<DOC>
<DOCNO>
593
</DOCNO>
<TITLE>
theoretical considerations of flutter at high mach
number .
</TITLE>
<AUTHOR>
morgan,h.g., runyam,h.l. and huckell,v.
</AUTHOR>
<BIBLIO>
j. ae. scs. 25, 1958.
</BIBLIO>
<TEXT>
  some of the theories for two-dimensional oscillatory air forces
which may be applied in flutter calculations at high mach numbers
are discussed .  these include linear theory, van dyke's
second-order theory, piston theory, landahl's method, tangentwedge
and tangent-cone approximations, newtonian theory, and
a new nonlinear-pressure method .  a comparison of the theories
is made by showing the results of flutter calculations for mach
numbers up to 10, and the possibility of flutter at these higher
mach numbers is pointed out .
  results of flutter calculations are shown to illustrate the various
effects arising from a nonlinear thickness theory .  the possibility
of large flutter speed thickness effects which depend on frequency
ratio is shown .  the influence of airfoil shape is discussed
and flutter speed trends with center of gravity and elastic axis
locations are presented .  some possible refinements of piston
theory are discussed for use at very high mach numbers .  these
include the use of local flow conditions and the use of newtonian
theory over the leading edge of a blunt-nosed airfoil .
</TEXT>
</DOC>
