United States     Motor Vehicle Emission Lab    EPA
Environmental Pint.-.-ti.MI 2585 Plymouth Rd       JuK 19
Agency       Ann ArK" Mirhui.in 48105
Assessment Of An
Empirical Technique
For Estimating
Vehicle Aerodynamic
Drag  From Vehicle
Shape Parameters

-------
          ASSESSMENT OF AN
       EMPIRICAL TECHNIQUE
            FOR ESTIMATING
   VEHICLE AERODYNAMIC DRAG
FROM VEHICLE SHAPE PARAMETERS
                      by


                W.M. Smalley and W.B. Lee
                The Aerospace Corporation
                El Segundo, California 90245
                 Contract No. 68-03-2482
             EPA Project Officer: Glenn D. Thompson
                   Prepared for

            ENVIRONMENTAL PROTECTION AGENCY
              Office of Air and Waste Management
            Office of Mobile Source Air Pollution Control
              Emission Control Technology Division
                Ann Arbor, Michigan 48105

                    July 1978

-------
This report is issued by the Environmental Protection Agency to report technical data of
interest to a limited number of readers. Copies are available free of charfe to Federal
employees, current contractors and grantees, and nonprofit organization* - as supplies
permit - from U.S. EPA, 2565 Plymouth Rd., Ann Arbor, Michigan 48105, or, for a fee,
from the National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the Environmental Protection Agency by The Aerospace
Corporation, El Segundo, California 90245, in fulfillment of Contract No. 68-03*2482.
The contents of this report are reproduced herein as received  from The Aerospace
Corporation. The opinions, findings, and conclusions expressed are those of the author
and not necessarily those of the Environmental Protection Agency. Mention of company
or product names is not to be considered  as an endorsement  by the Environmental
Protection Agency.
                        Publication No. EPA-460/3-78-010

-------
                             FOREWORD
        This report, prepared by The Aerospace Corporation for the U.S.
Environmental Protection Agency, Emission Control Technology Division,
presents the results of a determination of aerodynamic drag coefficient, C_,
based on an empirical prediction technique developed by The Aerospace
Corporation in a previous EPA-sponsored study.  Values of C~ so deter-
mined are compared with C~ values derived from wind tunnel test data.
                                  iii

-------
                          ACKNOWLEDGMENTS
         During the course of this study, Mr.  Glenn Thompson of the

Environmental Protection Agency's  Emission  Control Technology Division,
who served as  EPA Project Officer  for the study,  provided valuable guidance
and assistance.  His efforts are gratefully acknowledged.

         The following technical personnel of The Aerospace Corporation

made valuable  contributions to the study.

                       William M.  Smalley
                       Warner B. Lee
                       Bernard Pershing
                       Mamoru Masaki
                                         L.  Forrest,  Systems Director
                                         Vehicle Performance Directorate
Approved by
M.  G. Hinton,  Principal Director
Mobile Systems Directorate
Eastern Technical Division
Eastern Technical Division
                             anager

-------
                           CONTENTS
FOREWORD	    iii
ACKNOWLEDGMENTS	    v
SUMMARY	    S-1
1.   INTRODUCTION AND BACKGROUND	    1-1
2.   ANALYTICAL APPROACH.	    2-1
3.   DATA BASE	    3-1
     3.1    Data Acquisition	    3-1
     3.2    Data Reduction	    3-6
4.   RESULTS   	    4-1
     4.1    Calculated CD Value	    4-1
     4.2    Comparison with Wind Tunnel Results  	    4-3
5.   CONCLUSIONS AND RECOMMENDATIONS  	    5-1
REFERENCES   	    R-l
APPENDICES
     A.     DRAG PREDICTION METHOD	    A-l
     B.     SAMPLE CALCULATION  	    B-l
     C.     VEHICLE DIMENSIONS AND AREAS	    C-l
                                vii

-------
                             TABLES
2-1.  Vehicle Characteristics     	  2-2
3-2.  Reference Panel Assignment   	  3-9
4-1.  Summary of Results	  4-2
4-2.  Comparison of Calculated Aerodynamic Characteristics
      with Wind Tunnel Results   	  4-5
                             FIGURES

3-1.  1977 Chevrolet Impala,  Front View  	  3-3
3-2.  1977 Chevrolet Impala,  Rear View   	  3-4
3-3.  1977 Chevrolet Impala,  Side View   	  3-5
3-4.  1977 Chevrolet Impala,  Front End Detail  	  3-7
3-5.  1977 Chevrolet Impala,  Rear Detail	  3-8
4-1.  Comparison of Test and Calculated Values of
      Aerodynamic Drag Coefficient	  4-6
4-2.  Porsche 924, Front End Detail	  4-3
A-l.  Vehicle Dimensions     	  A-2
A-2.  Hatchback-Notchback Drag Coefficient Ratio   	  A-6
                                viii

-------
                             SUMMARY
        Aerodynamic drag coefficients for a fleet of twenty 1977/1978
model year passenger cars were derived using an empirical drag predic-
tion technique previously developed for EPA by The Aerospace Corporation.
This method utilizes an aircraft type "drag build-up" approach wherein the
total drag is calculated as  the sum of C_ contributions from various com-
ponents of the vehicle.
        The development  of the aerodynamic drag coefficient using this
method requires that an extensive data base of vehicle  dimensions be
determined.  This was done by direct measurements in the field and from
8 x 10 photographs of the vehicles.  To minimize distortion,  photographs
were taken from a distance of 100 meters using a telephoto lens in combina-
tion with a 35mm single lens reflex camera.  The required projected areas
were determined by planimetry from the photographs.
        Results of the study indicate that the largest single contributor to
the overall drag coefficient is the front end drag coefficient,  CD  , which
constitutes, on the average, about 29% of the total average drag coefficient.
The other major contributors were found to be the base region drag co-
efficient,  CD  (20%) and the front wheel and wheel well drag  coefficient,
CD  (26%).   5
         Twelve of the twenty vehicles evaluated in this study were also
tested by  the Lockheed-Georgia Company in their Low Speed Wind Tunnel
(LSWT).  The LSWT test results were reported for two methods  of wind
tunnel blockage  corrections: the area ratio method and the ceiling static
pressure  signature method. The latter blockage correction method re-
sulted in  8% lower values  of C_ than those based on the area ratio method.
        A comparison of  the LSWT test results based on the area ratio
blockage  correction method with the  values  derived in  this study  showed
that nine  of the  twelve vehicles were within + 10% of the wind tunnel test
                                  S-l

-------
results.  The remaining three vehicles were found to be 12 to 18% lower
than the wind tunnel results.
         Wind tunnel test results based on the ceiling static pressure block-
age correction method could be compared to five of the vehicles evaluated
in this study.  Calculated C's for four of these vehicles were within +10%
of the wind tunnel test results, while the CD for the fifth vehicle was 16. 5%
higher than the wind tunnel test result.
         The  reasons for the differences with the wind tunnel results are not
known precisely, although several potential sources of error have been iden-
tified which could have contributed to this lack of agreement. One is the
of precision involved in the use of edge  radius as a sole descriptor of
contour in certain critical drag regions such as the vehicle front end.  A
second factor is the high degree  of sensitivity of the results  to the ratio of
the edge radius and the projected length of that radius.  Modifications to the
calculation technique in these and other areas could improve the accuracy of
the method.
        A summary of the  drag  prediction method used in this study is givet\
in Appendix A. Sample calculations and individual vehicle dimensions  and
areas are provided in Appendix B and C, respectively.
                                   S-2

-------
                                SECTION 1
                   INTRODUCTION AND BACKGROUND
         The current federal test procedure for certification testing of light
duty vehicles consists of running the vehicle on a dynamometer through a
prescribed duty cycle.  The power absorption unit of the dynamometer is
adjusted according to a table of 50-mph road-load horsepower settings which
are defined for a discrete set of loaded vehicle weights.  Beginning with the
1979 model year,  the method of determining the nominal dynamometer road
load setting will be based primarily upon the vehicle reference frontal area
(rather than vehicle inertia weight) and adjustments will be made according
to whether the vehicle is classed as a fastback or non-fastback model (Ref. 1).
Implicit in these procedures is the assumption that aerodynamic drag effects
correlate simply with weight or frontal area and body type.  Since, in general,
the  aerodynamic drag is variable with specific vehicle shape and contours as
well as size, the ability to estimate the drag of individual vehicle  configura-
tions could provide an analytical basis for improving the accuracy of fuel
consumption and exhaust emissions testing.
         In a previous study  for EPA  (Ref. 2), the Aerospace Corporation
developed an empirical technique which estimates the aerodynamic drag of
road vehicles from various vehicle configuration parameters.  The present
study is directed toward the  acquisition and application of vehicle  measure-
ments data as required to evaluate aerodynamic road load  by this  prediction
method for comparison with measured values.  The  intent  of this work is to
test the  relative accuracy of this prediction system as compared with the
1979 federal test procedure for determining dynamometer  road  load power
absorption settings.
                                   1-1

-------
                              SECTION 2

                      ANALYTICAL APPROACH
        The technique used to develop the aerodynamic drag coefficient is
based on the method developed in The Aerospace Corporation report,
"Estimation of Vehicle Aerodynamic Drag," Reference 2.  This method con-
sists of an aircraft-type "drag build-up" wherein the total drag is considered
to be equal to the sum of the contributions of the various components of the
vehicle.  The individual equations for each C-. component,  together  with a
definition of terms,  are given in Appendix A for convenient reference.  The
development of the aerodynamic drag coefficient by this method requires
that numerous vehicle physical  dimensions be determined,  including several
projected areas, edge radii and associated lengths, and the slope of the
windshield and hatch portions of the vehicle.  The methods used to obtain the
required dimensions and areas  are discussed in Section 3.
        A total of twenty 1977/1978 model year vehicles were  investigated
in the course  of this study.  Vehicles selected were based on a list of pri-
mary vehicle  choices provided by the EPA.  Characteristics of the individ-
ual vehicles are summarized in Table 2-1, including  specific protuberances
such as antenna, rear-view mirrors, etc.,  on  each vehicle.
                                   2-1

-------
                               Table  2-1.  Vehicle Characteristics
Manufacturer
Chrysler



Ford






General Motors






Porsche
Volkswagen
Model
Year
1977
1977
1978
1978
1977
1977
1977
1977
1978
1978
1978
1977
1977
1977
1978
1978
1978
1978
1978
1977
Make
Plymouth
Plymouth
Chrysler
Plymouth
Ford
Ford
Ford
Ford
Ford
Ford
Ford
Chevrolet
Chevrolet
Oldsmobile
Chevrolet
Chevrolet
Chevrolet
Oldsmobile
Porsche
Volkswagen
Model
Arrow
Volare
LeBaron
Volare
Granada
LTD II
Mustang II
Pinto
Fairmont
Granada
LTD II
Impala
Nova
Cutlass
Supreme
Impala
Monza
Nova
Cutlass
Supreme
924
Rabbit
Body Style
2-d». Coupe
Station Wagon
4-dr. Sedan
Station Wagon
4-dr. Sedan
4-dr. Sedan
2-dr. Notch-
back
3 -dr. Runaboi*
4-dr. Sedan
4-dr. Sedan
4-dr. Sedan
4-dr. Sedan
4-dr. Sedan
2-dr. Coupe
4-dr. Sedan
2-dr. Fastback
4-dr. Sedan
2-dr. Coupe
2-dr. Coupe
2 -dr. Hatch-
back
Wheelbase
92.1
112.7
112.7
112.7
109.4
118.0
96.2
94.5
105.0
109.9
114.0
116.0
111.0
112.0
116.0
97.0
111.0
108.1
94.5
94.5
Protuberances
(1). (2)
(1). (3), (4). (6)
(D.(3),(6)
(1). (3). (4)
(1), <5), (6)
(1). (5). (6)
UU5)
(1). (5)
(1), (5). (6)
(1), (2), (6)
<1).<2),<6)
(5)
(5)
(5). (6)
(5)
(2)
(5)
(3). (6)
(1). (5)
(D,(3)
 (1)  External antenna
 (2)  Two bullet mirrors
 (3)  Two conventional mirrors
 (4)  Luggage rack
 (5)  One conventional mirror
(6J Hood ornament

-------
                              SECTION 3

                              DATA BASE
         As indicated in Appendix A,  the development of the aerodynamic
drag coefficient C_. using the drag build-up method requires that an exten-
sive data base of vehicle dimensions be developed.  This was done by direct
measurement in the field  and from  8 x 10 photographs of the vehicles.
3.1     DATA ACQUISITION
         The numerous edge radii required to develop the various compon-
ents of C_ as defined in Appendix A were obtained by direct measurements
of the vehicles.  For edge radii <0.75 inch, a series of fixed templates were
used to match the vehicle contours. For edge radii > 0. 75  inch, a flexible
curve was fitted to the vehicle contour, transferred onto paper and matched
to a known radius.  The corresponding edge lengths were primarily deter-
mined by measurements from the photographs,  as discussed in Section 3.2.
If a true projected length (e.g., vertical length) could be measured in the
field, it was recorded and served as confirmation of the  value determined
from the photograph.
         The angle of inclination of the windshield and hatch portion, which
are required in the evaluation of C—  and C_.  ,  respectively, were measured
                                  2        5
with an inclinometer reading to the nearest 0. 5 degree.  The local horizontal
at the vehicle was also determined in order to obtain the true angle of the
windshield and hatch portion.
         Direct field measurements were also made of antenna, hood orna-
ments, and radiator dimensions in order to determine their projected areas,
since these could not be measured  from the photographs.
         The remaining required areas,  as shown in Figure A-l,  Appendix A,
include the projected frontal area (AR),  the projected area of the  front end
(A—), the projected area  of the windshield (A^), the projected area of the
                                  3-1

-------
body below the hood -wind shield intersection (A, ), the projected area of the
flat portion of the base region (A,J, the projected area of the upper  rear or
hatch portion of the base region (Ar),  and the projected area of various pro-
tuberances such as mirrors and luggage racks (A  }.
                                                i
         In addition to these projected areas, certain vehicle dimensions
also had to be determined from the photographs.  These included the proj-
ected length of the hood (L^),  the projected length (L.) and width (W)  of the
vehicle underbody and the vehicle height (H).
         In order to obtain the above required information, front,  side, and
rear views were taken of each vehicle from  a distance of 100 meters.  This
camera-to-subject distance was selected on the basis of the recommendations
presented in Reference 2, which indicates that a camera-to-subject  distance
of at least 100  meters should  be used to minimize errors due to perspective.
         Two reference panels having known dimensions and areas were
included in each view, as indicated in Figures 3-1 to 3-3.   For the front and
rear views (Figures 3-1 and 3-2), panel number I, to the  right of the vehicle,
was located at  a distance of 100 meters, in line with the front of the  vehicle.
Panel number II,  on the left,  was located at the mid-point of the wheelbase.
In the side view (Figure 3-3),  the near face of the vehicle was at 100 meters,
with both panels located at the vehicle longitudinal center line.
         Because of the necessity of taking both front/rear and side  views of
the vehicle and the approximate 2 to 1 vehicle dimensional disparity  in these
views,  lenses of two different focal  lengths were used in conjunction with an
Olympus OM-1 35mm single lens reflex camera.  For the side view, a
400mm focal length, f5.6 lens was used.  For the front and rear views, the
400mm lens was used in combination with a  2X converter, which gave an
effective focal  length of 800mm.  The objective in selecting these focal
lengths was to  obtain sufficient image size to minimize the degree of enlarge-
ment required  in the 8x10 photographs.  To minimize camera motion, the
lens/camera was mounted on a tripod. In addition, the camera mirror was
locked up prior to .photographing the vehicle, and the  shutter was tripped by
the built-in  shutter release.
                                   3-2

-------
UJ
I
OJ
                                Figure 3-1.  1977 Chevrolet Impala,  Front View

-------
Figure 3-2.  1977 Chevrolet Impala, Rear View

-------
i
Ul
                                Figure 3-3.  1977 Chevrolet Impala, Side View

-------
         In order to adequately outline the underbody profile, a white panel
was placed behind each vehicle in all three views.
         Test photographs indicated that thermal effects could create an
extreme image distortion effect, particularly on an asphalt surface.  Accord-
ingly, a concrete surface was selected in order to minimize this effect.
         In addition to those photographs taken at a distance of 100mt
three-quarter front and rear views were also taken of each vehicle using a
standard 50mm lens from a distance of 5 to 10 feet in order to provide
additional detail of front and rear body configurations and contours.  Exam-
ples of these are shown in Figures 3-4 and 3-5.
3.2      DATA REDUCTION
         Area measurements were made by planimetry, using a K & E
Model 4242 Compensating Polar Planimeter.  The planimeter was calibrated
in terms of photo area (at a specific tracer arm setting) by use of the
                 2
standard 10. 00 in  Test Rule provided with the instrument.  The calibration
of actual (vehicle) area to photo area was obtained by determining the photo
area of the 6. 00 ft  reference panels (formed by a 54 in x 16  in rectangle).
The latter area was found by measuring the height and width on the photo of
the reference rectangle, and taking the product of photo height and photo
width.  This  procedure was adopted because it was more rapid than plani-
metering the reference panels in the photo.  Check measurements verified
that both procedures gave the same results for the photo area of the refer-
ence panels.
         For the front and rear  views,  reference panel I was located at the
100 meter line (adjacent to the front or rear bumper, respectively) while
panel II was located on the other side of the car, at the midpoint of the wheel
base.  The reference panel(s) used in conjunction with each planimetered
area are indicated  in Table 3-2.
         The notation (I + II)/2 means that the area calibration was taken to
be the arithmetic average of the calibration factors determined for each
                                   3-6

-------
OJ
                              Figure 3-4.  1977 Chevrolet Impala,  Front End Detail

-------
00
                                Figure 3-5.  1977 Chevrolet Impala,  Rear Detail

-------
                Table 3-2. Reference Panel Assignment
            Area
                           Symbol
Area Calibration
Based on Panel(s)
                              FRONT VIEW
Reference
Hood and Front
Front
Windshield
Protuberance (Mirror
  or Luggage Rack)

Base
Hatch
  Non-Station Wagons
  Station Wagons
                                  AR
                                                      I + II
                                                        I
                                                       II
                                                       U
                              REAR VIEW
                                    B
panel. It is seen that the calibration factor for each planimetered area was
based on the panel nearest to the segment of the vehicle defining that area.
For an area defined by  vehicle segments lying between the two panels,  or
comprised of sectors near each panel, the average calibration factor of the
two panels was utilized.  The rationale for this approach  is illustrated by
the case  for vehicle frontal area A...,  as follows.
                                 t\.
         The selection of the average  of Panels I and IT for use as the  cali-
bration factor in determining the vehicle reference frontal area, A._, was
                                                                £x
based on an assessment of the elements of the vehicle  outline in the front
view.  For that portion of the vehicle  below the front wheel well, the con-
trolling perimeter is composed of the front wheel well, bumper, and front
                                  3-9

-------
under carriage, all well forward of the Panel II location at the mid-point of
the wheelbase and behind Panel I.  Above the front wheel well,  the controlling
perimeter moves aft to the base of the windshield, then along the A-post and
finally across the  top of the vehicle (at or near the Panel n location).  Thus,
the controlling outline appears to range between Panel I and Panel II.  If
Panel n alone had been used in  evaluating A_, the calculated frontal area
                                          tv.
would have been, on the average, about 2% larger.  An increase of 2% in A,.,
                                                                        .R
would have reduced C_. by about 1. 5% and the product C_.A which is used in
determining the aerodynamic drag  force, would have been reduced by about
0.5%.
        Reproducibility and precision of the planimetry was established by
performing replicates of the planimetry operation for two cars,  including
the effect of varying the pole position for each measurement.  Based on
the results, the photo areas  of the  remaining vehicles were planimetered
twice with additional measurements taken if the two readings differed by
more than 1% and  by more than 0.02 planimeter unit (the precision of reading
was +0.01 planimeter unit).
          Lengths  were measured by engineering  scale (60 divisions per inch)
 with the  aid of an optical magnifier.  The photo lengths were calibrated in
 terms of actual length by the previously measured photo length of one side of
 the reference rectangle.  The reference panel (1 or II) which was located
  closest  to the dimension being measured was used.  For the side view photos,
  an'additional (and longer)  reference length was provided by the field measure-
  ment of the spacing between the reference panels, both of which were the
   same distance from the camera.  All photo measurements were made from
   8 x 10 enlargements.
           The basic definitions of the various length and area terms are de-
   fined in Appendix A.  The specific definitions varied for each car, however,
   and were keyed to the actual vehicle geometry. For example, in order to
    establish the front end projected area Ap,  it was necessary to define three
                                      3-10

-------
aerodynamic "breaklines," i.e., front-hood, front-underbody and front-side.
In some cases the definition of the breakline was evident; in other cases,
however,  complex trim, and sheet metal contours made this decision more
subjective.  In these cases, a value judgment was made, based on field notes
and measurements and the photographs (both long range and closeup detail
shots).  In any event,  the objective of the procedure was to ensure that a com-
mon set of breaklines  was used to define the various areas, lengths and radii
of curvature for a given vehicle.
         For the purpose of planning future work,  it may be noted that the
determination of the aerodynamic drag coefficient,  C-., using the drag build
up technique employed in this study typically required about 8 hours per
vehicle.   Field data collection,  including vehicle measurements and position-
ing the vehicle and reference panels for photographic purposes, required
about 3 hours.  Data reduction, including area determinations by planimetry
and linear measurements from the photographs, and the determination of
field measurements of the various  radii of curvature required 3 to 4  hours,
while the computations,  including the length weighted R/E ratios and the
C-p. calculations^ required an additional 1 to 2 hours.
                                   3-11

-------
                              SECTION 4

                               RESULTS
4. 1      CALCULATED CD VALUES

         The individual components (CD ) of the total drag coefficient, C_,
were evaluated as outlined by the "drag "build-up" method (Ref.  2) given in
Appendix A.  A sample calculation of these individual drag components for
the 1977 Chevrolet Impala is shown in Appendix B.
         The projected frontal area, A_, the individual drag components,
CD  -  C_  , and the total drag coefficient,  CQ for each of the test vehicles
are summarized  in Table 4-1.
         Examination of these  C_  components indicates that the largest
single  contributor to C_ is the frtint end drag coefficient,  C_ , with an aver-
age value of about 0. 154, or about 29% of the total average C—.  The contribu-
tion of the base region,  CD  is about 0.105, or about 20% of the total.   The
third major contributor is tne  front wheel and wheel well drag coefficient Cn  ,
                                                                          7
taken to be a constant value of 0.140 (26% of the total Cn). These three com-
ponents; Cn  , Cn  , and Cn ;  thus constitute, on the average, about 75%  of
            1     5         7
the total CD.
         It will also be noted that the front end drag coefficient,  C-.  , en-
compasses the greatest vehicle-to-vehicle variation, ranging from 6.075
for the Porsche 924 to 0.228 for the 1978 Ford LTD  II.  In evaluating C_ ,
                                                                       1
it was found that the results were extremely sensitive to the edge radii
and associated edge lengths.   Examination of Equation 1,  Appendix A shows
that of the three  edge  radii/length ratios, (R/E), the greatest weight is
placed on  (R/E)  ,  relating to the vertical edge geometry. Because the vertical
edge length,  E , is considerably shorter than upper  or lower edge lengths,
the (R/E)  ratio  is typically larger than the other two; i.e., (R/E)   and (R/E),.
Hence, this ratio is generally dominant in the evaluation of CD.  And, since
the vertical edge length was found to be quite  similar on many of the domestic
                                   4-1

-------
Table 4-1.  Summary of Results
Manufacturer
Chrysler



ford






General Mofura






Porochc
Volkdwagon
M. v.
1977
1977
1978
1978
1977
1977'
1977
1977
1976
1978
1978
1977
1977
1977
1978
I97B
197 S
1978
1978
(977
Make
Plymouth
Plymouth
Chrydar
Plymouth
Ford
Ford
Ford
Ford
Ford
Ford
Ford
Chevrolet
Chevrolet
Oldamubile
Chevrolet
Chevrolet
Chevrolet
Oldamobilo
Poracho
Volkuwagen
Model
Arrow
Volaro
LeBaron
Volaro
Granada
LTD II
Mualang II
Pinto
Fairmont
Granada
LTD 11
Impala
Nova
Cutlasa
Itnpala
Monca
Nova
CulUui
924
Rabbit
Body Style
2-dr. Coupe
Station Wagon
4-dr. Sedan
Station Wagon
4-dr. Sedan
4-dr. Sedan
2-dr. Nolchback
3 -dr. R unabout
4-dr, Sedan
.4-dr. Sedan
4-dr. Sedan
•4-dr. Sedan
4-dr. Sedan
2-dr. Coupe
4-dr. Sedan
2-dr. Fallback
4-dr. Sedan
2-dr. Coupe
2-dr. Sport q>e
2-dr. Hatchback
Frontal
Area,
HZ
17.82
22.76
23. OS
22.79
22.22
23.22
19.29
19.46
21. OS
22. 18
23.21
24. 14
22. 56
22.42
23.89
19.04
22.77
21.58
IS. 88
19.77
C°,
Front
End)
0. I8S
0. 133
0. 182
0. 146
0. 200
0. 223
0. 145
0. 100
0. 113
0.214
0.228
0. 179
0. 106
0. 157
0. 170
0. 165
0.093
0. 149
0.075
0. Ill
C"2
(Wtnd-
•hleldl
0.017
0.046
O. 044
0.051
0.024
0.023
0.019
0.031
0.030
0.028
0. 021
0.029
0.026
0.032
0.031
0.017
0.024
0.019
0. 018
0.035
C°»
(Front
Hood)
0.014
O.OI3
0.009
0.013
0.006
0. OOfc
0. Oil
0.022
0.009
0.007
0. 005
0.010
0.012
0.016
0.009
0.027
0. 0)2
0.019
0.055
0.037
X
(Rear
Verticil
Edge)
-0. 002
-0.001
-0. 002
-0.001
-0. 003
-0. 002
.0. 002
-0. 002
-0. 002
-0. 002
-0.001
-0.001
-O. 002
-0. 001
-0. 001
-0.004
-0. 002
-0. 001
-O. 008
-0. 002
C°5
(Baie
Region
0.097
a 111
O. Ill
0. 108
0. 107
0.099
0. 1)4
0. 124
0. 110
0. 114
0.098
0. 106
0. 105
0. 103
0. 108
0.084
0. (05
0. 116
0.073
0. 102
X
(Under
body)
0.037
0.044
0.044
0.044
O.O44
0.045
0.043
0.040
0.042
0.043
0.046
0.045
0.043
0.041
0.046
0.041
0.041
fl. 042
0.039
0.031
X
(Front
Wheel
Well)
0. 140
0. 140
0. 140
0. 140
0. 140
0. 140
0. 140
0. 140
0. 140
0.140
0. 140
0. 140
0. 140
0. 140
0. 140
O. 140
0. 140
0. 140
0. 140
0. 140
X
(Rear
Wheel
Well)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0. O
0.0
0.0
0. O
0.0
0.0
0,0
0.0
0. 0
0.0
0.0
0.0
0.0
CD,
(Protub-
erances)
0. 004
0.022
0.014
0.023
0.008
0.008
0.007
0,007
0.009
0.003
0. 002
0.007
0.006
0.009
0.006
0.0
0.007
0. 013
0.011
0. 009
CD,0
Bullet
Mirror)
0.007
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.004
0.004
0.0
0.0
0.0
0.0
0.005
0.0
0.0
0.0
0.0
CD,I
[Radia-
tor)
0.029
0. O46
0.043
0.041
0. O49
0.054
0.036
O.O14
0.052
0.041
0. O50
0.047
0.042
0.044
0.048
0.036
0.042
0.048
0.027
0.026






















CD
(£cDi(
0.528
0.554
0.585
0.565
0,575
0,596
0.513
0.496
0.501
0.592
0.593
0.562
0.478
0.543
0.557
0.511
0.462
O. 547
0.430
0.489

-------
cars, the value of this ratio was largely dependent on the value of the vertical
edge radius in the fender/headlight region.  It is believed that this particular
edge radius was largely responsible for the variation seen in C— .
                                                            Ul
4.2      COMPARISON WITH WIND TUNNEL RESULTS
         Twelve of the twenty vehicles  evaluated in this study were also tested
by the Lockheed-Georgia Company,  Marietta,  Georgia in the Low Speed Wind
Tunnel (LSWT), as reported In References 3 and 4.  Wind tunnel test results
were given in Reference 3 for eight of the 12 vehicles and were based on the
area ratio method of determining the wind tunnel blockage correction.  In this
method,  the test section blockage is computed as a function of the ratio of
automobile frontal area to test section cross section area; i.e.,  K = 1/2 (S/C),
where S  is the  automobile frontal area  and C is the test section cross sectional
area.
         Lockheed subsequently reported (Ref. 4) that studies of wind  tunnel
blockage methods showed that the conventional area  ratio method under-
corrects blockage and buoyancy for bluff bodies such as automobiles,  due to
large wake  effects.  A method of accounting for the large wake,  derived by
the Lockheed-Georgia Company, uses  the test section ceiling static pressure
distribution to arrive  at the blockage correction.  For this ceiling static
pressure signature method,  test section static pressures along the ceiling
centerline are measured with the model  both in and out of the test section.
Lockheed reported that a comparison of  the data using the two blockage
methods showed that coefficient data based on the area ratio method are higher
than those based on the ceiling  static pressure signature method by 2.8 to 12
 percent for the range of vehicles tested  (Ref. 4).
         Reference 4  provides wind tunnel test results for four additional
vehicles examined in  this study as well as a retest of the 1977 Ford Granada
 reported in Reference 3.  The data presented are based on both the area ratio
 blockage correction method and the ceiling pressure signature method.
 ""Lockheed values of frontal area were generally within +_ 1 percent of values
  determined by Aerospace.
                                     4-3

-------
        A comparison of the LSWT test results with the values derived in
this study are shown in tabular form in Table 4-2 and graphically in Figure
4-1.  The wind tunnel test results were given in terms of C^A and were der-
ived from F^/Q, where Fn is the drag force in pounds and Q is the dynamic
           U   2        ^
pressure in Ib/ft .  The  values of CD  shown for the wind tunnel results were
derived by dividing the reported value of C_A by the projected frontal area,
AR, as  determined by the present study.
        As indicated in Table 4-2,  the calculated values of C~ developed in
this study average 5. 0% lower than the wind tunnel results based on the area
ratio  blockage correction method and 5.9% higher than the wind tunnel results
based on the  ceiling static pressure signature method.  Thus,  on average, the
calculated  values of C_ would appear to be in good agreement with the wind
tunnel results.  As indicated in Table  4-2,  however, the data also shows a
high degree of dispersion; the standard deviation of the area ratio data set is
8. 1%  compared  to a mean deviation of -5.0%, while the static pressure data
set shows a standard  deviation of 7.4% compared to a mean deviation of 5. 9%.
The dispersion in the area ratio set is due primarily to the results obtained
for the Pinto, the Mustang II, the  1978 Volare Station Wagon, and to a lesser
degree, to the Porsche 924.  In the case of the static pressure data set,  the
primary outlier is the 1973 Le Baron.  Further discussion of these outliers
is provided below.
        The vehicles which show the greatest disagreement with the area
ratio  wind  tunnel results are the Pinto (-18.4%), the Mustang H (-16.9%), the
1978 Volare Station Wagon (-11.9%), and the Porsche 924 (+8. 3%).  In the
case of  the Pinto, an  examination of the individual components of C_ given in
Table 4-1 shows that  C-.  , the front end drag coefficient,  is one of the lowest
the  data set.  This value  is due  primarily  to the large (6 in.) upper edge
radius,  R  , above the grille at the hood-front breakline.  The Mustang H,
however,  does not show any single component of CD that is noticeably lower
than the other vehicles.  Similarly, the disagreement indicated for the 1978
Volare Wagon is not explainable in terms of component drag peculiarities.
It should be noted that calculated CD values for the 1978 model Volare are
                                   4-4

-------
Table 4-2.  Comparison of Calculated Aerodynamic Characteristics
            with Wind Tunnel Test Results
Vehicle
'77 Chevrolet Impala
'77 Ford Granada
'77 Ford Granada
•77 Ford Mustang II
•77 Ford Pinto
'77 Plymouth Arrow
'77 Plymouth Volare
Wauon
•77 Porache 924
>77 VW Rabbit
'76 Chevrolet Inipala
>78 Plym.Volaro Wagon
'78 Chrysler LeDaron
'7B Cutlass Supreme
Calculated Results
Projected
Frontal Area.
ARftZ
24.14
22.22

19.29
19.46
17.82
22.76
18. SB
19.77
23.89
22.79
23.05
21.58
'(talc. - W. T.)/W.T.
ZAl SO niph.
V2'
0.562
0.575

0,513
0.496
0.528
0.554
0.410
0.489
0.557
0.565
0.585
0.547
C A(2)
CDA
13.54
12.77

9.90
9.67
9.40
12.63
8. 13
9.64
13. 31
12.88
13.48
11.80
Wind Tunm
Area Ratio
Blockade Method
CD<2,.W
0.588
0.602
0.580
0,617
0.608
0.545
0.558
0.397
0.523
0.577
0.641
0.545
0.5HO
r A'Z)
CDA
14.I6<4>
I3.36<4>
12.88<5>
ll.90(4>
ll.85«>
9.70<«>
12.72«4>
7.50«4>
10.36'4'
13.79(5)
• 4.6l'5'
12.S7(S)
I2.5l'5>
1 Reaulta
Pressure Signature
Blockage Method
c (2), (3)


0.535






0.521
0.584
0.502
0.538
C A(Z)
CDA


11.90<5»






12.45<5'
I3.31<5'
11.58<5>
ll.6l'5»
'Derived from CDA/AR 'Reference 4 Mean % d CQ
Refe rence 3 SUnda rrf DevlaUon „
* A CD"»
Area Ratio
Method
-4.4
-4.5
-0.9
r!6.9
-18.4
-3. 1
-0.7
+ 8. 3
-6.5
-3.5
-11.9
+ 7.3
-5.7
-S.O
8. 1
Pressure
Signature
Method


+7.5






+6.9
-3.3
+ 16.5
+ 1.7
+ 5.9
7.4

-------
   0.70
   0.6!
   0.60
   0.55
 1.  1977 Chevrolet Impala
 2.  1977 Ford Granada
 3.  1977 Ford Mustang 11  Notch back
 4.  1977 Ford Pinto
 5.  1977 Plymouth Arrow
 6.  1977 Plymouth Volare Station Wagon
 7.  1977 Porsche 924
 8.  1977 VW Rabbit
 9.  1978 Chevrolet Impala
10.  1978 Plymouth Volare  Station Wagon
11.  1978 Chrysler LeBaron
12.  1978 Oldsmobile Cutlass Supreme
O  Area Ratio Method, Ref. 3
a  Area Ratio Method. Ref. 4
0  Pressure Signature Method, Ref. 4
                                                   202     /
                                                   10    Xmio
                                          05
                                .  #     '
                                6 EJJ2 /
                                     /
                                              /
                                                 /
                                      08<
                                      /
                                         G3

                                        04
                                    /
                                 /
                              /
                           /
              s\
                     ,'*
0.35      0.40      0.45      0.50
                       Cn, LSWT
                                          0.55
                                     0.60
0.65
Figure 4-1.  Comparison of Test and Calculated Values of
              Aerodynamic Drag Coefficient
                                4-6

-------
very similar to those for the 1977 model, which showed excellent agreement
•with the test result (-.7%).  The similarity in component C 's would be
expected in view  of the minor styling changes between the two model years.
         The value of Gn derived for the Porsche 924 was found to be ex-
tremely sensitive to  the front hood configuration and  the related effects on
C   and C-. .  The values of C_  and  C~  shown in Table 4-1 were based on
  D,       UQ                 JJ,       Uj
the assumption that the front of trie hood began at the top edge of the front
bumper.   The selection of this line of demarcation resulted in the low value
(0.075) for Cn  and the comparatively high value (0.055) for Cn .  Examina-
tion of the front end  detail of the Porsche 924,  shown in Figure 4-2,  suggests
the possibility of using an alternate breakline between the hood and front end;
that is,  the line of intersection of two planes on the hood. This breakline
would result in a larger front end area, A^, and a smaller hood area
                                         £
 (A,  - A^).  The  net  effect would  be to reduce C-,  by 0.010.  The net effect
   h    r                                      JJ-i
 on Cp. , however, is difficult to assess since an effective upper edge radius,
       1
 R , cannot be determined.  As seen in Figure 4-2, this front-hood breakline
 is essentially the intersection of  two planes, with a very small radius of
 curvature (i.e., 1/16 in.) at the  point of intersection.   However,  since the
 angular change at this breakline is on the order of 25 to 30°, it would seem
 that some larger effective upper  edge radius should  be used.  Indicative of
 the sensitivity of C_ to this upper edge radius is  the net change in C
 which occurs when the value of R^ is altered.   If,  for example, the value of
 1/16 in. were used,  C_ would increase by 0.024 over that shown in  Table
                        1
 4-1.  K, on the other hand, a value of say 6 in.  were assumed, Cn   would
 be reduced by 0.040.                                             1
          Based on the foregoing discussion,  it would appear that the  derived
 value of C_ for  the Porsche may be too high, although any revision to the
 derived value would require a more definitive assessment of the upper edge
 radius than is provided for  in the technique used in this  study.
          Of the five  vehicles available for comparison with the wind  tunnel
 data based  on the ceiling static pressure blockage correction method,  the
                                    4-7

-------
00
                                 Figure 4-2.  Porsche 924, Front End Detail

-------
1978 Chrysler Le Baron shows the greatest disagreement;  the calculated
value is 16.5% higher than the wind tunnel results.  An examination of the
individual C_ components for this vehicle (Table 4-1) does not reveal any
significant differences from the other vehicles.  Hence,  the reason(s) for
the discrepancy in results is not apparent.
                                     4-9

-------
                              SECTION 5

               CONCLUSIONS AND RECOMMENDATIONS


        The aerodynamic drag coefficient, C_, as developed by the "drag
build-up" method, was determined for a total of twenty 1977/1978 model
year vehicles.  Results of the low speed wind tunnel tests conducted by the
Lockheed-Georgia Company (based on an area ratio blockage correction
method) on twelve of the vehicles were available for comparison,  and
showed that the empirically derived value of C_. for nine of the twelve
vehicles was within +10% of the wind tunnel results.  Of these nine vehicles,
the value of Cn determined for the Porsche must be considered somewhat
suspect in view of the uncertainties in defining the hood-front breakline and
the associated edge radius.  The other three  vehicles  (the  Mustang II,  Pinto,
and 1978 Volare  station wagon) were found to be 12 to  13%  lower than the
wind tunnel results.  The reason for this difference is not apparent in the
case of the  Mustang II and Volare.  The low value of Cn calculated for the
Pinto may be due in part to its low value of Cn  (0. 100) which derives from
the large edge radius (6 in.) at the hood-front breakline above the grille.
         Wind tunnel test results  using the ceiling static pressure signature
blockage correction method were available for comparison for five  of the
vehicles evaluated.  The empirically derived C_^ values for four of the five
vehicles were also within +10% of the wind tunnel results.   The value of C_
                         ~~                                            D
for the remaining vehicle (the Le Baron) was found to be 16.5% higher than
the wind tunnel results.
         In summary, the empirical evaluation of the  vehicle aerodynamic
drag coefficient  by the drag build-up method showed good  agreement with
 the wind tunnel results in most, but not all,  cases.  Several factors are
 believed to have contributed to the lack of agreement.  One is the subjective
 interpretation required in evaluating certain edge radii.  A second factor  is
 the high degree  of sensitivity of the results to the ratio of the edge radius  to
                                   5-1

-------
the projected length of that radius  (R/E).  This factor was found to be parti-
cularly important in the case of C_ , but it also  affected the evaluation of
C_  and C_ , although to a lesser degree.  While this effect was recognized
in developing the equations for evaluating the forebody drag components
(Ref. 2), the results of this study  suggest that the method could be  improved
by modifying some of the simplifying assumptions made In defining the effect
of rounded edges.
         Beginning with 1979  model year vehicles,  the method used by EPA for
establishing dynamometer power absorption settings for emission certification
and fuel economy testing of light duty vehicles will be based on vehicle equiv-
alent inertia weight,  vehicle  reference frontal area,  and vehicle protuberances,
using a formula in which aerodynamic drag  road  load effects are  approximated
by the relation

                               HP = cA + P

where A is the vehicle projected frontal area, c  is a constant which has differ-
ent values  for fastback and non-fastback vehicles, and P is a protuberance
factor.  This equation implicitly assumes that the contribution to the aero-
dynamic drag coefficient from the  vehicle body (excluding protuberances) is
equal (constant) for all vehicles in each configuration category.
         Using C's developed from the above relation, the accuracy of assum-
ing constant drag coefficients can  be evaluated and compared to the accuracy
of the drag coefficient buildup method of this report.  However,  it must be noted
that the wind tunnel testing, which encompasses  two different blockage correc-
tion methods, provides comparable data for only five of the 20 vehicles eval-
uated in this study (see Table 4-2).  This small  sample size precludes a  rigor-
ous  statistical analysis of the accuracy of the methods.
         For the five  vehicles that can be compared to both sets of wind tunnel
results, a simple computation of the average disparity^ between Cn calculated
 "defined as£[ %& CD|/N
                                    5-2

-------
and Cn tested yields (a) 6.2% and 7.2% for the drag buildup method as refer-
enced to the area ratio and pressure signature blockage correction test results,
respectively,  and (b) 3.3% and 10.5% for corresponding values derived from the
EPA dynamometer  relation.   Slight differences in numerical values notwith-
standing, the  significant aspect of this  result is that the disparities are small
and similar in magnitude for the two methods.  Thus, for this specific set of
five vehicles, the use of a relation based on a constant average C_. for the
vehicle body with correction for protuberances  appears to provide as accurate
a prediction of the  vehicle C_. as is obtained from the drag coefficient buildup
approach.
         It is concluded that the data developed in this study  does not indicate
an increase in the accuracy of predicting drag coefficient using the drag coeffi-
cient buildup approach compared with the  accuracy obtained  by assuming a
constant average drag coefficient for all similar  vehicles.  Therefore, no
changes to the current relation defining dynamometer road load horsepower
settings are recommended on the basis of the present work.
                                      5-3

-------
                            REFERENCES
1.      Federal Register, Vol. 4Z, No. 176, September 12, 1977.

2.      Estimation, of Vehicle Aerodynamic Drag, Aerospace Report No.
        ATR-77(7359-l), The Aerospace Corporation, El Segundo,
        California, October 1976.

3.      E. A. Payne, Low Speed Wind Tunnel Test to Determine the
        Aerodynamic Characteristics of Thirteen Automobiles,  Report
        No. LSWT 211, Lockheed-Georgia Company, Marietta, Georgia,
        May 1977.

4.      D. L. Bruce, Determination of Automobile Aerodynamic
        Characteristics, Low Speed Wind Tunnel Tests, Lockheed-Georgia,
        Company, Marietta, Georgia,  June  1978.
                                  R-l

-------
                                APPENDIX A

                     DRAG PREDICTION METHOD
             The drag prediction technique developed by The Aerospace
Corporation in Reference 2 breaks the drag of a road vehicle into 11 dis-
crete contributions.  The reference area, A_,  which is used to normalize
the component drag contributions, is taken to be the projected frontal area
of the vehicle including tires and underbody details but excluding protuber-
ances such as mirrors, antenna, and luggage carriers.  The contribution
of a component is a function of its size so that typically a representative
area A. of each component,  as well as A_,  appear in the formulas.  The
relevant vehicle dimensions and areas are illustrated in Figure A-l.  The
details of the drag build-up are presented in the following pages.
                                   A-l

-------
IS)
                                                                 A  - LxW
                                                                  P
                                           W
                                 r     A,
                                                 0
                                   Figure A-1. Vehicle Dimensions

-------
Front End Drag Coefficient,  C^
                     'A   \(           /  \         /  \         /   \
                     -^M  1. 0 - 2. 79 (•£•!  + 0. 82 f-g-K - 5. 21 (-^-1
                            J£.l   1  O - 7  •« q I •"•
                            ^ST" It \ Ji* v» ™ t,» C.J \ ^Sf
        (1)
where
      Ap = projected frontal area of the vehicle including tires and
       *   underbody details, m2 (ft2)
      A— = front end projected area, m  (ft )
       £
      R  = edge radius, m (ft)
      E  = projected length of the edge radius, m (ft)
and the subscripts u, 1, and v refer to the upper, lower,  and vertical edges
of the front end, respectively.  The (R/E). are to be taken as 0.105 when
the estimated values exceed this magnitude.
Windshield Drag Coefficient, Cp 	
          =0.707
       ^2

 where
,  cos2y  (2)
          = projected area of windshield,  m  (ft  )
      y   = slope of the windshield measured from the vertical,  deg
      ft   = 27
 and the subscripts u'  and v1 refer to the roof-windshield intersection and the
 windshield posts, respectively.  The value  of cos£ is to be taken as zero
 for V larger than 45° and the (R/E). are to  be taken as 0.105 for estimated
 values exceeding this magnitude.
                                  A-3

-------
Front Hood Drag Coefficient, Cp 	
where


         = projected area of body below the hood-windshield
           intersection, m^  (ft2)

         = length of hood in the elevation or  side view, m (ft)


and the quantity (A^ - AF) is to be taken as zero if it is negative.


Rear Vertical Edge  Drag Coefficient,  C^
                •V-'-^W'-W0-105!
                            /E. \           /R  '         >
                    = -0. 02 (TT        for  -^-) > 0.105
                            \ «  /
where


      RV = radius of rear vertical edges,  m (ft)


      W  = projected width of rear vertical portion,  m (ft)

      E,  = projected length of rear vertical edge radius,  m (ft)


      H  = vehicle height,  m (ft)


Base Region Drag Coefficient,  C,
                                                                  (5)
                                 A-4

-------
where

           = projected area of flat portion of base region
      A-,  = projected area of upper rear or hatch portion of base
             region measured from the upper rear roof break (or for
             smoothly curved rooflines, that point where the roofline
             slope is 15°) to the top of the flat base, m2 (ft2)

      Cn  = drag coefficient of the flat base
       DB

      CD  - drag coefficient of the upper rear or hatch portion of
         H   the base region

 and the ratio (Cn /Cn ) is shown in Figure A-2 as a function of 4>t the
                 H    B
 angle of the line r?om tfie upper rear roof break to the top  of the flat base

 as measured from the horizontal.

 Underbody Drag Coefficient,  CD 	


             Cn = 0. 025 (0. 5 - x/L) (-T2-) for 0 < x/L < 0. 5
              ^6                   \  R/                         (6)

                 = 0                       for x/L > 0. 5

 where

      x  = smoothed forward length of the underbody, m (ft)

      L  = vehicle underbody length, m  (ft)
                                                         2    2
      A  = projected plan area of the vehicle underbody, m  (ft)


 Wheel and Wheel Well Drag Coefficient.  CD 	


                            CD   =0.14                             (7)


 Rear Wheel Well Fairing  Drag Coefficient,  CD 	


                            Cf.   = -0. 01 for rear wheel well covered
                                                                     (8)
                            C—  = 0. 0 for real wheel well not covered
                               8
                                   A-5

-------
     2.0
  CO
 o
o
  x 1.8
 o
o
5   u

i—
LiJ
G   0-8
o

o
<:
a:
o
0.4
       0
                                    NOTCHBACK
                                                  HATCHBACK
                                      I
                                        I
I
        0      10      20      30      40      50      60      70

                                  HATCHBACK SLOPE,  ~ deg
               FASTBACK

                    o
                                                                     90
                     100
                 Figure A-2.  Hatch back-Notch back Drag Coefficient Ratio

-------
Protuberance Drag Coefficient,  Cp __






                            D9   AR



where


      A   = projected area of jth protuberance, m  (ft )

       Pj


Bullet Mirror Drag Coefficient, Cn  	
                                       Ai
                           C_    = 0.4-r                          (10)

                            D10
where
      A., = projected area of mirror with bullet fairing,  m  (ft )



Cooling Drag Coefficient, C—










where


      A      = radiator area, m  (ft  )


      u      = exit velocity of cooling air from radiator, m/sec (mph)


      u      = vehicle speed, m/sec  (mph)


      (ur/u) = 0.233 [1.0 - k (u/100)2]




 and


      k      = 1.146  (m/sec)"2 [or 0.229 (mph)"2]*
 "Represents a correction to Ref. 2, published as .299.
                                   A-7

-------
                           APPENDIX B
                         Sample Calculation
Vehicle   1977 Impala
License No.    807SMV
               1.625 in.
             65.45 in.
  (R/E)u   0.0248  (max. = 0.105)
        R£    0.935 in.
        Ej   68.41 in.
  (R/E).    0.0137  (max. = 0.105)
               1.029 in.
              17.74 in.
           0.0580  (max. =0.105)
               9.657 ft*
              24.137 ft*
 'D  '
                 /AF\
      ;   a0.707US.)
       Dl        \AR/
          =0.1785
  (AF/AR)  0.4001

2.79(-|-).. + 0.82

ru
(£-}  -
\*h
'R \
.T/v
         RU,    2.5 in.
         EU,   50.43 in.
         Rv.    1. 5 in.
         Ev.   15. 28 in.
  (R/E)u,   0.0496    (max. = 0.105)
  (R/E)v,   0.0982    (max. = 0.105)
                                B-l

-------
                    Sample Calculation (Continued)
CD  (Cont'd)
              53*
               5. 517 ft*
        AR    24. 137 ft
          =0.0286
                          2y = 106°     (cos£= 0 fory> 45°)
                      (AW/AR)  0.2286
                          ,02 - 2.79
                                 L, COS0-5.21  -£-
                                                              cos
             12. 708
       D
                           5.118ft
9.657ft2 A,, 24.137ft2
0.707
I /5,, , Fn /\
TI J '
'D4'
          =0.0104
RV    0.854 in.

W    67. 08 in.
             18. 65 in.
       H     43. 10 in.
           -0.02(4)
     CD  =0.0010
        4
                                     0.0127
                              0* 4327
                             for l-^-)< 0.105

                                /R  \
                             for!
> 0.105
                                B-2

-------
                 Sample Calculation (Continued)
             9. 157 ft
            24. 137 ft

            20°
             8.629ft*
           0.3794
CD   CD   °' 925
  H/  £
            0.3575
                          » from Fi«- A'2)
    CD  = 0.1065
      5
'V
       L   211.50 in.
       W    58. 55 in.

    Cn  =0.025 (0.5 -x/L)
     D6
  A (=L x W) 86. 00
    P
ft)
      for 0 <  x/L < 0. 5
    CV°
        for x/L > 0. 5
    Cn = 0.0445
      D6
    CD  = 0.140
'D  '
         -.  = 0 (rear wheel wells not covered)
          8

         -.  = -0.01  (rear wheel well covered)
         D8
                              B-3

-------
               Sample Calculation (Continued)
    A_(mirror) 0.1591     A^	   AD  24.137
       <
r

 D9
     =0.0073

   9
c    .  °'4AM


 D10     *R~
C    =0.0
   k « 1. 146 (m/sec)"2




     = 0.229 (mph)"2
  /ur/u\ = 0.233 [l.O - k (u/100)2]








   A  (= L  x h  ) 3.438 ft2, Ap 24.137 ft2
    r     r   r  ———i^^—   iv. •———•—•
                           B-4

-------
                   Sample Calculation (Continued)


  j   (Cont'd)

  -II.            /A  \/u  \[           >u Y)
     CD   =l.8f1^)(-Tf-)|l.0.0.75(-^)i =0.3303 (T^-)® 50 mph



     C^   = 0.0470
CD:
                   0.5618
                                 B-5

-------
                            APPENDIX C

                  VEHICLE DIMENSIONS AND AREAS
        The individual vehicle dimensions and areas which are required to
evaluate the aerodynamic drag coefficient according to the methods outlined
in Appendix A are given for each of the 20 vehicles evaluated.
        When more than one edge radius is indicated for a given portion of
the vehicle, the effective value was determined as follows:
where
      R  = effective edge radius
      Ri = specific radius over length Ei
      Ei = projected length. associated with a given radius, Ri
         The parameter (R/E) was then taken to be the ratio of the effective
edge radius to the sum of the individual edge lengths, Ei.
                                  C-l

-------
                     VEHICLE DIMENSIONS/ARE AS

 Vehicle:  Manufacturer     Chrysler	
          Make             Plymouth Arrow
          Model            2-dr.  Coupe
          Model Year       1977	
          License No/VTN   Dlr 2529 (Calif. )/7P24K78901899
 Projected Frontal Area, ft   17,82
 C_  :   Frqnt_End Drag Coefficient
 ——     Location
   1.  hood portion      R    0.125 in.   E     46.59 in.   (R/E)  0.0027
                        u:              Uj                   u	—.
   2.  above headlights  R    0.25 in,    E      4.24 in,
                        U2              U2
   1.  body sheet metal Rj   0.125 in.   Et   51.45 in.   (R/E). 0.0024
      below bumper      L1              zl                   /      "—•
   1.  upper portion of  R    0.375 in.   E      6 in.      /R/E)  0.0625
      fender            vl              Vl                   v	'
   2.  lower portion of  R    1 in.       E      2.5 in.
      fender             2                2
   3,  upper portion of  RV   1.625 in.   EV   4.5 in.
      bumper and lower  3                3
      sheetmetal
   4,  lower portion of  Ry   1.313 in.   EV   3 in.
      bumper            4                4
                                                        Ar  6. 985 ft2

 Cjj :  Windshield Drag Coefficient
——      Location
   1.  roof windshield   RU,   4.5 in.     EU,   39.76 in.   (R/E)V  0.113*
      intersection                                                     ~
   2.  A-post           RV,   3 in.        EV,   13.25 in.   (R/E)v,  0.226*
   3.  windshield  slope  y     60°	
      from vertical                                         use 0,105

                                 C-2

-------
Vehicle:  1977 Plymouth Arrow (Continued)
C_  :  Front Hood Drag Coefficient
	       Location
   1.  front area below windshield        A.    9.413 ft
   2.  front end area                     AF   6.985 ft
   3.  hood length                        1    4,028 ft
CD  :  Rear Vertical Edge Drag Coefficient
   —     Location
   1.  upper portion  of  R     0.875 in.   E,    10.5 in.  R     1.030 in.
      vertical section    vl                1              v
   2.  lower portion  of  RV   1 in.       E,     3 in.    E,    18.75 in.
      vertical section     2                2
   3.  upper portion  of  R     1.5 in.     E,     2. 25 in. W    57. 50 in.
      bumper             3                3
   4.  lower portion  of  RV   1.25 in.    E^     3 in.    H    37.07 in.
      bumper             4                4 ~~~
CD  :  Base Region Drag Coefficient
	     Location
   1. area of base region                A«     7.845 ft
   2. area of hatch portion              A,,    4.267 ft
   3» rear slope from horizontal        
-------
Vehicle:  1977 Plymouth Arrow  (Continued)
C_ : Protuberance Drag Coefficient
          Location
  1.  antenna                  Ap    0.0609 ft2      £Ap   0.0609ft2

Cn   :  Bullet Mirror Drag Coefficient
 D10
  •  "•     Location
  1.  one each side             ^T.I   ^* ^2^  ^
Cn   :  Cooling Drag Coefficient
      radiator height   12.125 in,
      radiator width    18.375 in.        Ar  1. 547 ft2
                                 C-4

-------
Vehicle:   Manufacturer     Chrysler	
          Make             Plymouth Velar e
          Model            Station Wagon
          Model Year       1977
          License No/VTN  Dlr 2529 (Calif. )/HH45G7G135783
Projected Frontal Area,  ft   22. 76
CD :  Front End Drag Coefficient
-         Location
   1.  above headlights RU   0. 125 in,   EU  20 in,      (R/E)  0. 0092

   2.  above parking   R    2 in,       E    16. 94 in,
      lights             U2              U2
   3.  above grille     RU   Q. 0625 in.  EU  27.23 in.
                         J                J
   1.  botton of bumper R,   1.75 in.    E-  66.30 in.   (R/E).  0.0264
                        *1              ll                  /
   1.  at fender        R    0. 563 in.   E      9 in.     (R/E)  0.0974
                        vl              vl                  v
   2,  upper portion of R     3.75 in.   E      2.75 in.
      bumper           V2              V2 ~~~"~~— —
   3.  lower portion of R     2.25 in.   E      4.25 in.
      bumper           V3              V3
                                                                   2
                                                       Ar  8.861 ft
 CD  :  Windshield Drag Coefficient
    .-     Location
   1.  roof-windshield  R ,   1.625 in.   E ,    49. 03 in. (R/E) , 0,0331
      intersection
   2.  A-post          R^,   1. 125 in.   EV,    16.24 in. (R/E) , 0.0693
   3.  windshield slope  y    51° _  AW     5. 888 ft
      from vertical
                                  C-5

-------
Vehicle: 1977 Volare Station Wagon (Continued)
CD  :  Front Hood Drag Coefficient
	     Location
  1.  front area below windshield        A    11.783 ft2
  2.  front end area                     Ap    8.861 ft2
  3.  hood length                        L^    4.508 ft

C_ : Rear Vertical Edge Drag Coefficient
——      Location
  1.  vertical portion   RV   0.688 in.    Eb    7 in.     R..   0.996 in.
      above bumper      1                1                       ~   "
  2.  upper portion of  R    1,875 in.    E,     2 in.     E,  15 in.
      bumper           V2                2
  3.  lower portion of  RV   1.063 in.    E^    6 in.     W  65.87 in.
      bumper            3                3
                                                       H   42.17 in.
^ : Base Region Drag Coefficient
11
1.
2.
3.
Location
area of base region
area of hatch portion
rear slope from horizontal
A^ 7.360ft2
AJJ 9.530ft2
* 45° Cn /Cn
1.0
                                                  H   "B
         rag Coefficient
Location
C_ : Underbody Drag Coefficient
 u .
  1.  underbody length          L  16.507 ft
  2.  underbody width           W   4.854 ft        Ap(= LXW)  80.13 ft2
                                 C-6

-------
Vehicle:  1977 Volare Station Wagon {Continued)
cr> : Protuberance Drag Coefficient
   9
-         Location
  1.  mirrors (one each side)   A     0,2417 ft
                                PI	
  2.  antenna                  A     0.0260 ft2
                                p2	
  3.  luggage rack             Aw    0.1828 ft2    £A     0.4505 ft2
                                p3	     p.	

CD   :  Bullet Mirror Drag Coefficient
	       Location
  1.  none

  n   :  Cooling Drag Coefficient
      radiator height   17.25 in.
      radiator width    26.25 in.       A   3.145ft2
                                 C-7

-------
Vehicle:  Manufacturer     Chrysler
          Make            Le Baron
          Model            4-dr. Sedan
          Model  Year      1978
          License No/VIN  311 TYY (Calif. )/FP41J8G145760

Projected Frontal Area, ft   23.05

C— : Front End Drag Coefficient

	—      Location

   1.  above headlights  RU   1.5 in.     EU   30.78 in. (R/E)u  0.0122

   2.  above grille      R    0.031 in.   E    31.38 in.
                        U2              U2
   1.  center segment   R,    2.75  in.    E.    31.03 in. (R/E).  0.0318
      of bumper         ^ 1              *>\                 *
   2.  outer  segments   R«   1.563 in.   E.    35,51  in.
      of bumper         ^2              ^2

   1.  headlight trim,    RV   0.75  in.    EV     1.5 in.  (R/E)v  0.0618
      horizontal portion  1               1
   2.  fender above      R    0.469 in.   E      2 in.
      headlights         V2               2

   3.  headlight trim,    Ry   0.031 in.   Ey     7.5 in.
      vertical portion     3               3
  4.  bumper          R     2.625 in.   E      5.5 in.
                       V4               4
                                                       AF  8.991ft
                                                                    2
CD : Windshield Drag Coefficient
	—      (Location)

  1.  roof-windshield  RU,   2.625 in.   EU, 47.90 in.   (R/E)u,  0.0548
      intersection                                             ——
  2.  A-post

  3.  windshield slope y   51.5°       A    ' oin ^2
      from vertical
                      R,   1.125 in.   E, 16.04 in.   (R/E),  0.0701
                               C-8

-------
Vehicle:  1978 Le Baron, (Continued)
*"• •
3
•MMI^™»
1.
2.
3.
CD :
•^••MM*
1.
2.
3.
4.
!v
i.
2.
3.
CD *'
6
1.
2.
Front Hood Drag Coefficient
Location
front area below windshield
front end area
hood length
A^ 11.500ft2
A^ 8. 991 ft2
1*. 4.766ft
Rear Vertical Edge Drag Coefficient
Location
vertical portion R 1.375 in.
of body vl
sloping portion R 1.281 in.
of body V2
upper portion of R 1. 875 in.
bumper 3
lower portion of R 1.25 in.
bumper 4
Base Region Drag Coefficient
Location
area of base region
area of hatch portion
rear slope from horizontal
Underbody Drag Coefficient
Location
underbody length L 16.
underbody width W 4.
E, Sin. R 1.394 in.
Et 3 in. E^ 18. 5 in.
^ 2. 5 in. W 66. 97 in.
E^_ Sin. H 42. 51 in.
°4
A,, 8.770ft2
A« 7. 866 ft2
6 22° Cn /C 1.06
DH DB
801 ft
818 ft A (= LXW) 80.94 ft2
                                C-9

-------
Vehicle:  1978 Le Baron (Continued)
CD  : Protuberance Drag Coefficient
—-—     Location
  1.  mirrors (one each side)   A     0.2475 ft

  2.  antenna                  A     0.0394 ft2

  3.  hood ornament            A     0.0104 ft2       £A     0.2973 ft2
                                P3                      pj            —
CD   :  Bullet Mirror Drag Coefficient
	    Location
  1*  none

C_    :  Cooling Drag Coefficient
      radiator height    17 in.
      radiator width   25.5 in,          Ar  3.0104 ft2
                                 C-10

-------
Vehicle:   Manufacturer     Chrysler	
          Make             Plymouth Volare
          Model            Station Wagon
          Model Year       1978
          License No/VIN  Dlr 2529 (Calif. )/HL45C8B170977
Projected Frontal Area,  ft2  22.79
C-. :  Front End Drag Coefficient
-         Location
   1.  above headlights RU   0. 125 in.   EU  19.48 in.  (R/E)u 0.0075

   2.  above parking    R    1.5 in.     E    18.10 in.
      lights             U2              U2 -
   3.  above grille     R    0.0625 in.  E    26. 97 in.
                        U3              U3 -
   1.  bottom of bumper R.   1.375 in.   E,  66.76 in.  (R/EL 0.0206
                        l\              t\ -     I
   1.  at headlights    R    0.438 in.   E      9 in.     (R/E>  0.0871
                        vl              vl            '      v
   2.  upper portion of R    3.25 in.    E      2.75 in.
      bumper            2              V2
   3.  lower portion    R    2.25 in.    E      4. 5 in.
      °f bUmper          3              "3             A    8.727ft2
CD  :  Windshield Drag Coefficient
.          Location
   1.  roof-windshield  R .   2. 5 in.     E...   48.27 in.  (R/E) .   0.0518
      intersection                        u          "  "      u -
   2.  A-post           Rv,   1 in.       EV,   17.64 in.  (R/E>v,   0. 0567
   3.  windshield slope  y   51° _ A...    5. 906 ft2
      from horizontal     —————    — ____^___
                                 C-ll

-------
Vehicle 1978 Volare Station Wagon (Continued)



C_  :  Front Hood Drag Coefficient
^1
1.
2.
3.
•
4
•^•^•M
1.
2.
3.
D5:
MHMM
1.
2.
3.
V
1.
2.
Location
front area below windshield
front end area
hood length
A,. 11.622ft2
A^, 8. 727 ft2
Lu 4. 537 ft
Rear Vertical Edge Drag Coefficient
Location
vertical portion R 0. 688
above bumper vl
upper portion of R 1.625
bumper 2
lower portion R 1. 125
of bumper V3
Base Region Drag Coefficient
Location
area of base region
area of hatch portion
rear slope from horizontal
Underbody Drag Coefficient
Location
underbody length L
underbody width W
in. E 7 in. R 0. 978 in.
in. E, 2 in. E, 14 in.
2 D "" 	
in. Eb 5 in. W 65.56 in.
3 H 40. 50 in.

A,, 6. 859 ft2
An 9. 476 ft2
0 45° Ct, /C
fcH DB 	 i—-
16.462 ft
4.882ft Ar(= LXW) 80T *A ft2
                               C-12

-------
Vehicle:  1978 Volare Station Wagon (Continued)
C_ : Protuberance Drag Coefficient
   Q
    •      Location
  1.  mirrors (one each side)   A    0,2570 ft

  2.  antenna                  A    0.0267 ft2
                                 b
  3.  luggage rack             A    0.1828 ft2        £A    0.4665 ft2
                                P3                      Pj

C    :  Bullet Mirror Drag Coefficient
   10
     i     Location
   1.  none


      :  Cooling Drag Coefficient
   11
  •«HBMMW
      radiator height     18.75 in.

      radiator width      22.0 in.        AT   2.865 ft2
                                   C-13

-------
Vehicle:   Manufacturer     Ford
          Make             Granada
          Model            4-dr. Sedan

          Model Year       1977	
          License No/VIN   132 RTT(Calif.)/7W81F121893

Projected Frontal Area, ft  22. 22
Y
i.
2.
3.
1.
1.
2.
: Front End Drag
Location
at fender
above headlights
above grille
bottom of
bumper
at fender
at bumper
Coefficient
Ru
ul
R
U2
R
U3
R/
*1
R
"l
R
V2
1.875 in.
2.625 in.
0.0625 in.
1.125 in.
0. 125 in.
2.25 in.

E . 1. 25 in.
Ul
E 28 in.
U2
E 33.5 in.
U3
E, 62. 61 in.
*1
E 12 in.
"1
E 7 in.
V2
(R/E).. 0.
(R/E)^ o.
. (R/EJv-O*.
AF 8.943
0198
0180
•— — ~
0478
CD :  Windshield Drag Coefficient
          Location
  1.  roof-windshield  RU,   4.5 in.     EU,  47.62 in.   (R/E)U,  0.0945^
      intersection
  2.  A-post          R^t   1.625 in.  EV.  14.87 in.   (R/E)..,  0.109^

  3.  windshield slope y     56°        A^   5.312 ft   *exceedg
      from vertical                                      uge Q
                                 C-14

-------
Vehicle:  1977 Ford Granada (Continued)
C   :  Front Hood Drag Coefficient

.11   -      Location
  1.  front area below windshield       A    11.033 ft2
  2.  front end area                     Ap   8.943 ft

  3.  hood length                        1     4.648 ft
C_  :  Rear Vertical Edge Drag Coefficient

-         Location
   1.  vertical portion  R     1. 125 in.   E,    1.75 in.  R    1. 576 in.
      above tail light    vl                Dl              v

   2.  tail light portion R,    0.6875 in.  E,    4.5 in.   E,   21. 51 in.
                        V2                °2 -  °

   3.  vertical portion  R     1.0 in.     E,     2. 5 in.   W   64. 60 in.
      below tail light    V3                D3

   4.  sloping portion   R     0. 906 in.   E,     5.26 in. H   38.21 in.
      above tail light    V4                D4          "~

   5.  bumper          RV   2.875 in.          7. 5 in.
 C_  : Base Region Drag Coefficient
  DC         —           -  — ^— — —
 -          Location

   1.  area of base region               A-   10.00 ft

   2.  area of hatch portion              A,,    6. 24 ft2

   3.  rear slope from horizontal        0    20° _ CD  /CD  0. 925
                                                           H    £

 C_  :  Underbody Drag Coefficient
  jj    -
 — —      Location

   1.  underbody length          L   16.281 ft

   2.  underbody width           W- 4.814ft     A (= LXW)   78.38 ft2
                                   -     p         -
                                  C-15

-------
Vehicle: 1977 Ford Granada (Continued)

C_  :  Protuberance Drag Coefficient
   9
	     Location

   1.  mirror                   A     0.1212 ft2


   2.  antenna                  A     0.0269 ft2
                                 fa

   3.  hood ornament            A     0.0113 ft2       IA    0.1594 ft2


C_   :  Bullet Mirror Drag Coefficient

	i£-    Location
  1.  none


  —   :  Cooling Drag Coefficient
  ^11
      radiator height   18 in.	

      radiator width    26.5 in.         Ay  3,313 ft2
                                C-16

-------
Vehicle:  Manufacturer     Ford
          Make             LTD II
          Model            4-dr. Sedan
          Model Year      1977	
          License No/VIN  404 SYY (Calif. )/7A31H156239
Projected Frontal Area, ft  23.22
r    :  Front End Drag Coefficient
_..  .-     Location
   1.  at fender         RU    1.375 in.   EU   20 in.     (R/E)U 0.0090

   2.  above headlights  R     0.563 in.   E    17 in.
                        U2                2
   3.  above grille      R     0.0625 in.  E^   28.9 in.

   1.  bottom of        R.    0.50 in.    E-   67.5 in.   (R/E)  0.0074
      bumper           Ll               Ll                  *
   1.  at fender         R     0.0625 in.  E    12.5 in.   (R/E)  0.0322
                        vl    (use 0)     vl                  v
   2. bumper          RV    1.75 in.    EV     7  in.
                                                        Ar 9.024ft2

 C   : Windshield Drag Coefficient
 _  2-      Location
   1.  roof-windshield  RU,   4.75 in.    EU,  46.57 in.  (R/E)u, 0.1020
       intersection
   2.  A-post          Rv,   1.125 in.   EV,  13.45 in.  (R/E)v, 0.0836
   3.  windshield slope  y    59°	 AW    4.993  ft
       from vertical
                                   C-17

-------
 Vehicle:   1977 Ford LTD n (Continued)
 CD  :  ^ront Hood Drag Coefficient
 ——      Location
   1.  front area below windshield        Ah  11.375ft2
   2.  front end area                     Ap   9.024 ft
   3.  hood length                        L^   5.407 ft

 CD  :  Rear Vertical Edge Drag Coefficient
 •         Location
   1.  fender           R,   0.0625 in.   EL    14.95 in.   R   1.079 in
                        Vl               bl               v	'	
   2.  bumper          R    3.25 in.     E,      7 in.      E, 21.95 in.
                        V2               D2	'    b ~~	•
                                                        W 65.51 in.
                                                        H 40. 52 in.
 C_  :  Base Region Drag Coefficient
~~"~     Location
   1.  area of base region                Afi  10.174 ft
   2.  area of hatch portion               A-,   6.040 ft2
  3.  rear slope                            19°
 _  : Underbody Drag Coefficient
 *J^
          Location
  1. underbody length          L  16.242 ft
  2. underbody width          W   5.113 ft       A (= LXW)   83. 05
                                 C-18

-------
Vehicle: 1977 Ford LTD II  (Continued)
C_ : Protuberance Drag Coefficient
   9
-   •      Location
   1.  mirror                   A    0.1153 ft2

   2.  antenna                   A    0.0269 ft
  3.  hood ornament            A     0. 0247 ft2        £ A    0. 1669 ft2
                                P3    -          p. -
C-.   :  Bullet Mirror Drag Coefficient
  ^10
-- iii-    Location
   1.  none                     A,.     0	

  n   :  Cooling Drag Coefficient
      radiator height  19.5 in.
      radiator width   28 in.            A   3.792 ft2
                                  C-19

-------
Vehicle:   Manufacturer     Ford
Make
Model
Model Year
License No/VTN
Projected Frontal Area, ft
Mustang II



2-dr. Coupe (Notchback)
1977



397 SYY (Calif. )/7R02Z 13 1023
19.29



CD : Front End Drag Coefficient
	 1_
1.
2.
3.
1.
1.
2.
3.
!v
i.
2.
3.
Location
above headlights
above grille
between head-
lights and grille
bottom of
bumper
at headlights
upper portion of
bumper
lower portion of
Windshield Drae
Location
roof -wind shield
intersection
A-post
windshield slope
R
ul
R
U2
R
U3
R.
R
Vl
R
V2
R
0.031 in.
0.0625 in.
1.75 in.
0.625 in.
0.031 in.
2. 5 in.
2.375 in.
E
Ul
E
U2
E
U3
E
E
Vl
E
V2
E
14 in.
33.75 in.
8 in.
58 in.
8.25 in.
3 in.
3 in.
Coefficient
Ru'
R ,
y
6 in.
1.75 in.
59°
Eu'
*v
AW-
41.69 in.
12.35 in.
4. 228 ft2
(R/E)u 0.0053
(R/E), 0. 0108
1 	 • 	
(R/E) 0. 0733
if ^"^^^•^^•^^•WfciWI
AF 6. 425 ft2
(R/E)u, .0144*

-------
Vehicle:   1977 Ford Mustang II (Continued)

C    :  Front Hood Drag Coefficient

•  ••     Location

   1.  front area below windshield       A,   8.843 ft

   2.  front end area                    A_, 6.425 ft

   3.  hood length                       L.   4.416 ft
C_  :  Rear Vertical Edge Drag Coefficient
          Location

                                        S
1. vertical portion  R   0.50 in.     E,     S in.      R     1.096 in.
   of body            vl              bl               v

2. sloping portion   R   0.625 in.    E,     5 in.      E,   17 in.
   of body            V2               °2               b	
   3.  upper portion of  Ry   2 in.        E^    3 in,       W  62.85 in.
      bumper            3                3                 ————

   4.  lower portion of  RV   1.75 in.     E,    4 in.       H  36.90 in.
      bumper            4                4                 ""

 C_  :  Base Region Drag Coefficient
    *5
    i-      Location

   1.  area of base region               Afi   7.747 ft

   2.  area of hatch portion              A,,   5.678 ft2

   3.  rear slope from horizontal        0    24°        C_ /C-.    1.21
                                                           DH   DB

 C-, •  Underbody Drag Coefficient

 	—      Location

   1.  underbody length          L   14.477 ft

   2.  underbody width           W    4.550 ft     A  (= LXW)  65.87 ft2
                                   C-21

-------
Vehicle:  1977 Ford Mustang n (Continued)

          tuberanc
          Location
C_ : Protuberance Drag Coefficient
  u


                                             2
  1,  mirror                   A    0.1017 ft


  2.  antenna                  A    0.0250 ft2         LA    0.1267
                                P2                       pj

C_   :  Bullet Mirror Drag Coefficient

- —    Location

  1.  none                     A,,     0


C     :  Cooling Drag Coefficient
 Dll
      radiator height  16 in.

      radiator width   19 in.            A  2.111 ft2
                                 C-22

-------
Vehicle:  Manufacturer
Ford
•oje<
Make
Model
Model Year
License No/VTN
cted Fromal Area, ft
Pinto
3 -dr. Runabout
1977
152 TDB (Calif. )/8RllY105096
19.46
: Front End Drag Coefficient
^M«
1.
2.
1.
1.
2.
3.
Location
above grille RU
above headlights R
bottom of Ri
bumper ^1
at headlights R
vl
upper portion R
of bumper 2
lower portion R
of bumper V3
6 in. E_ 41. 5 in. (R/E) 0.0707
0.0625 in. E 18 in.
U2
0.625 in. E, 61 in. (R/E). 0.0102
LI /
0. 0625 in. E 9 in. (R/E) 0.0736
3 in. E 2 in.
2. 5 in. E 4 in.
A^ 6.741ft2
: Windshield Drag Coefficient
^^«M
1.
2.
3.
Location
roof- wind shield R ,
intersection
A-post R ,
windshield slope
4 in, E., 36. 87 in. (R/E), 0. 109 in.
0.375 in. E ., 12. 19 in, (R/E), 0.031 in.
60° A^ 4. 091 ft2 *exceeds max.
       from vertical
                               use 0.105
                                   C-23

-------
 Vehicle:  1977 Ford Pinto (Continued)
 CD  :  Front Hood Drag Coefficient
  •        Location
   1.  front area below windshield        A,    9.690 ft
   2.  front end area                     Ap   6.741 ft
   3.  hood length                        L^    3.819 ft

 CD  :  Rear Vertical Edge Drag Coefficient
 ••        Location
   1.  body portion     R     1. 188 in.   E,      10 in.     R    1. 693 in
                        vl               bl               v
   2.  upper portion of  R     3.25 in.    E,       2 in.     E,  16. 5 in.
      bumper           V2               D2               b - "
   3.  lower portion    R     2.125 in.   E,       4. 5 in.   W  60.73  in
      of bumper         V3                3              R  37. 05  in.
C,j  :  Base Region Drag Coefficient
^— —     Location
  1.  area of base region                Afi   6.629 ft
  2.  area of hatch portion               A-*   6.615 ft
  3.  rear slope from horizontal         0    27
Cn : Underbody Drag Coefficient
 \j
  •        Location
  1. underbody length          L   13.964 ft
  2. underbody width          W    4.473 ft     A (= LXW)  62.46 ft2
                                                 P1
                                  C-24

-------
Vehicle: 1977 Ford Pinto  (Continued)
Cn  • Protuberance Drag Coefficient
  u
•  7.     Location
  1.  mirror                   A^    0.1037 ft2
  2.  antenna                  A     0.0250 ft          £A     0.1287
                                P2                        Pj	
C_   J  Bullet Mirror Drag Coefficient
   10
—   •      Location
  1.  none                     A,.      0

Cn   :  Cooling Drag Coefficient
~~     radiator  height   16.75 in.
      radiator  width    17.125  in.        A   1.992 ft2
                                  C-25

-------
Vehicle:  Manufacturer     Ford
          Make            Fairmont
          Model            4-dr. Sedan
          Model Year      1978
          License No/VIN  031 UDH (Calif. )/8K92T132207
Projected Frontal Area,  ft2  21.05 ft2
CD : Front End Drag Coefficient
— — —      Location
  1.  above grille     RU   2.25 in.    EU   32.41 in.   (R/E)u   0.0229

  2.  above headlights R     0.375 in.   E    27.87 in.
  1.  bottom of        R.    0. 50 in.
1.
2.
3.
!v
i.
2.
3.
bumper
at fender
upper portion
of bumper
lower portion
of bumper
Windshield Drag
Location
roof-windshield
intersection
A-post
windshield slope
L\
R
R
"2
R
1.125 in.
2. 75 in.
2.125 in.
V3'
Coefficient
R i
R .
y
3.5 in.
2.25 in.
54°
L\
E
E
V2
E
V3
Eu'
Ev'
AW-
8
in.
2. 5 in.
3
46.
17.
5.
in.
0 in.
11 in.
668 ft2
I 	 B
(R/E^^O,
AF 7.608
-" ' ^
J955
ft2
(R/E)U, 0. 076j^
(R/E)V. 0.132*
*
exceeds max.
      from vertical                                      use 0. 105
                                 C-26

-------
Vehicle: j^978 Ford Fairmont  (Continued)

CD  :  Front Hood Drag Coefficient

.          Location

   1.  front area below windshield        A.    9.828 ft2
                                         W\ ^••^^^^•^^^^^•^^^^•(••i
  2.  front end area                     A_,  7.608 ft

  3.  hood length                       1^   4.352 ft
C_  :  Rear Vertical Edge Drag Coefficient
   -•     Location
1.  vertical portion  R     1.375 in.  E,    4.203 in.   R    1.
   of base region     vl               Dl               v
                                                                557 in.
   2.  sloping portion   R     1.313 in.  E,   10. 088 in.   E,  20. 175 in.
      of base region     V2                D2                °

   3.  upper portion    R     2. 75 in.   E.    2. 942 in.   W  63.47 in.
      of bumper          3                 3 — —~-— —

   4.  lower portion    RV   2 in.       E.    2. 942 in.   H  40.53 in.
      of bumper          4                 4

  TV  *  Base Region Drag Coefficient
   5
   —      Location
   1.  area of base region               A_   9. 181 ft

   2.  area of hatch portion              A__   6.713 ft2

   3.  rear slope from horizontal            20° _  C_  /C_    0. 925
                                                           DH  DB

 C-.  :  Underbody Drag Coefficient
  jj
    . .      Location
   1. underbody length          L   15.492 ft

   2. underbody width          W    4. 558 ft    A  (= LXW)   70. 62 ft2
                                    C-27

-------
Vehicle: 1978 Ford Fairmont  (Continued)
C,-j : Protuberance Drag Coefficient
   9
  —      Location
  1.  mirror                   A^    0.1383 ft2
  2.  antenna                  A     0.0252 ft2        LA    0.1635 ft2
                                P2                        PJ             •
      : Bullet Mirror Drag Coefficient
    —     Location
  1. none                     A~,      0
Cn  : Cooling Drag Coefficient
 ^11
     radiator height     19 in.
     radiator width      25 in.          A   3.299 ft2
                                         r
                                 C-28

-------
Vehicle:  Manufacturer     Ford
          Make            Granada
          Model            4-dr. Sedan
          Model Year       1978
          License No/VIN  492 TSP (Calif. )/8W82F108082
Projected Frontal Area, ft   22.18
C~  :  Front End Drag Coefficient
  D.                *	
— * •     Location
   1.  fender and body   R    1.75 in.    E      11.75 in.  (R/E)   0.0066
      excluding head-    ul              ul                   u
      lights &c grille areas
   2.  above headlights  RU   0.1875 in.  EU    20 in.

   3.  above grille      R    0.0625 in.  E      31.5 in.
                         3                3
   1.  bottom of        R.   1.125 in.   E/    63.25 in.  (R/E),  0.0178
      bumper           Ll              *1                   /
   1.  at fender         Rv   0.125 in.   E      11 in.     (R/E)   0.0392
                      .  vl  (use 0)      vl                   v	
   2.  upper portion    Ry   2.25 in.    E        3 in.
      of bumper         2          "    V2 ~—"—~—~——-
  , 3. lower portion    Ry   1.5 in.     E        3.5 in.
      of bumper         3                3                   8.529ft2
     :  Windshield Drag Coefficient
    ~      Location
   1.  roof-windshield  R.  4.75 in.     E .     47.93 in. (R/E)  .  0.0991
       intersection
   2.  A-post          R.  1.25 in.     EV<     14.26 itu (R/E)y.  0.0877
   3.  windshield slope y    56°         A...      5.252 ft2
       from vertical
                                  C-29

-------
 Vehicle:  1978 Ford Granada  (Continued)
 CD : Front Hood Drag Coefficient
 "         Location
                                                     o
   1*  front area below windshield        A,   10.724 ft
   2. front end area                    A^,  8.529 ft2
   3. hood length                       L,   4.719 ft

 C_  :  Rear Vertical Edge Drag Coefficient
   fL
 •  •  •      Location
   1. sloping portion   R      1 in.      E     6 in.      R    it 543 ^
      of body             1                Dl           '    v	—
   2. vertical portion  R      1.375 in.
                        v.
      of body             2
   3.  upper portion    R      2.75 in.   E^     4 in.      W__66.85m.
      of bumper           3                3
   4.  lower portion    R      1.5 in.    E,     3.5 in.    H   41.0 in..
      of bumper           4                4      "
  n  :  Base Region Drag Coefficient
          Location
                   • A *>r+ ^"%*»                /_
                                         B
1.  area of base region               A_   10.151 ft
2.  area of hatch portion              A,.    6,706 ft
3.  rear slope from horizontal         0    21°	
C_ :  Underbody Drag Coefficient
"'  •      Location
  1.  underbody length         L  16.201 ft
  2.  underbody width
                                  C-30

-------
Vehicle:  1978 Ford Granada  (Continued)
C-.  :  Protuberance Drag Coefficient
  DQ	B	
...  7      Location
   1.  antenna                  A    0.0530 ft2        lA     0.0530 ft2
                                 Pl                       Pj
C    :  Bullet Mirror Drag Coefficient
     -    Location
   1.  one each side             AM  0.2277 ft2

C_   :  Cooling Drag Coefficient
      'radiator height     16.5 in.
      radiator width     24 in.          A,  2.750 ft
                                    C-31

-------
 Vehicle:  Manufacturer     Ford
          Make             LTD II
          Model            4-dr. Sedan

          Model Year       1978	
          License No/VIN   Dlr 6985 (Calif. )/8A30S175412

          Frontal Area, ft    23.2

 C_  :  Front End Drag Coefficient
Projected Frontal Area,  ft   23.23
   'i
   —     Location
   1.  fender and body  RU   1.25 in.     EU     20 in.    (R/E)     0. QQ82
      exluding head-      11                  u         "
      lights and grille
      areas
   2.  above headlights  R    0. 5625 in.   EU     17 in.
                         2                2

   3.  above grille      R    0.031 in.    E      28. 9 in.
1.
1.
2.
3.
bottom of
bumper
at fender
upper portion
of bumper
lower portion
Rf
R
V
R
' V2'
R .
0.625 in. E.
LI
0. 0625 in. E
(use 0) 11
1. 813 in. E
2
2 in. E
68. 5 in.
12.5 in.
3 in.
3.5 in.
(R/E)
£~
(R/E)v _
0. 0091
0.0345
-•—•••«•• •
C   : Windshield Drag Coefficient

	       Location
  1.  roof-windshield   RU,  6 in.       EU,     46.26 in. (R/E)u,  0.1297*
      intersection                                                      ~~
  2.  A-post           Rv,,  1.25 in.     EV,

  3.  windshield slope  y    59° _  AW      4. 901 ft    exceeds max.
      from vertical                                         use 0. 105
                                  C-32

-------
Vehicle: 1978 Ford LTD II (Continued)
CD  !  Front Hood Drag Coefficient
-         Location
   1.  front area below windshield       A.  11.459 ft2
   2.  front end area                    Ap   9.309 ft2
   3.  hood length                       L^   5.563 ft

C~  :  Rear Vertical Edge  Drag Coefficient
   4
—	     Location
   1.  at fender         R    0.0625 in.  E.     14.85 in. R    0.856 in.
                        vl               bl	  v	
   2.  upper portion    R    3.25 in.    E,       3.25 in. E,  21.60 in.
      of bumper         V2               b2      	  °	
   3.  lower portion    R    2 in.	 E.       3.5 in.  W   66.01 in.
      of bumper          3                3 •~~~~~—~~—    —————
                                                        H   40.25 in.
C_  :  Base Region Drag Coefficient
-         Location
   1.  area of base region               Ap    10.273 ft2
   2.  area of hatch portion              A-,     6.069 ft2
   3.  rear slope  from horizontal         #     18°	Cn  /C_   0,80
                                                         DH  DB
C—  :  Underbody Praia; Coefficient
   6
—        Location
   1.  underbody length         L   16.971 ft
   2.  underbody width          W   5.042 ft     A (= LXW)   85.56 ft2
                                   C-33

-------
Vehicle: 1978 Ford LTD n (Continued)
C-. : Protuberance Drag Coefficient
   9
  1.  antenna                  A     0.0252 ft2

  2.  hood ornament            A     0.0247 ft2         £A     0. 0499 ft2
                                P2                        Pj           ~~

 D   : Bullet Mirror Drag Coefficient
   = —    Location
  1.  one each side             Aj^   0. 2303 ft2

 T,   : Cooling Drajg Coefficient
 Dll
      radiator height      18  in«
      radiator width      28  in.         Ar  3. 50 ft
                                 C-34

-------
Vehicle:  Manufacturer     General Motors
          Make            Chevrolet Impala
          Model            4-dr. Sedan
          Model Year       1977	
          License No/VIN  807 SMV (Calif. )/lL69U7C147622

Projected Frontal Area, ft    24.14

C~  '  Front End Drag Coefficient
  D,   —	B	
   *-     Location
   1.  hood-front       R     1. 625 in.  E    65.45 in,   (R/E)   0.0248
      breakline         Ul              Ulu	

   1.  center segment   R.     1.25 in.   E.   37.06 in.   (R/E).  0.0137
      of bumper         Ll              *1                   *

   2.  outer segment    R.     0.563 in. E*   31.35 in.
      of bumper         *2              *2

   1.  at fender        R      0.125 in. E    10.74 in.   (R/E)   0.0580
                        Vj              yi                   v	

   2.  upper section    R      3 in.     E      4 in.
      of bumper         2                2
   3. center section    RV     1.375 in. Ey    1.75 in.
      of bumper         3                3
   4. lower section    RV     2 in.     EV    1.25»in.
      of bumper         4                4             Ap  9.657ft2


 r   : Windshield Drag Coefficient
  D,  —	
 .,  r-      Location
   1.  roof-windshield  RU,    2.5 in.   EU,   50.43 in.   (R/E)u,  0.0496
       intersection
   2.  A-post          RT.    1.5 in.   EV>   15.28 in.   (R/E)^.  0.0982

   3.  windshield slope y    53°       AW    5.517 ft2
       from vertical
                                  C-35

-------
Vehicle: 1977 Chevrolet Impala  (Continued)
C_  :  Front Hood Drag Coefficient
  u    --.._.-.
•  "        Location
  1.  front area below windshield       A.   12.708 ft2
                                         n i  "
  2.  front end area                    AF   9.657 ft2
  3.  hood length                       L    5.118 ft
CD : Rear Vertical Edge Drag Coefficient
 1111      Location
  1.  fender portion   R    0.125 in.   E.    10.55 in.   R    0.854 in.
                         1                1               v~~        ~~~
  2.  upper portion    R^   2.875 in.   Efe    3.25 in.   E   17.05 in.
      of bumper         V2                2                             ~
  3.  center portion   RV   1.375 in.   Eb    1.75 in.   W   67.08 in.
      of bumper          3                3
  4.  lower portion    RV   1 in.       Efe    1.5 in.    H   43.10 in.
      of bumper          4                4
C_  : Base Region Drag Coefficient
———      Location
  1.  area of base region               A^   9.157 ft
  2.  area of hatch portion              AJJ   8,629 ft
  3.  rear slope from horizontal          20	 CD /CD  0.925

CD  : Underbody Drag Coefficient
11          Location
  1.  underbody length          L  17.625 ft
  2.  underbody width           W   4.879ft     Ap(= LXW)    86.00 ft2
                                  C-36

-------
Vehicle: 1977 Chevrolet Impala  (Continued)

C   :  Protuberance Drag Coefficient
  Dp
   '-     Location

   1.  mirror                   A^    0.1591 ft         DA   	0.1591ft2
C    •  Bullet Mirror Drag Coefficient
  D10   	°	
   "*"•    Location

   1.  none



        Cooling Drag Coefficient

      " radiator height    18 in.

      radiator width     27. 5 in.        A   3.438 ft2
                                   C-37

-------
Vehicle:   Manufacturer
          Make
          Model
          Model Year
                         General Motors
                         Chevrolet Nova
                         4-dr, Sedan
                         1977	
          License No/VIN   125 SZS (Calif. )/lX69D7L146791
Projected Frontal Area,  ft   22.56
CTN • Front End Drag^Coefficient
  —      Location
  1.  above headlights  R
2.  above grille
                           1 in.
Ll               "1
     1. 375 in.  E
               En    20• 5 fa«   
-------
Vehicle: 1977 Chevrolet Nova (Continued)
CD :  Front Hood Drag Coefficient
—   •      Location
   1.  front area below windshield       A.    11.225 ft2
   2.  front end area                    Ap    8.393 ft2
   3.  hood length                       L^    4.674

CD : Rear Vertical Edge Drag Coefficient
—.         Location
   1.  body above       RV    0.375 in.  E.    11.326 in.  R    1.195 in.
      bumper            1                1         "~    v
   2.  upper portion    R     3.5 in.    E.     3.5 in.    E   18.826 in.
      of bumper          2                2               b          "
   3.  lower portion    RV    1.5 in.    E.     4 in.      W   62.291 in.
      of bumper          3                3             TT   ,. f., .
                                                        H   40. 556 in.
CD  :  Base Region Drag Coefficient
-.         Location
   1.  area of base region               A,,    8.001 ft2
                                         J3 ——i>-_____
   2.  area of hatch portion             A,,    7.734ft2
   3.  rear slope from horizontal       
-------
Vehicle: 1977 Chevrolet Nova (Continued)
C_  :  Protuberance Drag Coefficient
	—     Location
   1.  mirror                   A    0.1169 ft2         LA    0.1169 ft2
                                 Pj                        PJ—

CD   :  Bullet Mirror Drag Coefficient
     •     Location
  1.  none                     Aj^

CD   :  Cooling Drag Coefficient
——~" radiator height     16 in.
      radiator width     26 in.           Ar   2.889 ft2
                                  C-40

-------
Vehicle:   Manufacturer     General Motors

          Make             Oldamobile Cutlass Supreme

          Model            2-dr. Coupe	
          Model Year       1977
          License No/VIN  866 SMA (Calif. )/3J57R7R209999

Projected Frontal Area,  ft2  22.62

Cn  :  Front End Drag Coefficient

-.  '-     Location
   1.  center portion   R    1.125 in.   E      10.75 in.  (R/E)   0.0116
                             .      .            .     .
                        ul              ul                   u
   2.  above headlights R    1.188 in.   E      32 in.
                             .      .
                        U2              U2
3.  sheet metal      R    0. 0625 in.   E      24 in.
    behind grille      U3               U3

1.  center portion of R .   2.25 in.     E      35 in.     (R/E)   0. 0296
                     *1               *1                   L
      bottom of bumper

   2.  outer segments   R.   1.625 in.   E.     31 in.
      of bottom of       iz              l^          ~~
      bumper

   1.  at fender         R    0.125 in.   E        9 in. _ (R/E)    0.0740
                        YI               Vi -      v -

   2.  upper portion    R    3.25 in.    E       3.75 in.
      of bumper          2                2

   3.  lower portion    Ry   2 in. _  E       5 in.
      of bumper          3               V3
                                                        Ar  8. 406 ft*


 CD  :  Windshield Drag Coefficient

 —  •      Location

   1.  roof-windshield  R..  4. 75 in.    E     45. 8 in.  (R/E)  .  0.1037
      intersection        u                u                   u  -

   2.  A-post          R^,  0.75 in.    EV,    14. 1 in.  (R/E)v,  0.0532

   3.  windshield slope  V   56° _ A.,,     4. 522 ft2
       from vertical       —————.
                                   C-41

-------
Vehicle: 1977 Oldsmobile Cutlaas Supreme (Continued)
C_ :  Front Hood Drag Coefficient
——•—      Location
  1.  front area below windshield       A   12.279 ft
  2.  front end area                    Ap   8.406 ft2
  3.  hood length                       L^   5.371 ft

CD : Rear Vertical Edge Drag Coefficient
 1         Location
  1.  body portion     Ry    0.25 in.   Eb      9.5 in.  R..    0.745 in.

  2,  upper portion    R     1.563 Jn^  E^      4.5 in.  Efe   18 in,
      of bumper          2                2                             ~
  3.  lower portion    RV    1 in.       E^      4 in.     W    65.46  in.
      of bumper          3                3
                                                        H    39. 93  in.
C   : Base Region Drag Coefficient
• - '	      Location
  1.  area of base region               A£   9.021  ft
  2.  area of hatch portion              AJJ   6. 991  ft2
  3.  rear slope from horizontal             20°	CD  /CD  .0.925^
                                                          rr    B
CD : Underbody Drag Coefficient
    1      Location
  1.  underbody length          L   15.800  ft
  2.  underbody width          W    4.970  ft         Ap(= LXW)  78.53 ft2^
                                 C-42

-------
Vehicle:  1977 Oldsmobile Cutlass Supreme  (Continued)
CD  :  Protuberance Drag Coefficient
—i  ••     Location
   1.  mirror                  A    0.1491 ft2

   2.  hood ornament           A^   0.0275 ft2         £A     o. 1766 ft2
                                 p2	            p.	

C_   :  Bullet Mirror Drag Coefficient
   10
          Location
   1.  none

      :  Cooling Drag Coefficient
  """""" radiator height      15. 5 in.
      radiator width      28 in.         Ar  3.014 ft2
                                    C-43

-------
Vehicle:   Manufacturer     General Motors
          Make             Chevrolet Impala
          Model            4-dr, Sedan
          Model Year       1978 _
          License No/VIN  759 ULU (Calif. )/lL69U8S193433
Projected Frontal Area,  ft  23.89
CD : Front End Drag Coefficient
   •       Location
  1.  above headlights RU   1.5 in.     EU    28. 52 in.   (R/E)u  0. 0244

  2.  above grille      R     1.625 in.   E     35.93 in.
                       U2                2
  1.  center segment  R.   1. 5 in.     R,    37.28 in.   (R/E)   0.0154
      of bumper        *\               ^ 1                   /      """""
  2.  outer segment   R.    0. 563 in.   R.    31.89 in.
      of bumper        *2               ^2
  1.  at headlights     RV    0. 125 in.   EV    10 in.      (R/E)y  0.0676

  2.  upper portion    RV    3.25 in.    EV     4 in.
      of bumper         2                2
  3.  center portion   R     1.5 in.     E      1.75 in.
       » i               V- ™~ •"""          v^
      of bumper         3                -5
  4.  lower portion    RV    2.125 in.   EV     1«25 in.
      of bumper         44
                                                        A    9. 843 ft2
CD :  Windshield Drag Coefficient
— —      Location
  1.  roof-windshield  RU,   2.625 in.   EU,   50. 51 in.   (R/E)u,   0. 0520
      intersection
  2.  A-post          RV,   1.375 in.   EV,   15.15 in.   (R/E)v,   0. 0907^
  3.  windshield slope X     53°        AW    5. 482 ft2
      from vertical
                                 C-44

-------
Vehicle: 1978 Chevrolet Impala  (Continued)
C *
3
MVM^^"
1.
2.
3.
!^!
i.
2.
3.
4.
5
1.
2.
e.
CD ''
6
1.
2.
Front Hood Drag Coefficient
Location
front area below windshield
front end area
hood length
A,. 12.659ft2
AF
Lu
9. 843 ft2
5. 067 ft
Rear Vertical Edge Draa Coefficient
Location
at fender R 0. 125 in.
1
upper portion R 3.25 in.
of bumper 2
center portion R 1.75 in.
of bumper V3
lower portion R 1.25 in.
of bumper V4
Base Region Drag Coefficient
Location
area of base region
area of hatch portion
rear slope from horizontal
Underbody Drag Coefficient
Location
underbody length L 17.
underbody width W 5.

°l~
^
°2
Efc
b3
^
D4
AD
*!!
0
63 ft
03 ft
10. 34 in. R 0. 997 in.
3. 25 in. E^ 16. 84 in.
1.75 in. W 67. 28 in.
1.5 in. H 43. 84 in.
9.110 ft2
8.710 ft2
20° C_ /C^ 0. 925
DH DB
A _(= LXW) 88.77 ft2
                                 C-45

-------
Vehicle: 1978 Chevrolet Impala  (Continued)



C_ : Protuberance Drag Coefficient
  M                        -


	      Location
  1.  mirror                   A    0.1295 ft2        XA^   0.1295ft2





      :  Bullet Mirror Drag Coefficient

   10
  —=—    Location
  1.  none




      :  Cooling Drag Coefficient



      radiator height    18 in.


      radiator width     27.5 in.       Ay  3.438 ft2
                                  C-46

-------
Vehicle:  Manufacturer     General Motors
          Make             Chevrolet Monza
          Model            2-dr. Faatback
          Model Year       1978
          License No/VIN  none (He s 3 ell Chev-rolet>/lR07A8U102658
Projected Frontal Area,  ft   19.04
V
1.
2.
1.
1.
Front End Drag
Location
above headlights
between head-
lights
body below
bumper
at headlights
Coefficient
Ru
Ul
Ru
U2
R
1
R
o.
0.
0.
0.
0625
0625
0625
0625
in.
in.
in.
in.
E
ul
E
U2~
E
1
E
30
26
53
8
in.
in.
in. .
.5 in.
(R/E)U .
u •
(R/E) m
- (R/E)V .
0.0011
0. 0012
0. 0294
                         l   (use 0)
   •2.  bumper          R    2 in.       E      3 in.
                        v2               V2

   3.  body below       R    0.0625 in.  EV     3 in.
 C_  :  Windshield Drag Coefficient
  j2    -
 —         Location
   1.  roof-windshield  R  .   6 in.       E^.    42. 98 in.  (R/E)u.  0.1396*
       intersection
   2.  A-post          RT.   2.5 in.     E^.    12.69 in.  (R/E>v.  0.197*
                                                      9    dc
   3.  windshield slope y     61° _  A..,      4.263 ft     exceeds max.
       from vertical                                        u«* 0. 105
                                  C-47

-------
Vehicle: 1978 Chevrolet Monza (Continued)
C_ :  Front Hood Drag Coefficient
——      Location
   1.  front area below windshield        A^  9.026 ft2
   2.  front end area                    Ap  5.268 ft
   3.  hood length                       1^  4.400 ft

C_ :  Rear Vertical Edge Drag Coefficient
4
MMMBB
1.
2.
3.
V
Location
tan light R
bottom of tail R
light to bottom
of bumper
below bumper R
Base Region Drag
Location

^1
12
2. 25 in. E
2. 75 in. E,
5 in. E,
V3~
Coefficient


                                               3.5 in.   R^    3.348 in.
                                               6 in.     E,   14 in.
                                              ~           D "
                                               4.5 in.   W   53.47 in.
                                                        H   39.18 in.
  1.  area of base region               A_   5,535 ft
  2.  area of hatch portion              A-,   5.089 ft2
                                               °
  3.  rear slope from horizontal         0    21

  D :  Underbody Drag Coefficient
  —-      Location
  1.  underbody length          L  14.056 ft
  2.  underbody width          W   4.477 ft         Ap(= LXW)   62.92
                                  C-48

-------
Vehicle: 1978 Chevrolet Monza  (Continued)
Co  ;  Protuberance Drag Coefficient
   ".     Location
1. none
                               A
                                 pl
  _   :  Bullet Mirror Drag Coefficient
   i2-    Location
   1.  one each side            Aj^   0.2313 ft

  _   :  Cooling Drag Coefficient
  Dll
      radiator height      15 in,
      radiator width      20 in.         Ay   2. 083 ft2
                                    C-49

-------
Vehicle:   Manufacturer     General Motors

Make
Model
Model Year
Chevrolet Nova
4-dr. Sedan
1978

License No/VIN None {Hessell Chevrolet)/lY69U8102645
Projected Frontal Area, ft2 22. 77
v
1.
1.
1.
2.
3.
4.
C_ :
MBMMMM
1.
2.
3.
: Front End Drag
Location
hood-front
breakline
bottom of
bumper
at headlights
above head-
lights
upper portion
of bumper
lower portion
of bumper
Windshield Drag
Location
roof-windshield
intersection
A-post
windshield slope
Coefficient
R 2. 125 in. E.. 62. 44 in.
1 1
R, 1.25 in. E, 64.27 in.
R . 031 in. E 7. 5 in.
vl (use 0) ^1
R^ 0.0625 in. E 1.25 in.
^2 2
R 4. 75 in. E 4 in.
V3 ^3
RV 2. 25 in. Ev 3. Sin.
Coefficient
R.., 3. 5 in. E.., 45. 65 in.
KV, 3 in. E^ 15,82 in.
X 54° A.,, 5.015ft2
. (R/E).. 0.0340
(R/E). 0.0194
. (R/E).. 0.1021
Aw 7. 967 ft2
(R/E) , 0.0767
(R/E)r, 0.1896*
exceeds max.
noo n i nc
                                C-50

-------
Vehicle: 1978 Chevrolet Nova  (Continued)
C_ :  Front Hood Drag Coefficient
   3
-i  ..      Location
   1.  front area below windshield       A,   10.846 ft
   2,  front end area                    AF   7.967 ft
   3.  hood length                      1     4.721 ft
 C   :  Rear Vertical Edge Drag Coefficient
    4
 -   •       Location
   1. body above       Ry   0.938 in.   E,   10.338 in.   R     1.537 in.
      bumper             1                1               v
   2. upper portion    R    3.25 in.    E,    4 in.       E,   18.338 in.
      of bumper         V2                °2               b	
   3. lower portion    R    1.375 in.   E,    4 in.       W   62.428 in.
      of bumper          3                3
                                                         H   41.292 in.
 C_ : Base Region  Drag Coefficient
    —      Location
   1. area of base region               A-    7.842 ft2
   2. area of hatch portion              Ay   8. 039 ft2
   3. rear slope from horizontal        0    21°	C_ /C_    1.0
                                                           DH   DB
 CD : Underbody Drag Coefficient
 •	       Location
   1. underbody length          L  15.160 ft
   2. underbody width          W  4.957 ft         A ( =LXW)    75.15 ft2
                                   C-51

-------
Vehicle: 1978 Chevrolet Nova (Continued)
C-. : Protuberance Drag Coefficient
   9
  1 '       Location
  1.  mirror                   A   0.1468 ft2         £A     0.1468 ft2


C_   :  Bullet Mirror Drag Coefficient

	—    Location
  1.  none                     A..      0	


Cn   :  Cooling Drag Coefficient
  ^11
      radiator height    16 in.

      radiator width     26 in.           A    2.889 ft2
                                  C-52

-------
Vehicle:   Manufacturer
General Motors
Make
Model
Model Year
License No/VIN
•ejected Frontal Area, ft
Olds mobile Cutlass
2 -dr. Coupe
1978
Supreme


448 TRW (Calif.)/3R47F8R407693
21.58

D : Front End Drag_ Coefficient
— Location
1. hood-front R
breakline ul
1. center segment R.
of bumper *1
2. outer segment R-
of bumper *2
1. at fender R
2. upper portion R
of bumper V2
3. lower portion R
of bumper V3
: Windshield Drag Coei
— Location
1. roof-windshield R ,
intersection u
2. A-post RV,
3. windshield slope y
0. 0625 in. E
Ul
0. 813 in. E.
1.75 in. Em
0.625 in. E
2. 375 in. E
"2
1.563 in. E
"3
Eficient
3.75 in. E ,
1.938 in. E .
59° A.
'iV
63. 20 in. (R/E) 0.0010
15 in. (R/E), 0. 0242
48 in.
8 in. (R/E) 0.0814
3.5 in.
4 in.
A^ 7.692ft2
46. Sin. (R/E)., 0.0806
14.8 in. (R/E) , 0.1309*
2 $
4.881 ft exceeds max..
                                                          use 0.105
                                  C-53

-------
Vehicle: 1978 Oldsmobile Cutlass Supreme (Continued)
CD : Front Hood Drag Coefficient
•          Location
  1.  front area below windshield        A  11,286ft
  2.  front end area                    Ap  7,692 ft
  3.  hood length                       1^  4.663 ft

C_ : Rear Vertical Edge Drag Coefficient
4
M^MMMMH
1.
2.
3.
!v
i.
2.
3.
Location
body portion R 0.0625 in.
vl
upper portion R 3 in.
of bumper V2
lower portion R 1.875 in.
of bumper V3
Base Region Drag Coefficient
Location
area of base region
area of hatch portion
rear slope from horizontal
Eb
Eb
Eb
b3
"R —
AJJ

9. 25 in. RT
3. 5 in. Eb
3. 5 in. W
H
8.660 ft2
7. 254 ft2
23° 1C.
1. 086 in.
16.25 in.
62.60 in.
41. 52 in.
/Cn 1.14
     :  Underbody Drag Coefficient
  —£-     Location
  1.  underbody length          L   15.233 ft
  2.  underbody width          W   4.716 ft       A ( = LXW)  71.84 ft2
                                  C-54

-------
Vehicle: 1978 Old3mobile Cutlass Supreme  (Continued)
C    :  Protuberance Drag Coefficient
   9
...  -•     Location
   1.  mirrors (one each side)   A    0.2575 ft

   2.  hood ornament           A    0.0091 ft2          LA    0.2666 ft2
                                 P2                        Pj

C_   :  Bullet Mirror Drag Coefficient
   10
.	—    Location
   1.  none
      :  Cooling Drag Coefficient

      radiator height    16 in.
      radiator width    28 in.           A   3.111 ft2
                                    C-55

-------
Vehicle:   Manufacturer     Porsche
          Make             Porsche

          Model
          Model Year
                           924
                           1978
          License No/VIN   Distr.  11976 (Calif.)
Projected Frontal Area, .ft  18. 88

C_  : Front End Drag Coefficient
—      Location
 1.  top edge of
    bumper

 1.  bottom edge of
    front dam

 1.  at bumper
                      R     0.438 in.   EU
R     7.0 in.
                                              54. 9 in.
                                 (R/E)u  0.0080
                            0.063 in.   E.     57,8 in.
                                        ll
                                                       (R/E).,   0.0011
                                               4. 75 in.
                                                       (R/E)..  1. 474
                                                              ^ «•
                                                                     *
                                                       exceeds max, use
                                                       0.105
                                                       Ar  4.633 ft2
J-i.
1.
2.
3.
!v
i.
2.
3.
Location
r oof -wind shie Id
intersection
A-post
windshield slope
from vertical
Front Hood Drag
Location
R , 12 in.
R , 4. 5 in.
y 60°
Coefficient

area of front below windshield
front end area
hood length
E , 44. 0 in.
E , 12. 9 in.
A 4. 1^2 ft
*Vt«r *• A-*** »**
A^ 10. 548 ft2
A^ 4.633 ft2
L, 4. 858 ft
                                                        (R/E)..,   0.273'
                                                             u
                                                        (R/E)v,   0.349'
                                                         exceeds max.
                                                         use 0.105
                                 C-56

-------
Vehicle:  1978 Porsche 924  (Continued)
C,   : Rear Vertical Edge Drag Coefficient
	^      Location
   1.  above tail lights RV      6 in.     Efe     5.12 in.   RV    5.275 in.

   2.  below tail lights  R,,      5.5 in.   E,     5.12 in.   E,   15 in.
                         V2                D2               b
    3. bumper          R,      4.25 in. E,     4.75 in.   W   54.885 in.
                         V- -               Q-    -             ~"
                                                          H   36.6 in.
  C    *  Base Region Drag Coefficient
  __   -      Location
     I. area of base region                A_   7.198 ft2
     2. area of hatch portion               A__   2,627ft2
     3. rear slope from horizontal         0   17.5°	 C   /C     0,76
                                                              DH  DB
   C— : Underbody Dray Coefficient
    ^J /  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*i^m^^*m*^^m*^f***^^
  __   -      Location
     1. underbody length          L   12.287 ft
     2. underbody width          W   4.740 ft        A (= LXW)  58.24 ft2

   C_. :  protuberance Drag Coefficient
  ^.—i      Location
      1.  mirror                  A    0.1455 ft2

      2.  antenna                  A_   0.0436 ft2         £A_    0.1891 ft2
                                   ~__   »w ^ »^ ^ ^»          ^^ * -in.
      v   :  Bullet Mirror Drag Coefficient
      10
             Location
      1.  none                      A,.     0

         :  Cooling Drag Coefficient
         ' radiator height     10.75 in.
         radiator width     20.375  in.       AT  1.5Z1 ft2


                                      C-57

-------
 Vehicle:   Manufacturer     Volkswagen

           Make             Rabbit (Diesel)

          Model            2-dr.  Hatchback

          Model Year       1977 	
          License No/VIN  Distr. 11976 (Calif. )/1773260730
Projected Frontal Area, ft    19.77

C-. :  Front End Drag Coefficient
—     Location
 1.  hood-front
    breakline
                        U
                            0.375 in.   E    52.1 in.    (R/E)   0.0072
                                         U

  1.  bottom of front   R.   0.031 in.   E    44.3 in.    (R/E).  0.0007
      underbody         *1               'l                  *
  1.  at fender
                     RV    1.75 in.    E
                                           13 in.
        ). 1346'
                                                         exceeds max.
                                                         use 0.105
                                                        A    7.188 ft2
D  :  Windshield Drag Coefficient
	     Location

 1.  roof-windshield  R ,   5 in.
    intersection

 2.  A-post
  3.  windshield slope  y
      from vertical
                           51'
C_ :  Front Hood Drag Coefficient
	      Location
  2.  front end area

  3.  hood length
                                        E ,   42. 2 in.
                                         u1   ••
                       R i   2.25 in.     E ,   15.6 in.
                                            5. 415 ft4
  1.  area of front below windshield      A,   10.325 ft
                                      A_   7.188ft*
                                       £ —————
                                            3,093ft
                                                       (R/E)..,  0.1185'
                                                            u
                                                       (R/E)v,  0.1449
'exceeds max.
 use 0.105
                                  C-58

-------
Vehicle: 1977 VW Rabbit(Diesel)  (Continued)
         ,r Vertica
          Location
C_  : Rear Vertical Edge Drag Coefficient
  1.  tail light and     R     0.25 in.    E_     10.25 in.   R     1.462 in.
      body above tail    vl               bi               v	
      light
  2.  body below tail  R     2.625 in.   E.      3 in.      Et   18.25 in.
      light              V2               *>2	   b	
  3.  bottom portion  R     3.25 in.    E.      5 in.      W    50.07 in.
      of body           V3               b3              __    .,  ._ .	
                                                         H    46. 35 in.
CD  :  Base Region Drag Coefficient
   —     Location
  1.  area of base region                A    8.094 ft2
  2.  area of hatch portion              A.,  5.331 ft2
  3.  rear slope from horizontal        0    42°	 Cn  /Cn    1.0

Cn  :  Underbody Drag Coefficient
——      Location
   1.  underbody length          L   10. 867 ft
   2.  underbody width           W    4. 487 ft.       A (= LXW)   48.76 ft2
 C-.  :  Protuberance Drag Coefficient^
   9
 .          Location
   1.  mirror                   A    0.1226 ft2
   2.  antenna                   A    0. 0474 ft2          I A   0.1700 ft2
 C-,  ' Bullet Mirror Drag Coefficient
  jj              -•
 -     Location
   1.  none                     A.,

 C-.   : Cooling Drag Coefficient
  Dll
       radiator height    12 in.
      radiator width     18.75 in.       Ar  1.562 ft2
                                   C-59

-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-460/3-78-010
4. TITLE AND SUBTITLE
Assessment of an Empiric
Vehicle Aerodynamic Drag
meters
2.
al Technique for Estimating
from Vahicle Shape Para-
7. AUTHOR(S)
W. M. Smalley, W. B. L«e
9. PERFORMING ORGANIZATION NAME AND ADDRESS
The Aerospace Corporation
El Segundo, California 90245
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency-
Office of Air and Waste Management
Office of Mobile Source Air Pollution Control
Emission Control Technology Division
3. RECIPIENT'S ACCESSION NO.
S. REPORT DATE
July 1978
6. PERFORMING. ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
AT3.-73(7623-03)-l
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-03-2482
13. TYPE OF REPORT ANO PERIOD COVERED
Final Task Report
14. SPONSORING AGENCY CODE
IS. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents the results of a determination of aerodynamic drag
coefficient, Cp, based on an empirical prediction technique developed by The
Aerospace Corporation Ln a previous EPA-sponsored study. This method utilizes
an aircraft type "drag build-up" approach wherein the total drag is calculated as the
sum of CQ contributions from components of the vehicle. Component contributions
are determined from various body/chassis shape parameters. The present study
was directed toward the acquisition and application of vehicle measurements data
as required to evaluate aerodynamic road load by this prediction method for com-
parison with measured values.
Twenty 1977/1978 model year passenger cars were examined for which
aerodynamic drag coefficients were derived. Comparison of these results with
wind tunnel test data on twelve of the vehicles showed good agreement on an average
basis; the maximum disparity in an individual result was 18 percent.
17.
a. DESCRIPTORS
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED TERMS
Aerodynamic Drag
Motor Vehicles
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report/
Unclassified
20. SECURITY CLASS (This page>
Unclassified

c. COSATi Field/Croup
13F
21. NO. OF PAGES
106
22. PRICE
EPA Form 2220-1 (9-73)

-------
                                                        INSTRUCTIONS

   1.   REPORT NUMBER
        Insert the EPA report number as it appears on the cover of the publication.

   2.   LEAVE BLANK

   3.   RECIPIENTS ACCESSION NUMBER
        Reserved for use by each report recipient.
        Title should indicate clearly and briefly the subject coverage of the report, and be displayed prominently. Set subtitle, if used, in smallei
        type or otherwise subordinate it to main title, when a report is prepared in more than one volume, repeat the primary title, add volume
        number and include subtitle for the specific title.

   8.   REPORT DATE
        Each report shall carry a date indicating at least month and year. Indicate the bash on which it was selected (tjg., date of issue, date of
        approve!, date of preparation, etc.).

   6.   PERFORMING ORGANIZATION CODE
        Leave blank.

   7.   AUTHORIS)
        Give name(s)  in conventional order (John R. Doe. J. Robert Doe, etc.).  List author's affiliation if it differs from the performing organi-
        zation.

   8.   PERFORMING ORGANIZATION REPORT NUMBER
        Insert if performing organization wishes to assign this number.

   9.   PERFORMING ORGANIZATION NAME AND ADDRESS
        Give name, street, city, state, and ZIP code. List no more than two levels of an organizational hirearchy.

   10.  PROGRAM ELEMENT NUMBER
        Use the program element number under which the report was prepared. Subordinate numbers may be included in parentheses.

   11.  CONTRACT/GRANT NUMBER
        Insert contract or grant number under which report was prepared.

   12.  SPONSORING AGENCY NAME AND ADDRESS
        Include ZIP code.

   IX  TYPE OF REPORT AND PERIOD COVERED
        Indicate interim final, etc., and if applicable, dates covered.

   14.  SPONSORING AGENCY CODE
        Leave blank.

   15.  SUPPLEMENTARY NOTES
        Enter information not included elsewhere but useful, such as:  Prepared in cooperation with. Translation of. Presented at conference of,
        To be published in. Supersedes, Supplements, etc.

   16.  ABSTRACT
        Include a brief (200 words or lea) factual summary of the most significant information contained in the report. If the report contains a
        significant bibliography or literature survey, mention it here.

   17.  KEY WORDS AND DOCUMENT ANALYSIS
        
-------