THE eventual solution to the question: “Shall it be of unit design or shall it have a separate frame?” will be known only when a complete understanding is reached of the ride problem, including car feel and quietness, and a better understanding is obtained of the structure's influence on these performance phases, Mr. Sherman believes. Such knowledge, he predicts, will result eventually in the lightest, least-expensive and best performing automobile, be it unitary in structure, conventional, or something as yet unconsidered. His paper brings out some of these considerations which have proved to be of paramount importance in research work conducted by his company.
Pointing out that it is impossible to predict ahead of time just how a new car design will perform, he contends that it will be much easier to adjust the job to the best rigidity range with the separate-frame construction than with the unitary construction. He shows that the stiffest all-steel body tested is only 1.8% as stiff as a true box having the average dimensions of a car body and having the same panel thickness, chiefly because of the door openings and the thinness and curved shape of the body panels.
It is concluded that it should be possible to reduce the weight of the average car of today by approximately 100 lb, still maintaining its riding and quietness qualities, by substituting a unit construction for a separate frame. It is emphasized, however, that the unit-construction car probably will cost more and will require considerable time for development and alterations. A new frame design to replace the X-member frame is promised that will improve car performance. Major phases of the problem are grouped under the following headings: The Experimental Background, General Viewpoints, The Ride Problem, The Structure's Effect on the Ride, The Car Body as a Structural Member, and Road Noise.