Static longitudinal aerodynamic characteristics of a 52 degree sweptback wing of aspect ratio 2.88 at Reynolds numbers from 2,000,000 to 11,000,000 Page: 2 of 23
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NACA RM No. L8a25
NATIONAL ADVISORY COMMITTEE ~FOR A RONAUTICS
RESEARCH MEMORANDUM
STATIC LO K UDINAL AERODYNAMIC CORAACTERISTICS
OF A 520 SWEP.BACK WCI OF ASPECT RATIO 2.88 AT REYN LDS
NTUMBES FROM 2,000,000 TO 11,000,000
By James E. Fitzpatrick and Gerald. T. Foster
SUMMARY
The effects of changes in Reynolds number on the longitudinal aero-
dynamic characteristics of a 520 sweptback wing with an aspect ratio of
2.88 and NACA 6kg-112 airfoil sections were investigated. The range of
Reynolds numbers was from 2,000,000 to 11,000,000. The model was tested
with the leading edge both smooth and rough. The tests also included a
study of the flow changes at moderate to high lift coefficients.
Abrupt changes in the variations of the forces and moments were
observed at moderate lift coefficients; that is, the lift-curve slope
became higher, the pitching-moment curve became more stabilizing and
the drag suddenly increased. These changes were coincident with sepa-
ration around the tip leading edge. As the angle of attack was further
increased, the pitchim nt curve broke in a destabilizing direction
at the point of initial lift-curve-elope reduction.
The lift coefficient at which the initial changes in the force and
moment variations occurred for the smooth wing increased markedly with
Reynolds number. Roughness reduced the influence of Reynolds number on
this lift coefficient for Reynolds numbers beyond 3,600,000.
A max rum lift coefficient of 1.12 was attained on the plain wing
at the highest Reynolds number of the test, an increase of only 0.03
over that obtained at the lowest Reynolds number. The addition of split
flaps did not appreciably increase the ma~Ttr lift coefficient.
Roughness on the leading edge reduced the lift coefficient at which
the force and moment variations suddenly changed but had little influence
on the maximum lift coefficient.
The lift-curve slope through zero lift was slightly higher than
would be indicated by the swept-liftinline theory of Weissinger. Good
Agreement was also obtained between the calculated and experimentally
determined values of aerodynamic-center location.a ,
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Fitzpatrick, James E. & Foster, Gerald V. Static longitudinal aerodynamic characteristics of a 52 degree sweptback wing of aspect ratio 2.88 at Reynolds numbers from 2,000,000 to 11,000,000, report, November 16, 1948; (https://digital.library.unt.edu/ark:/67531/metadc57790/m1/2/: accessed April 22, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.