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).
Design progress on the Bensport engine, supercharger, and fan drive, including challenges with the blower length.
| Identifier | ExFiles\Box 140\1\ scan0008 | |
| Date | 15th August 1932 | |
| X 209. To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} Wer. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Da.{Bernard Day - Chassis Design} Hsy. E.H/HP.15.8.32. Bensport Progress - R.1/M.13.8.32. We are working hard to let you have as soon as possible a complete drawing of the Bensport engine, and supercharger, but in this connection we should like to mention that the recent change in design policy occurred at the last moment, just before the holidays - July 22nd, and we have, therefore, only been back a week, during which time we have sent to WW. two designs dealing with the blower to the front of the engine, fan drive, etc. - LeC.3162, and 3166. LeC. 3162 shows the standard long blower, and LeC.3166 a proposed intermediate proportion. It is unfortunate when it comes to the point of actually using the standard long blower that Mr. Eyston (during his visit here of Friday last) should definitely advise against it on the grounds that this blower has been found to exceed a practical length, both mechanically and from the point of view of volumetric efficiency, and he does not think the latter can be dealt with by using double feed and delivery ports without over-weakening the cage. We, therefore, sent you a print last Saturday of LeC.3166 showing an intermediate policy which would provide for a moderate fan drive from the camshaft. We did look into the scheme of using the dynamo drive passing right through the pump. We arranged an outboard ball bearing for the pulley, and two double glands on the pump spindle. The overhang of the pulley on the present pump mounting would be six inches, but we think the tappet cover carrying the pump could be extended forwards to reduce this. Another scheme would be to change over the position of dynamo and pump, so that the dynamo could carry the fan pulley. This demands a stronger fan spindle, however, to withstand the heavier accelerating torque due to driving the dynamo. Neither of these schemes are as simple as driving off the camshaft. | ||