<DOC>
<DOCNO>
232
</DOCNO>
<TITLE>
accuracy of approximate methods for predicting pressure
on pointed non-lifting bodies of revolution in supersonic
flow .
</TITLE>
<AUTHOR>
ehret,d.m.
</AUTHOR>
<BIBLIO>
naca tn.2764.
</BIBLIO>
<TEXT>
  the accuracy and range of applicability of the linearized theory,
second-order theory, tangent-cone method, conical-shock-expansion theory
and newtonian theory for predicting pressure distributions on pointed
bodies of revolution at zero angle of
attack are investigated .  pressure
distributions and integrated pressure
drag obtained by these methods are
compared with standard values obtained
by the method of characteristics
and the theory of taylor and maccoll .
three shapes, cone, ogive, and a
modified optimum body, are investigated
over a wide range of fineness
ratios and mach numbers .
  it is found that the linearized
theory is accurate only at low values
of the hypersonic similarity parameter
number to body fineness ratio) and that
second-order theory appreciably
extends the range of accurate application .
the second-order theory gives
good results on ogives when the ratio of
the tangent of maximum surface
angle to the tangent of the mach angle
is less than 0.9 .  tangent-cone
method cannot be widely applied with
good accuracy .  in general, the
conical-shock-expansion theory predicts
pressure and drag within engineering
accuracy when the hypersonic similarity
parameter is greater than 1.2 .
although newtonian theory gives good accuracy,
except for cones, at the
highest values of the hypersonic similarity
parameter investigated, it is
less accurate than the conical-shock-expansion theory .
</TEXT>
</DOC>
