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National Advisory Committee for Aeronautics, Technical Notes - Free Spinning Wind Tunnel Tests of a Low Wing Monoplane with Systematic Changes in Wings and Tails - III - Mass Distributed Along the Wings

Eight wings and three tails, covering a wide range of
aerodynamic characteristics, were independently ballasted
so as to be interchangeable with no change in mass distri~
bution. For each of the 24 resulting wing~tail combina—
tions, observations were made of the steady spin ior four
control settings and of recoveries for five control manip—
ulations, the results being presented in the form of charts
comparing the spin characteristics. The tests are part of
a general investigation that is being made in the H.A.G.A.
free~spinning tunnel to determine'the effects of systematic
changes in wing and tail arrangement upon the steady-spin~
Ring and the recovery characteristics of a conventional
low-wing monoplane for various loading conditions.

The present loading was derived from the basic load—
ing condition (representative of an average of values for
21 American airplanes for which the moments of inertia
were available) by moving weight from the center of grav—
ity toward the wing tips so that the distribution of mass
along the wings was increased.

For the tail with deepened fuselage, raised stabilizer,
and full—length rudder, recovery was satisfactory and the
results were similar to those reported for the basic—loading
condition. For the tail with deepened fuselage, raised sta—
bilizer, and short rudder, an adverse effect resulted as
compared with the basic—loading results for the wings with
Army tips and H.A.G.A. 23012 or H.A.G.A. 6718 section and
for the wing with flaps. Eor the more nearly conventional
tail, an adverse effect resulted for the wing with Army
tips and N.A,C.A. 23012 section,_both with and without
flaps. For the wing with H.A.G.A. 0009‘section and for the
Army standard wing, this loading appeared to have a some-
what favorable effect.

The N.A.C.A. has undertaken a systematic_investiga—
tion in the free-spinning wind tunnel to determine, by
major independent variations, which of the dimensional and
the mass characteristics_pf an_airpl§ne_mhst greatly af~
feet the spin (reference l).

The results of tests ofweight wings and three tails
for a basic loading condition, representative of an aver-
age of values for 21 American airplanes for which the mo—
ments of inertia were available, have been reported in
reference 1. In reference 2 were presented the results
for the loading obtained by moving weight from the wing
tips-toward the center of gravity, the model thereby hav-
ing its mass distributed chiefly along the fuselage. The
Present paper contains the results of a similar series of-
tests for a loading obtained by'moving weight_from the ,
center of gravity toward the wing tips, the model thereby
having its mass distributed chiefly along the wing.