From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Engine test report detailing performance characteristics including compression, detonation, vibration, and valve clearances.
| Identifier | ExFiles\Box 180\M1\1\ img003 | |
| Date | 1st August 1921 | |
| Contd. -2- The maximum HP. is practically the same as Goshawk 1. when fitted with the R-R Carburetter. The HP. at low speeds is not quite as good but we think we ought to improve this. Compression. The compression by gauge is 90 lbs. with mixture. The compression ratio is 5.3 to 1. Cubic capaci of combustion chamber 7.5 cu.ins. Detonation. It is possible to hear distinct sounds of detonation when the engine is pulling at low speeds with igni early. This is more noticeable than Goshawk 1 but a lot of this may be due to the extra high compression on this engine. We have put in hand some pistons to enable us to test a lower compression. Vibrations. We have tested the engine without the friction damper fitted and the spring drive choc-a-bloc. There is a period between 1100 and 1200 R.P.M. and above 2300, the engin gears rattle very badly. With the damper fitted, the engin appears free from periodic vibrations. One has the impressio though, that the engine is harsh due most probably to the high compression. Valve Mechanism. The valves leave the seats at about 3100 to 3200 R.P.M. We have measured the difference in the tappet clearance with the engine cold and hot. Tappet. Clearance engine cold. Clearance when engine is running Full Power 2400 R.P.M. No.1 inlet. .004" .007" No.6 inlet .004" .007" No.1 exhaust. .004" .008" No.6 exhaust. .004" .005" contd:- | ||