Disc Shaped Reentry Vehicle
Transcript of Disc Shaped Reentry Vehicle
DEN-Tt_ ---
X-652
AT TRANSONIC AND LOW
SPEEDS
_rankA. Lazzeroni
Research Center
Field, C al-Z_.
FIDENTIAL
ADMINISTRATION
May 1962
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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
TECHNICAL M_ORANDUM X-652
i , , , , ,
EXPERIMENTAL INVESTIGATION OF A DISK-SH_ REENTRY
CONFIGURATION AT TRANSONIC AND LOW
SUPERSONIC SPEEDS*
By Frank A. Lazzeroni
SUMMARY
An investigation has been made to determine the static longitudinal
and lateral-directional aerodynamic characteristics of a disk-shaped
reentry configuration. The model had an elliptic profile with a maximum
thickness-diameter ratio of 0.325. The tests vere conducted to maximum
angles of attack and sideslip of 22 ° over a Mach number range from 0.95
to 1.50 at a Reynolds number of 3.5×10s-
The basic disk was longitudinally unstable about a center of gravity
at 40 percent of the diameter from the leading edge. Addition of a canopy,
vertical stabilizing surfaces_ and horizontal control surfaces provided
static longitudinal and directional stability through the angle-of-attack
range at Mach numbers above 1.0. At a Mach number of 0.95, a slight
pitch-up occurred at angles of attack above 5° .
INTRODUCTION
The design of a space vehicle capable of reentering the earth's
atmosphere at satellite speed and above involves many compromises to
cope with the problems of aerodynamic heating, stability and control,
vehicle performance, etc. As a result, both lifting and nonlifting vehi-
cles have been considered and the resulting shapes have been extremely
varied (e.g., refs. 1 through 4). For manned flight, the lifting-type
vehicle is especially attractive. One such vehicle receiving consider-
ation is the lenticular shape. This vehicle would enter the atmosphere
at a high angle of attack (50 ° to 90o ) to produce a high drag and reduce
heating; then, as the velocity decreased and the high heating period
• ' *Title Unclassified
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passed, the angle of attack would be reduced and the vehicle would enter
a gliding phase. It is intended that the vehicle would be landed by
conventional techniques.
It was recognized that control in low-speed flight could be a problem
for the unorthodox disk-shaped vehicle. Accordingly, a study was con-
ducted in the Ames 12-Foot Pressure Wind Tunnel of this phase of the
flight regime of such vehicles (refs. _ and 6). Out of this study two
particular shapes appeared sufficiently promising to warrant some study
at supersonic speed and were the subject of an investigation at a Mach
number of 2.2 (ref. 7). These shapes were circular in plan form with
elliptic cross sections and incorporated control and stabilizing surfaces
at the rear of the vehicle and a canopy. One model had a thickness-to-
diameter ratio of 0.325 and a symmetrical section and was the subject of
an investigation at a _ch number of 3-5 (ref. 8). The present report
presents the results of an investigation with a model having this same
geometry at Mach numbers from 0.95 to 1.50 and a Reynolds number of
3._×i06 based on the plan-form diameter. Previous test results for uncam-
bered circular disks have sho_n stable trim points at high angles of
attack at transonic and supersonic speeds (refs. 8, 9, and i0). Lower
angles of attack are more appropriate to this speed regime for such
vehicles so the present study was confined to angles of attack less than24 o .
NOTATION
The results are presented in standard coefficient form. Lift and
drag coefficients are referred to the wind axes; all other aerodynamic
coefficients are referred to the body axes. All moments are referred to
a point in the longitudinal plane of symmetry on the major axis of the
elliptical cross section 0.40 diameter aft of the leading edge. The
reference area in each case is the plan-form area of the particular
configuration (including the area of the horizontal control surfaces for
the complete model).
drag
qSdrag coefficient,
drag at zero lift
cD
%o
CLlift
lift coefficient,qS
side-force coefficient,side force
qS
C_ rolling-moment coefficient, rolling momentqSd
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Cm
Cn
pitching-moment coefficient, pitching moment
qSd
yawing-moment coefficient,yawing moment
qSd
d diameter
Llift-drag ratio
M free-streamMach number
q free-stream dynamic pressure
Reynolds number, pVd
r radial distance from center of model
plan-form area of model (including horizontal control surface area
for the complete model)
t
dmaximum thickness-to-diameter ratio
V free-stream velocity
y vertical distance from chord plane
angle of attack, measured with respect to the chord plane
angle of sideslip
deflection of horizontal control surface, positive downward (see
fig. l)
p free-streamdensity
free-stream viscosity
dCL_
\-gJJ o° tos°lift curve slope between _ = 0° and 5 °, per deg
dCm
\d-_LJ CL=O to o.l
pitching-moment curve slope from CL = 0 to 0.i
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cy_
cz6
Cn__=0 0 to 5 °
derivatives with respect to
per deg
_, between _ = 00 and 5°,
APPARATUS AND MODEL
The experimental investigation was conducted in the Ames 6- by 6-Foot
Supersonic Wind Tunnel which is of the closed-circuit variable-pressure
type with a Mach number range from 0.7 to 2.2. A dimensional drawing of
the model is presented in figure i, and a photograph of the model is shown
in figure 2. The basic shape was circular in plan form with a thickness-
to-diameter ratio of 0.32_ and an elliptic profile, the shape being gener-
ated by revolving# about the minor axis, the elliptic sections defined by
the coordinates given in table I.
The horizontal control surfaces were thick flat plates extending
radially from the trailing edge of the basic disks as shown in figure 1.
The horizontal control surfaces consisted of two inboard and two outboard
surfaces with a total area which was 25 percent of the plan-form area of
the basic disk. The hinge lines of the controls were normal to radial
lines of the disk at the centers of the respective controls.
The vertical stabilizing surfaces were two constant thickness tri-
angular shapes with rounded leading edges swept back 65 °. Each vertical
surface was 5-1/2 percent of the plan-form area of the basic disk, giving
a total exposed area of ll percent of the plan-form area.
Details of the model canopy are shown in figure 3. A small fairing
at the rear of the models accommodated the support sting. An internal
six-component strain-gage balance was used to measure the forces andmoments on the model.
TEST AND PROCEDURES
Measurements of the static longitudinal aerodynamic characteristics
of the model were made at Mach numbers from 0.95 to 1.50 for a Reynolds
number of 3.5 million based on the diameter of the model. The angle-of-
attack and angle-of-sideslip ranges were from -6° to +22 ° and the
horizontal control surface deflections were from -20 ° to +5 °.
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Stream Variations
Surveys of the stream characteristics of the wind tunnel have shown
that essentially no stream curvature exists in the vicinity of the model
and that the axial static-pressure variations are less than 1 percent of
the dynamic pressure. Therefore, no corrections for stream curvature or
static-pressure variations were made in the present investigation. The
data have been adjusted to take account of the stream angles in the
vertical plane along the tunnel center llne measured in these surveys.
Support Interference
Interference from the sting support on the aerodynamic characteristics
of the model was considered to consist primarily of a change in the pres-
sure at the base of the model. Accordingly, the static pressures within
the balance cavity of the model were measured and the drag data were
adjusted to correspond to free-stream static pressure within the cavity
and on the base of the annulus of the model fairing around the sting.
Tunnel-Wall Interference
The effectiveness of the perforations in the wind-tunnel test section
in preventing choking and in absorbing reflected disturbances at low super-
sonic speeds has been established experimentally. Unpublished data fromthe wind-tunnel calibration indicate that reliable data can be obtained
throughout the Mach number range of the tunnel if certain restrictions
are imposed on the model size and attitude. The configuration used in
the present investigation complied with these restrictions and shadowgraphobservations of the flow around the model substantiated the fact that no
choking or reflected disturbances were present for the test conditions
reported herein.
RE SULT S
The results of the experimental investigation are presented in
figures 4 through 9. Longitudinal aerodynamic characteristics of the
basic disk are presented in figure 4. Lift and pitching-moment curve
slopes and drag at zero lift are shown as functions of Mach number in
figure 5 for the basic disk. Data from M = 0.25 to M = 0.9 were obtained
from reference 6 while data at M = 2.2 were obtained from reference 7.
Longitudinal and lateral-directional aerodynamic characteristics of the
complete model with canopy, vertical surface, and horizontal control
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6 CONFIDENTIAL
surfaces are presented in figures 6 and 7, respectively, while the lift
and pitching-moment curve slopes and drag at zero lift as a function of
Mach number are summarized in figure 8. The lateral-directional stability
derivatives are summarized in figure 9. As with the basic disk, the
summary data from M = 0.29 to 0.90 and at M = 2.2 for figures 8 and 9
were obtained from references 6 and 7, respectively.
With the center of moments 0.4 diameter aft of the leading edge, the
slope of the pitching-moment curve for the basic disk (figs. 4 and D)
had a positive value at low lift coefficients and decreased to zero or
became slightly negative at higher lift coefficients. When the canopy_
vertical surfaces, and horizontal control surfaces at zero deflection
were added to the basic disk, the pltching-moment curves had a stable
slope throughout the Mach number range of the present investigation
(figs. 6 and 8). Ul_ward (negative) deflection of the horizontal controls
reduced the static longitudinal stability at Mach numbers of 0.95, 1.O0,
and 1.10 (figs. 6(a), (b), and (c)), and neutral or slightly unstable
conditions were present for certain lift coefficients, depending on the
Mach number. At Mach numbers of 1.30 and 1.50 (figs. 6(d) and (e)) the
pitching-moment curves with the controls deflected were more linear than
at the lower Mach numbers, and stable trim conditions were evident to
near maximum L/D. The effects of control deflection on L/D were small
for the Mach number range of the investigation.
The yawing-moment and side-force data presented in figure 7 indicate
that the vertical surfaces maintain their effectiveness to high angles
of sideslip throughout the transonic speed range at angles of attack of
0° and 5°. The rolling-moment data indicate that the vertical surfaces
provide a negative increment of dihedral effect at low angles of attack
in the transonic speed range. The summary of results in figure 9 for
the complete model shows a reduction of directional stability with
increasing Mach number in the supersonic speed range and a negative
dihedral effect at transonic speeds for an angle of attack of 0 °. The
dihedral effect was positive throughout the speed range for an angle of
attack of 5° •
A
6
1
4
Ames Research Center
National Aeronautics and Space Administration
Moffett Field, Calif., Mar. 6, 1962
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REFERENCES
lo
•
.
.
Staff of Langley Flight Research Division (compiled by
Donald C. Cheatham): A Concept of a Manned Satellite Reentry
Which is Completed With a Glide Landing. NASA TM X-226, 1959-
Foster_ Gerald V.: Exploratory Investigation at a Mach Number of
2.01 of the Longitudinal Stability and Control Characteristics of
a Winged Reentry Configuration. NASA TM X-175, 1959.
Eggers, Alfred J., Jr., and Wong, Thomas J.: Re-entry and Recovery
of Near-Earth Satellites, With Particular Attention to a Manned
Vehicle. NASA MEMO I0-2-58A, 1958.
Grant, C. Frederick: Importance of the Variation of Drag With Lift
in Minimization of Satellite Entry Acceleration. NASA TN D-120,
1959.
5. Demele, Fred A., and Browns,n, Jack J.: Subsonic Longitudinal
Aerodynamic Characteristics of Disks With Elliptic Cross Sections
and Thickness-Diameter Ratios From 0.225 to 0.425. NASA TN D-788,
1961.
. Demele_ Fred A., and Brownson_ Jack J.: Subsonic Aerodynamic
Characteristics of Disk Re-entry Configurations With Elliptic Cross
Sections and Thickness-Diameter Ratios of 0.225 and 0.325. NASA
TM X-566, 1961.
7- Lazzeroni_ Frank A.: Aerodynamic Characteristics of Two Disk Re-entry
Configurations at a Mach Number of 2.2. NASA TM X-567, 1961.
Q
•
i0.
Demele, Fred A., and Lazzeroni, Frank A.: Effects of Control Surfaces
on the Aerodynamic Characteristics of a Disk Re-entry Shape at
Large Angles of Attack and a Mach Number of 3-5. NASA TM X-576,
1961.
Mugler, John P., Jr., and 01stad, Walter B.: Static Longitudinal
Aerodynamic Characteristics at Transonic Speeds of a Lenticular-
Shaped Reentry Vehicle, NASA TM X-423, 1960.
Jackson, Charlie M., Jr., and Harris, Roy V., Jr.: Static Longi-
tudinal Stability and Control Characteristics at a Mach Number of
1.99 of a Lenticular-Shaped Reentry Vehicle. NASA TN D-514, 1960.
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TABLEI.- COORDINATESOFSURFACEOFMODEL[All dimensions in inches]
T
d
A
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t/d = 0.325
r ±y r ±y
0
.25
.50
-75i.OO
1.25
1.5o
1.75
2 .o0
2 -25
2.50
2.753.00
3.25
3.5o
1.950
1.948
1.943
1.935
1.923
i .908
1.888
3.60
3.754.00
4.25
4.50
4.75
5.oo
i .560
1.522
i.453
i -376
1.290
1.191
1.0781.865
1.8381.808
1-773
1.7331.689
1-639
1.584
5.25
5-50
5.6O
5-70
5.80
5-90
5 -956 .oo
.944
•779
•7oo.6o9
.499
.355
.251
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•55 o
Figure 3-- Canopy details.
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