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The Drag of Airplane Wheels, Wheel Fairings, and Landing Gears, III

The tests reported in this paper conclude the investiga-
tion of landing-gear drag that has been carried out in the
N. A. C. A. £0—foot wind tunnel. flhey supplement
earlier tests (reported in Technical Report No. 485) made
with full-scale dummy wheels, wheel faitings, and landing
gears intended for airplanes of 3,000 pounds gross weight
and include tests of tail wheels and tail skids.

For airplanes of this weight classification the results
indicate that the drag Qt: a landing gear having slight
wheel-strut interference will be materially less when
equipped with the proper size of streamline wheels than
when furnished with low-pressure wheels. The drag of
a cantilever landing gear is as low when equipped with
the proper size of streamline wheels as when equipped
with low-pressure wheels and the best type of wheel
fairing.

Two of the landing gears tested combine, to a high
degree, the structural advantages of the tripod types with
the low drag of the full cantilever types.

The drag of a conventional tripod landing gear with
streamline wheels can be reduced about 3.9 percent by
careful fairing of all strut intersections.

The suggestions and queries that followed the publi-
cation of reference 1 resulted in a considerable exten—
sion of the original program of the investigation of
landing-gear drag. The first part of the extended pro-
gram was reported in reference 2 and deals with tests
of landing gears for low-wing monoplanes having a
gross weight of about 16,000 pounds. The second
part of the extended program is herein reported and
contains information on the drag of nonretractable
landing gears for airplanes of about 3,000 pounds
gross weight.