AIR RESISTANCE OF MOTOR VEHICLES
TESTS WERE MADE ON 54 AUTOMOBILES IN THE WIND TUNNEL AT KANSAS STATE COLLGE IN 1932 AND 1933. CHECK TESTS WERE MADE ON TWO CARS BY COASTING DOWN HILLS. THE 54 CARS REPRESENT 14 MAKES, 7 YEARLY MODELS, AND 4 BODY TYPES. A SUCCESSION OF YEARLY MODELS OF THE SAME MAKE WERE SECURED WHENEVER POSSIBLE. DUPLICATE WIND TUNNEL TESTS WERE MADE ON THREE CARS AT A LATER DATE AND UNDER DIFFERENT ATMOSPHERIC CONDITIONS. THE GREATEST INDIVIDUAL DIFFERENCE IN THE DUPLICATE TESTS WAS 4 PERCENT. IT IS CONCLUDED THAT: (1) A WIND TUNNEL CAPABLE OF TESTING FULL-SIZE AUTOMOBILES OFFERS A PRACTICAL MEANS OF DETERMINING THE WIND RESISTANCE OF AUTOMOBILES. THERE IS NO SCALE EFFECT FOR SUCH TESTS. ROLLING RESISTANCE IS NOT A FACTOR. COMPARISON WITH THE COASTING TESTS INDICATES THAT THE MUCH DREADED GROUND EFFECT IN WIND TUNNEL TESTS IS PROBABLY SMALL; (2) COASTING TESTS CAREFULLY MADE ON SMOOTH PAVEMENTS AFFORD A PRACTICAL METHOD OF DETERMINING THE WIND RESISTANCE; (3) IN THE WIND RESISTANCE FORMULA THESE TESTS INDICATE THAT THE EXPONENT IS CLOSE TO 2, THE AVERAGE BEING 2.02 FOR THE FIFTY-FOUR CARS TESTED; (4) OF THE CARS TESTED, THE LATER MODELS SHOW IN GENERAL A DEFINITE IMPROVEMENT IN AERODYNAMIC CHARACTERISTICS; AND (5) THE PASSENGER LOAD IN A CAR DECREASES THE WIND RESISTANCE BELOW WIND TUNNEL VALUES IN DIRECT PROPORTION TO THE DECREASE IN PROJECTED AREA. /AUTHOR/
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Supplemental Notes:
- Vol 15, pp 70-80, 2 FIG, 4 TAB, 4 REF. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Conrad, L E
- Dawley, E R
- Publication Date: 1936
Media Info
- Media Type: Digital/other
- Monograph Title: Proceedings of the Fifteenth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 4-6, 1935
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Serial:
- Highway Research Board Proceedings
- Volume: 15
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Motor vehicles; Wind tunnels
- Subject Areas: Highways; Safety and Human Factors;
Filing Info
- Accession Number: 00223304
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: Jun 11 1971 12:00AM