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• August 26, 2016 Create Date
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National Advisory Committee for Aeronautics, Report - The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears, I

Tests were made in the 7’- by 10-foot wind tunnel
and in the 20-foot tunnel of the National Advisory
Committee for Aeronautics to determine the drag of a
number of airplane wheels, wheel fairings, and land—
ing gears designed or selected for an airplane of 3,000
pounds gross weight. All tests were made on full-
sieed models; those in the ’7— by 10-foot tunnel were
made at air speeds up to 80 miles per hour and those
in the 90-foot tunnel were made at air speeds up to
100 miles per hour. Although most of the landing—
gear tests were made in conjunction with a fuselage
and at 0° pitch angle, some of the tests were made in
conjunction with the fuselage plus wings and a radial
air-cooled engine and at pitch angles from —5° to 6°
to obtain an indication of the general eyfect of these
various items on landing-gear drag. All tests were
made in the absence of propeller slipstream.
The results of the investigation show that the lowest
drag recorded for any landing gear tested was 13
pounds, at 100 miles per hour and 0° pitch, and that
it might be possible to reduce this drag approximately
6' pounds by totally encasing the wheels of this gear
in fairings. The highest laruti/ng-gear drag recorded
was .98 pounds. Other points of interest brought out
were .' Fitting-plus-interference drag of ordinary
types of landing gears averages about 4.4. percent of
the drag due to these gears ,' low-pressure wheels and
tires may be used with little or no increase in landing-
gear drag; the proper wheel fairing may reduce the
drag due to a landing gear more than any other re-
finement; fairing of all struts is of great importance ,-
and landing gears having a single supporting strwt
have less drag than any other types of nonretracting;
gears. Also, the substitution of low-drag or retrac-
table landing gears for conventional types on high
drag airplanes results in a negligible increase in high
speed. Low-drag or retractable gears used in place of
conventional gears on low-drag airplanes result in a
substantial inwease in high speed or saving in power
at the same speed, the low-drag gear accomplishing
a large percentage of the gain obtainable from the use
of the retractable gear.