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).
Pros and cons of radiator and cooling system design for the 40/50 HP car.
| Identifier | ExFiles\Box 24\4\ Scan187 | |
| Date | 22th August 1924 | |
| COPY OF MEMORANDUM PN{Mr Northey}2/DN22.8.24 to BJ. COOLING SYSTEMS. I have read BY21/H19.8.24 and I have gone closely into the pros and cons of this subject with Hs.{Lord Ernest Hives - Chair} I do not find myself in entire agreement with By.{R.W. Bailey - Chief Engineer} throughout. For instance, it cannot be taken that the effective area for cooling of a radiator is merely that part immediately in part front of the fan, because at certain high road-speeds, or when driving against a wind, all other parts of the radiator have air forced through them quite independently of the fan suction, and it then becomes more a matter of how the great the facilities may be which are provided for the extraction of such heated air. Undoubtedly in this respect, our standard 40/50 HP type is bad, but I should expect that considerable improvement will result from the modifications recently made to the under portions of the engine guards. To what extent this is so, it is very important to determine as early as possible. It will be noticed on our 40/50 HP that there is still nearly 1 3/4" space available beneath our radiator which might be used for extending the matrix. Also, that the fan blade in the downmost position more than covers the existing standard radiator. I urge that this additional matrix area be provided on all 40/50 HP radiators as soon as possible. It would appear that the effect one would expect of the increased depth of radiator tubes (fore and aft) does not have an equivalent effect in providing additional cooling, and that consequently if we insist upon a certain definite amount of cooling under stated conditions, we must at the same time be prepared to provide not less than a definite amount of radiator face area. Undoubtedly the radiator face area which is now available on our cars, is not sufficient to deal satisfactorily with Continental conditions in motoring, quite apart from any hill-climbing when lower geared ratios might be employed. I have suggested to Hs.{Lord Ernest Hives - Chair} that if he will let us know the minimum area of face radiation which must be provided to meet the conditions we set up, we can then decide to what extent this condition can be fulfilled, having regard to such points as appearance and "safety" lines of bonnet. Our difficulties cannot be ameliorated by merely increasing the fan speed, because this inevitably results in impossible noises or rumbles. | ||