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 issues, fan efficiency, bonnet lift, and preventing water loss from boiling.
| Identifier | ExFiles\Box 38\2\ Scan219 | |
| Date | 8th September 1924 guessed | |
| contd :- -2- that not one car in 500 is satisfactory under full throttle, low speed, and hot weather, and the larger the engine the greater the deficit. Careful comparison will be made: reports are not to be relied upon. Limits of what can be done. It is practically impossible to do better than outlined - i.e. a 23" matrix, and large and efficient fan. (We must let heated air escape). Practically all bonnets lift with the air pressure at high speeds. We have a better fan, both in size, design and drive, than anyone, most of them look like toys. I have said that to change to a lower gear is a decided advantage, but have never said that it would prevent boiling, at full throttle with high air temperatures - 27oC mentioned = 80.F. In the past we have been and still shall be, slightly low in face area, but not in cooling area. We have always had a good fan at a good speed, but have never been able to get the air away, without shuttered or louvred bonnets. Overfilling and boiling away. No trouble has ever arisen through loss of water through boiling. If filled right up first a lot of water is thrown out, then boiling can go on for a long time without losing much water, therefore, it seems desirous to prevent overfilling (space for 1 gal. expansion is required) then test should be made to see if more water added boiling could go on for 2 or 3 hours under trying circumstances, (80.F. air temperature) before replenishing is really needed. We had already designed an auto valve to prevent overfilling which will be always open when radiator cap removed. Clean water should always be used XXXXXXXX as some additions (such as soda) cause priming, and much water is thrown out. R.{Sir Henry Royce} MADE AT CROXLEY | ||