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).
Overheating on the 40/50s model, weighing the pros and cons of exhaust versus water-heated throttles.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan130 | |
| Date | 28th April 1925 | |
| THROTTLE HEATING - EXHAUST OR WATER. R CLASSIC PROS & CONS QQ-CL. FROM R.{Sir Henry Royce} Copy to - HS.{Lord Ernest Hives - Chair} " " - EAC re. OVERHEATING OF 40/50s. CJI/E27.4.25. I have just heard of the Australian trouble. My impression is that the choke valve in the exhaust pipe, and the exhaust heated throttle are more harmful than the benefits we have derived and that it would be wise to do away with the valve entirely, and if we cannot make the exhaust heated throttle work without it we had better heat the throttle with water as previously. You will remember that it was on account of early complaints from America directly after the war that caused us to do an endless number of experiments, the best of which appeared to be the substitution of exhaust heat for water heated throttles. All the other improvements here and in USA. were found to have no benefit. It now seems that we should have done better to have even avoided this particular one. Probably we had better wire Australia some improved instructions. (Written before receiving your wire.) Regarding the high speed fan I do not approve of this because of the difficulty of driving it. The best scheme of making the radiator effective is probably the more easily driven fan we are now fitting to EAC. combined with a louvred bonnet. It appears that the cars as fitted with water heated throttles, even with the old smaller radiator, were quite satisfactory in Australia. It is admitted that ours, and all other cars with large engines fitted with radiators of moderate dimensions will boil under trying circumstances, but the evidence shews that this does no harm, and is a lesser evil than an excess of radiator with its height, weight, and other difficulties. On the question of Mr. Hanbury's difficulties in the south of France, I have received no information as to the cause of the failure. There will always be a slight gain in a water heated throttle because the ingoing gases will not be so hot, and therefore there will be less liability to detonate, and the throttle will be assisting the radiator slightly instead of the increased gas temperature in the exhaust heated throttle adding to the heat of the circulating water. Under hot atmospheric conditions the exhaust heated throttle, at its extra high temperature, is undesirable. I have only just heard of these more recent and definite troubles, and the above was written before receiving your telegram. I suggest wiring Australia with Derby's approval as to possibilities of doing so, etc, as follows:- "CANCEL VALVE IN EXHAUST AND REVERT TO" "WATER HEATED THROTTLE RETEST AND REPORT." R.{Sir Henry Royce} | ||