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 under-bonnet temperature control, with proposed modifications for the Phantom III.
| Identifier | ExFiles\Box 92\6\ scan0275 | |
| Date | 29th October 1936 guessed | |
| (2) Such a scheme would of course not reduce the ultimate temperatures reached when heat balance is established under all out conditions by prolonged running, but it should materially reduce the average temperature. The required behaviour of the thermostat controlling the shutters can be modulated by the use of springs set up if required, and it is also suggested that the same bellows unit controlling the bypass might be used instead of an independent heating element connected by a super tube with the bellows unit in the radiator. To increase the maximum air flow through the radiator and thereby reduce the maximum under temperature the present engine guards might be replaced by valances carried on the frame to act as mud shields, leaving the space between the engine and the frame open in a downward direction. It has been urged in the past that it was undesirable to see the road surface after having lifted the bonnet in this way, but we think the requirements of cooling are more important. There may be more tendency too for the engine to get dirty under these conditions, but the development of a suitable valance should reduce this minor difficulty to the minimum. Any increase on the bonnet width at the rear is of help in providing more space for the air to get away from under the bonnet, and we are taking full advantage of this in the modification that will be tried out on the long wheelbase Phantom III. With the radiator shutter control relieved of the duty of looking after the engine, it may be found possible to use thermostatically controlled bonnet shutters, as the under bonnet temperature would then be more proportionate to running conditions, and not be held at its present artificial level. The effect of a lower average under bonnet temperature on carburation would have to be investigated, but with the water heated type of induction pipe jacket one would not expect much trouble from this source. We suggest that experiments could be made right away to test the effect of running with the shutters in the suggested position, and in the meantime we propose to prepare some rough schemes for trying out the suggested control. | ||