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).
Comparing the cooling performance of a Hispano engine with a 40/50 HP engine at different speeds.
| Identifier | ExFiles\Box 181\M8\ img001 | |
| Date | 25th November 1924 | |
| R.R. 403A (20H) (D.A. 652 20-3-24) J.H.D. EXPERIMENTAL REPORT. Expl. No. REF: Hs{Lord Ernest Hives - Chair}/R m/LG25.11.24. HISPANO AND 40/50 HP: R-R COOLING. 20 M.P.H. ------------------- The 40/50 HP. is not so well cooled as the Hispano at 30 m.p.h. - the standard speed at which our tests are taken. At 20 M.P.H. the Hispano will have just about the same critical air temperature as it did at 30 m.p.h. The 40/50, however, will be in a less advantageous position at 20 m.p.h. than at the higher speed, i.e., its critical atmospheric temperature will be lowered. There are two reasons for this :- (a) At 30 m.p.h. the 40/50 engine gives off 20% more heat to the cooling water than the Hispano - at 20 m.p.h. this is increased to about 28%. Therefore if the Hispano can just hold its own at the lower speed, the 40/50 HP. may be expected to be definitely worse off purely from the point of view of heat generated. (b) The Hispano matrix depth is 4". Our matrix depth is 4.8". It is therefore manifest that we shall feel a drop in air velocity through the radiator more than the Hispano. Therefore, from the point of view of heat dissipated, we expect the 40/50 HP. to be worse off at 20 m.p.h. contd :- | ||