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).
Vehicle cooling system tests, focusing on ventilation and bonnet shutters to prevent overheating.
| Identifier | ExFiles\Box 14\7\ Scan011 | |
| Date | 25th June 1930 | |
| Hs{Lord Ernest Hives - Chair}/ml/W25.6.30. contd. -2- it. Therefore, in order to establish a basis of comparison for all conditions, the car was driven at a constant speed of 62 M.P.H. round the track until the heat dissipated by the cooling system balanced the heat generated by the engine at this speed. A typical curve obtained in a test such as this is shewn in Graph (1). Under these conditions various stages of ventilation were tested giving the results shewn in Graph (2). From this it will be seen that the atmospheric temperature at which the car will over-heat at high speeds can be raised 8.5° C. by ventilating the front undershield and fitting a louvred bonnet. Almost the same result can be obtained by fitting four bonnet shutters and ventilating the front undershield. At present we fit two rear shutters only as standard. With the Phantom II radiator it appears that front shutters are more effective than those at the rear, probably because the crankcase, engine bearer arms, and shock absorbers prevent the air passing through the lower half of the matrix to the back of the engine. We therefore consider that if two bonnet shutters only are to be fitted, it would be best to have them at the front. Experience in France has indicated that even if we remove the front underpan entirely, it does not cause much trouble, but we are confirming this point. If it is so, it seems to be the best move to improve the cooling system while causing the minimum increase in noise from the engine. | ||