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).
Radiator cooling performance, including frontal area, bonnet ventilation, and fan specifications.
| Identifier | ExFiles\Box 15\1\ Scan214 | |
| Date | 4th February 1930 | |
| x7250 To Lr.{Mr Ellor} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson}1/WJ.4.2.30. FRONTAL AREA, COOLING SURFACE, TUBE LENGTH & DIAMETER. x7250 x4516 We have had various frontal areas at different times and the attached sheet shews some dimensions. The radiators which give the best results are starred. The S.S. radiator with the tube 4" long and the larger frontal area gives better low speed cooling, as might be expected. You will be able to calculate any cooling areas and free air areas that you require from these dimensions. (4) & (5). I am afraid that we have never taken these figures but owing to the poor bonnet ventilation we should say that at maximum H.P. the air velocity through the radiator would be 35 m.p.h. When we fit a louvred bonnet, the cooling capacity of the radiator is at once increased by 15%. With a ventilated bonnet standard fan and radiator we can say that the car will not over-heat up to an atmospheric temperature of 38°C. at maximum power output ( forward speed of car 70 m.p.h.). We should say roughly that at 30 m.p.h. forward car speed, the fan is responsible for 30% of the cooling with a louvred bonnet. Again at 30 m.p.h. with louvres and the fan in action, the heat dissipated is increased 8% by removing the bonnet. (5a) Fan Dia. 9.35 x 2 = 18.7. Speed 1.2 Engine speed (5" Top pulley). (6) At maximum power 2750 Engine R.P.M. 30gal/min. (7) 450 R.P.M. Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} | ||