered important) and also for V-bombers carrying heavy nuclear weapons. 30 successful test flights were carried out by Comets, from May 1951, but gas turbine performance improved rapidly, and so RATO was not required in service.
A 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...
monopropellant
Monopropellant
Monopropellants are propellants composed of chemicals or mixtures of chemicals which can be stored in a single container with some degree of safety. While stable under defined storage conditions, they react very rapidly under certain other conditions to produce a large volume of energetic gases...
was used, decomposed into oxygen and steam over a metallic calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
catalyst. The maximum thrust was 5000 lbf (22.2 kN), varying over the 16 second burn time for a total impulse of 55000 lbf (244.7 kN) seconds.
Variants
- DSpr.2
- silver-plated nickel-gauze catalyst, tested in Comets during April 1952
A technology update then took place with the proving of silver plated nickel gauze packs as catalysts with the establishment of optimum loadings and flows. This practice was replicated in all future applications with the catalyst no longer consumed.
In April 1952 the DSpr.2 proved this modification impressively in Comet demonstration with clean exhaust. The next stage was pursued with the Super Sprite (DSpr.4) following the ATO development precedent with 'hot' operation but now enhanced in simplicity by ability to inject kerosene fuel once chamber pressure was established by the catalysed peroxide flow. The units, flight approved in August 1953, reverted to the practice of being parachuted after firing for routine re-use in service
operations with the Vickers Valiant
Vickers Valiant
The Vickers-Armstrongs Valiant was a British four-jet bomber, once part of the Royal Air Force's V bomber nuclear force in the 1950s and 1960s...
V bomber.
Super Sprite
The Super Sprite DSpr.4 was a re-development of the Sprite application, using a significantly different 'hot' propellant technology, that of hydrogen peroxide / kerosene. Although the peak thrust was actually reduced, burn time was 2.5 times longer, with a proportionate increase in total impulse.For simplicity, there were no fuel pumps and the tanks were pressurised by nitrogen from nine cylinders wrapped around the combustion chamber.
The Super Sprite was packaged as a self-contained engine in its own nacelle, jettisoned after take-off and retrieved by parachute. Inflatable air bags cushioned its impact with the ground. To obtain a clean separation from the carrier aircraft, the production engines fitted to the Vickers Valiant
Vickers Valiant
The Vickers-Armstrongs Valiant was a British four-jet bomber, once part of the Royal Air Force's V bomber nuclear force in the 1950s and 1960s...
had a small canard vane at the nose, pitching the nacelle downwards on separation.
De Havilland regarded the 166 units manufactured as a standard production item, supported by their Service Department alongside piston and turbojet engines. It was the first rocket engine to gain formal type approval
Type approval
Type Approval is granted to a product that meets a minimum set of regulatory, technical and safety requirements. Generally, type approval is required before a product is allowed to be sold in a particular country, so the requirements for a given product will vary around the world...
.
The Super Sprite project was cancelled in October 1960, at a reported total cost of £ 850,000.