<DOC>
<DOCNO>
288
</DOCNO>
<TITLE>
the rolling up of the trailing vortex sheet and its
effect on the downwash behind wings .
</TITLE>
<AUTHOR>
spreiter,j.r. and sacks,a.h.
</AUTHOR>
<BIBLIO>
j. ae. scs. 18, 1951.
</BIBLIO>
<TEXT>
  the motion of the trailing vortices associated with a lifting wing
is investigated by theoretical and visual-flow methods for the
purpose of determining the proper vortex distribution to be used
for downwash calculations .  both subsonic and supersonic speeds
are considered in the analysis .
  it is found that the degree to which the vortices are rolled up
depends upon the distance behind the wing and upon the lift
coefficient, span loading, and aspect ratio of the wing .  while the
rolling up of the trailing vortices associated with high-aspectratio
wings is of little practical importance, it is shown that, with
low-aspect-ratio wings, the trailing vortex sheet may become essentially
rolled up into two trailing vortex cores within a chord
length of the trailing edge .
  the downwash fields associated with the two limiting cases of
the flat vortex sheet and the fully rolled-up vortices are investigated
in detail for both subsonic and supersonic speeds .  the
intermediate case in which the rolling-up process is only partially
completed at the tail position is also discussed .
</TEXT>
</DOC>
