Dynamic Stability and Control Characteristics of a Delta-Wing Vertically Rising Airplane Model in Take-Offs, Landings, and Hovering Flight Page: 5 of 16
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CONF IDENT IAL
NtA RM L!:t IaA
stability and control characteristlcs of the model No tests were made
to simulate rough air or flight near ground obstructions.
The stability , control . aili ty, and general flight behavior w.er
determined from motion-picture records, from visual observation of the
flight tests) and from the pilot's impressions of the flying qualities
of the model. General flight behavior is a term used to describe the
over-all flying characteristics of a model and indicates the ease with
which a model can be flown. In effect, the general flight behavior is
much the same as the pilot's opinion of the flying qualities of an air-
plane and indicates whether stability and controllability are properly
proportioned.
Vertical take-offs were made by rapidly increasing the speed of the
propellers until the model took off. These take -..offs were rather abrupt
and the model generally climbed to a height of about 10 feet before the
power operator adjusted the power for steady hovering flight.
Tail-down landings were made by decreasing the speed of the pro-
pellers so that the model descended slowly until the landing gear was
about 1 foot above the ground. At this point the power was cut off
completely and the model dropped to the ground.
During the hovering flights with the tail near the ground, the
model was flown with the trailing edge of the control surfaces 12 to
18 inches above the ground. This height was maintained to the best of
the power operator's ability. Actually the model dropped so low at
times that the landing gear touched the ground and it rose so high at
times that the 'control surfaces were several feet above the ground, The
flight behavior of the model was judged, however, only when the control
surfaces were about 12 to 18 inches above the ground.
Some preliminary force tests were made to determine the center-of-
gravity locations which would result in satisfactory static longitudinal
stability in the normal, unstalled, level-flight condition.
RESULTS AND DISCUSSION
The results of the preliminary force tests (not presented herein)
indicated that, with a center-of-gravity location of 1 percent of the
mean aerodynamic chord, the model would have a reasonable degree of
stability of angle of attack over the range of angles of attack covered
in the force tests (00 to 31.). This center.-of-gravity location was
therefore, considered as the normal location and was used in most of
the flight testsCOND E.NTIAL
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Lovell, Powell M., Jr.; Bates, William R. & Smith, Charles C., Jr. Dynamic Stability and Control Characteristics of a Delta-Wing Vertically Rising Airplane Model in Take-Offs, Landings, and Hovering Flight, report, October 9, 1951; (https://digital.library.unt.edu/ark:/67531/metadc59023/m1/5/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.