1. CFD Analysis of a Single-Stage Suborbital Rocket
Christopher Simpson & Dr. Charles O’Neill
The University of Alabama

2. Overview Scope and Objectives Stability: An Overview
Computational Fluid Dynamics
6 Degree of Freedom Solver
Results, Discussion, & Future Work
Q&A

3. Research Scope and Objectives

4. Scope of the Project Rocket Design Model Single-stage Suborbital
No Controls
Computational Scope
Max speed: M=0.6
Interpolation of data from FUN3D
6DOF tracks flight path
6DOF gives stability derivatives
Objectives
Stability
CFD
6DOF
Application

5. Objectives Realistic Modeling
CFD provides accurate prediction of aerodynamic forces
Can introduce multiple, “What if,” scenarios
Stability and Controls
Output stability margins
Build a base model
Controls will be introduced later
Rapid Prototyping
Objectives
Stability
CFD
6DOF
Application

6. Stability: An Overview

7. Stability: xcp , xnp , and Derivatives
Examination of a single-stage suborbital hobby rocket with an L-class motor
Tracking xcp and xnp over the simulated flight of the rocket
Easy extraction of stability derivatives
Objectives
Stability
CFD
6DOF
Application

8. Stability Derivatives
Objectives
Stability
CFD
6DOF
Application

9. Computational Fluid Dynamics

10. Rigid Body Model
Objectives
Stability
CFD
6DOF
Application

11. Mesh
Objectives
Stability
CFD
6DOF
Application

12. Pointwise: Mesh Creation
NASA Geolab’s worksheet for estimating normal spacing to be used in a viscous CFD grid was consulted:
ds = 6.92E-05, found using Re for max velocity
Estimates the spacing normal to a solid surface required to yield 1 grid point in the laminar sublayer
Objectives
Stability
CFD
6DOF
Application

13. FUN3D (CFD)
Objectives
Stability
CFD
6DOF
Application

14. 6 Degree of Freedom (6DOF) Solver
Christopher Simpson
The University of Alabama

15. 6 Degree of Freedom Solver
6DOF uses a 13 state variable equation to solve for the system through numerical integration
Quaternions are used to update the orientation from the body axis to the inertial frame
Objectives
Stability
CFD
6DOF
Application

16. 6 Degree of Freedom Solver
The non-inertial formulation of the 6DOF rigid body dynamics solver allows for an intuitive and simple stability derivative extraction routine
The stability derivatives allow NP and CP to be tracked as the apparent AOA changes
Objectives
Stability
CFD
6DOF
Application

17. Cx CZ
Objectives
Stability
CFD
6DOF
Application

18. CMx
CMy
Objectives
Stability
CFD
6DOF
Application

19. Results, Discussion, & Future Work

20. Results & Discussion
Objectives
Stability
CFD
6DOF
Application

21. Results & Discussion
Up to 20.5 lbs. could be added at the aft of the vehicle
Correct estimates are critical to design
Objectives
Stability
CFD
6DOF
Application

22. Future Work Conversion of code from interpreted to compiled code
Introduction of controls into the system
Further CFD analysis of the rocket body
Linearized expressions to optimize design before CFD work
Objectives
Stability
CFD
6DOF
Application

23. Christopher Simpson The University of Alabama
Q&A?
Christopher Simpson
The University of Alabama

24. Alabama Rocket Engineering Systems Rocket Launch
Objectives
Stability
CFD
6DOF
Application