| RB.108 | |
|---|---|
 Preserved RB.108 at theRoyal Air Force Museum Cosford | |
| Type | Turbojet |
| Manufacturer | Rolls-Royce Limited |
| First run | 1955 |
| Major applications | Short SC.1 |
| Developed into | Rolls-Royce RB145 lift/cruise engine |
TheRolls-Royce RB.108 was a Britishjet engine designed in the mid-1950s byRolls-Royce specifically for use as aVTOLlift engine. It was also used to provide horizontal thrust in theShort SC.1.
The RB.108 was the first direct-lift turbojet produced by Rolls-Royce. It originated from a VTOL concept in whichAlan A. Griffith proposed using a small number of specialised lift engines in a VTOL aircraft, separate from the engines which provided forward propulsion. Its power output (thrust) was not high enough for use as a practical engine in a production aircraft[1] and was used only for research into VTOL. It was constructed from conventional materials. (The next lift engine, theRB.162, would have a compressor built mainly from glass-fibre composite and have a higher T/W ratio.) The RB.108bearings andoil system were designed to operate with an engine attitude envelope which covered engine and aircraft tilting while transitioning between hovering and forward flight. When a fifth engine was installed in the SC.1 to provide forward thrust it had to be mounted at about 45 degrees to remain within the envelope. The exhaust was directed horizontally with a curved jetpipe.
The RB.108 was used in theShort SC.1, which used four for lift with an additional one mounted at an angle at the rear for propulsion, and theDassault Balzac V, which used eight vertically mounted RB.108s for lift. TheVereinigte Flugtechnische Werke (VFW)SG 1262 used five RB.108s, three mounted in tandem on the centreline, with one RB.108 either side.
The RB.108 was also the intended powerplant for several other VTOL aircraft designs, including one byDornier.
A similar lift jet was designed byBristol Siddeley, the BS.59, with a thrust of 8,000 lb the engine was intended for the projectedFocke-Wulf Fw 260.[2]
Data fromAircraft engines of the World 1964/65.[3]
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