Investigation at low speeds of deflectors and spoilers as gust alleviators on a model of the Bell X-5 airplane with 35 degree swept wings and on a high-aspect-ratio 35 degree swept-wing-fuselage model Page: 7 of 38
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NACA TN 4057
The inboard ends of these controls were at 0.54b/2 except for the
18-percent-span controls, which began at 0.41b/2. It can be seen from
these data that when the deflector was located along the 35-percent-
chord line the reduction in lift-curve slope did not decreasewith
decreased span of control as rapidly as when the deflector was located
along the 25-percent-chord line. It may also be seen that for the
35-percent-chord location the lift curve was linear, whereas for the
25-percent-chord location the lift curve was nonlinear.
Figure 6 shows the effect of spoiler projection on the linearity
of the lift curve of a typical spoiler-slot-deflector arrangement on
the X-5 model. In order to obtain linear or near linear lift curves
the correct ratio of spoiler projection to deflector projection must be
determined for each installation. For the X5, figure 6 indicates that
d -0.025
resulted in a linear lift curve. The effect, if any,
as -0.15
that nonlinear lift curves have on the gust-alleviation capabilities has
not been determined.
The effect of ventilation from lower to upper surface on the lift
curve is shown in figure 7. As the ventilation is increased, at least
up to the maximum used for these tests, the reduction in lift-curve
slope becomes larger.
The longitudinal stability characteristics of the X-5 model with a
butterfly-valve arrangement are presented in figure 8 for two spans. It
can be seen that the control with the longer span had a destabilizing
effect on the pitching moment, whereas the control with the shorter span
was more stable than the plain wing configuration up to a lift coefficient
of 0.70. These results indicate the problems that may be encountered with
some wings. The longitudinal aerodynamic characteristics of all the con-
trol configurations are presented in figures 9 to 25.
The effects of the devices on the lateral control characteristics
of the X-5 model are shown in figure 26, where the rolling-moment coeffi-
cient due to 100 of aileron deflection is plotted against angle of attack
for the wing equipped with a butterfly-valve or a spoiler-slot-deflector
arrangement. The inboard end of the aileron was at 0.66b/2,'and when the
devices extended outboard of this point (from 0.34b/2 to 0.84b/2), the
aileron was ineffective in the low and moderate angle-of-attack range.
However, when the devices were located entirely inboard of the aileron
(from 0.34b/2 to 0.66b/2), aileron control was maintained throughout the
moderate angle-of-attack range and the aileron had more than 50 percent
of the effectiveness of the aileron on the plain-wing configuration.
Since these spoiler-slot-deflector devices resemble a spoiler-slot-
deflector type of aileron, a few tests were made to evaluate such a6
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Croom, Delwin R. & Huffman, Jarrett K. Investigation at low speeds of deflectors and spoilers as gust alleviators on a model of the Bell X-5 airplane with 35 degree swept wings and on a high-aspect-ratio 35 degree swept-wing-fuselage model, report, June 1957; (https://digital.library.unt.edu/ark:/67531/metadc56647/m1/7/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.