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<DIV><FONT face=Arial size=2>Actually, this explanation has problems with
physics:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><STRONG><EM>Unlike the spin where the stall and wing drop are supposed to
occur simultaneously, the snap may have the pitch (stall) and the autorotation
begin simultaneously OR sequentially in that order (pitch then autorotation). No
downgrade applies if he starts the pitch and autorotation together. No downgrade
applies if he pitches and then immediately starts auto-rotating. If, however, he
initiates the rotation first without a pitch you ding him .5 for each 5 degrees
he rotates before he shows you the pitch. If he gets to 90 degrees without a
pitch, you zero the maneuver. </EM></STRONG></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>If you allow the simultaneous onset of the
autorotation and the pitch break without downgrade, it means that the
"autorotation" at the very beginning is actually just a sloppy roll. The
airplane isn't autorotating until the sudden yawing motion forces the retreating
wing to stall, or be more stalled then the advancing wing. Keep
trying!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Ed</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mups1953@yahoo.com href="mailto:mups1953@yahoo.com">mike mueller</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, February 04, 2009 8:30
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] IMAC and snap
roll rules</DIV>
<DIV><BR></DIV>
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<DIV> This is long but clear to me. I'd like to see our snap
discrption follow this one so we could clear up the unclear situation we
have now. Here it is. Thanks, Mike Mueller</DIV>
<DIV> </DIV>
<DIV><BR>by Bruce Hanley, IMAC Rules Committee Chair ---
<BR><BR>WLW-PilotsJudgesCornerAerobaticTurns_E6D7-Bruce_thumbThe first
issue you must decide when judging snaps is that he did or did not do
the type of snap called for by the Aresti. Snaps can be positive (pitch
to the canopy) or negative (pitch to the wheels). If he does
the wrong type, he gets a zero for the maneuver - the whole maneuver. If
he gets this part right, you go on to judge the rest of the
maneuver.<BR><BR>“Is it a snap” is the second decision you, as a judge,
must wrestle with. This is a binary choice. There is no gray area. You
must decide if he did or did not snap. If the answer is no, you zero the
maneuver - the whole maneuver. If the answer is yes, then you proceed to
judge the applicable downgrades for the snap and apply them to the
maneuver.<BR><BR>So lets deal with “Is it a snap”. To be a snap there
must be a stall and there must be autorotation. That is what the
F&JG tells us. The stall is a high speed stall induced by the pilot
with a rapid pitch movement that increases the angle of attack
sufficiently to stall a wing. The lift on the wing that is still flying
will force rapid rotation about the roll axis and also, combined with
rudder deflection, will produce a yaw in the direction of the roll. So
everything is moving here. A judge-able snap will have movement on all
three axis - pitch, roll and yaw.<BR><BR>When must the pilot get these
three motions all moving? Unlike the spin where the stall and wing drop
are supposed to occur simultaneously, the snap may have the pitch
(stall) and the autorotation begin simultaneously OR sequentially in
that order (pitch then autorotation). No downgrade applies if he starts
the pitch and autorotation together. No downgrade applies if he pitches
and then immediately starts auto-rotating. If, however, he initiates the
rotation first without a pitch you ding him .5 for each 5 degrees he
rotates before he shows you the pitch. If he gets to 90 degrees without
a pitch, you zero the maneuver. Note that many pilots intentionally and
legitimately delay the start of autorotation momentarily to be sure to
clearly show the pitch/stall before the start of autorotation in order
to minimize the risk of getting a zero.<BR><BR>So, how do you, the
judge, know that all this is happening as it should? Its hard since it
all happens so quickly but you can clearly identify the pitch that
starts it all. Without a pitch there will be no stall. No stall equals
no snap and results in a zero. Just don’t ding the guy if the
autorotation starts at the same time as the pitch/stall. At the point of
the break (stall) into the snap you have a couple of indicators that you
can use to make the “Is it a snap” decision. If he did
snap:<BR><BR> - There will be displacement of the plane’s
pitch axis relative to the entry line, i.e., entering the snap the plane
should not be on the same exact line as it was prior to the snap. If he
stalled, he went either to the canopy or the wheels and he shouldn’t be
on the identical line.<BR><BR> - There will be yaw
displacement. The rudder deflection and stall of the wing will yaw the
plane in the direction of rotation. So on entering the snap the plane
will be pointed at some angle (it may be small) to the line he was on
before the snap.<BR><BR>Note that these are only indicators. They are
not of themselves judging criteria.<BR><BR>But, to look at it another
way, if he remains on exactly the same line during his snap he did an
aileron roll. If he spirals around his entry line, he is doing a barrel
roll. Neither case qualifies as a judge-able snap and each should be
zeroed.<BR><BR>Before we talk about downgrades for judge-able snaps,
lets consider what the pilot must do after the snap. What he must do is
immediately get the plane back on the required flight path in the
appropriate attitude. So, given the discussion above, since he has
pitched and yawed from his original track, he will likely have to make a
pitch and a yaw correction to resume the correct flight path. If the
snap is being done on a line, the post snap line should be parallel to
the pre-snap line but not identical to it since it will be displaced by
some distance from the pre-snap line. This may be a very small distance.
If the snap is being done on an arc, he may or may not need to realign
in order to continue along the radius he is flying. The critical point
is that you should not downgrade the guy for realignment movements done
immediately after the snap. These movements may not be perceptible but
if they are he is allowed to “straighten” the plane without downgrade.
He must do this immedia<BR>tely after completion of the snap. If the
realignment is necessary and he delays it he will be showing you a
misaligned line or arc that is inconsistent with the Aresti and you
should downgrade that line or arc.<BR><BR>OK - he did a snap, it was the
correct type of snap and you did not zero it. What are the downgrades
that may apply. For the snap element itself, the only downgrade is under
or over rotation. Once autorotation is initiated in the snap the pilot
must maintain autorotation to exactly the stopping point called for by
the Aresti. If he stops early, you downgrade .5 for every 5 degrees that
he under rotated. Same if he over rotates. Note that it is common to see
a pilot come out of autorotation early and aileron to the finish - and
some pilots do it very skillfully. This gets a downgrade and is treated
as the under rotation just covered, i.e., you ding him .5 for 5 for
however much he is aileron-ing to the finish. The indicator that you
look for to identify that this is happening is a change in the rate of
rotation. Rotation rate is not in itself a judging criteria within
snaps, but the rate of rotation within an autorotation will be pretty
constant and any change will be gradual as the<BR>plane loses energy in
the snap. So, a perceptible and perhaps abrupt change of roll rate
toward the end of the snap is a clue that the pilot is not auto-rotating
to the finish but, rather, is completing his snap with ailerons. It can
be a tough call.<BR><BR>Beyond the snap element itself you must, in
judging a snap, be alert to the following:<BR><BR>- Line
centering: If the snap is done on a line, it must be centered on
the line. If it is not the following downgrade applies based on the two
line segments either side of the snap:<BR><BR> - line
segments vary but the difference is less that 2 to 1 - deduct 1
pt<BR><BR> - line segments differ by 2 to 1 but less than 3
to 1 - deduct 2pt<BR><BR> - line segments differ by 3 to 1
or more - deduct 3 pt max<BR><BR> - omits one line segment
- deduct 4 pt<BR><BR> - omits both line segments - deduct 2
pt<BR><BR>- Exit of a part loop: If the snap is done when exiting a part
loop such as at the exit of an Immelman it must be done exactly at the
completion of the part loop. If not the following downgrades
apply:<BR><BR> - If done early before the completion of the
part loop ding him .5 for each 5 degrees that he is early<BR><BR>
- If done late and he shows you a line after completion of the
part loop and before the snap, it is a t least a two point deduction -
more if the line is extended. The F&JG doesn’t help us with applying
a deduction of more than two points. Also, at some point the line can
get so long that the maneuver should be zero’d. Again the F&JG
doesn’t help us here. It is up to you to set some personal standard for
these cases. Just be consistent.<BR><BR>- Entry to a part loop: If the
snap is done when entering a part loop such as at the beginning of an
Split S, the arc of the part loop must begin immediately after
completion of the snap.<BR><BR> - If he shows you a line
after the snap and before starting the arc, it is again the same “at
least two points” deduction just discussed above. Again, you have to
personally come up with a scheme for handling the “more if
extended”.<BR><BR> - If he is late and starts the arc
(establishes a radius...) and then does the snap we again are left on
our own. If he only impinges a little on the arc and does the snap I
would ding him .5 for 5 for being late. If he is very noticeably late I
would zero the maneuver. What is a “little” and what is “noticeably
late” again requires that you set a personal standard that you can apply
consistently.<BR><BR>- Arc centering: If the snap is done on an arc
(loop or part loop) it must be centered on that arc. If it is not
centered the following downgrade applies:<BR><BR> - 5 for
each 5 degrees that he misses the center<BR><BR>- Follow the arc:
If the snap is being done on an arc (loop or part loop) it must follow
the radius of that arc during the time that it is being executed. The
alternative is to flatten out the radius and do the snap on a line. In
general, adding a line where you shouldn’t have one is a 2 pt deduction.
So, if he does not follow the arc during the snap and instead does it on
a line, or shows you well defined lines before and/or after the snap,
the following downgrades apply:<BR><BR> - 2 pt if he
flattens out and does the snap on a line<BR><BR> - 2 pt per
line if he shows you a defined line (no radius) before the snap is
initiated or after the snap is completed. What is the length that makes
it a “defined line” is up to you.<BR><BR>Note that the snap may be done
as part of a combination of optional elements. For example: a line that
has a snap followed by an opposite half roll. If so, then the downgrades
discussed above (centering, follow the arc, etc...) always apply to the
total combination. The exception to this is the spin. The spin is an
optional element which ends with a down line. Another optional element
such as a snap after the spin may be required on that down line and if
so there is no centering requirement imposed upon it.<BR><BR>So that is
pretty much it. The difficulty in judging the snap lies with the speed
of the maneuver and how quickly it all happens. You really have to be
paying attention and anticipating the snap so you are concentrating on
what the pilot actually shows you. As with all judging it is critical to
know the sequence to avoid looking away from the plane - and, as always,
the pilot gets the benefit of the doubt.</DIV></TD></TR></TBODY></TABLE><BR>
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