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 excessive oil consumption and temperature in the Griffon engine, with comparisons to the Buzzard engine.
| Identifier | ExFiles\Box 179b\2\ img046 | |
| Date | 28th October 1932 | |
| -3- Oil consumption and temperature rise over the engine are excessive. At 2400 R.P.M. the oil consumption is approx 115% greater than the maximum allowable for a Buzzard engine whilst at the comparative endurance running figure the heat flow to oil per BHP. of the Griffon is almost 400% greater than the Buzzard. The clearance employed for main and big ends with the lead bronze bearings are very little greater than those of the standard Buzzard - white metal - Comparing Griffon .0045 Main. .004 Big end Buzzard .004 " .00375 " This minute difference in clearance should not give rise to greater oil leakage from the bearings and therefore should not be a greater amount of residual oil in the crankcase. The excessive oil consumption, oil temp. rise and frothing might arise from a large quantity of oil being thrown about in the crankchamber. It is suggested that a 1931 'R' type lower half be fitted since this has a greater capacity than the present type and in addition it is felt that advantage could possibly be taken of the oil agitation in the crankcase to use a direct cooling scheme as 'R' type pistons having scraper rings at the bottom should reduce the oil consumption to a reasonable figure. The fuel consumption compares favourably with the standard Buzzard but the consumption loop has a very pronounced 'nose'. This is probably due to a certain extent to the mixture pipe (M.P.R.39737) which is of the staggered manifold type. A pipe of this type has been tried out on standard Buzzard engines - report ref. Hs{Lord Ernest Hives - Chair}/Yms.1/A3.27.11.31. - and was found to exhibit the same characteristic. These staggered manifold pipes have been tried and rejected on both Kestrel and Buzzard engines. It is considered therefore, that a mixture pipe conforming with standard Kestrel and Buzzard practice could be fitted to the Griffon engine with advantage. As yet no work has been carried out on the carburetter. It is pointed out that this is materially the same as the 'R' engine carburetter - a design two years old. A point which will probably receive adverse criticism from aircraft constructors is the position of the circulating water inlet pipe. This is bolted on at the rear of the carburetter bowl. A considerable distance will therefore | ||