What surprises me is the velocities projected on that flight profile diagram posted above. Running mach 4 at various altitudes between 20 and 50 kilometers through an online atmospheric properties calculator, it appears that some parts of the vehicle skin may be exposed to total air temperatures exceeding 700 degrees C. Not your typical Long-EZ!
Edited to add that: Even if the ship is accelerated to mach 4 while level at 50,000' then zoom climbed to apogee, total air temp still exceeds 600 C.
Last edited by westhawk; 21st Aug 2011 at 09:23.
Reason: Additional info