<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2900.2523" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>Earl:<BR><BR>Really good description! I am
working now on my own snaps to improve the initial elevator "break". I
suggest to everyone else to take the time to think over how you do a snap.
This next year, I will be looking much harder for a break prior to
rotation... If not, you will know that you earned that zero!
LOL</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Tony Stillman<BR>Radio South<BR>3702 N. Pace
Blvd.<BR>Pensacola, FL 32505<BR>1-800-962-7802<BR><A
href="http://www.radiosouthrc.com">www.radiosouthrc.com</A></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=ehaury@houston.rr.com href="mailto:ehaury@houston.rr.com">Earl
Haury</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">Discussion List, NSRCA</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, December 29, 2004 11:43
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Fw: snap displacement</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV style="FONT: 10pt arial">----- Original Message -----
<DIV style="BACKGROUND: #e4e4e4; font-color: black"><B>From:</B> <A
title=ehaury@houston.rr.com href="mailto:ehaury@houston.rr.com">Earl Haury</A>
</DIV>
<DIV><B>To:</B> <A title=tony@radiosouthrc.com
href="mailto:tony@radiosouthrc.com">tony@radiosouthrc.com</A> </DIV>
<DIV><B>Sent:</B> Wednesday, December 29, 2004 10:22 AM</DIV>
<DIV><B>Subject:</B> Re: snap displacement</DIV></DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>A snap is a complicated maneuver that's performed
in a blink of an eye. The words of the rules are static and may be studied at
leisure. Perfect resolution of either is not easy! I perceive confusion
between "break" and "offset", the rules state that "the CG should
<EM>ideally</EM> follow the geometric path of the maneuver". I suggest that
everyone interested in flying and/or judging snaps carefully read the maneuver
description in the rule book(s).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>OK - so why the weasel word "ideally" in the
rules? The answer provides the opportunity for us to improve snaps! The clue
is in the statement "initiated by a <EM>rapid stall</EM> of the wing induced
by a change in pitch <EM>attitude". </EM>Unfortunately, no matter how rapidly
the pitch attitude is changed, the wing will generate some lift until it
reaches critical AOA and stalls. This brief moment of lift moves the aircraft
from the original track, providing the "separation". The separation is
<STRONG>NOT </STRONG>the "break", but it is a consequence.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>How come some snaps jump all over the place, both
in pitch and yaw directions, and others don't? Set-up and
execution.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>First - set-up: The faster the pitch
attitude change the better. Fast strong servos are a must. A secret - we've
always considered setting up linkage to maximize servo travel for best
resolution - servos are so good now that we can change the linkage to reduce
servo travel and therefore transit time for snaps. Another secret - if you
have expo in the setup for snaps the break will be slower and more offset will
occur. Travel amounts will vary by airplane - have enough to clearly display
snap characteristics and no more. BTW, upline / downline snaps require more
pitch change to achieve critical AOA as the wing isn't lifting aircraft
weight.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Second - execution: Use the snap switch for
engine kill - forget it for snaps. Stuffing both sticks into the corners
doesn't get it either. Rapidly apply elevator first to achieve a pitch break
and stall, follow very closely with rudder (rudder application before the
stall results in sideways offset) to achieve the snap while reducing the
elevator to minimize pitch progression (the wing is stalled - not the
elevator) for precise exits. Oh - aileron application at the same time as
rudder will handle the wing rotation inertial issues. Exit by simply
releasing. Control input timing takes practice and will likely be different
with the same airplane for snaps in different attitudes (horizontal - vertical
- etc.) </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Quique has been mentioned in this thread, as have
the skills of some judges. I'll offer that Quique has idealized his snaps so
that they minimize disruption of maneuver geometry. On a horizontal line
and/or center maneuvers the break is clear in pitch and there is very little
offset, the tail cones as the aircraft rotates on the CG, and the pitch
attitude clearly is returned to the original attitude at the snap finishes.
Guys -that ain't a zero and I don't score it as such! On the other hand - the
same snap on a turn-around vertical presents so that the pitch break is not
visible - even though I think I know what's going on, if I don't see the break
I will and have zeroed those. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I see a whole lot more of are snaps
that are pitched / yawed slowly so that the track changes 10 or 15
degrees (along with similar roll) before the stall occurs - hmm - down to a
seven or so, then the snap rotation is stopped an equal amount early so that
the airplane can be flown to the finish. These things are easily a 4 or less!
Unfortunately, some of the perpetrators of these abominations are the first to
criticize those who have done the work to figure it out.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I hope some of this info is useful. Be critical
of your snaps and study how set-up and technique effects the outcome. A video
camera is very useful for study of snaps (amazing how many are really barrel
rolls), use slo-mo for critical examination. A data logger is also useful as
it logs elevator input - altitude - speed changes. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Earl</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=tony@radiosouthrc.com
href="mailto:tony@radiosouthrc.com">tony@radiosouthrc.com</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> Wednesday, December 29, 2004 8:41
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> snap displacement</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>I have seen many full-scale pilots do snaps
without any noticeable displacement. I have also seen these same
pilots do poor ones that did displace. I think you must downgrade it
some (1 point per 15 deg).</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Tony Stillman<BR>Radio South<BR>3702 N. Pace
Blvd.<BR>Pensacola, FL 32505<BR>1-800-962-7802<BR><A
href="http://www.radiosouthrc.com">www.radiosouthrc.com</A></FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>