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 shutters, and factors influencing engine boiling.
| Identifier | ExFiles\Box 24\5\ Scan089 | |
| Date | 18th June 1925 | |
| -2- With regard to the question of the shutters or louvres being made to open completely, I assume this means the louvre to move through 90°. If this is what is intended, then it can easily be shewn that the radiator matrix cannot pass the air through which is provided by even present opening, a fact which can be easily verified by opening shutters the amount arranged at present as maximum, driving car on track and noting temperature of water, and then closing shutters say one notch on quadrant and repeating performance. There are no further experiments in hand to increase our cooling capacity for present chassis, for as R.{Sir Henry Royce} recently pointed out, we have reached our limitations as controlled by radiator height to give road view, width of radiator as determined by side members, and steering lock necessities and depth by fact we cannot cover it with fan. Referring now to QJ9/E.16.6.25 there are absolutely no data recorded or mentioned to fix the value of this performance. A head wind as against a side or trailing wind would fully cover the phenomena recorded, and whilst fully admitting the evidence that the jacket water did not boil even on long hills, this does not necessarily mean there is any real difference in the two chassis in regard to the heat given to the jacket water per B.H.P. actually employed. There will always be slight differences between precisely similar engines due to a number of varying factors being all maxima or all minima, but the accumulative effect will not show a 5% variation between the best and worst. It is agreed that there are reasons why PN{Mr Northey}'s engine boiled its jacket water, and the Spanish trials engine did not, but the reasons are differences in a/- The B.H.P. developed for a given speed of car. b/- The direction of the wind. c/- The air temperature, and unless accurate measurements and records of these always varying factors are carefully taken, no real comparison can be made or any useful facts deduced. There is no evidence put forward to show that Spanish trials car was driven to its limit of speed, and even then if it were, whilst a head wind would possibly keep it from boiling under the actual -Cont'd- | ||