1. Alex Woods January 24th Aerodynamics Determination and Influences of Center of Pressure
AAE 450 Spring 2008

2. Analytic Cases Subsonic – Vanguard geometry Transonic Supersonic
Lateral Area – 55.99% lfn
Barrowman – 25.73% lfn
Transonic
Detailed Analysis Forthcoming
Vanguard Case: ~50% lfn
Supersonic
Holt Ashley ~ .3654% lfn
lfn = Body length from nose
Coefficients pulled from Holt Ashley, applied to Vanguard geometrical case
AAE 450 Spring 2008
Group Name (i.e.Trajectory Optimization)

3. Influences of CP Considerations Future Work Geometry Angle of Attack
Primarily influenced by nose, shoulders, boat-tails, and fins
Angle of Attack
Most rockets travel at < 6% angle of attack
Influenced by horizontal wind patterns
Mach Number
Moves aft while M ≤ 1
Moves back for M > 1
Becomes Mach independent for hypersonic flow
Most Classic Rocket shapes are statically unstable for the open loop case
Maintaining a CP behind the CG will be difficult without the use of fins
Blunt nose cones increase drag but decrease normal loads and pitching moment
Future Work
Transonic Case Analysis
CFD Analysis of Pressure Distribution
Linearized Flow and Newtonian for Analysis of Super / Hypersonic Cases
AAE 450 Spring 2008
Group Name (i.e.Trajectory Optimization)

4. Backup Slides References
(1)Barrowman, James and Barrowman, Judith, "The Theoretical Prediction of the Center of Pressure" A NARAM 8, August 18,
(2) Wade, Mark; "Vanguard" Stage Data
(3) Klawans, B. and Baughards, J. "The Vanguard Satellite Launching Vehicle - an engineering summary" Report No , April 1960
AAE 450 Spring 2008
Group Name (i.e.Trajectory Optimization)

5. References Cont.
(4) Ashley, Holt, Engineering Analysis of Flight Vehicles, Dover Publications Inc., New York, 1974, pp
(5) Morrisette, E. L., Romeo D. J., “Aerodynamic Characteristics of a Family of Multistage Vehicles at a Mach Number of 6.0”, NASA TN D-2853, June 1965
Thanks to the Aerothermodynamics team for advice and direction
AAE 450 Spring 2008

6. Assumptions Subsonic Cases Lateral Area Barrowman (lifted from report)
1. Ninety Degree AOA
2. Uniform aerodynamic force across surfaces incident to flow
3. No significant lifting surfaces (wings)
Barrowman (lifted from report)
All flow is potential flow
Point of the nose is sharp
Fins are thin plates with no cant
The angle of attack is very near zero
Flow is steady state and subsonic
The rocket is a rigid body
The rocket is axially symettric
AAE 450 Spring 2008

7. Assumptions (Cont.) Hypersonic (Ashley case)
Flow is mach number independent
Pitch axis is located at the center of lateral area
Geometry of the Vanguard is reasonably close to that used in the Morrisette and Romeo wind tunnel tests
AAE 450 Spring 2008