Effect on Drag of Longitudinal Positioning of Half-Submerged and Pylon-Mounted Douglas Aircraft Stores on a Fuselage with and without Cavities between Mach Numbers 0.9 and 1.8 Page: 2 of 46
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F L6NACA M L"54E26
NATIONAL ADVISORY CCWMITTEE FOR AERONAUTICS
EFFECT ON DRAG OF LONITUDINAL POSITIONING OF
HALF-SUfERGED AND PYLON-MOUNTED DOUGLAS
AIRCRAFT STORES ON A FUSELAGE WITH
AND WITHOUT CAVITIES BETWEEN
MACH NUMBERS O.9 AND 1.8
By Sherwood Hoffman and Austin L. Wolff
The effect on drag of positioning symmetrically mounted Douglas
Aircraft Company, Inc. stores in pairs on a parabolic fuselage of fine-
ness ratio 10.0 has been determined by flight tests of rocket-propelled,
zero-lift models through a range of Mach number from 0.9 to 1.8. The
stores were mounted in half-submerged positions and on pylons and were
tested in three longitudinal locations on the fuselage with the forward
position being located at the maximum diameter of the fuselage. The
effects on drag of removing the half-submerged stores or extending them
outward on pylons also was investigated by tests of models with half-
submerged-store cavities on the fuselage. Two pylons differing in air-
foil section and thickness were tested at the forward position of the
stores on the fuselage with cavities.
The half-submerged stores gave the smallest drag increments, which
were approximately equal regardless of their respective longitudinal
locations. Removing the half-submerged stores to expose the cavities
increased the drag increments from two to three times. For the pylon-
mounted stores, the store in the midposition had less drag than in the
forward or rear positions at supersonic speeds. Adding the half-
submerged-store cavities to the pylon-mounted-store configurations
reduced the drag at the rear position between Mach numbers 0. 95 and 1.50
and increased the drag at the midposition throughout the speed range.
Changing from the 6-percent-thick flat pylon to the 10-percent-thick
airfoil pylon increased the total drag slightly above Mach number 1.10.
Good agreement was obtained between the experimental and theoretical
interference drag coefficients for the pylon-mounted stores (without
fuselage cavities) in the three longitudinal locations tested at Mach
numbers 1.2 and 1. 5.
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Hoffman, Sherwood & Wolff, Austin L. Effect on Drag of Longitudinal Positioning of Half-Submerged and Pylon-Mounted Douglas Aircraft Stores on a Fuselage with and without Cavities between Mach Numbers 0.9 and 1.8, report, July 15, 1954; (digital.library.unt.edu/ark:/67531/metadc64117/m1/2/: accessed February 17, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.