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National Advisory Committee for Aeronautics, Report - Comparison Between Theory and Experiment for Wings at Supersonic Speeds

In this paper, a critical comparison is made between emper-
imental and theorefical results for the aerodynamic char-
acteristics of wings at supersonic flightspeeds. As a prelimi-
nary, a brief, nonmathematical review is given of the basic
assumptions and general findings of supersonic wing theory
in two and three dimensions. Published data from, two-di—
mensional pressure-distribution tests are then used to illus-
trate the efiects of fluid viscosity and to assess the accuracy
of linear theory as compared with the more ezact theories
which are available in the two-dimensional case. Finally,
an account is presented of an NAC’A study of the orer—all
force characteristics of three-dimensional wings at super—
sonic speed. In this study, the lift, pitching moment, and
drag characteristics of several families of wings of varying
plan form and section were measured in the wind tunnel
and compared with values predicted by the three-dimensional
linear theory. The regions of agreement and disagreement
bet-ween experiment and theory are noted and dismcssed.

The aerodynamics of wings at supersonic flight speeds is
currently the subject of much research and discussion. As a
result of many recent investigations, based on the earlier
work of Prandtl, Ackeret, Busemann, and von Karmén, the
theory of the subject is well advanced, both as applied to
airfoil sections in two-dimensional flow and to complete,
three-dimensional wings. Experimental knowledge is, by
contrast, considerably less extensive, particularly with regard
to the three-dimensional case. There are, however, sufficient
experimental data in hand to permit a reasonably systematic
comparison between theory and experiment. It is the pur-
pose of this paper to present such a comparison insofar as the
current availability of experimental results will allow.

To provide background for those who are unacquaiuted
with the fundamentals of supersonic wing theory, it may be
useful to review briefly the assumptions and findings of work
in this field.