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 cooling tests comparing water-cooled and evaporatively cooled systems and investigating hot spots.
| Identifier | ExFiles\Box 179\3\ img056 | |
| Date | 1st March 1932 | |
| -3- (1) Under water cooled conditions at normal boost the cylinder head temperature is only about 20°C. higher than the outlet water. Under full throttle conditions (full supercharged engine) the temperature does not rise more than 37°C. above that of the water. (2) Under evaporatively cooled conditions at normal boost the temperature rise is the same as when water cooled - or only 20°C. higher than the outlet steam and water. (3) Evaporatively cooled at "take off" boost and revs, the temperature soars up to 275°C. (4) Changing the plugs to Lodge X.170's (Schneider Trophy plugs) the temperatures are reduced but still reach 210°C. These results seem to indicate that when running evaporatively cooled with high power demand and the presence of detonation there is every evidence of steam pockets forming in the head and giving rise to these excessively hot spots. We next intend to follow up the investigation with more thermo couples fixed to the head and every available core plug fitted with a steam outlet pipe to try to avoid the suspected steam pockets. The thermo couples will be a good and quick indication of the effect of free steam outlets. We think these thermal tests may throw some light on the cylinder leakage troubles we have experienced even on water cooled engines. Permitting an engine to boil inadvertently when taking out high power, such as omitting to open the radiator shutters when on a climb, may give rise to hot spots such as we have recorded and be the basis for the development of cylinder leaks. HE/LOV.{Mr Lovesey} | ||