• Version
• 155 Downloads
• 914.14 KB File Size
• 1 File Count
• November 28, 2016 Create Date
• November 28, 2016 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - Interference of Wing and Fuselage from Tests of 17 Combinations in the NACA Variable Density Tunnel Combinations with Special Junctures

As part of the wing—fuselage interference program in
progress in the N.A.C.A. variable-density wind tunnel, a
method of eliminating the interference burble associated
with critical midwing combinations was investigated. The
tinterference burble of the critical midwing combination
was shown to respond to modifications at the nose of the
juncture and_to be entirely suppressed with little or no
adverse effect on the high—speed drag by special leading-
edge fillets.

An extensive program of research is being conducted
in the N.A.G.A. variable—density wind tunnel on the inter-
ference between wing and fuselage at large values of the
Reynolds Number (references 1, 2, 3, and 4). Reference 1
outlined the wing—fuselage interference program and pre—
sented the initial and basic parts thereof, comprising
test results for 209 combinations that represented, to the
widest practical extent, the most important parameters of
combination, such as: wing position relative to the fuse-
lagea wing shape, Juncture shape, and fuselage shaPe. The
discussion therein was fundamental in nature and treated
the interpretation of wing—fuselage interference.

It was soon evident that many combinations having ex~
cellent high—speed drag characteristics would be barred
from consideration in any practical design problem because
of low maximum lifts. Specifically, the unfavorable ones
were mainly_midwing combinations of round fuselages and
low~drag efficient airfoils of moderate thickness and small
camber (e.g., the N.A.G.A. 0012). A premature flow break~
down, or interference burble, was usually associated with
such midwing combinations, whether or not split flaps were
employed (reference 4), and was responsible for the low
maximum lifts. Interference burbles may vary in character
and severity, however, and may not seriously reduce the
maximum lift, as Was'demonstrated by some unfilleted lowa
wing combinations. The different types of interference
burble were discussed in reference 1.

In the investigation reported.herein, a study of the
interference burble of the critical midwing combination
was made and a means for its elimination was derived. The
descriptions in table V of.the combinations tested indi»
cate the scope of the experimental investigation.