Supplementary Investigation in the Langley Free-Spinning Tunnel of a 1/20-Scale Model of the Douglas XF4D-1 Airplane Including Spin-Recovery Parachute Tests of the Model Loaded to Simulate the Douglas F5D-1 Airplane Page: 3 of 15
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Because of pilot confusion during a recent spin test demonstration
of an X4D-I airplane the controls were moved improperly for spin recov-
ery, and it became necessary for the pilot to use the spin-recovery par-
achute to recover from an inverted spin. Spin-tunnel tests conducted
previously on a model of the XFhD-1 (ref. 1) had indicated that rudder
reversal to full against the spin should satisfactorily terminate inverted
spins. In order to avoid pilot confusion in in applying the rudder in
inverted spins, however, it would appear desirable merely to neutralize
the rudder, provided this movement would lead to satisfactory recoveries.
Accordingly, supplementary tests were undertaken on the available 1/20-
scale model of the Douglas XtD-1 airplane in the Langley 20-foot free-
spinning tunnel to determine whether neutralization of the rudder would
satisfactorily terminate inverted spins. In addition, some erect spins
were conducted on the model to determine whether partial movement of
ailerons to with the spin would be sufficient to insure recovery from
erect spins. (Previous results presented in reference 1 indicated that
full aileron movement to with to with the spin would satisfactorily terminate
erect spins but that aileron movement to only one-third with the spin
was inadequate.) Tests were also conducted on the XFD-1 spin model
loaded to s muj te the F5D-1 loading to determine the size parachute
required for emergency recovery from demonstration spins for the F5D-1
airplane. (The XF4D-1 and F5D-1 airplanes are fairly similar
b wing span, ft
S wing area, sq ft
c mean aerodynamic chord, ft
x/5 ratio of distance of center of gravity rearward of leading
edge of mean aerodynamic chord to mean aerodynamic chord
Z/E ratio of distance between center of gravity and fuselage
reference line to ea aerodynamic chord (positive when
center of gravity is below line)
m mass of airplane, slugs
IX' ,IZ moments of inertia about X, Y, and Z body axes respectively,
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Klinar, Walter J. & Lee, Henry A. Supplementary Investigation in the Langley Free-Spinning Tunnel of a 1/20-Scale Model of the Douglas XF4D-1 Airplane Including Spin-Recovery Parachute Tests of the Model Loaded to Simulate the Douglas F5D-1 Airplane, report, December 30, 1955; (digital.library.unt.edu/ark:/67531/metadc64771/m1/3/: accessed January 20, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.