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).
Optimal size for radiator tubes and their effect on engine cooling and performance.
| Identifier | WestWitteringFiles\U\2January1930-September1930\ Scan212 | |
| Date | 14th July 1930 | |
| HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} Copy to SG.{Arthur F. Sidgreaves - MD} Copy to WOR.{Arthur Wormald - General Works Manager} Copy to BY.{R.W. Bailey - Chief Engineer} re. CAR WORK. R1/M14.7.30. x7250 x766. x7260. It appears from your memo. HSRM 97 that you have tested smaller radiator tubes than the 6 m/m standard. I want you to test larger radiator tubes because I fear we are wasting money and weight on making the tubes slightly too small instead of working with less surface and more air. We quite agree that the petrol supply at maximum speed should be ample, and the mixture be arranged by the carburetter not to run off weak. It would be better for it to be slightly over-rich, which I believe is what happens because our air valve gets to the top before the maximum speed, that is, supposing the petrol in the float feed is maintained at its proper level. Regarding the indented tubes I have stated before that I do not agree with these because they may get obstructed and insulated with dirt, and also as mentioned above we may want to get rather more air, than heat the air to a higher temperature. The temperature of the air under the bonnet compared with the external air, as well as the temperature of the water, would give some indication as to whether the air circulating through the matrix of the radiator was sufficient. The carburetter on P. 2. is much less likely to get overheated with overhot air when compared with P. 1. It will be noted that if you use larger radiator tubes the temperature under the bonnet would be cooler, that is to say, the direct cooling of the engine, crankchamber, oil, and everything would be better, and actually give more power for perhaps the same amount of heat to the cooling water. In conclusion, one might say that the radiator tubes ought to be slightly too large than too small. R.{Sir Henry Royce} | ||