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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).
Analysis of engine tests focusing on excessive oil consumption, temperature, and frothing at various RPMs.

Identifier  ExFiles\Box 179b\2\  img045
Date  29th October 1932
  
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During the running of the power curve it was observed that the oil consumption was excessive, particularly at 2400 RPM. Tests of oil consumption were consequently carried out at 2400 and 2150 RPM, over periods of 15 mins. The oil consumption was at the rate of 32 pints/hr. at the former speed and 21 pts/hr. at the latter.

The oil temp. rise over the engine appeared to be higher than usual. Oil flow checks made at 2200, 2300, and 2400 R.P.M. gave 7.30, 7.32, 8.33 galls/min. at the respective speeds. A figure of heat flow to the oil taken during the 15 mins. oil consumption test at 2400 gave 2.47 BTU/BHP/Min. whereas the Buzzard figure is only 0.9 BTU/BHP/Min.

A point which was particularly noticeable was the smoothness of the running of the engine at 2400 RPM, as compared with 2150.

Oil frothing was excessive compared with both standard Kestrel and Buzzard engines, and the amount of frothing increased with the engine speed. The tooth form and diameter of the oil pump gears are the same as the Buzzard but the pump runs at a higher speed (1.087 E.S. against .8 S.) and has 0.1" wider gears.

Tests were carried out to investigate if the oil was building up in the crankcase. The R.A.E. Compressor drive blanking plate was removed after a period of light running. The oil level in the bottom half was found to be just level with the orifice.

The engine was then run at 2400 RPM. and there was found to be no difference in the oil level on shutting down quickly and removing the compressor drive blanking plate.

CONCLUSIONS.

The power of the engine is satisfactory and will be somewhat above the estimated rating of 1000 BHP. at 2150 RPM. when the 6/1 C.R. pistons are fitted.

When the engine is seen running on the test bed at the respective speeds of 2400 and 2150 R.P.M. the ease and sweetness of operation of the former figure is at once appreciated. It is considered that the rated normal speed should definitely be around 2400 R.P.M.

Before any definite conclusions can be drawn as to reduction gear noise the engine will have to be run on a hangar but judging from the running already carried out the double helical gear will probably be a great improvement on the existing type.
  
  


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