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<DIV><FONT face=Arial size=2>Hi Dean,</FONT></DIV>
<DIV><FONT face=Arial size=2>I haven't kept up with rules in pattern but it is
not clear where this "break" in pitch prior to the snap came from. If the
airplane snaps it must have reached a high angle of attack meaning it
pitched. Why must the pitch lead the yaw? In fact it sounds like
everyone likes the opposite yaw prior to the pitch. Something doesn't add
up.</FONT></DIV>
<DIV><FONT face=Arial size=2>Jim</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=d.pappas@kodeos.com href="mailto:d.pappas@kodeos.com">Dean Pappas</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, December 30, 2004 11:19
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: Displacement during snap
rolls (was Why is it so quiet?)</DIV>
<DIV><BR></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff
size=2>Harrumph, Bob!</FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff
size=2>There will and must be a high G spike in an unloaded snap to get the
stall to occur. Once the stall develops, the G loading is limited, but not
necessarily to 1G.</FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff size=2>If
the entry speed is higher than the 1G stall speed, then the G loading during
the first half turn or so is going to be a function of the higher
speed. </FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff size=2>Then
the energy bleeds off rather quickly.</FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff
size=2>That's almost a good functional definition of a high-energy
snap.</FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff size=2>I've
ridden through a great many snaps in a Decathlon, and because they were always
entered at moderate (sub maneuvering) speed, they weren't all that
violent.</FONT></SPAN></DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=941073315-30122004><FONT face=Arial color=#0000ff
size=2>Happy New Year ...</FONT></SPAN></DIV>
<DIV> </DIV>
<P><FONT face="Times New Roman">Dean Pappas</FONT> <BR><FONT
face="Times New Roman">Sr. Design Engineer</FONT> <BR><FONT
face="Times New Roman">Kodeos Communications</FONT> <BR><FONT
face="Times New Roman">111 Corporate Blvd.</FONT> <BR><FONT
face="Times New Roman">South Plainfield, N.J. 07080</FONT> <BR><FONT
face="Times New Roman">(908) 222-7817 phone</FONT> <BR><FONT
face="Times New Roman">(908) 222-2392 fax</FONT> <BR><FONT
face="Times New Roman">d.pappas@kodeos.com</FONT> </P>
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<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
discussion-request@nsrca.org [mailto:discussion-request@nsrca.org]<B>On
Behalf Of </B>Bob Richards<BR><B>Sent:</B> Thursday, December 30, 2004 10:26
AM<BR><B>To:</B> discussion@nsrca.org<BR><B>Subject:</B> Re: Displacement
during snap rolls (was Why is it so quiet?)<BR><BR></FONT></DIV>
<DIV>A stalled wing is still producing lift. Just look at the 3D
fliers.</DIV>
<DIV> </DIV>
<DIV>If you look at a lift curve (angle-of-attack vs lift), the lift keeps
increasing linearly until the wing begins to stall. Even after a portion of
the wing has begun to stall, the lift will still increase, just not
linearly. At some point (a very deep stall) the lift will decrease, but
never go to zero.</DIV>
<DIV> </DIV>
<DIV>JMHO.</DIV>
<DIV> </DIV>
<DIV>You are correct that a stall can occur at any airspeed or attitude.
Also, the plane does not have to be stalled just because it is below the
"stall speed".</DIV>
<DIV> </DIV>
<DIV>Someone mentioned in this discussion about it being impossible to
break a wing doing a snap roll, if they do then they did not do a proper
snap roll. It is possible to break a wing, from the mere fact that the
angle-of-attack can't possibly increase from a normal to a stalled condition
instantaneously -- it must go through a range of AOA that will include the
maximum lift AOA. Technically, the "snap" did not break the wing, the entry
into the snap DID.</DIV>
<DIV> </DIV>
<DIV>In full-scale planes, there is something called "maneuvering
speed". Over that speed, it is possible that full control surface
deflection can cause the G forces to exceed the design limits of the
airframe. I'll bet that the number of full-scale pilots that have
succesfully performed snap-rolls under the "maneuvering speed" far exceeds
those that have done snaps over that speed. :-)</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Bob R.</DIV>
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