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).
Vehicle weight reduction, chassisless design, and the principles of skin stressing for improved performance and safety.
| Identifier | ExFiles\Box 117\1\ scan0086 | |
| Date | 31th May 1936 guessed | |
| 4. here and there to live up to the above mentioned creed. A motor coach must justify its existence by the revenue it earns while carrying passengers. Every pound of weight added to its construction means that its operating cost will be higher, its various components must work harder. The passenger car field has not felt the full force of this weight problem as the pressure of reduced operating costs is at a minimum in comparison. However, reduced weight in this field can by no means be ignored. With the coming of advanced spring suspension designs, better balance in location of operating parts, the old theory of heavy cars for a soft ride, etc., is reduced to the questionable stage. Another very important angle to the weight question is fuel economy. The saving here is so obvious that I think nothing more need be said about it. These few simple statements bring us back directly to the chassisless vehicle. It is perfectly possible to discard the main frame of your conventional design, add a small portion of this frame's weight to your present day all-steel body at the proper points for reinforcement and have an infinitely stronger, more stable, shock resisting unit. You have immediately saved weight, increased the longitudinal and torsional rigidity, provided a safer vehicle and simplified the design with one stroke. One very interesting side light of this construction is the method of carrying the load partially on the body surfaces, or so-called skin stressing of the material. In your conventional vehicle the body is supported or carried on a platform and is not designed with the idea of supporting the load. It is strictly an enclosure for passenger comfort, beauty and utility of operation of the vehicle. To me, this conventional unit has the self-same appearance of just this idea. The frame is built first. Then the body is set on it. Then the hood is fastened on. Then the fenders are fastened on. Then the various trim pieces are fitted to cover the gaps left vacant by applying these parts. Even with much design study to achieve a smoothness of line for this vehicle, it does not completely cover the disjointed effect. Returning to our skin stressed vehicle, the body sheet must necessarily completely cover the framework of the vehicle, to accomplish the proper distribution of load to the surfaces. Consequently, it is very easy to include in the design, the proper lines, and smoothness of surface to create a vehicle of pleasing appearance. A lasting impression of this contrast is to compare the present day air liner to the old fashioned "crate" of barnstorming days at the county fair. You are probably justified by now in asking just what this has to do with safety in body design. But I have purposely tried to create a background which will enable you to see more simply the action of chassisless design under extreme conditions which may be encountered. To properly study the safety problem we must appreciate the major items that affect safety and their relative importance to the vehicle design. 1. Nothing is more important on the road than a properly balanced, easily handled vehicle. In times of sudden | ||