<DOC>
<DOCNO>
1347
</DOCNO>
<TITLE>
approximate analysis of atmospheric entry corridors
and angles .
</TITLE>
<AUTHOR>
luidens,r.w.
</AUTHOR>
<BIBLIO>
nasa tn.d590, 1961.
</BIBLIO>
<TEXT>
  a simple closed-form solution
for the achievable corridor depths
and entry angles as a function of
g-load limit, entry velocity, and
vehicle aerodynamics and thermodynamics
is developed for two modes of
vehicle operation, constant angle
of attack and modulated angle of attack .
  for constant angle of attack,
operation at maximum negative lift
coefficient on the overshoot bound,
and at an angle of attack between
zero and that for maximum lift-drag
ratio on the undershoot bound, gives
the deepest corridor .  for modulated
angle of attack, operating at maximum
negative lift coefficient on the
overshoot bound and modulating
the angle of attack from maximum
positive lift coefficient to zero on
the undershoot bound give the deepest
corridor .  the modulated angle of
attack gives corridor depths two to
four times larger than the fixed
angle of attack .  for both cases the
corridor depth is increased by increasing
maximum lift-drag ratio,
increasing g limit, and decreasing
entry velocity .
  consideration of hot-gas radiation
places a limit on the maximum
angle of attack for either mode of
operation .  if a maximum free-stream
reynolds number limit must be placed
on the vehicle to ensure a laminar
boundary layer, the deep atmospheric
penetrations associated with configurations
with high lift-drag ratio
may be ruled out .  both of these
thermodynamic considerations reduce
the acceptable corridor depth below
the value calculated from aerodynamic
considerations alone .
</TEXT>
</DOC>
