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• January 29, 2017 Create Date
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National Advisory Committee for Aeronautics, Technical Notes - Lift and Moment Responses to Penetration of Sharp Edged Traveling Gusts, with Application to Penetration of Weak Blast Waves

The lift and moment responses to penetration of sharp-edged
traveling gusts are calculated for wings in incompressible and supersonic
two-dimensional flow, for wide delta. and rectangular wings in supersonic
flow, and for very narrow delta wings. By using the two-dimensional
indicial-lift functions, some calculations of normal-acceleration response
are made for two mass ratios.

The results of these calculations indicate that the forward speed
of the gusts has a. large effect on the lift- and moment-response func-
tions. For incompressible flow, peaks exist in the early portion of the
lift response, which may be much larger than the steady-state value.
Some peaks also occur in the lift-response functions for supersonic
speeds but are much less pronounced and exceed the steady-state value in
only a few instances.

Calculations have also been made of the normal-acceleration response
to sharp-edged traveling gusts and indicate that this response tends
to follow the lift response very closely in the first few instants of
penetration; thus, the large peaks which exist in the lift response at
subsonic speeds are duplicated in the acceleration response.

The relation between gusts traveling at supersonic speeds and blast
waves is indicated, and the manner in which the calculated lift and
moment responses can be used in a linearized approach to the blast-load
problem is outlined.

The growth of the lift and moment on a wing entering a stationary
sharp-edged gust has been the subject of numerous investigations since
it was first calculated for incompressible two-dimensional flow in
references 1 and 2. However, very little work appears to have been done
on the subject of lift and moment response -to traveling sharp-edged gusts,
the only published results being those presented. for incompressible two-
dimensional flow in reference 3.