Page 7 - Combined_22_OCR

INTRODUCTION

This report presents the preliminary results from wind tunnel tests of a
3/8-scale 1969 ("E" Series) Plymouth Road Runner, two -door hardtop (ER-23),
modified to simulate a NASCAR race car model. The tests were conducted at
Wichita State University's 7 x 10-foot low speed wind tunnel during the first week
of April 1969.

Previous tests had shown that over the range of the test variables, Reynolds
number effects were small. Therefore, all data during these tests were taken at a
tunnel dynamic pressure (uncorrected for blockage and buoyancy) of 40 psf. These
data were then corrected for the above mentioned tunnel effects and scaled directly
to a dynamic pressure of 92.4 psf (V=190 mph) and full-scale conditions. All forces
presented herein are, therefore, forces that would be experienced by the actual race
vehicle at a velocity of 190 mph. All forces are presented in the body axis system
with the reference center of gravity located mid-way between the wheel base and
26.67 inches above the road surface. (See Figure 1.)

Six component data were taken over a vehicle body rake angle range from
0° to -2.5°. At a body rake angle of -0.5° six component data were measured as
the vehicle was yawed in increments of 3 degrees, from -12° to +6°.

Experience gained through wind tunnel testing of the Dodge Charger (Reference
1) has shown the prime areas of investigation for drag reduction to be: front end aero­
dynamic fairing; undernose spoilers; and backlight. Therefore, these regions were
subjects for investigation on the Plymouth. Figure 2 shows a general layout of the
front end aerodynamic fairing added to the Plymouth. A typical spoiler installation
is shown in Figure 3 with complete spoiler identification given in Table 1. Figure 4
shows the two special backlights investigated. The extent of the modification to the
standard backlight can be gleaned from the clay-fiberglass intersections seen in the
pictures.

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