NASA/CR{2001{211267

Inviscid Flow Computations of the

Shuttle Orbiter for Mach 10 and 15 and

Angle of Attack 40 to 60 Degrees

Ramadas K. Prabhu

Lockheed Martin Engineering & Sciences Company, Hampton, Virginia

December 2001
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NASA/CR{2001{211267

Inviscid Flow Computations of the

Shuttle Orbiter for Mach 10 and 15 and

Angle of Attack 40 to 60 Degrees

Ramadas K. Prabhu

Lockheed Martin Engineering & Sciences Company, Hampton, Virginia

National Aeronautics and

Space Administration

Langley Research Center Prepared for Langley Reseach Center

Hampton, Virginia 23681{2199 under contract NAS1-00135

December 2001
Available from the following:

NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS)

7121 Standard Drive 5285 Port Royal Road

Hanover, MD 21076{1320 Springeld, VA 22161{2171

(301) 621{0390 (703) 487{4650
Summary

This report documents the results of a computational study done to compute the inviscid longitudinal

aerodynamic characteristics of the Space Shuttle Orbiter for Mach numbers 10 and 15 at angles of attack of

40, 50, 55, and 60 degrees. These computations were done to provide limited aerodynamic data in support

of the Orbiter contingency abort task. The Orbiter had all the control surfaces in the unde
ected position.

The unstructured grid software FELISA with the equilibrium air option was used for these computations.

Normal force, axial force, and pitching moment coecients were computed. The hinge moment coecients of

the body
ap and the inboard and outboard elevons were also computed. These results were compared with

data from Operational Aerodynamic Data Book (OADB) and those computed using the software GASP. The comparison with the GASP results showed excellent agreement in Cm and CA, and also in the 
ap

and elevon hinge moment coecients at all the points. The present axial force coecients were smaller

than those computed by GASP. Similar agreement was notice with the elevon and body
ap hinge moments.

There were noticeable dierences between the present results and those from the OADB at angles of attack

greater than 50 degrees.

Software

The present computations were done using the unstructured grid inviscid 
ow software FELISA. This soft- ware consists of unstructured surface triangulator, volume grid generator, and 
ow solvers. The 
ow solver

can be run with any of the options including the perfect gas, equilibrium gases (air and Mars gas), and Mars

real gas. More information about FELISA may be found in [1]. FELISA software has been successfully used

for inviscid hypersonic 
ow computations, (See for example [2], [3], [4], and [5].) The present computations were done using the hypersonic 
ow solver with the equilibrium air option.

Grids

Two separate grids were used in these computations. The two grids had the same spacing distributions every

where except near the nose of the Orbiter. Around the nose, the minimum spacing was 2 inches in the coarse

grid, whereas it was reduced to 0.2 inches in the ne grid. This led to better capturing of the 
ow features

near the nose of the Orbiter. A view of the two grids on the symmetry plane near the Orbiter nose is shown

in Fig. 1 The information on these grids is given here:

Fine Grid Coarse Grid

No. of Surface Points 91,895 64,365

No. of Surface Triangles 183,786 128,726

No. of Tetrahedral Elements 10,950,214 7,979,561

No. of Nodes 1,855,685 1,350,843

Freestream Conditions

The freestream conditions for the two Mach number cases used in the present computations are as follows:

1
NOSE

(a) Coarse Grid

NOSE

(b) Fine Grid

Figure 1: Comparison of the surface triangulations near the nose.

2
Mach Number 10.0 15.0

Velocity 10,552 ft/s 15,679.05 ft/s

(3217.2 m/s) (4779.0 m/s)

Temperature 463.7 R 454.7 R

(257.6 K) (252.6 K)

Density 5.28E-6 slugs/ft3 7.77E-6 slugs/ft3

(2.7213E-3 kg/m3) (4.0047E-3 kg/m3)

The computed normal and axial forces, the pitching moment, the body
ap hinge moment, and the

elevon hinge moments were non-dimensionalized in the conventional way. The reference quantities used for

this purpose are as follows:

Coecients CN , CA, Cm Flap H.M. Elevon H.M.

Reference Area (in2) 387,360 19,440 30,240

Reference Length (in) 474.72 81.0 90.7

The pitching moment reference point is located on the symmetry plane, 841.7 in. behind the nose and

38.5 in. above the longitudinal axis. The longitudinal axis passes through the nose of the Orbiter.

The hinge moment of the body
ap was computed about the hinge line located at a distance of 1296

in. from the nose and 51 inches below the the longitudinal axis. This hinge line is perpendicular to the

symmetry plane.

The hinge moment of the elevon was computed in a similar manner The elevon hinge line is located at a

distance of 1151 in. from nose. The hinge line meets the symmetry plane at 76.652 in. below the longitudinal

axis, and makes a dihedral angle of 5.229 deg.

Results

The computations were done on the NAS Origin 2000 parallel computers using 64 processors. The results are

listed in Table 1. Similar computations had been done by Papadopoulos, P.E. et al, ([6]) assuming 5-species

nonequilibrium air. Present results and the GASP results are shown plotted in Figures 2 - 8 along with the

corresponding data from OADB. See [7]. It should be noted that the OADB and GASP results are for Mach

15.

Rening the grid near the Orbiter nose did not make any noticeable dierences in the results at Mach

10. The dierences in the results obtained using the coarse and the ne grids were less than 1%. The

contribution of the nose to the aerodynamic coecients is predicted adequately by the coarse grid. The ne

grid, however, allowed better capturing of the sonic line on the symmetry plane (See Figure 5.)

Figures 4 indicates that the present values of CA are lower than both OADB data and the GASP results.

This is the result of absence of skin friction in the present computations. At high Mach numbers and

particularly at high angles of attack, the normal force is primarily due to the pressures on the windside of

the vehicle. Inviscid 
ow computations adequately predict the 
ow over the windside surfaces. The OADB

Cm and CA values deviate from the FELISA computations as well as the GASP results at angles of attack

greater than 50 degrees.

Hinge moments of the body
ap, and the inboard and the outboard elevons were computed, and are listed

in Table 2. Results are shown plotted in Figure 6 - 8. Also shown plotted in these gures are the hinge

moment coecients from OADB and those computed using the GASP software.

3
M achN o: AngleofAttack CA CN Cm Grid

(degree)

15.0 40.0 1.1666E+00 5.2610E-02 -2.1479E-02 Coarse

15.0 50.0 1.6219E+00 5.3694E-02 -6.1119E-02 Coarse

15.0 55.0 1.8389E+00 5.2696E-02 -8.6418E-02 Coarse

15.0 60.0 2.0361E+00 5.0532E-02 -1.1205E-01 Coarse

10.0 40.0 1.2100E+00 5.1487E-02 -3.8619E-02 Coarse

10.0 50.0 1.6598E+00 5.2579E-02 -7.9042E-02 Coarse

10.0 60.0 2.0509E+00 5.0837E-02 -1.1930E-01 Coarse

10.0 40.0 1.2103E+00 5.1676E-02 -3.8489E-02 Fine

10.0 50.0 1.6601E+00 5.2720E-02 -7.8926E-02 Fine

10.0 60.0 2.0509E+00 5.1016E-02 -1.1926E-01 Fine

Table 1: Inviscid aeroynamic data for Mach 10 and 15.

α, deg.

Cm

25 30 35 40 45 50 55 60 65 -0.16

-0.12

-0.08

-0.04

0

0.04

OADB, M=15

GASP, M=15

FELISA, GRID0; M=15

FELISA, GRID0; M=10

FELISA, GRID1; M=10

Figure 2: Pitching moment coecient

4
α, deg.

CN

25 30 35 40 45 50 55 60 65 0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

OADB, M=15

GASP, M=15

FELISA, GRID0; M=15

FELISA, GRID0; M=10

FELISA, GRID1; M=10

Figure 3: Normal force coecient

α, deg.

CA

25 30 35 40 45 50 55 60 65 0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

OADB, M=15

GASP, M=15

FELISA, GRID0; M=15

FELISA, GRID0; M=10

FELISA, GRID1; M=10

Figure 4: Axial force coecient

5
α=50°

α=60°

α=40°

Figure 5: Symmetry plane sonic lines (ne grid); Mach 10, =40, 50, and 60 deg.

The OADB hinge moment coecients curves have an in
exion point at about an angle of attack of 45

degrees. However, the computed data do not exhibit this trend. It may be observed that the FELISA results

agree very well with the GASP results. The computed inboard elevon hinge moment coecients agree with

the OADB data upto an angle of attack of 60 degrees. The maximum dierence is about 0.025 at  = 50

degrees. The outboard elevon hinge moment coecients agree with the OADB data only upto an angle

of attack of 50 degrees. At angles of attacks greater than 50 degrees, the outboard elevon hinge moment

coecients continue to increase negatively, whereas the OADB data tend to level o. At  = 60 degrees the

dierence between the computed and OADB data is 0.25. The computred body
ap hinge moment coecients

agree with the OADB data except at an angle of attack of 60 degrees where the dierence between the two

is 0.05.

6
(g) () ()

15.0 40.0 -2.7225E-01 -1.4658E-01 -7.3060E-02 Coarse

15.0 50.0 -4.2318E-01 -2.2984E-01 -1.0923E-01 Coarse

15.0 55.0 -5.0862E-01 -2.7592E-01 -1.2916E-01 Coarse

15.0 60.0 -5.9762E-01 -3.2156E-01 -1.4806E-01 Coarse

10.0 40.0 -2.9027E-01 -1.6308E-01 -8.1999E-02 Fine

10.0 50.0 -4.4477E-01 -2.5192E-01 -1.2019E-01 Fine

10.0 60.0 -6.0888E-01 -3.3267E-01 -1.5078E-01 Fine

Table 2: Flap and elevon hinge moment coecients for Mach 10 and 15.

α, deg.

Bodyflap hinge moment coefficient, CHBF

25 30 35 40 45 50 55 60 65 -0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

FELISA, M=10

FELISA, M=15

GASP, M=15

OADB, M=15

Figure 6: Body
ap hinge moment coecients

7
α, deg.

Outboard elevon hinge moment coefficient

25 30 35 40 45 50 55 60 65 -0.18

-0.16

-0.14

-0.12

-0.1

-0.08

-0.06

FELISA, M=10

FELISA, M=15

Figure 7: Outboard elevon hinge moment coecients

α, deg.

Inboard elevon hinge moment coefficient, CHEI

25 30 35 40 45 50 55 60 65 -0.4

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

FELISA, M=10

FELISA, M=15

GASP, M=15

OADB, M=15

Figure 8: Inboard elevon hinge moment coecients

8
References

[1] Peiro, J., Peraire, J., and Morgan, K., \FELISA System Reference Manual and User's Guide," Tech.

Report, University College of Swansea, Swansea, U.K., 1993.

[2] Prabhu, R.K., \Computational Study of a McDonnell Douglas Single-Stage-to-Orbit Vehicle Concept for

Aerodynamic Analysis," NASA Contractor Report 20160, September 1996.

[3] Prabhu, R.K., \An Inviscid Computational Study of an X-33 Conguration at Hypersonic Speeds,"

NASA CR-1999-209366, July 1999.

[4] Prabhu, R.K., \Inviscid Flow Computations of the Orbital Sciences X-34 Over a Mach Number Range

of 1.25 to 6.0," NASA Contractor Report 210849, April 2001.

[5] Prabhu, R.K., \Summary Report of the Orbital X-34 Wing Static Aeroelastic Study," NASA Contractor

Report 210850, April 2001.

[6] Papadopoulos, P.E. et al, \CFD Simulations in Support of Shuttle Orbiter Contingency Abort Aerodynamic Database Enhancement," AIAA 2001-3067, 35th AIAA Thermophysics Conference, June, 2001.

[7] \Operational Aerodynamic Data Book," Boeing, Human Space Flight and Exploration, Huntington

Beach, CA, Boeing Document STS85-0118 CHG 9, 2000.

9
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Prescribed by ANSI Std. Z39-18

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

December 2001

3. REPORT TYPE AND DATES COVERED

Contractor Report

4. TITLE AND SUBTITLE

Inviscid Flow Computations of the Shuttle Orbiter for Mach 10 and 15 and

Angle of Attack 40 to 60 Degrees

5. FUNDING NUMBERS

C NAS1-00135

WU 706-85-41-01

6. AUTHOR(S)

Ramadas K. Prabhu

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Lockheed Martin Engineering & Sciences Company

C/O NASA Langley Research Center

Hampton, VA 23681–2199

8. PERFORMING ORGANIZATION

REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681–2199

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/CR–2001–211267

11. SUPPLEMENTARY NOTES

Langley Technical Monitor: Kenneth Sutton

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited

Subject Category 02

Distribution: Nonstandard

Availability: NASA CASI (301) 621–0390

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

This report documents the results of a computational study done to compute the inviscid longitudinal aerodynamic

characteristics of the Space Shuttle Orbiter for Mach numbers 10 and 15 at angles of attack of 40, 50, 55, and 60

degrees. These computations were done to provide limited aerodynamic data in support of the Orbiter contingency

abort task. The Orbiter had all the control surfaces in the undeflected position. The unstructured grid software

FELISA was used for these computations with the equilibrium air option. Normal and axial force coefficients and

pitching moment coefficients were computed. The hinge moment coefficients of the body flap and the inboard and

outboard elevons were also computed. These results were compared with Orbiter Air Data Book (OADB) data and

those computed using GASP. The comparison with the GASP results showed very good agreement in Cm and Ca

at all the points. The computed axial force coefficients were smaller than those computed by GASP. There were

noticeable differences between the present results and those in the OADB at angles of attack greater than 50

degrees.

14. SUBJECT TERMS

Shuttle Orbiter, Unstructured Grid CFD, Hypersonic Speeds, Aerodynamic Loads

15. NUMBER OF PAGES

14

16. PRICE CODE

A03

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