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).
Confidential memorandum discussing a proposed car programme, including engine and chassis specifications.
| Identifier | WestWitteringFiles\V\March1931-September1931\ Scan305 | |
| Date | 8th July 1931 | |
| SG.{Arthur F. Sidgreaves - MD} FROM R.{Sir Henry Royce} C. to WOR.{Arthur Wormald - General Works Manager} HS.{Lord Ernest Hives - Chair} ORIGINAL CONFIDENTIAL J.{Mr Johnson W.M.} 2. - 25HP., AND PRIVATE VENTURE AERO, ETC. Regarding the suggestion of a conference on the car programme the actual proportions of any design are difficult to decide until we have had considerable experience on the drawing board with any new scheme of construction, and we had not ourselves decided the exact proportions of the Japan engine until quite recently when we decided the following programme: We have very nearly the same dimensions for the following engines:- (1) Japan engine, (2) 12 cyl. Private Venture engine. ENGINE. For a comprehensive system of manufacture the parts of these two engines where possible should be brought into line so as to be interchangeable and require the minimum/cost of tools and spares. We are best able to do this if we/retain for these two engines a bore 3.25" equal to the present 'China' engine, but in the case of the 6 cyl. we are proposing that the stroke shall be increased from 4.5 ('China') to 5" ('Japan'). The Private Venture aero engine however will remain 4.5" stroke. Being a Vee engine the same con. rods cannot be used and we/fear that the 5" stroke would make the engine too bulky for a good installation under the bonnet. FRAME. Regarding the rest of the chassis we are proposing to requisition a new frame which has already been designed and sent to Derby. As was shewn some weeks ago it is 8" deep instead of 6", has stiffer ends, and does not need the tie-rod. It makes the attachment of the springs easier, requiring simpler fittings, and it provides a much better space for the rear shock dampers, and as far as we can see at the present there is no question but that this will be a good and economical move. BACK AXLE. The back axle is to be of the hypoid type already tested. This permits of the lowest frame and seat of any type of axle with a given road clearance. FRONT AXLE. The front axle is intended to have parallel control so that very flexible springs can be used without fear of the front brakes turning over the axle. FRONT SPRINGS. We have decided to lengthen the front springs by 2" although they are already longer than on other chassis of similar size. CARBURETTERS. In the specification of the engine we need not decide at the moment whether we use one or two carburetters. It will depend upon Derby's experience with the best carburetters we can design and those that can be bought. At the moment we believe it will be 2 separate single fixed jet non-expanding carburetters, the designs of which have already been sent to Derby. (1) | ||