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).
Comparison of cooling fan efficiency and suggestions for further road testing.
| Identifier | ExFiles\Box 75\3\ scan0052 | |
| Date | 24th February 1925 guessed | |
| CONTD :- -2- We have previously discovered that the 6-bladed RR. fan is responsible for improving the cooling capacity of the system by 30%. If we take the better of these two fans to be of equal value to the original 6-bladed RR. fan, we find that the EFC. fan is (5.5% of 30%) or 18% less efficient at 30 m.p.h., (4.3% of 30%) at 40 m.p.h., or 14% less efficient than the RR. fan. This is, of course, a very rough way of comparing the actual fan efficiencies from road tests. We suggest that it would be instructive to run these two fans at 1175 and 1445 r.p.m. and take the thrust given by each fan at this speed. If the EFC. fan still produces the greater thrust at the given r.p.m., then there is some very large factor which alters the fan value when working under road conditions. HSR/mn | ||