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• December 13, 2016 Create Date
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National Advisory Committee for Aeronautics, Technical Notes - Floating Characteristics of Rudders and Elevators in Spinning Attitudes as Determined from Hinge Moment Coefficient Data with Application to Personal Owner Type Airplanes

A study was made of available rudder and elevator hinge—moment—
coefficient data in order to determine the floating characteristics of
various types of rudders and elevators in spinning attitudes. Some
of the data were applied to specific spin attitudes obtained from
tests of a model of a typical personal—owner-type airplane in the
Langley 20—foot free—spinning tunnel. The results were studied with
regard to obtaining spin‘recovery upon releasing the controls.

The plain rudder generally floated with the spin at all spinning
attitudes. 0f the rudders investigated, the horn—balanced rudder
should be the most adaptable for obtaining desirable floating charac—
teristics at spinning attitudes. The partial—length overhangébalanced
rudder (rudder above the horizontal tail) should float near neutral
for steep spins and against the spin for flatter spins. The full—
length overhang—balanced rudder (a part of the rudder extending below
the horizontal tail), however, may float with the spin.

Plain, overhang4balanced, and beveled—trailingeedge elevators
should float in an up position in spins although the beveled—trailing—
edge elevator should float closest to neutral from an up position.
Horn—balanced elevators should also float in an up position. use of
large tabs deflected up should cause the elevator to float down in
spinning attitudes.

The problem of spin recovery has been extensively studied in
the past from the viewpoint of obtaining recovery by rapid manual
movement of the controls. References l and 2 present results of such
studies that may be considered applicable to personal—owner—type
airplanes. Civil Air Regulations, however, require_personal—owner—type
airplanes to recover from spins upon releasing the controls. (See
reference 3.) Some recent designs of personalrownerhtype airplanes
are considerably heavier than those of the past and difficulty has
been encountered in complying with these Civil Air Regulations.