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).
Performance calculations for the Eight-Cylinder Bentley, comparing the 11.B.V. model to the 4.B.30.
| Identifier | ExFiles\Box 124\2\ scan0166 | |
| Date | 14th May 1940 | |
| Tele. 1044 To EV.{Ivan Evernden - coachwork} from Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} c. to JNR.{Charles L. Jenner} c. to Rm{William Robotham - Chief Engineer}/CPS. c. to Rm{William Robotham - Chief Engineer}/PJH. c. to Rm{William Robotham - Chief Engineer}/WYM.{G. Harold Whyman - Experimental Manager} c. to RR/FD.{Frank Dodd - Bodies} Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}6/JMc.14.5.40. Eight-Cylinder Bentley Performance. During the past few weeks considerable interest has been aroused by the performance of 11.B.V. It has been so much better than 4.B.30., which in many respects is a nicer car to handle, that there has been a tendency to hail it as a freak. In order to find an answer to this, and because of suspicion that 4.B.30 is not doing its best, the following calculations have been made. From test bed power figures for the units in the respective chassis and a knowledge of tyre windage and transmission losses involved the horse power available for acceleration in each case was obtained. Hence complete sets of acceleration figures and maximum speed figures were obtained by methods shewn in the attached appendix. In the first place, performance figures for the two cars in their normal conditions were worked out and found to tally quite accurately with results obtained on the road In only two out of thirteen sets of figures was there a difference between the known and the calculated of more than 4% and most of the errors were even less than this. Hence, it is fairly safe to assume that this method of calculating performance is satisfactory. From previous experience we should say that the maximum speeds calculated are a very close approximation to Brooklands lap speeds. (cont'd) | ||