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).
Underbonnet temperature tests and the results of various modifications.
| Identifier | ExFiles\Box 125\3\ scan0127 | |
| Date | 3rd July 1939 | |
| -3- Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards}5/JH.3.7.39. justified by results as the graph of water temperature against time is only slightly curved and an average gradient is easily obtained. It will, however, be realised that these figures are not dead accurate, but they form a useful guide in assessing the comparative idling qualities of various systems. (5) Underbonnet temperatures. In all cases these appeared quite reasonable, the maximum value being 51.5°C when using the Buick fan, a figure which can be compared favourably with the Buick's 69°C, both figures being obtained at 30 m.p.h. full throttle. Bonnet flip flaps - two fitted on each side - made very little difference to this temperature, and removing the bonnet altogether only dropped it by 9°C. (6) Miscellaneous tests. A number of miscellaneous tests were carried out and results are as under - (a) Bonnet flip flaps open - Critical air temperature increased by 2½% under flat out conditions, fan air temperature reduced by 3½% and under bonnet temperature unchanged. (b) Bonnet removed altogether. Critical air temperature increased 11½% on standard conditions, fan air temp. reduced by 7½% and underbonnet temp. reduced by 21%, these figures represent the optimum conditions obtainable with the existing layout. (c) Spot light removed. This test was carried out on No.1 matrix, and appeared to make no difference whatever. All the results obtained are etabulated in Fig.V. 14 | ||