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National Advisory Committee for Aeronautics, Technical Notes - Summary of Flutter Experiences as a Guide to the Preliminary Design of Lifting Surfaces on Missiles

A limited review is made of some experiences in the flight testing
of missiles and of wing flutter investigations that may be of interest
in missile design. Several types of flutter which may be of concern in
missile studies are briefly described. Crude criteria are presented
for two of the most common types of flutter to permit a rapid estimate
to be made of the probability of the occurrence of flutter. Many of the
details of the flutter picture have been omitted, and only the broader
elements have been retained so as to give the designer an overall view
of the subject.

Many different types of flutter may be encountered on airplanes,
propellers, helicopters, and missiles and the speed ranges and conditions
encountered lead to flutter phenomena that are widely different. Broadly
speaking, the phenomenon of flutter is generally concerned with vibra-
tions or oscillations of a lifting surface. Oscillations of a lifting
surface give rise to oscillations of the aerodynamic forces which in
turn, under certain conditions, may have phase characteristics that
increase the oscillations to dangerous amplitudes. Some types of flutter
may be mild; others may be disastrous. Flutter may involve fully estab—
lished flow or broken-down flow, high or low frequencies of the structure,
and one or more modes of vibration.

The missile not only experiences many of the flutter problems
encountered with airplanes but also presents many new and different
problems, depending upon the design and purpose of the missile. Examples
are: skin flutter, flutter of automatic controls or servomechanisms,
and flutter of short wings with ram Jets or external stores. Many of
these types of flutter can best be studied by difficult experiments,
others require long and tedious theortical investigations. For the more
common types there exist sufficient experimental data to evaluate simple ‘
criteria. In general so many factors enter into a flutter case that a u ‘
comprehensive criterion becomes quite unwieldy.