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).
Comparison of detonation, performance, and cooling drag between air-cooled and water-cooled aero engines.
| Identifier | ExFiles\Box 179b\3\ img269 | |
| Date | 17th February 1933 | |
| -4- Hs.{Lord Ernest Hives - Chair}7/W.17.2.33. Cont'd.{John DeLooze - Company Secretary} shewn any real signs of internal heating. We have had one case where the joint ring shewed signs of detonation, but compared with the air cooled people we have not started to warm up the engine. Burned pistons is their worst failure. The problem of detonation is so entirely different on the air cooled and water cooled engine - as soon as the air cooled starts to detonate it is finished because it has no means of getting rid of the excess heat. With the water cooled engine we can detonate and go on detonating because the extra heat goes into the water. We feel, however, that we are often rated under the same conditions as the air cooled when the same conditions do not apply whatsoever. For instance, the A.M. test for detonation is the same for water cooled and air cooled. We are positively of the opinion that this is wrong but as however we are the only firm left exploiting the water cooled engine it means that we are on our own in making out the case for the water cooled engine. We know our engines never get warm in the air because we have had to agree to use sparking plugs for service in the air which would not stand up to our normal test bed work. We can afford to make an engine that is working nearer the top limit of the fuel to compete with the air cooled. The other point which has got to receive some attention if we are going to hold our own against the air cooled is the reduction of drag on the installation. The recent tests on the "Fury" show that by adding over 100 HP. increases the machine speed about 10 M.P.H. On the other hand the addition of spats (fairing) on the wheels increased the speed of the machine 7 or 8 M.P.H. We have, by some means or other, got to get rid of the drag of the radiator. One way of course is evaporative cooling but we have not yet exhausted the possibilities of reducing the drag of water cooling. At the present time it should be realised that R.R. are the only aero engine manufacturers in the World who are making solely water cooled engines. All the Research establishments throughout the World are concentrating on improving the air-cooled engine and we must say that results shew that they have achieved considerable success. Hs.{Lord Ernest Hives - Chair} | ||