1 Alex Woods February 21st Aerothermodynamics Group Aerodynamic Forces Code

2 Aerodynamic Forces  Predicts coefficients of pressure over the surface of the rocket  Integrates Cp to find coefficients of normal force and pitching moment (Cn, Cm)  Uses Cn and Cm to determine the location of the center of pressure  Thanks to Kyle Donahue for additional geometric data Group Name (i.e.Trajectory Optimization)

3 Structural Forces  Uses Cn data to determine shear forces within the rocket, as well as determining bending moments.  Code computes data for each stage coupling. Future Work:  Ensure accuracy for high aoa cases  Modify code for changing design parameters

4 References  Ashley, Holt, Engineering Analysis of Flight Vehicles, Dover Publications Inc., New York, 1974, pp  Anderson, John D., Fundamentals of Aerodynamics, Mcgraw-Hill Higher Education, 2001  Professor Williams, concerning the use of pressure coefficients to determine aerodynamic forces  The Aerothermodynamic Group for help with the code

5 Assumptions and Concerns  The linear theory used to determine pressure coefficients is primarily valid for thin airfoils; additional terms are necessary for better application to slender rocket bodies.  Small angles of attack – Normal forces become non-linear past 6 degrees.  Results vary by the number of data points and the locations from which they are taken; small step sizes bias the effects of long cylindrical sections

6 Concerns cont.  Code does not yet compute axial forces, which would allow for the computation of drag.  Moment values being found are unusually small compared to results found in the Holt Ashley text  Location of center of pressure is unusually far aft compared to Vanguard example

7 Pretty Pictures

8 Contributions  Center of Pressure code –Calling function for all applicable codes –Rocket volume computations –Pressure Coefficient integrations –Normal force coefficients –Pitching moment coefficients –Shear Forces –Bending Moments

9 Contributions Cont.  Sea Launch –Tugboat hiring costs –Barge rental costs Thanks to Jerry White of Oregon Offshore Towing for these estimates  Drag Code Assisted Jayme Zott in creating and integrating drag models  Wing Code Assisted Brian Budzinski in the modification of his wing and fin codes

10 Contributions Cont.  MAT team member – helped troubleshoot version 1.0, ran six two stage cases for the initial group of cases.