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/

  • Supplemental Notes:
    • Vol 15, pp 70-80, 2 FIG, 4 TAB, 4 REF
  • Authors:
    • Conrad, L E
    • Dawley, E R
  • Publication Date: 1936

Media Info

  • Monograph Title: Proceedings of the Fifteenth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 4-6, 1935
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00223304
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jun 11 1971 12:00AM