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).
Weight reduction, body construction, and performance improvements for the future 20HP model.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan075 | |
| Date | 16th April 1929 | |
| SECRET ORIGINAL DA{Bernard Day - Chassis Design}1/M16.4.29. FROM DA.{Bernard Day - Chassis Design} FUTURE 20HP. X5770 X4012 X2066 X5830 X5310 C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} HN.{F. C. Honeyman - Retail orders} HS.{Lord Ernest Hives - Chair} BY.{R.W. Bailey - Chief Engineer} EP.{G. Eric Platford - Chief Quality Engineer} ES. As regards the alternatives Y and Z, given in R1/M8.4.29., we are in favour of limiting the weight, either by restricting the body capacity, or, if from the Sales point of view it is decided that the restricted body is impracticable, by controlling the construction. We believe we are right in saying that the Chrysler, with which we are compared, is always a 4 seater. In spite of HS{Lord Ernest Hives - Chair}1/LG12.4.29. there is evidence that recent experimental bodies, when compared with similarly made bodies supplied to customers, are appreciably lighter and more durable. The designed methods of construction are not always taken full advantage of. When they are we think a real saving is effected, as witness the recent Phantom Sports bodies, and those now under construction at coachbuilders. We think that off the largest bodies we could take 2 to 3 cwts. by more scientific construction, and careful scrutiny of the weight of trimmings and fittings. But it would be necessary to control the coachbuilders and fitting manufacturers closely, as in the case of the sports bodies. Four seater bodies should always be easily within the prescribed weight limit. We think that when all the weight saving possible has been effected we shall still be glad of the further improvements in the performance, which we might expect from:- (1) The slight increase in the capacity which we understand may be found possible with the existing engine. (2) A lower gear ratio. As we understand the Works would like Hypoids for the 20HP. as soon as they can be brought in, advantage could be taken of the fact that these gears can be made stronger and more durable than the corresponding spiral bevel gears, to obtain an axle ratio of approximately 5 to 1., or as we think would be still better 4.750 to 1., the engine speed at 70 MPH. in this latter case being 3500 with the large wheels, and 3750 with the small wheels, (instead of 4.54 to 1 as existing.) We have made preliminary designs of this axle. (3) The facile gear change which we are working on. DA.{Bernard Day - Chassis Design} aW | ||