Atul Kumar Presentation Week 3: February 1 st , 2007

1. Atul KumarPresentation Week 3: February 1st , 2007 Aerodynamics Team Re-Entry vehicle analysis - Lifting body 1

2. Mass calculations Mass and Volume of the payload. For transfer from HMO to the surface of Mars at the end of 2nd synodic period. Carrying Habitat 2, Mars taxi 2, an ISPP and a taxi capsule Heat shield mass based on a rough estimate made by the Thermal team’s - 20 kg/m^2 for the Mars Lander vehicle.

3. Peak aerodynamic load (Gmax) • Max g’s experienced by the vehicle at an assumed entry speed of 7620 m/sec or Mach~ 33 from a height of 10.8 km above the Martian surface. • 7620 m/sec is the speed of the space shuttle at entry. g’s experienced by the vehicle versus flight path angle 2

4. Geometry of the vehicle 3-D drawing of the proposed reentry vehicle. Drawn by Atul Kumar Generalized geometry of a hypersonic vehicle. Figure based on book by Hankey, Wilbur L. Reentry Aerodynamics et al. ref 1

5. Backup slides

6. Plots L/D versus Angle of attack Ballistic coefficient, β versus L/D ratio The two most aerodynamic characteristics, L/D ratio and the Ballistic coefficient define the undershoot boundary. Once the entry vehicle design requirements and crew load tolerances are computed, the entry flight path angle needed to limit undershoot can be computed. The undershoot boundary defines the constraints for heat load or g-limit.

7. Calculations - flight path angle e - 2.71828 ge- Gravitational constant, 9.81m/sec^2 Hs- scale height of Mars atmosphere, 10.8km Ve- entry speed taken 7620 m/sec Gmax = 7620^2*sin(10*pi/180)/(2*2.71828*9.81*10800) = 17.5050 m/sec^2 Mtotal – total mass of the vehicle Cd – coefficient of drag S – Reference area

8. Plots MARS Atmosphere Variation of Temperature, Pressure and Density of the Mars atmosphere with altitude

9. Computer codes Code to compute the properties of Martian Atmosphere. Pressure, temperature, density and acceleration due to gravity as functions of height.

10. Plots Well sustained crew can withstand a maximum deceleration of 12 g’s for a short period of time. And for a deconditioned crew this limit is between 3.5- 5g’s. - Too little deceleration can cause the vehicle to skip off the planet’s atmosphere like a bouncing rock and too much deceleration can cause excessive heating and can damage the vehicle and jeopardize the crew’s safety. Deceleration of the vehicle versus flight path angle

11. Plots Plots for variations of coefficients of drag and lift with angle of attack

12. Equation used to computeCl and Cd Equations taken from the book Re-entry Aerodynamics, ref 1

13. Contd

14. Drawings Different types of aerodynamic ManeuversFigure based on book by Larsonand Pranke et al. ref 2

15. Drawings Entry Corridor Figure based on book by Larsonand Pranke et al. ref 2

16. References • Hankey, Wilbur L., Re-Entry Aerodynamics Chapter-3 Hypersonic Aerodynamics, pgs 70, 71, 72 & 73 • Larson, Wiley J., Pranke Linda K. Human Spaceflight Mission Analysis and Design, pgs 279, 314-315 • Schneider, Steven PMethods for analysis of preliminary Spacecraft Designs, September 19th 2005 • Lessing, Henry C. Coate, Robert E., A Simple Atmosphere Reentry Guidance Scheme For Return From The Manned Mars Mission • Griffin, Michael D. , French, James R. Space Vehicle Design, Chapter 6- Atmospheric entry, section -1, pg 231 • Anderson, John D., Jr. Fundamentals of Aerodynamics, chapter 14. • Technical overview of the space shuttle orbiter http://www.columbiassacrifice.com/&0_shttlovrvw.htm • Mars Fact sheetwww.spds.nasa.gov/planetary/factsheet/marsfact.html+surface+density+of+mars&hl=en&gl=us&ct=clnk&cd= • NSTS 1988 News Reference manual http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/stsref-toc.html • Wikipedia, www.wikipedia.org 7