Langley full-scale-tunnel investigation of the fuselage boundary layer on a typical fighter airplane with a single liquid-cooled engine Page: 2 of 18
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3 1176 01433 3174
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
TECHNICAL NOTE NO. 1087
LANGLEY FULL-SCALE-TUNNEL INVESTIGATION OF THE FUSELAGE
BOUNDARY LAYER ON A TYPICAL FIGHTER AIRPLANE
WITH A SINGLE LIQUID-COOLED ENGINE
By K. R. Czarnecki and Jerome Pasamanick
SUMMARY
An investigation has been made in the Langley full-
scale tunnel to determine the thickness and shape of pro-
file of the boundary layer on the fuselage of a typical
monoplane fighter airplane with a single liquid-cooled
engine. The results showed that, for the range of angles
of attack and fuselage stations investigated, the maximum
displacement thickness was nearly 1.2 inches and was at
the most rearward station (81.6 percent of the fuselage
length). The displacement thickness was found to'be
greatly affected by the pressure gradients over the
windshield-canopy combination and in the wing-fuselage
juncture. An average value for the shape parameter (ratio
of displacement thickness to momentum thickness) between 1.53
and 1. was obtained for the turbulent boundary layer.
INTRODUCTI ON
The design of efficient charge-air and cooling-air
inlets for locations where the boundary layer is of
aopreciable thickness is generally complicated by the
tendency of the boundary layer toward separation in thfi
range of inlet-velocity ratios normally encountered in
high-speed or cruising flight. In some designs, par-
ticularly those in which the inlet is located ifn a region
of adverse pressure gradient or in which the inlet is
, flush with the fuselage surface, the pressure losses
resulting from flow separation are so large that it is
usually necessary to dispose of the boundary layer by
, means of an external gutter or an internal bypass duct.
Some idea of the quantities of air that must be removed
in order to obtain smooth flow with good pressure
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Czarnecki, K. R. & Pasamanick, Jerome. Langley full-scale-tunnel investigation of the fuselage boundary layer on a typical fighter airplane with a single liquid-cooled engine, report, June 1946; (https://digital.library.unt.edu/ark:/67531/metadc54857/m1/2/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.