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 discussing the benefits and technical details of using ethylene-glycol coolant in aero engines.
| Identifier | ExFiles\Box 151\3\ scan0086 | |
| Date | 29th March 1929 | |
| OY3 Mr. Sidgreaves, Rolls Royce Ltd., London, England. My dear Mr. Sidgreaves: March 29th, 1929. cc to London for Mr. Royce Mr. Hives London File AERO ENGINES In a recent newspaper paragraph it is stated that great improvements in effectiveness of water-cooled engines have resulted (following experiments at McCook Field, the U. S. Government -test Station) from the use of ethylene-glycol in the cooling system instead of water. It is claimed that the necessary radiating surface is reduced to one fourth with great saving in weight - 400 lbs. stated for a large aeroplane - and increase of 10 m.p.h. in speed through reduced head resistance. The statements are probably garbled and possibly exaggerated, but I will look for similar articles in the technical press, and will send anything which appears authentic. It probably refers to a mixture of ethylene glycol and water perhaps in the proportion of 50-50 which has a boiling point around 300ºF and will thus allow increased operating temperatures and increased cooling efficiency. The freezing point is about - 10ºF. {Mr Friese} A spring-loaded blow-off valve is used presumably to prevent loss and allow of raising the temperature above the normal boiling point at altitudes. The system in other respects is normal except for reduced radiating surface. Ethyl gasoline is used to prevent detonation at the higher temperature. -continued- | ||