Confidential memorandum detailing design proposals for the J.2 25 HP car and Private Venture aero engine.
| Identifier | ExFiles\Box 5a\1\ 01-page176 | |
| Date | 1st July 1931 | |
| CONFIDENTIAL. X5770 Sg. {Arthur F. Sidgreaves - MD} from R. {Sir Henry Royce} R2/MB.7.31. c. Wor. {Arthur Wormald - General Works Manager} Hs. {Lord Ernest Hives - Chair} X.5770 c. Ev. {Ivan Evernden - coachwork} E. {Mr Elliott - Chief Engineer} Da. {Bernard Day - Chassis Design} X.1906 J.2 - 25 HP., 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(Experimental Engine) engine until quite recently when we decided the following programme. We have very nearly the same dimensions for the following engines :- (1) Japan(Experimental Engine) 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(Experimental Engine) engine, but in the case of the 6 cyl. we are proposing that the stroke shall be increased from 4.5 (China(Experimental Engine)) to 5" (Japan(Experimental Engine)). 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 shown 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 d fear of the front brakes turning over the axle. | ||
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).