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).
Road-based cooling tests comparing the 40/50 HP model with a Hispano model.
| Identifier | Morton\M8\ img002 | |
| Date | 25th November 1924 | |
| R.R. 493A (20H) (D.A. 652 20-8-24) J.E.D. To R COOLING TESTS (ROAD) EXPERIMENTAL REPORT -5- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}/LG25.11.24. 40/50 is enormously dependent upon its Fan. When the RR. fan is removed, the efficiency of the system drops 30%. The Hispano efficiency, on the other hand, under similar circumstances, only drops 10%. EAC.11. Radiator Tubes. Shortening the radiator tubes from the standard length of 4.8" to 4.4" reduces the efficiency of any given size of matrix by about 4% at 30 m.p.h. Painting the matrix face. We could detect no difference between the performance of painted and unpainted matrices. Present limit of improvement of 40/50 HP. By fitting the 23 3/4" matrix and 8" X 14 1/2" shutters, the efficiency of the 40/50 HP. cooling system can be brought within 2% of that of the Hispano at 30 m.p.h. This means that under these circumstances the critical temperature of the latter will only be just over one degree more than that of the RR. At 20 m.p.h. however, the discrepancy between the two cars increases, as the R-R system cannot deal with the heat given to the cooling water so well at this speed. In all cases, unless the RR. fan is functioning satisfactorily, over-heating is liable to occur under quite normal atmospheric conditions. contd :- | ||