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 systems, radiator reliability, pressure cooling, and the use of Ethylene Glycol.
| Identifier | ExFiles\Box 131\5\ scan0117 | |
| Date | 5th December 1938 | |
| -3- Rm{William Robotham - Chief Engineer}/Std.14/MR.5.12.38. (6) No trouble has been experienced in flight with radiator reliability which is attributable to pressure in the cooling system - actually the main cause of aero radiator trouble is vibration. (Soldered round tube (hex ends) radiators are used). (7) With pressure cooling it is essential to have a well designed water pump and water passages capable of keeping up flow with inlet temperatures of 90 - 95°C., and also the coring of the cylinder head must be watched to avoid steam pockets - in this connection it is very desirable to work with a fairly high cylinder block coolant pressure (say 10 - 15 lbs/sq.in. in excess of general cooling system pressure). It must be stressed that the only real trouble experienced by the Aero people (attributable to pressure cooling) has been due to steam pocketing and has occurred when running at approx. zero pressure at approx. 100°C - when functioning under limit conditions of 15 lbs/sq.in. and 121°C this steam pocket trouble does not occur. In this connection our engine thermostats would greatly help matters. In case of either pressure cooling or Ethylene Glycol, the higher coolant temperature materially increases detonation - Glycol being considerably worse than pressure cooling in this respect owing to the high metal temperature already mentioned. In addition to the above specific information, Dr. Still (he has come to this firm recently from Messrs. Clayton Dewandre who do a good deal of consulting work for the War Office relating to cooling problems) informed the writer that the War Office have adopted pressure cooling on armoured cars after abandoning evaporative and glycol cooling. Also the Harrison Radiator Corporation are now experimenting with pressure cooling - we intend to ask them, however, whether they have any experience with Ethylene Glycol. | ||