THE GOOD OL' DAYS
The 1934 Cars — Page 3
The problem, first of all, was to obtain a car shape which would have minimum wind resistance, which means that the car is so formed that air flows smoothly over it from front to rear and eddy currents are reduced to a minimum. To demonstrate the excellence of the final design the writer was shown two models in the wind tunnel, one a conventional car and the other a streamlined job which accurately represented the De Soto or Chrysler.
Short silk ribbons were glued at their forward ends to various points on both cars. With the air rushing by at 60 m.p.h. the ribbons on the conventional car were whipped violently in various directions while they lay flat along the surfaces of the streamlined car, showing that air flow is smooth. Consequently wind roar is greatly reduced and conversation in ordinary tones becomes feasible at high speed.
Shrouded rear wheels with tail lights streamlined into the fender are seen on several makes. The Nash installation has a distinctive design emphasizing the false hub.
Having arrived at these new contours it was found that a revolutionary change in body construction could be effected. In the conventional car, frame and body stiffen each other except forward of the cowl where the frame alone takes front end stresses. Also the combined stiffness of frame and body is not as great as many would like to have it. As a result, the bending of the frame under road stresses distorts the body, and squeaks and rattles may appear.
But Chrysler has solved this problem. Because of the unusual body shape, it is possible to build the steel framework of the body like a bridge and this whole structure acts as a frame — in other words the depth of this "frame" is the height of the body. It is true that these cars have frames but only for assembly purposes and as something to attach the springs to. Obviously it would be difficult to run the car down the assembly line without some kind of a frame to tie the various units together. The frame has a section of only 3-1/2 inches which is about half the depth used last year. This new body and frame combination has forty times the torsional stiffness of last year's design. With such high rigidity there should be perfect freedom from squeaks and rattles.
Instead of utilizing streamlining to raise the speed of the car, it has been used to increase body width 10 inches with the result that three people can be seated comfortably in both front and rear seats. The maximum speed of the De Soto is 80 m.p.h. which is about what it was last year. To many, the unusual roominess of these cars will be the most appealing feature.
With the new streamlined shape, it was found possible to move the engine far forward without interfering with an ideal streamline form. The center of the engine is directly over the front axle. This permitted seating the passengers 20 inches further forward so that the rear seat is well ahead of the rear axle — an important consideration from a riding quality standpoint. This change, together with the rear streamlining, gives unusually large luggage space between the rear seat back and the sloping rear panel or deck.
Somewhat softer leaf springs front and rear, and moving the engine forward, have assisted in making these De Soto and Chrysler cars remarkably easy riding. It should be apparent that with the weight of the engine concentrated directly over the front axle, when the wheels hit a bump the frame of the car will be thrown upward less than if the weight were further back and thus the rear of the car will be depressed less. In other words pitching will be reduced.
A demonstration showed that these simple but logical changes have made a surprising improvement in riding quality. The writer drove these cars on various types of roads about 50 miles northeast of Detroit. Another car with conventional springing was provided to give a good comparison. On medium rough concrete, the back seat ride of the conventional car was rather uncomfortable because of pitching, while on some of the rougher roads with severe thank-you-mam's it was necessary to use a hand to brace yourself against the top of the car to avoid hitting the head hard against the roof.
Over these same bumps in the new De Soto and Chrysler there was no tendency to leave the seat, while on the medium rough concrete previously mentioned the back seat ride was very comfortable. A simple way to check the quality of a ride is to slouch down and lean back so that the head is resting on the top of the seat back. The jolts received on the conventionally sprung car were very objectionable, but traveling in this sleeping position in the new cars was as comfortable as could be.
One thing that contributes to the pleasantness of this ride involves the human interior. By experiment it has been found that when a man is walking, his greatest speed for minimum fatigue averages 2-1/2 m.p.h. If he pushes his gait up to 3 or 4 m.p.h. he tires at a much faster rate.
While walking at 2-1/2 m.p.h., the resulting slight jolt at each step adds up to 90 per minute for most men. Or to use the engineering term, his natural periodicity is 90 per minute. Throughout the ages, man has become accustomed to this periodicity and all the organs which are hung inside him have gotten used to this rate without causing discomfort.
In automobiles, as built heretofore, the pitching periodicity has ranged from 120 to 140, according to Chrysler engineers, whereas in the new models the rate has been reduced to 90 to 105 depending on the passenger load. Thus, while pitching in these new cars has been greatly reduced, the little that remains is not objectionable as a demonstration will quickly show.
As to whether these De Soto and Chrysler cars ride and handle more or less satisfactorily than independently sprung cars is open to pro and con argument.