The de Havilland Sprite is a British rocket engine that was built by

de Havilland The de Havilland Aircraft Company Limited (pronounced , ) was a British aviation manufacturer established in late 1920 by Geoffrey de Havilland at Stag Lane Aerodrome Edgware on the outskirts of North London. Operations were later moved to ...

in the early-1950s for use in RATO (Rocket-assisted take off) applications. A developed engine with slightly less

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

but a longer burn time was known as the Super Sprite, production ceased in October 1960.

Design and development

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 The de Havilland DH.106 Comet is the world's first commercial jet airliner. Developed and manufactured by de Havilland in the United Kingdom, the Comet 1 prototype first flew in 1949. It features an aerodynamically clean design with four ...

1 airliners (as

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. The lower air density reduces the power output from an airc ...

operations in the

British Empire The British Empire comprised the dominions, Crown colony, colonies, protectorates, League of Nations mandate, mandates, and other Dependent territory, territories ruled or administered by the United Kingdom and its predecessor states. It bega ...

were considered important) and also for

V bomber The "V bombers" were the Royal Air Force (RAF) aircraft during the 1950s and 1960s that comprised the Nuclear weapons and the United Kingdom, United Kingdom's strategic nuclear strike force known officially as the V force or Bomber Command Mai ...

s 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 is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...

was used, decomposed into oxygen and steam over a metallic

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

catalyst. The maximum thrust was , varying over the 16 second burn time for a total impulse of 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 demonstrations 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 The Vickers Valiant was a British high-altitude jet bomber designed to carry nuclear weapons, and in the 1950s and 1960s was part of the Royal Air Force's " V bomber" strategic deterrent force. It was developed by Vickers-Armstrongs in respon ...

V bomber.

Variants

;Sprite DSpr.1 ;Sprite DSpr.2: Silver-plated nickel-gauze catalyst, tested in Comets during April 1952 ;Sprite DSpr.3 ;Super Sprite DSpr.4

Super Sprite

The Super Sprite 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

had a small canard vane at the nose, pitching the nacelle downwards on separation. De Havilland regarded the 166 Super Sprite 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 or certificate of conformity 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 Super Sprite project was cancelled in October 1960, at a reported total cost of £850,000.

Applications

Specifications (Sprite (DSpr.l))

References