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• December 6, 2016 Create Date
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National Advisory Committee for Aeronautics, Technical Notes - Flight Measurements of Buffeting Tail Loads

The magnitudes and frequencies of buffeting loads on the horizontal
tail of a fighter—type airplane have been determined in flight for
Mach numbers to about 0.80. Conditions of flight under which buffeting
of the horizontal tail occurs have also been determined.

For the test airplane, buffeting of the horizontal tail occurred
simultaneously with the attainment of maximum normal force at Mach
numbers below about 0.6h. Above this value of Mach number, buffeting
occurred before the attainment of maximum normal force. In the range
tested, Reynolds number had no appreciable effect on the buffeting
boundary determined in abrupt pull—ups. The buffeting tail-load increment
for constant dynamic pressure decreased as the flight Mach number was
increased to 0.8. The data indicate that critical combinations of buf—
feting and maneuvering tail loads that are above the limit load and approach
the design load for the horizontal stabilizer may occur in lowhaltitude,
lowespeed flight with rearward center—of—gravity positions at limit design
acceleration values.

Airplanes operating at high subsonic Mach numbers have encountered
tail buffeting of sufficient magnitude in maneuvering flight to be
objectionable to pilots and possibly to endanger the airplane structure.
Some previous study has been made of the buffeting problem (see
references 1 to 3); however, little of the available data was directly
applicable to the estimation of buffeting tail loads for design purposes.
A preliminary investigation of buffeting tail loads was accordingly
proposed as part of a program of aerodynamic—loads research planned on
a high—speed fighter—type airplane. The results of this investigation
are presented herein.

Studies have been made to determine the magnitudes and frequencies
of the buffeting tail loads at several altitudes for Mach numbers to 0.80.
The critical combinations of buffeting and maneuvering tail loads have
been ascertained by a comparison with the limit—load and designrload
conditions for the horizontal tail.