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).
Vehicle performance, component testing, and achieved speeds on a track.
| Identifier | ExFiles\Box 181\M9\ img010 | |
| Date | 5th August 1931 | |
| -2- A 3" dia. propeller shaft was fitted to prevent whirling - we already have a design of cross member which enables us to utilise this. The P.II. exhaust system was fitted with a cut-out. The various lap speeds attained are shown on Rm.{William Robotham - Chief Engineer}28. The speed of 65.78 in standard condition is interesting as it shows that the body of this car is good for windage. The maximum 25 HP. bodied car lapped with a similar unit at only just over 61 M.P.H. whilst intermediate cars such as 19-GIV and GBR-14 lapped at 63.7 and 63.2 M.P.H. respectively. The car ran remarkably well at the higher speeds, lapping most consistently without loss of tune, which taking into account the considerable amount of full throttle work that the unit had done on the test bed, was very satisfactory. The unit showed signs of roughness above 3500 R.P.M., it was fitted with a small pin, unbalanced, nitro hardened crankshaft. The track was in a very bad condition; the standard springing and damping allowing a lot of wheel spin and considerable crashing on the buffers. The 11/50 axle ratio was too low for the speeds attained on the track but seemed ideal for road work in England with the increased power the 3rd. speed ratio seems rather low and is hardly ever used. A number of speeds over the half mile were recorded, but owing to the way they are affected by the wind are not of much comparative value. It is worth recording, however, that a speed of 77 m.p.h. was timed over the half mile with the standard R.R. carburetter on the high power unit. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||