AAE450 Senior Spacecraft Design Atul Kumar Presentation Week 3: February 1 st, 2007 Aerodynamics Team Re-Entry vehicle analysis - Lifting body 1

AAE450 Senior Spacecraft Design Mass calculations Mass components Unit (M/T) Payload Propellant Structural mass w/o heat shield Heat shield mass (underestimate) ~ Total Mass Heat shield mass based on a rough estimate made by the Thermal team’s - 20 kg/m^2 for the Mars Lander vehicle. Mass and Volume of the payload. For transfer from HMO to the surface of Mars at the end of 2 nd synodic period. Carrying Habitat 2, Mars taxi 2, an ISPP and a taxi capsule

AAE450 Senior Spacecraft Design Peak aerodynamic load (G max ) 2 g’s experienced by the vehicle versus flight path angle  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.

AAE450 Senior Spacecraft Design Geometry of the vehicle Generalized geometry of a hypersonic vehicle. Figure based on book by Hankey, Wilbur L. Reentry Aerodynamics et al. ref 1 3-D drawing of the proposed reentry vehicle. Drawn by Atul Kumar

AAE450 Senior Spacecraft Design Backup slides

AAE450 Senior Spacecraft Design Plots Ballistic coefficient, β versus L/D ratioL/D versus Angle of attack 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.

AAE450 Senior Spacecraft Design Calculations - flight path angle e 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* *9.81*10800) = m/sec^2 Mtotal – total mass of the vehicle Cd – coefficient of drag S – Reference area

AAE450 Senior Spacecraft Design Plots MARS Atmosphere Variation of Temperature, Pressure and Density of the Mars atmosphere with altitude

AAE450 Senior Spacecraft Design Computer codes Code to compute the properties of Martian Atmosphere. Pressure, temperature, density and acceleration due to gravity as functions of height.

AAE450 Senior Spacecraft Design Plots Deceleration of the vehicle versus flight path angle 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 g’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.

AAE450 Senior Spacecraft Design Plots for variations of coefficients of drag and lift with angle of attack Plots

AAE450 Senior Spacecraft Design Equation used to compute Cl and Cd Equations taken from the book Re-entry Aerodynamics, ref 1

AAE450 Senior Spacecraft Design Contd

AAE450 Senior Spacecraft Design Drawings Different types of aerodynamic Maneuvers Figure based on book by Larsonand Pranke et al. ref 2

AAE450 Senior Spacecraft Design Drawings Entry Corridor Figure based on book by Larsonand Pranke et al. ref 2

AAE450 Senior Spacecraft Design 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, Schneider, Steven P Methods for analysis of preliminary Spacecraft Designs, September 19 th 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 Mars Fact sheet NSTS 1988 News Reference manual Wikipedia, 7