<DOC>
<DOCNO>
199
</DOCNO>
<TITLE>
measurement of two dimensional derivatives on a wing-aileron-tab
system .
</TITLE>
<AUTHOR>
wight,k.c.
</AUTHOR>
<BIBLIO>
part i, arc r + m 2934, 1955.  part ii arc r + m 3029, 1958.
</BIBLIO>
<TEXT>
  measurements have been made of the direct
two-dimensional damping and stiffness derivatives for a
in incompressible flow .
  corrections arising from the apparatus are discussed and
reference is made to an attempt to measure the direct
tab derivatives .
  the effects are shown of frequency parameter, amplitude of
oscillation, reynolds number, aileron angle and position
of transition on the wing .
  variation with frequency parameter is substantially the
same as for vortex-sheet theory and variation of amplitude
produces little change in both derivatives .  at the lowest
reynolds number there is little change in both derivatives
with variation of aileron angle for the condition of natural
transition, but at higher reynolds numbers the stiffness
derivatives increase at .
  a forward movement of transition reduces the stiffness
derivatives at the smaller aileron angles, but at,
at the lowest reynolds number, an increase results .
  similar trends are observed for the damping derivatives above .
  comparison with vortex-sheet theory shows that the
measured values of the stiffness and damping
derivatives are approximately 0.6 of the theoretical values .
  measurements have been made of the direct
tab derivatives and cross aileron-tab derivatives for a
per cent aileron and 4 per cent (approx.) tab .  in addition
some measurements of the direct aileron derivatives have been
made for comparison with earlier results together with a
number of static derivatives for the wing and controls .
  the influence is shown of frequency parameter, reynolds
number, position of transition, mean tab angle and sealing
of the control hinge gaps .  some tests have been made with
the ailcron set at minus 8 deg and the tab at plus 12 deg
for which condition the hinge moment on the aileron was zero .
  reasonable agreement with the values given by the /equivalent
profile/ theory is shown for both direct damping
derivatives and for the direct tab stiffness derivative .  the direct
aileron stiffness derivative shows some departure from
the theoretical value when .
  at and the natural transition, comparison
with the values given by flat-plate theory gives the
following approximate factors, where suffix denotes the
theoretical values ..
</TEXT>
</DOC>
