Abstract
EXPERIMENTS carried out on models in a wind tunnel by R. H. Heald, of the U.S. Bureau of Standards, shows that the trend towards stream-line form in the construction of modern cars leads at high speeds to a substantial saving of power and therefore of petrol. The tests show the air resistance of the 1933 car is more than twice that of a completely stream-lined car of the same frontal area. According to a mail report from Science Service, the tests were made on models ranging from one quarter to one fifteenth natural size with wind velocities varying from thirteen to seventy miles per hour. Some of the models were of cars of the past, but two represented cars which may be used in the future. The 1933 model had disk wheels, exposed bumpers, fenders, head-lights and a spare tyre. One of the models of the motor-car of the future had a wind-shield which made an angle of 45° with the horizontal, the chassis was rounded at the top and back and the lines were smoothly moulded. The other model had the whole upper part rounded, was blunt at the front and tapered at the back. Mr. Heald computes from his results that, at 60 miles per hour, the 1922 Sedan requires 27 h.p. to overcome air resistance; 26 h.p. is taken by the 1928 Sedan and 18 h.p. for the 1933 model. The two stream-lined models took 8 and 6 h.p. respectively. At 48 miles per hour it was found that the horse-power expended on air resistance was halved and at 76 m.p.h. it was doubled. Mr. Heald concludes that the 1933 motor, shorn of its projecting bumpers, head-lights and spare tyre, and fitted with a rounded top and sloping wind-shield, would consume 10 h.p. less at 60 m.p.h. and 20 h.p. less at 70 m.p.h.
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Stream-line Form in Motor-Cars. Nature 133, 21–22 (1934). https://doi.org/10.1038/133021d0
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DOI: https://doi.org/10.1038/133021d0