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• January 29, 2017 Create Date
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National Advisory Committee for Aeronautics, Technical Notes - Investigation at Low Speeds of Deflectors and Spoilers as Gust Alleviators on a Model of the Bell X-5 Airplane with 35° Swept Wings and on a High  Aspect Ratio 35° Swept Wing Fuselage Model

An investigation was made at low speeds in the Langley 500 MPH 7-
by 10-foot tunnel to determine the gust-alleviation capabilities (reduc—
tion in lift-curve slope) of spoilers and deflectors on a high-aspect-
ratio 55° swept-wing-—fuselage model and a l/h-scale model of the Bell
X—5 airplane with 55° swept wings.

The results indicate that deflector and spoiler-deflector types of
controls can be designed to provide considerable gust alleviation for a
swept-wing airplane while still maintaining stability and control.

Results reported in reference 1 showed that spoilers and deflectors,
when mounted near the leading edge of the unswept wing of a transport
model, were effective in reducing the normal acceleration due to gusts
by reducing the lift-curve slope. It was anticipated that this type of
control would be extended when rough air was encountered by a transport
airplane and remain extended as long as the airplane remained in rough
air. The investigation has been extended in this report to include
similar devices on swept wings.

A preliminary series of tests, referred to in reference 1, was made
on a wing with an aspect ratio of 8.55 and 5h.90 of sweep (referred to
the unswept-wing quarter-chord line). The results indicated that the
devices should be placed farther back on a swept wing than on the unswept
wing model of reference 1 and might require ventilation from the lower
to the upper wing surface. Several of the more effective configurations
found in these prelflminary tests were incorporated in the investigation
of the high-aspect-ratio model and the l/h—scale model of the Bell X-5 air-
plane with the wings swept back 35°.