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).
Letter to L.P. Saunders discussing experiments with copper brazed radiators, pressure cooling, and ethylene glycol cooling.
| Identifier | ExFiles\Box 149a\3\ scan0229 | |
| Date | 17th November 1938 | |
| L.P.Saunders, Esq. -2- 17th. November 1938. You say that you are using experimentally, copper brazed radiators for pressure cooled work - we presume that this means that you have run into trouble with the ordinary soldered radiator when running pressure cooled, and we would welcome information on this point. After our bitter experiences with oil coolers we are very dubious about putting pressure into a soldered radiator and regard this as the chief objection to pressure cooling on chassis work. Our Aero people have done a good deal of work on high temperature cooling, both pressure water and ethylene glycol (Prestone) cooling and both are being used in production service aircraft. On the whole the opinion of the Aero people seems to be that eventually pressure cooling will replace glycol cooling, but a certain amount of trouble has, and is being experienced due to steam pocketing, which does not occur when operating at maximum pressure and temperature but rather when running at zero pressure and just on 100°C engine coolant outlet. The trouble is bound up entirely with cylinder head and block water space design, water pump design and cylinder block water pressures and we think that you have probably as much, if not more information than us on these questions. I have attached a summary of the information available (or at any rate which our Aero side are prepared to disclose) on the subject of pressure cooling as requested by you, and also on ethylene glycol cooling, but do not think that it contains anything very startling. We would like to know whether you have considered or done anything with ethylene glycol cooling for automobile work - cost of the coolant seems the factor most likely to kill it for this purpose. With regard to the copper brazing of radiators (fin and tube type, I gather) we would like some detailed information on the method of doing this, if it is in order for you to disclose it. We are making enquiries into the possibility of getting hydrogen brazing done in this country and believe that facilities are available and that something might be done in this line if we decided on pressure cooling. I was surprised to hear from Llewelyn Smith that you consider it possible to make a much more efficient matrix (from standpoint of heat dissipated per unit of weight) by using the fin and tube construction instead of the film type, if the cost of the core is not of vital importance. | ||