Preliminary Wind Tunnel Tests on the Influence of Ground Board Length on the Aerodynamic Drag of Simple Commercial Vehicle Models

SEP 1986 Cranf ield

College of Aeronautics Report No. 8619

June,1986

DELFT

'ECHNIEK

BIBLtOTHEEK

KJuyverweg 1 -

O Ë U T

Preliminary Wind Tunnel Tests on the Influence

of Ground Board Length on the Aerodynamic Drag

of Simple Commercial Vehicle Modeis

by K P Garry

College of Aeronautics

Cranfield Institute of Technology

Cranfield, Bedford MK43 OAL, England

Cranfield

College of Aeronautics Report No. 8619

June.1986

Preliminary Wind Tunnel Tests on the Influence

of Ground Board Length on the Aerodynamic Drag

of Simple Commercial Vehicle Models

by K P Garry

College of Aeronautics

Cranfield Institute of Technology

Cranfield, Bedford MK43 OAL, England

ISBN 0 947767 47 9

£7.50

"The views expressed herein are those of the authors alone and do not necessarily represent those of the Institute."

.^^^iüë^^

Cranfield

CONTENTS

SUMMARY

NOTATION

LIST OF FIGURES

1. INTRODUCTION

2. EXPERIMENTAL TECHNIQUE

2.1 Wind Tunnel Models

2.2 Wind Tunnel Balance

2.3 Wind Tunnel Facility

3. TEST PROGRAMME

4. RESULTS

4.1 Influence of ground board length changes for models a

zero yaw

4.2 Influence of ground board length on streamlining

4.3 Influence of ground board length changes with model

at yaw.

5. DISCUSSION OF RESULTS

6. CONCLUSIONS

7. RECOMMENDATIONS FOR FURTHER WORK

8. REFERENCES

9. ACKNOWLEDGEMENTS

TABLES

FIGURES

1

-SUMMARY

Preliminary results are presented following a series of tests in a

closed working section, open return wind tunnel on eight simple rectangular

block models mounted above a full span ground board.

Measurements of body axis drag, si deforce and yawing moment were made on

each vehicle in the yaw angle range -6 to +20 degrees. The ground board is

fitted with removable sections such that its overall length, and consequently,

the position of its trailing edge downstream of the model base, can be varied.

Tests were carried out with ground board trailing edge positions in the range

3.2w to 0.25w downstream, where w is the width of the body under test:

Variations in drag coefficient are considered with respect to changes

in model geometry, yaw angle and ground board length. Changes in Cj. (relative

to that measured for the largest ground board case) in the order of 5% were

recorded and indications of the susceptability of various model geometries,

to ground board length observed.

Explanations of the influence of ground board length on the flowfield

and the mechanisms involved are limited by the data available from these

simple tests. It is however apparent that ground board length can have a

considerable effect on measured aerodynamic drag and recommendations are made

for further tests.

-

11

-NOTATION

D Drag force (N)

Y Side force (N)

N Yawing moment (Nm)

Cy Side force coefficient

C». Yawing moment coefficient

C[j Drag coefficient

suffixes

used:-(x/w) streamwise location of ground board

trailing edge in terms of model width

(x/w) largest possible separation of ground

board trailing edge and model. Usually

the ground board case taken as reference

for other measurements

B yaw angle

ACp difference between two specified drag coefficients

V flow velocity (m/s)

X streamwise coordinate, refers to the position of the ground board

trailing edge measured relative to the model base at zero yaw (m)

w model width (m)

$ yaw angle relative to the freestream (degrees)

Model dimensions (see figure 1 ) :

-1 rear body length

k front body (cab) length

d front body (cab) width

w rear body width

h front body height

s front - rear body separation

g rear body height

R, rear body leading edge radii (vertical, side, and top edges only)

R» front body leading edge radii (vertical, side, and top edges only)

Rj rear body rear edge radii (vertical, side, and top edges only)

c rear body ground clearance

I l l

-LIST OF FIGURES

1. Characteristic dimensions and layout of wind tunnel models

2. Schematic layout of instrumentation and data recording system

3. Force and Moment sign convention

4. 'Donnington' 0.9 m x 0.9 m wind tunnel

5. Working section model and ground board arrangement

6. Variation of drag coefficient (C^) with ground board length at

zero yaw models A, B, C and F

7. Variation of drag coefficient (Cp) with ground board length at

zero yaw models X, Y, W and V

8. Variation of Cr. with (x/w) at zero yaw. Influence of overall model

length, models B and Y

9. Variation of C^ with (x/w) at zero yaw. Influence of cab geometry,

models C, F and W

10. Variation of Cp with (x/w) at zero yaw. Influence of cab plus container

layout, models V and X

11. Variation of changes in drag coefficient due to streamlining with ground

board l e n g t h . [ ( C p - Cp )/C^ ]

Easeline sfream baseline

12. Variation of changes in drag coefficient due to streamlining with ground

board length. [(C^ - Cp ) /(C^ " ^p ) ]

basëine stream [x/vt] baseline stream /^x/w'^^

möx

13. Influence of yaw angle on drag coefficient for each of the models tested

^^ (^/^^max

14. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model A

15. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model B

16. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model C

17. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model F

18. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model V

19. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model W

20. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model X

21. Variation of Cp with (x/w) at 0, 19 and 20 degrees yaw. Model Y

22. Base drag as a proportion of total drag for a typical rigid cab container

model (reproduced from Ref. 2 ) .

23. Pressure variation on the rear of a blunt base rectangular block with

changes in ground clerance (reproduced from Maull, ref (3))

j

WORKING SECTION SHOWING MODEL AND GROUND BOARD INSTALLATION

(looking downwind)

1

-1. INTRODUCTION

The majority of wind tunnel tests involving surface vehicles necessitate

the use of some form of ground simulation. Various techniques have been

employed depending on (1) the vehicle type, particularly its ground clearance

(2) the type of wind tunnel available for the test, and (3) the forces/moments

required to be measured.

In the case of commercial vehicles, the most common technique used to

date has been to mount the model above a fixed ground plane effectively dividing

the working section into two parts. The 'new' boundary layer which develops

downstream of the ground plane leading edge is usually considerably thinner

than that on the working section walls at a corresponding position, and

consequently its effect on the flowfield around the model less significant.

Understandably, the division of the wind tunnel working section in this

way can have a considerable effect on its flow characteristics, particularly

if a large model is under test. In order to 'balance' the flow above and

below the ground board a trailing edge flap is sometimes fitted and adjusted to

ensure zero circulation within the working section. Such an arrangement requires

readjustment if, for example, the model is yawed relative to the freestream

-increasing the effective frontal area. As the majority of wind tunnel tests on

commercial vehicles require measurements over a range of simulated crosswind

conditions, continuous adjustment of this trailing edge flap is necessary and

can be very time consuming. In practice the ground board is often set at a

height such that the flow above and below is balanced, for some 'mean' model

position, without the use of a flap.

Another feature of this type of wind tunnel test is the influence of the

model's position, (relative to the ground board's leading and trailing edges)

on the measured forces and moments. Very little is known of the significance

of ground plane behind the model and it is this aspect of the experimental

arrangement with which this note is concerned.

It is assumed that when using a ground board the model is positioned

such that its longitudinal centre line lies along the centre line of the ground

board, and at a suitable distance downstream of the leading edge to ensure

that the ground plane boundary layer thickness is small relative to the model's

ground clearance.

2

-The test programme reported here is therefore based on a variety of

simple rectangular box models mounted at a fixed ground clearance above a

full span ground board, the length of which can be varied by removing sections

behind the model position. The ground board is not fitted with a flap and no

attempt is made to balance the working section flowfield at this stage.

3

-2. EXPERIMENTAL TECHNIQUE

2.1 Wind Tunnel Models

The eight different models used for this programme were made from a

series of simple rectangular blocks, arranged so as to simulate commercial

vehicle type configurations. Each module has provision for the leading/

trailing edges to be changed thus enabling various 'streamlined' and 'sharp

edged' configurations to be tested. Details of the models tested, together

with the model 'codes' are given in Table (1) and Figure (1). All the model

sections are manufactured from expanded polystyrene and balsa wood to keep

them as light as possible due to force balance requirements (see section 2.2)

and finished to give a smooth upper and underbody surface.

2.2 Wind Tunnel Balance

The 3 component strain gauge balance was designed for the dynamic tests

outlined by the author in Ref. (1). It consists of 4 strain gauged supports

which link the internal frame of the model to a rotating turntable. Signals

from the four supports are fed via amplifiers to a mixing unit which outputs

analogue signals corresponding to body axis Drag, Sideforce and Yawing Moment,

see Figures (2) and (3).

Signals from the output unit are fed via a 12 bit analogue to digital

converter to a Commodore PET microcomputer and subsequently stored on magnetic

disc for analysis. Each channel is sampled at a rate of 10 samples/sec for 4

seconds and a mean output computed for analysis.

2.3 Wind Tunnel Facility

The facility used for this programme was the 3 ft x 3 ft (0.91 m x 0.91 m)

closed working section, open return 'Donnington' wind tunnel in the Aerodynamics

Dept., CoA, see Figure (4). The 0.022 m thick ground board is positioned 0.175 m

above the working sectin floor. A 360 degree rotating turntable is let into

the ground board flush with the upper and lower surfaces, driven from a stepper

motor/gearbox system beneath the wind tunnel, the drive to which is shrouded

by a 0.150 cylinder. Turntable position and movement is controlled and monitored

by the microcomputer.

The wind tunnel working section is 2.4 metres long with corner fillets

varying in depth from 0.15 to zero over that length. Working section flow velocity

is monitored by the pressure difference between two static wall tapping rings at

the mouth of the working section and in the setting chamber - this pressure

difference having previously been calibrated against that of a pi tot-static tube

mounted at the model's longitudinal centre line.

4

-3. TEST PROGRAMME

A total of eight model configurations were used, coded A, B, X and Y

for single rectangular box shapes and C, F, W and V for simple cab plus

container arrangements. Details of each model geometry is given in Table (1).

The ground board length is adjustable by means of seven removable sections

such that the trailing edge position can be varied, relative to the model

position, which is fixed. The ground board configuration is expressed as the

distance of the trailing edge downstream of the model base at zero yaw (x)

non dimensionalised by the model width (w, = a constant for all the models

in this sequence of tests). Values of (x/w) in the range 0.250 to 3.211 are

attainable with the present ground board arrangement. The position of the

ground board leading edge relative to the model remained fixed for this series

of tests.

All tests were carried out at the same working section flow velocity,

nominally 20 m/sec, giving Reynolds numbers of 0.485 x 10 , based on the

square root of the model projected frontal area (A). Measurements were made

of body axis drag, sideforce and yawing moment (see sign convention in figure

(3)), in the yaw angle range -6 to +20 degrees.

Each model was tested at each of the nine ground board lengths attainable.

This involved a total of 11 tests per model, beginning at (x/w) through

to (x/w) . followed by two repeat tests at (x/w)„,„.

m m max

The test sequence itself was intended to minimise hysteresis effects

as

follows:-(i) zero yaw; wind off balance data

(ii) zero yaw; wind on balance data

(iii) yaw model to -8 degrees

(iv) yaw model to -6 degrees, wind on data

progressively in 2 degree steps to +20 degrees

(v) yaw model to zero yaw wind on data

5

-4. RESULTS

Analysis of the force and moment measurements is restricted at this stage

to variations in drag coefficient (Cp), for each of the models tested.

4.1 Influence of ground board length changes for models at zero yaw

The variation of C^ with ground board length for each model is given

in Figure 6 (-models A,B,C and F) and Figure 7 (-models V,W,X and Y ) . In

order to simplify analysis, changes in drag coefficient (AC^) are expressed

relative to the Cp. measured at maximum ground board length

[Cn(x/w)^aj,]-Significant variations in Cr. are apparent throughout the range of

ground board trailing edge positions that were tested. The general trend is

for drag coefficients to rise as the ground board is shortened, reaching a

peak when the trailing edge is between 1.50 and 0.75 body widths downstream,

followed by a sharp drag reduction as the trailing edge approaches the model

base. Maximum increases in C^ of 4.5% were recorded for models and V and X.

Within the limitations of this experiment it would appear that;

(i) changes in drag coefficient are independant of overall model length,

see figure (8) for simple rectangular box models and figure (9) for cab

plus container configurations.

(ii) the magnitude of the maximum variation in drag coefficient (AC-,) is

u max

dependant on model base geometry.

(iii) the ground board length for which ACp. occurs is dependant on model

base geometry.

4.2 Influence of ground board length on streamlining

In order to assess the likely influence of ground board length on

measurements aimed at streamlining certain models, data from seven of the

models tested was used to study changes in drag coefficient due to geometry

changes with ground board length.

The models chosen were taken in 4 pairs, one so called 'streamlined'

configuration the other a 'baseline' configuration as in the table overleaf.

Differences in Cp between baseline and streamline models at each ground

board position are presented as a fraction of the baseline model C^, in

figure (11).

6

-Baseline Model Streamlined Model

A - B

Y - X

C - F

C - V

Modification

radiusing front side

and upper leading edges.

boattailing a

stream-lined simple rectangular

box model.

radiusing the leading

edges of a cab plus

container model.

the addition of a

boattail to a sharp

edged cab plus container

model.

It can be seen from figure (11) that streamlining the front leading

edges of these simple models leads to the most significant reductions in

baseline drag coefficient (37% to 42%) compared to rear edge radiusing,

boattailing (-1% to 3 % ) .

Variations in the measured drag reductions with ground board length

appear very small and only really apparent for the two model combinations

that involve base radiusing; (i) model C - model V and (ii) model Y - model X.

This influence is emphasised by expressing the difference in drag coefficient

measured at each ground board length as a proportion of the difference

measured at the maximum ground board length (x/w)„^^; see figure (12). This

would appear to confirm the intuitive result that changes to models involving

variations in base geometry are most susceptible to changes in the relative

positions of ground board trailing edge and model base.

4.3 Influence of ground board length changes with model at yaw

Model tests were carried out at 14 yaw angles - over the range -6 to

+20 degrees at 2 degree increments - and for each ground board length.

In order to examine the basic characteristics of each model at yaw, the

variation of drag coefficient (C^) with yaw angle (0), normalised with respect

to C^ at 6 = 0°, is plotted versus yaw angle, for the (x/w)^^^ ground board

case, in Figure (13). It is clear that the models fall into four distinct

characteristics: 7 characteristics:

-(a) Models F,W : streamlined cab plus container.

(b) Models C,V : sharp leading edge cab plus container.

(c) Models B,X,Y : streamlined single box models.

(d) Model A : sharp leading edge single box model.

The rapid increases in drag coefficient with increasing yaw angle are

associated with flow separation from the leeward leading edges of the model,

see Ref. (2), and it would appear that changes in base geometry, i.e. boattailing

have relatively little effect in comparison. On this basis it is considered

exceptable to simplify the analysis of changes in ground board length and yaw

angle by considering the data obtained for 0, +10 and +20 degree yaw cases only.

The variation of drag coefficient versus ground board length (x/w) for each

model at each of these three yaw angles is given in Figures (14) to (21). The

following observations are apparent;

(i) the magnitude of reductions in drag coefficient relative to the (x/w)

case, increase with increasing yaw angle, particularly for shorter

ground boards; (x/w) < 1.0.

(ii) the value of (x/w) for which AC^ is a maximum is not so apparent at

larger yaw angles, at 20 degrees yaw for example, reducing ground board

length results in a progressively larger drag reduction for each model

configuration tested.

(iii) the influence of yaw angle on the susceptability of the model to changes

in ground board length, is dependant on model geometry as outlined in the

following table.

1 MODEL CODE

1 A,C

and V

1 B.X

and Y

F and VV

INFLUENCE OF YAW ANGLE (B)

Changes in the ACp vs. (x/w)

curve for both 10 and 20 degrees

yaw: Figures (14), (16) and (18)

ACp) vs (x/w) curves appear

siffiilar at 0° and 10° but change

at 20° yaw. Figures (15). (20)

and (21)

No change in the ACp vs. (x/w)

plots with changes in yaw angle.

Figures (17) and (19)

MODEL 'GROUP' 1

Sharp leading edge

cab plus container

and single box layout

Streamlined leading

edge single box

layout

Streamlined leading

edge cab plus

container layout

The model 'groups' defined in the above table closely resemble the groups

identified when analysing the C^ vs. 6 data discussed earlier in this section.

This appears to confirm the intuitive result that the influence of ground

board length coupled with changes in yaw angle is dependant on model geometry

according to the onset of flow separation. For the simple models under

8

-consideration here this suggests that the susceptability of drag

coefficient to ground board length is dependant on the size of the vehicle's

wake.

9

-5. DISCUSSION OF RESULTS

In general terms, the results presented in the previous section

illustrate that changes of drag coefficient in the order of 5% are attributable

to variations in the position of ground board trailing edge relative to the

rear of a simple bluff vehicle model. More significantly this variation in

drag changes sign - initially a drag increase as the ground board is shortened,

reaching a peak when the trailing edge is approximately one body width downstream

of the model, followed by a sharp fall off in drag eventually giving overall

drag reductions with the trailing edge half a body width (w) downstream. Both

model geometry and yaw angle (B) are seen to influence these effects.

It is expected that these changes in drag are as a result of variations

in base pressure. It has been shown that the base drag of a Volvo F88 rigid

chassis vehicle fitted with a container the same height as the cab is

approximately 20% of the total drag, see figure (22). Consequently a 3% change

in total drag as a result solely of a change in base drag means a 15% variation

in base pressure. Such a change would require a significant modification to

the flowfield.

It has been shown by Maull(3) and others that for blunt trailing edge

models, moving the body nearer to the ground produces an increase in pressure

near the top of the base (reduced base drag) compared to the out of ground

effect case, see Figure (23). If we assume that reducing the ground board

length (i.e. moving the ground board trailing edge nearer the model base) is

^ analogous to moving the model further away from the ground then this would

confirm the results which suggest large reductions in overall drag at values

of (x/w) < 0.75, i.e. shorter than 3/4 of the body width downstream of the

model. These results however do not explain the increases in drag coefficient

which are apparent at ground board lengths in the region 0,75 < (x/w) < 1.50.

Clearly the wake flow itself is very complex and the fact that there appears

to be an

opt-irmm

ground board trailing edge position for

maximum drag inarease,

supports the 2D concept of a "vortex formation region" put forward by Bearman

(4). This may also explain the effect 'boattailing' has on both (i) the

magnitude of the change in drag coefficient and (ii) the relative position of

ground board trailing edge for maximum influence, since it is assumed that

changing the base shape of the body would vary the position of the vortex

formation region.

10

-The situation for the yawed model tests is likely to be even more

complex. Whether the changing influence of ground board length with yaw

angle can be explained in terms of wake structure or simply in terms of

wake size is unclear. It is apparent that the vehicle's forebody geometry

has a significant influence on the results at yaw and Cowperthwaite (5)

has shown that forebody shape significantly effects the intensity of vortices

entrained into the wake region from upstream leading edges. If the position

of such vortices were affected by ground board length then corresponding

variations in base pressure would be possible.

It is difficult to interpret the results from this series of simple

tests without recourse to further analysis of the flow. In particular

(i) model base pressures, (ii) wake size and (iii) ground board surface

pressures would be of interest and a further test programme is in preparation.

It has been assumed throughout the analysis that changes in ground

board length have no significant effect on the flow characteristics of the

wind tunnel working section itself. This assumption is based on a series of

checks on the model centre line velocity calibration and flow angularity

for the range of ground board lengths of interest, during which no measurable

variation was found. However, these tests were by necessity carried out on the

empty wind tunnel and no measurements are available of the flow characteristics

with the models in place. It is possible, particularly as no ground board

trailing edge flap was used, that the flow characteristics above and below the

ground plane are altered by varying the ground board length. It is thought

unlikely that any changes of this type would account for the variations in drag

that were observed although no experimental evidence is available in support

of this and such considerations warrant further investigation.

11

-6. CONCLUSIONS

Significant variations in drag coefficient are apparent with changes in

ground board length for the simple block models considered. The general trend

is for Cp. to rise as the ground board is shortened, reaching a peak when the

trailing edge is approximately one body width downstream of the model base.

Thereafter, the drag falls off rapidly resulting in overall drag reductions

for ground board trailing edge positions very close to the model.

This 'peak' in C^ is only really apparent at zero freestream yaw.

If the model is rotated to simulate crosswind conditions then the overall

effect of shortening the ground board is to progressively reduce the drag

coefficient.

The susceptability of a particular model to ground board length changes

is primarily depednent on base geometry i.e. boattailing. At yaw however,

forebody shape dominates the overall flowfield and consequently the influence

of ground board length.

12

-7. RECOMMENDATIONS FOR FURTHER WORK

It would appear that these effects warrant further investigation,

particularly with a view to isolating the flowfield changes that are

induced by ground board variations. For simple bluff models of this type,

base pressure measurments linked with wake size and ground board surface

pressures, would aid analysis and further tests are planned.

It is also important to understand, and isolate, secondary effects

such as changes in the working section flowfield induced by alterations to

the length of the ground board - a trailing edge flap, to balance the upper

and lower section flow, should be considered.

13

-REFERENCES

1. K.P. GARRY

Comparison of quasi-static and dynamic wind tunnel measurements on

simplified tractor-trailer models.

Proc. 6th Colloquium on Industrial Aerodynamics, Aachen, F.D.R. June 1985

Eds: C. Kramer H.J. Gerhardt

2. K.P. GARRY

Wind tunnel techniques for reducing commercial vehicle aerodynamic

drag.

PhD Thesis Cranfield, College of Aeronautics, September 1982

3. D.J. MAULL

Mechanisms of two and three-dimensional base drag.

'Aerodynamic drag mechanisms of bluff bodies and road vehicles'.

Ed. Sorran, Morel, Mason Jr. G.M. Research Lab, Michigan, September 1976.

Plenum Press 1978.

4. P.W. BEARMAN

Flow behind a two-dimensional model f i t t e d w i t h s p l i t t e r p l a t e s .

Jn. F l u i d Mech. V o l : 21 p t . 2 pp 241-255 1965

5. N.A. COWPERTHWAITE

Aero. Dept., College of Aeronautics, Cranfield.

Private communication

14

-ACKNOWLEDGEMENTS

Financial support for the manufacture of both the wind tunnel balance

and models was provided by the Science and Engineering Research Council (S.E.R.C.)

under agreement GR/B9468.7

The author would like to thank Mr Alan Taylor for his assistance

during the wind tunnel tests whilst on a temporary appointment with the

College of Aeronautics.

Table 1

Characteristic dimensions of wind tunnel models

MODEL CODE

A

B

C

F

V

W

X

Y

Rear Module

Front Module

h

0

0.167

0

0

0

0

0.167

0.167

«2

-0

0.167

0

0.167

-h

0

0

0

0

0.167

0

0.167

0

h

-1.167

1.167

1.167

1.167

-s

-0.250

0.250

0.250

0.250

-1 -1

2.220

2.220

2.220

2.220

2.550

2.550

2.550

2.550

All dimensions in terms of the rear body width (w) = 0.142 m

front body width (d) = 1.000 w

rear module height (g) = 1.167 w

front body length (k) = 0.330 w

ground clearance (c) = 0.167 w

( ^

y^

// y ^^ y /// / ////

A

Axis of Rotation

1

FIGURE 1

CHARACTERISTIC DIMENSIONS AND LAYOUT OF WIND TUNNEL

MODELS.

Wind tunnel

balance

Strain guage

amplifiers

Flow velocity

pressure transducer

Turntable

position indicator

Tlimtrihla rlr'h/o neeomhixt

•"

Signal conditioning

unit

L

Transient

recorder

Microcomputer

1

'

>/r cfjfjci IIVIVI 1 . m II1 V . / 1 1 ( 9

J

FIGURE 2

D -^

0.167 m.

>

^

Y

FIGURE 3.

Settting chamber

Semi circular lipped

intake

\

Motor and fan

assemt>ly

FIGURE 4

Groundboard

Flow Velocity (V)

lOf^

0 7

^

_{Turntable Drive}

Assembly

\

FIGURE 5

5 . 0

^

o^

I

Ö

^

0 0.5 1.0 1.5 2 . 0 2 . 5 3.0 3 . 5

FIGURE 6.

o MODEL X

o MODEL Y

V MODEL W

4- MODEL V

0 0 . 5 1.0 1.5 2 . 0 2 . 5 3 . 0 3 . 5

FIGURE 7

5 . 0

'S'

n MODEL B

o MODEL Y

-3.0-1

0 0 . 5 1.0 1.5 2 . 0

FIGURE 8

VARIATION OF CD WITH (X/W) AT ZERO YAW

2 . 5

3 . 0

3 . 5

5 . 0

4 . 0

[-3.0

2 . 0

O MODEL C

X MODEL F

V MODEL W

- 3 . 0

0 0 . 5 1.0 1.5 2 . 0

FIGURE.9

VARIATION OF CD WITH (X/W) AT ZERO YAW

2 . 5

3.0

3 . 5

g

6

5

^

JS

^

^

4- MODEL V

o MODEL X

- 3 . 0

FIGURE 10

VARIATION OF CD WITH (X/W) AT ZERO YAW

2 . 5 3.0 3 . 5

0.50n

0.40

-0.30

"5

> 0.20

.vS^

^

0.10

0

-0.1IÏ

A

•

A

_A

•

A

•

A

A

•

A

A

•

A

•

MODEL ( BASELI^E

A A - B

• Y - X

• C - F

• C - V

- STREAMLINED )

J I I L

J I I i 1 I I I I I L

0 0.4 0.8 L2

'/w

L6 2.0 2.4 2.8

3.2 3.6

FIGURE 11

MODEL ( BASELINE

A A - B

• Y - X

• C - F

• C - V

- STREAMLINED )

1.0 1.5 2.0 2.5 3.0 3.5 4.0

X/.

FIGURE 12 ^^

2.0

0.&

MODEL CODE

A A

oW

• X

O V

vB

+ C

xF

Y

(x,) maximum

±

- 6 - 4 - 2 0 2 4 6

Yaw angle (degrees)

8

10

12

14

16

18

20

FIGURE 13(A)

0^e-| I I I I I I I I ' ' I ' - I

- 6 - 4 - 2 0 2 4 6 8 10 12 14 16 18 20

Yaw angle (degrees)

FIGURE 13(B)

^

o^

I

MODEL A

A 0 DEG

• 10 DEG

o 20 DEG

0

0.5

L0

L5

2.0

2.5

3.0

3.5

4.0

FIGURE 14

^

o^

6

4

2

0

-2

-4

6

-—

1

^

^

1

r?^

1

MODEL B

A 0 DEG

• 10 DEG

o 20 DEG

^

^

^

>

"

^

1

^

fw

1 1

0

0.5

L0

1.5

2.0

2.5

3.0

3.5

4.0

FIGURE 15

4

-MODEL C

A 0 DEG

• 10 DEG

o 2 0 DEG

^

o^

C3

0

-2

-4

V^,

0

0.5

1.0

L5

2.0

2.5

3.0

3.5

4.0

FIGURE 16

4

0

-2

-4

0

0.5

1.0

MODEL F

A 0 DEG

• 10 DEG

o 2 0 DE

1.5

2.0

2.5

^ /

w

3.0

3.5

4.0

FIGURE 17

1

MODEL V

A 0 DEG

• 10 DEG

o 20 DEG

FIGURE 18

6

r-^

^

"^

0

-2

-4

0

0.5

1.0

MODEL W

A 0 DEG

• 10 DEG

o 2 0 DEG

1.5

2.0

2.5

J L

3.0

3.5

4.0

FIGURE 19

^

o^

o

FIGURE 20

er*

^

- ^

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

FIGURE 21

i5

5

6^

81

FIGURE 22.

BASE DRAG AS A PROPORTION OF TOTAL DRAG FOR A TYPICAL

CAB * CONTAINER MODEL.

0.1

ACp

0.05

•0.05

0.1 L

^T^;

clg = 0

y/g

FIGURE 23.

PRESSURE VARIATION ON THE REAR OF A BLUNT BASE

RECTANGULAR BLOCK WITH CHANGES IN GROUND CLEARANCE

Model A

MODEL R

GROUND BORRD LENGTH<METRES)» 1 . 3 6

DftTfl FILE fl/8/'3

VfiW nNGLE<DEG> DRAG

- 6.0 - 4.e - 2.9 • .e • 2.e • 4.0 • 6.0 * 8.0 • 10.0 •f12.0 •f14.0 + 16.0 + 18.0 •20.0 r.OEFF.<CD> 0.915 0.895 0.876 0.875 0.888 8.904 0.92<» 0.957 0.988 1.015 1.031 1.046 1.050 1.056 SIDEFORCE COEFF.<CV) -0.353 -«.258 -0.116 +0.009 +0.163 +0.265 +0.371 +«.472 *ö» Oo€ +0.678 +0.786 +0.887 +1.005 +1.120 \ VflHING MOMENT COEFF.<CN> +0.230 +0.164 +0.062 -0.023 -O.128 -«.212 -0.246 -0.254 -0.229 -0.192 -0.149 -0.099 -0.056 -0.012 MODEL n

GROUND BOf«D LENGTH<METRES>• 1.31

•R FILE fl/7/'3 1 RNGLECDEG) DRHG - 6.0 - 4.0 - 2.0 + .0 • 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 • 14.0 + 16.0 + 18.0 •20.0 COEFF.<CD> 0.914 0.896 0.874 0.875 0.886 0.904 0.933 0.959 0.987 1.015 1.035 1.043 1.033 1.054 SIDEFORCE COEFF.CCV> -0.347 -0,248 -0.125 •o.oie +0.158 +0.267 +0.372 +0.469 +0.568 +0.674 +0.789 +«.891 +1.O0O +1.118 VflWING MOMENT COEFF.<CN> +0.219 +«.159 +«.063 -0.824 -0.139 -0.203 -0.253 -0.249 -0.227 -0.191 -e. 143 -0.098 -0.057 -0.009 MODEL R

GROUND BORRD LENGTH<METRES)- 1.26

DRTfl FILE fl/6/3 VflW HNOLE<DEG> - 6.0 - 4.0 - 2.0 + .0 • 2.0 + 4.0 + 6.0 + 8.0 • 10.0 • 12.0 • 14.0 • 16.0 +18.0 •20.0 DRRG COEFF.CCD> 0.921 0.902 0.881 0.878 0.892 0.910 0.931 0.967 0.994 1.019 1.033 1.045 1.035 1.062 SIDEFORCE COEFF.<CV) -0.353 -0.249 -0.117 +0.021 +0.159 +0.261 +0.380 +0.477 +0.575 +0.677 +0.784 +0.900 +1.013 +1.122 VRMING MOMENT COEFF.<CN> +0.220 +0.161 +0.062 -0.027 -0.131 -0.210 -0.247 -0.255 -0.235 -0.192 -0.146 -0.097 -0.056 -0.014

Model A

MODEL R

GROUND BORRD LENGTH<METRES)" 1.21

DRTR FILE

_n/^/-3

o.9ei

GROUND BORRD LENGTHCMETRES)» 1.16 DRTfl FILE fl/4/3 VflU nNGLE<DEG) - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 +12.0 + 14.0 + 16.0 + 18.0 +20.0 DRHG COEFF.<CD) 0.924 0.907 0.884 0.882 0.893 0.912 0.937 0.966 0.996 1.024 1.039 1.030 1.060 1.061 SIDEFORCE COEFF.<CV) -0.363 -0.245 -0.124 +0.021 +0.164 +0.274 +0.372 +0.473 +0.572 +0.687 +0.791 +0.900 +1.007 +1.129 VflWING MOMENT COEFF.<CN) +0.217 +0.159 +0.070 -0.036 -0.129 -0.199 -0.246 -0.251 -0.231 -0.187 -0.144 -0.095 -0.054 -0.010 MODEL fl

GROUND BOBRO LENGTH<METRES)- 1.11

DRTR FILE H/S/'S VRW RNGLE<DEG) - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 • 16.0 • 18.0 •20.0 ORRG COEFF.<CD) 0.922 0.906 0.889 0.886 0.898 0.916 0.937 0.965 0.994 1.014 1.033 1.044 1.057 1.058 SIDEFORCE COEFF.<CV) -0.363 -0.247 -0.129 +0.010 +0.163 +0.267 +0.381 •0.470 +0.562 +0.676 +0.788 •0.898 +1.009 +1.131 VflWING MOMENT COEFF.<CN> +0.219 +0.150 +0.063 -0.026 -0.139 -0.203 -0.246 -0.253 -0.225 -O.191 -0.144 -0.100 -0.055 -O.015

Model A

MODEL R

GROUND BORRD LENGTHCMETRES)» 1.06

DRTfl FILE fl/2/3 VflW ANGLECDEG) - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 DRRG COEFF.<CD) 0.923 0.907 0.893 0.891 0.899 0.916 0.933 0.964 0.988 1.009 1.027 1.038 1.052 1.052 SIDEFORCE COEFF.<CV) -0.357 -0.249 -0.125 +0.011 +0.163 +0.269 +0.370 +0.468 +0.563 +0.673 +0.778 +«.893 •1.003 +1.116 VflWING MOMENT COEFF.<CN) +0.216 +0.156 +0.066 -0.033 -0.132 -0.208 -0.244 - -0.246 -0.226 -0.191 -0.143 -0.098 -0.055 -0.012 MODEL R

GROUND BORRD LENGTH<METRES)» 1.01

DRTR FILE VflW flNGLE< - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 • 16.0 • 18.0 •20.0 fl/1/3 OEG) DRAG COEFF.<CD) 0.917 0.902 0.885 0.881 0.892 0.909 0.925 0.949 0.980 1.000 1.015 1.024 1.031 1.032 SIDEFORCE COEFF.<CV) -0.357 -0.252 -0.128 +0.015 +0.154 +0.262 +0.361 +0.462 +0.559 +0.665 +0.767 +«.877 +0.984 +1.098 VflWING MOMENT COEFF.<CN) •0.211 +0.158 +0.070 -0.028 -0.129 -0.212 -0.246 -0.255 -0.233 -0.198 -0.153 -0.102 -0.061 -0.022 MODEL fl

GROUND BORRD LENGTH<METRES)» .96

DRTfl FILE 0/0/3 VflW flNGLE(DEG) - 6.0 - 4.0 - 2.0 • .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 • 16.0 +18.0 +20.0 DRAG COEFF.<C0) 0.897 0.887 0.868 0.858 0.875 0.893 0.907 0.930 0.954 0.974 0.986 0.991 0.996 0.996 SIDEFORCE COEFF.<CV) -0.343 -0.249 -0.125 +0.013 +0.162 +0.261 +0.348 +0.438 +«.531 +0.631 +0.734 +0.846 +0.963 +1.074 VflWING MOMENT COEFF.<CN) +0.215 +0.173 +0.076 -0.022 -0.135 -0.200 -0.244 -0.252 -0.240 -0.204 -0.160 -0.114 -0.070 -0.028

Model B

MODEL B

GROUND BOflRD LENGTHCMETRES)' 1.36

DflTR FILE B/8/3 VflW flNGLE<DEG) DRflG - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 COEFF.<CO) 0.563 0.545 0.526 0.507 0.522 0.544 0.560 0.581 0.607 0.639 0.662 0.683 0.695 0.704 SIDEFORCE COEFF.<CV) -O. 379 -0.270 -0.145 +0.009 +0.159 +0.294 +0.430 +0.565 +0.705 +0.851 +0.985 +1.101 +1.216 +1.322 VflWING MOMENT COEFF.<CN) -0.081 -0.060 -0.029 •0« 000 •0.029 +0.058 +0.082 •e.102 +0.116 +0.123 +0.121 +0.132 +0.153 •0.174 MODEL B

GROUND BOflRD LENGTH<METRES)» 1 . 3 1

DflTR FILE VflW ANGLE' - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 •2o.e B/7/3 DEG) DRAG COEFF.<CD) 0^562 0.544 0.523 0.505 0.521 0.546 0.558 0.580 0.611 0.640 0.666 0.684 0.699 0.705 SIDEFORCE COEFF.<CV) -0.379 -0.267 -0.140 +0.014 +0.163 +0.294 +0.432 •0.570 +0.711 +0.852 +0.980 +1.105 +1.221 +1.336 VAWING MOMENT COEFF.<CN) -0.080 -0.061 -«.028 -0.000 +0.031 +0.056 +0.081 +0.102 •0.117 +0.119 +0.119 +0.132 •0.153 •«.170 MODEL B

GROUND BOflRD LENGTHCMETRES)> 1.26

DflTfl FILE B/6/3 VflW flNGLE(DEG) DRAG - 6.0 - 4.0 - 2.0 • .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 • 14.0 + 16.0 • 18.0 +2O.0 COEFF.<CD) 0.567 0.552 0.528 0.512 0.528 0.547 0.564 0.583 0.615 0.644 0.677 0.689 8.701 0.7O8 SIDEFORCE COEFF.<CV) -«.381 -«.268 -«.146 +«.008 +0.160 +0.291 +0.428 +«.571 +0.709 +0.852 +0.982 +1.101 +1.220 •1.336 VflWING MOMENT COEFF.<CN) -0.081 -0.057 -O.028 +0.000 +0.029 +0.056 +0.082 +0.106 +0.119 +0.124 +0.124 +0.133 +0.154 +0.174

Model B

MODEL B

GROUND BOflRD LENGTHCMETRES)»

1.21

DATA FILE B/5/3

VAW ANGLECDEG) DRAG

- 6.0 - 4.0 - 2.0 • .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 COEFF.CCD) 0.568 0.552 0.531 0.512 0.530 0.550 0.565 0.586 0.615 0.646 0.674 0.692 0.704 0.711 SIDEFORCE COEFF.CCV) -0.385 -0.271 -0.144 +0.012 +0.160 +0.294 +0.430 +0.570 +0.710 +0.854 +0.983 +1.100 +1.219 +1.337 VAWING MOMENT COEFF.CCN) -0.080 -0.059 -0.028 +0.000 +0.030 +0.058 +0.083 +0.100 +0.116 +0.121 +0.122 +0.131 +0.153 +0.174 MODEL B

GROUND BOARD LENGTHCMETRES)» 1.16

DATA FILE B/4/3

VAW ANGLECDEG) DRAG

- 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 • 14.0 + 16.0 + 18.0 +20.0 COEFF.CCD) 0.572 0.556 0.533 0.516 0.535 0.553 0.570 0.588 0.618 0.649 0.676 0.694 0.702 0.711 SIDEFORCE COEFF.CCV) -0,385 -0.272 -0.144 +0.010 +0.159 +0.295 +0.430 +0.570 +0.715 •0.860 •0.989 •1.111 +1.232 +1.338 VAWING MOMENT COEFF.CCN) -0.082 -0.060 -0.031 -0.001 +0.028 +0.057 +0.079 +0.101 +0.112 +0.122 +0.123 •0.136 +0.156 +0.177 MODEL B

GROUND BOARD LENGTHCMETRES)» 1.11

DATA FILE B/3/3 VflW flNGLECOEG) DRflG - 6.0 - 4.0 - 2.0 • .0 • 2.0 • 4.0 • 6.0 + 8.0 • 10.0 • 12.0 • 14.0 • 16.0 • 18.0 +20.0 COEFF.CCD) 0.574 0.563 0.339 0.520 0.538 0.557 0.572 0.592 0.620 0.652 0.678 0.696 0.709 0.712 SIDEFORCE COEFF.CCV) -0.388 -0.274 -0.146 +0.010 •0.162 •0.295 •0.431 •0.575 •0.717 •0.856 +«.989 +1.117 +1.227 •1.346 VflWING MOMENT COEFF.CCN) -0.082 -0.059 -0.030 -0.001 •0.028 •0.056 +0.081 +0.103 +0.116 +0.123 +0.124 +0.133 +0.154 +0.176

Model B

MODEL B

GROUND BOflRD LENGTHCMETRES)» 1 . 0 6 DflTR F I L E B / 2 / 3 VRW RNGLECDEG) - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 DRflG COEFF.CCD) 0.576 0.559 0.540 0.520 0.537 0.559 0.572 0.593 0.623 0.651 0.681 0.696 0.702 0.709 SIDEFORCE COEFF.CCV) -«.387 -0.274 -0.145 +0.008 +0.157 +0.290 +0.430 +0.570 +0.710 +0.856 +0.985 +1.105 +1.220 +1.333 VflWING MOMENT COEFF.CCN) -0.083 -0.059 -0.028 -0.001 +0.029 +0.058 +0.081 +0.105 +0.118 +0.129 +0.132 +0.135 +0.154 +0.175 MODEL B

GROUND BOARD LENGTHCMETRES)= 1.01

DRTR FILE B/1/3 VflW flNGLECOEG) DRflG - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 COEFF.CCD) 0.568 0.555 0.526 0.509 0.527 0.548 0.566 0.586 0.616 0.646 0.674 0.688 0.692 0.706 SIDEFORCE COEFF.CCV) -0.383 -0.268 -0.141 +0.011 +0.158 •0.297 •0.434 •0.565 +0.709 +0.851 +0.977 +1.091 +1.207 +1.310 VAWING MOMENT COEFF.CCN) -0.079 -0.061 -0.030 -0.001 +0.028 +0.058 +0.082 +0.102 +0.118 +0.126 +0.126 +0.131 +0.149 •0.166 MODEL B

GROUND BORRD LENGTHCMETRES)- .96

DATA FILE B/0/3

VAW ANGLECDEG) DRAG

- 6.0 - 4.0 - 2.0 • .0 + 2.0 + 4.0 + 6.0 + 8.0 +10.0 + 12.0 + 14.0 • 16.0 • 18.0 •20.0 COEFF.CCD) 0.559 0.544 0.519 0.507 0.520 0.538 0.555 0.572 0.604 0.627 0.652 0.670 0.673 0.682 SIDEFORCE COEFF.CCV) -0.377 -0.264 -0.135 +0.005 +0.150 +0.291 +0.429 +0.566 +0.708 •0.837 +0.959 +1.067 +1.167 +1.274 VAWING MOMENT COEFF.CCN) -0.079 -0.058 -0.030 +0.001 +0.032 +0.058 +0.078 +0.100 +0.116 +0.116 +0.113 •0.120 •0.134 •0.153

Model C

MODEL C

GROUND BOARD LENGTHCMETRES)» 1 . 3 6

DATA FILE C/8/3

VAW ANGLECDEG) DRAG

- 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4,0 + 6.0 + 8.0 + 10.0 • 12.0 + 14.0 + 16.0 + 18.0 +20.0 COEFF.CCD) 0.921 0.900 0.866 0.858 0.866 0.900 0.935 0.956 0.984 1.051 1.167 1.238 1.278 1.294 SIDEFORCE COEFF.CCV) -0.394 -0.269 -0.141 -0.006 +0.133 +0.274 +0.422 +0.574 +0.728 +0.826 +0.909 +1.019 +1.153 •1.275 VAWING MOMENT COEFF.CCN) -0.047 -0.036 -0.032 -0.009 +0.001 +0.016 +0.034 +0.071 +0.119 +0.053 -0.022 -0.014 +0.037 +0.114 MODEL C

GROUND BOflRD LENGTHCMETRES)»

_1.31

DATA FILE VAW ANGLECDEG - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 C/7/3 ) DRflG COEFF.CCD) 0.933 0.903 0.864 0.859 0.871 0.903 0.934 0.955 0.983 1.054 1.167 1.237 1.275 1.296 SIDEFORCE COEFF.CCV) -0.399 -0.282 -0.135 -0.006 +0.125 +0.276 +0.428 •0.586 +0.720 +0.825 +0.916 +1.030 +1.153 +1.278 VflWING MOMENT COEFF.CCN) -0.053 -0.035 -0.032 -0.011 +0.004 +0.014 +0.034 +0.072 +0.117 +0.047 -0.021 -0.019 +0.040 +0.115 MODEL C

GROUND BOflRD LEhCTHCMETRES)» 1 . 2 6

DflTfl FILE C/6/3 VflW flNGI FCOEG) DRflG - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 +14.0 +16.0 + 18.0 •20.0 COEFF.CCD) 0.930 0.901 0.880 Va O D O 0.873 0.905 0.938 0.965 0.986 1.054 1.169 1.243 1.283 1.297 SIDEFORCE COEFF.CCV) -0.394 -0.286 -0.129 -0.003 +0.135 +0.275 +0.424 •0.575 •0.733 +0.835 +0.922 +1.020 •1.139 •1.282 VAWING MOMENT COEFF.CCN) -0.046 -0.034 -0.031 -0.016 +0.004 +0.009 +0.032 +0.071 +0.121 +0.048 -0.024 -0.021 +0.035 +0.116

Model C

MODEL C

GROUND BOARD LENGTHCMETRES)» 1.21 DATA FILE C/5/3 VAW ANGLECDEG) - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 DRAG COEFF. CCD) 0.932 0.907 0.881 8.868 0.876 0.906 0.939 0.965 0.989 1.056 1.170 1.243 1.278 1.298 SIDEFORCE COEFF.CCV) -0.406 -O.277 -0.133 -0.007 +0.126 +0.280 +0.437 +0.581 +0.731 •0.834 •0.917 +1.027 +1.157 •1.293 VAWING MOMENT COEFF.CCN) -0.050 -0.032 -0.031 -«.010 +0.004 +0.021 +0.029 +0.065 +0.117 +0.041 -0.025 -0.019 +0.039 +0.111 MODEL C

GROUND BOARD LENGTHCMETRES)» 1.16

DATA FILE VAW ANGLE' - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 +20.0 C/4/3 DEG) DRAG COEFF.CCD) 0.935 0.908 0.885 0.866 0.880 0.907 0.938 0.963 0.997 1.062 1.173 1.239 1.271 1.297 SIDEFORCE COEFF.CCV) -0.410 -0.284 -0.142 -0.009 +0.133 +0.271 +0.421 +0.581 +0.735 +0.835 +0.919 +1.021 +1.159 +1.278 VAWING MOMENT COEFF.CCN) -0.048 -0.032 -0.027 -0.011 +0.009 +0.011 +0.032 +0.074 +0.121 +0.047 -0.026 -0.020 +0.038 +0.114 MODEL C

GROUND BOflRD LENGTHCMETRES)» 1.11

DflTfl FILE C/3/3 VflW flNGLECOEG) DRflG - 6.0 - 4.0 - 2.0 + .0 + 2.0 + 4.0 + 6.0 + 8.0 + 10.0 + 12.0 + 14.0 + 16.0 + 18.0 •20.0 COEFF.CCD) 0.939 0.910 0.887 0.875 0.885 0.912 0.946 0.964 0.989 1.068 1.178 1.246 1.274 1.295 SIDEFORCE COEFF.CCV) -0.405 -0.283 -0.142 -0.003 +0.119 +0.274 +0.424 +0.581 +0.728 +0.845 +0.924 +1.031 +1.158 +1.283 VflWING MOMENT COEFF.CCN) -0.050 -0.041 -0.031 -0.012 +0.002 +0.011 +0.029 +0.070 •0.117 •0.048 -0.027 -0.019 +0.041 +0.117