De Havilland Sprite
| Country of origin | UK |
|---|---|
| Manufacturer | de Havilland |
| Application | RATO |
| hydrogen peroxide monopropellant | |
| Walter 'cold' cycle | |
| Performance | |
| Thrust | 5,000 lbf (22.2kN) |
| Total impulse | 55,000 lbf seconds |
| Burn time | 16 seconds |
| Propellant capacity | 39 gallons |
| Dimensions | |
| Dry weight | 350 lbs |
| Country of origin | UK |
|---|---|
| Manufacturer | de Havilland |
| Application | RATO |
| Predecessor | Sprite |
| Liquid-fuel engine | |
| Propellant | hydrogen peroxide / kerosene |
| Performance | |
| Thrust | 4,200 lbf (18.7kN) |
| Total impulse | 120,000 lbf seconds |
| Burn time | 40 seconds |
| Propellant capacity | 60 gallons (approx.) |
The Sprite was a British rocket engine built by de Havilland for use in RATO (Rocket-assisted take off) 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 5,000 lbf (22 kN), varying over the 16 second burn time for a total impulse of 55,000 lbf (240 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.
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.
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Wikipedia