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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>Thanks, Don!</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>I think I follow, mostly.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>(quite a challenge presenting those details
without pictures and equations, I know) ;-)</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>Here's how I interpret:</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>1.) Increasing counter rudder required throughout
vertical deceleration.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff><SPAN
class=781175802-28102007>2.) Amount of counter rudder ("steepness" of
curve) is proportional to amount of directional stability.
</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff></FONT> </DIV>
<DIV><SPAN class=781175802-28102007></SPAN><FONT face=Arial><FONT
color=#0000ff>A<SPAN class=781175802-28102007>s a totally green pattern flyer, I
think I learned something practical here to take to the
field.</SPAN></FONT></FONT><BR></DIV>
<DIV><SPAN class=781175802-28102007><FONT face=Arial color=#0000ff>No wonder my
rotations often occur too early! :-)</FONT></SPAN></DIV>
<DIV><SPAN class=781175802-28102007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
<DIV><SPAN class=781175802-28102007><FONT face=Arial color=#0000ff>Jim
A</FONT></SPAN></DIV>
<DIV><SPAN class=781175802-28102007><FONT face=Arial
color=#0000ff></FONT></SPAN> </DIV>
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<FONT face=Tahoma size=2><B>From:</B> tocdon@netscape.net
[mailto:tocdon@netscape.net] <BR><B>Sent:</B> Saturday, October 27, 2007 8:01
PM<BR><B>To:</B> alberji@charter.net;
nsrca-discussion@lists.nsrca.org<BR><B>Subject:</B> Re: [NSRCA-discussion]
Weather Vane<BR></FONT><BR></DIV>
<DIV></DIV>The physical effect of weather vaning, as best explained in a
vertical upline (most profound and easily seen example).<BR><BR>Measure the
distance front of the aircraft to the center of gravity, subtract the
difference from that point to the center of side area lift (fuselage side
lift), times velocity squared, divided by the co-tangent of the angle
from vertical upline (this can be calulated by the second differential
equation at airspeed "a", for the horizontal component of velocity"b", during
a verical up-line of length "c"- which approaches zero in a perfectly wind
corrected crab angle- at least at any given instant) This is used
to calculate side- intertial force at each discrete point in time
"t" (otherwise the same lift-inertial phenomenon we feel during the
dreaded "downwind turn"). So the corrective input becomes a
parabolic arc (charted on a graph with the rudder input being the vertical
axis and inverse of velocity on the horizontal axis) for the rudder stick
to counteract the lift (minus x-axis (side force) gravitational pull as
the aircraft slows), such as that at the top of a stall turn, just before the
pivot.<BR><BR>In other words, differing rudder inputs are needed to
maintain the correct crab angle during each maneuver. Some planes that
have a center of lift far behind the center of gravity, requiring more rudder
correction to keep the plane from weather vaning too much. Thats why you
see some weather-vaning pattern designs moving the canopy forward, to bring
the two closer together (but ideally not at the same point) and therefore make
the plane feel as though it is self-correcting in a cross
wind.<BR><BR>All the above is referenced with respect to where the judges
(are) firmly planted.<BR><BR>All the best,<BR><BR>Don<BR>
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