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National Advisory Committee for Aeronautics, Report - Interference and Fuselage from Tests of 209 Combinations in the NACA Variable Density Tunnel

Tests of 209 simple wing-fuselage combinations were
made in the N. A. C. A. variable-density wind tunnel to
provide information regarding the efiects of aerodynamic
interference between wings and fuselages at a large value
of the Reynolds Number. This investigation is part of
a basic investigation of aerodynamic interference now
in progress at the Committee’s laboratory and considers
the interference as afiected by the more important variables
of a combined wing and fuselage.

Most of the tests were made with a round fuselage in
combination with a rectangular wing of symmetrical
section. Variations of the vertical position, longi-
tudinal position, and angular position were covered.
A suficient number of tests of other variables, such as
the wing and fuselage shape, were made to give a general
understanding of the efi'ects of these variables. 'For some
of the combinations in which the wing and fuselage were
not connected, the air forces on the wing and fuselage
were determined separately in order to investigate the
mutual interference.

The principal results are given in tabular form and
summarized by presenting the important characteristics
for all the combinations by means of parameters in a
single table so that the relative merits of the various
combinations may be readily compared. The results are
discussed in relation to the character, cause, and signifi-
cance of the interference efi'ects encountered under various
conditions.

The continual improvement in the aerodynamic
efliciency of airplanes may be ascribed to a gradually
increasing knowledge of the flow about single bodies
and the interference between them. As the units
making up a combination have been improved, the
residual drag arising from the interference has become
an increasingly important factor in relation to the
total drag. Many experimental data have now been
secured on which to base the design of efficient com-
ponent parts but adequate data concerning the inter-
ference between them are still lacking.