<DOC>
<DOCNO>
1353
</DOCNO>
<TITLE>
investigation of a two-step nozzle in the langley 11in .
</TITLE>
<AUTHOR>
 hypersonic tunnel .
</AUTHOR>
<BIBLIO>
mclellan,c.h.
naca tn.2171, 1950.
</BIBLIO>
<TEXT>
 hypersonic tunnel .
  flow surveys have been made in
the first of several nozzles to be
investigated in the langley 11-inch
hypersonic tunnel .  the nozzle was
designed by the method of characteristics
for a mach number of 6.98 .  two
step expanded the air in the
horizontal plane to a mach number of 4.36
and the second in the vertical
plane to a mach number of 6.98 .
  the test results showed that, although
a maximum mach number of
about 6.5 was obtained, the flow in the
test section was not sufficiently
uniform for quantitative wind-tunnel test
purposes .  deviations from the
design flow were traced to the presence
of a thick boundary layer which
developed in the first step along the
parallel walls .
</TEXT>
</DOC>
