<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hey Mark,<br>
<br>
I was going to add that it doesn't take a rocket scientist to have to
explain all of this to us....then Jerry posted. :)<br>
<br>
You are right, we are making this much more difficult. The real
problem is - we are not going to have this discussion all winter long
as usual since it was brought up in October!<br>
<br>
Chris<br>
<br>
Atwood, Mark wrote:
<blockquote
cite="mid:99B8EFCA36A5724F87FF3C71B431D87216DB45B2D5@PEVM01.paragon-inc.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html; ">
<meta name="Generator" content="Microsoft Word 12 (filtered medium)">
<!--[if !mso]>
<style>
v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style>
<![endif]-->
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";}
span.apple-style-span
{mso-style-name:apple-style-span;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;}
span.EmailStyle23
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="Section1">
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">So
at the end of the day, we don’t really do a snap…ever.
I think many have always known that but this (assuming Sir Budd’s math
is
correct) basically ends the debate.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">So
what we’re doing then in Pattern is trying to emulate
the look of a snap…not actually snap. As such, I have a VERY hard
time with the zeroing of a poor attempt. Downgrade yes, but not the
spurious snap nazi zero. (I’m pretty sure I just set myself up for
a few of them)… <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">This
suddenly because a lot easier. It’s like
judging a loop. Instead of trying to draw a circle were trying to make
the plane look like it snapped… and some will do a better job than
others. As with the loop there will be variances… Loops big
and small, snaps tight or open, etc, but at the end of the day, if you
recognize the maneuver, it should probably be scored. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">My
$0.02<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><b><span
style="font-size: 13.5pt; color: rgb(118, 146, 60);">Mark Atwood</span></b><span
style="font-size: 13.5pt; color: navy;"><br>
</span><span style="font-size: 10pt; color: rgb(31, 73, 125);">President<br>
</span><b><i><span style="font-size: 11pt; color: rgb(31, 73, 125);">Paragon
Consulting</span></i></b><span
style="font-size: 10pt; color: rgb(31, 73, 125);"><br>
office ~ 440-684-3101 ext. 102<o:p></o:p></span></p>
<p class="MsoNormal"><u><span
style="font-size: 10pt; color: rgb(84, 141, 212);"><a class="moz-txt-link-abbreviated" href="mailto:mark.atwood@paragon-inc.com">mark.atwood@paragon-inc.com</a></span></u><u><span
style="color: rgb(84, 141, 212);"><o:p></o:p></span></u></p>
<p class="MsoNormal"><b><span
style="font-size: 10pt; font-family: "Tahoma","sans-serif"; color: navy;"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span
style="font-size: 10pt; font-family: "Tahoma","sans-serif"; color: rgb(118, 146, 60);">IT
Solution Providers: Custom Software Development. Staff
Augmentation. </span></b><span style="color: rgb(118, 146, 60);"><o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><o:p> </o:p></span></p>
<div>
<div
style="border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; border-width: 1pt medium medium; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span
style="font-size: 10pt; font-family: "Tahoma","sans-serif";">From:</span></b><span
style="font-size: 10pt; font-family: "Tahoma","sans-serif";">
<a class="moz-txt-link-abbreviated" href="mailto:nsrca-discussion-bounces@lists.nsrca.org">nsrca-discussion-bounces@lists.nsrca.org</a>
[<a class="moz-txt-link-freetext" href="mailto:nsrca-discussion-bounces@lists.nsrca.org">mailto:nsrca-discussion-bounces@lists.nsrca.org</a>] <b>On Behalf Of </b>Budd
Engineering<br>
<b>Sent:</b> Wednesday, October 14, 2009 6:13 AM<br>
<b>To:</b> General pattern discussion<br>
<b>Subject:</b> Re: [NSRCA-discussion] How I became an expert Snap
Judge (TIC)<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Chris, Vicente, et al.,<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Angle of attack, alpha or AOA, for the aircraft
is the
difference between the flight path angle, gamma, and the aircraft
attitude,
theta (assuming the airfoil zero lift angle is essentially aligned with
the
aircraft reference datum, which for all practical purposes on our
designs, it
is). Reference: <a moz-do-not-send="true"
href="http://www.aerospaceweb.org/question/aerodynamics/q0165.shtml">http://www.aerospaceweb.org/question/aerodynamics/q0165.shtml</a>.
Flight path angle is the aircraft trajectory, or in pattern speak,
"track"
but along the pitch axis, i.e. climbing or descending. In level,
steady
state flight (~1-g), the flight path angle is zero. Which means that
the
angle of attack is equal to the aircraft pitch attitude. If you run
the
numbers using a reasonable airfoil lift curve slope at a representative
level
flight speed for our planes you'll find that our planes trim out around
~ 0.5
degrees alpha (Lift = Weight = CL * Qbar * S where CL is the lift
coefficient,
Qbar is the dynamic pressure, and S is the reference wing area). This
is
because of our extremely low wing loading, it simply doesn't take a lot
of
angle of attack to generate 1-g of lift when your airplane only weighs
10 or 11
lbs. Here's the other part: with the exception of velocity (or
airspeed),
the equation is linear, which means that if you double the aircraft
weight, for
the same flight speed, you get twice the alpha (again, for 1-g trim).
Or
if you kept the weight at say 10 lbs, but cut the wing area in half,
the angle
of attack would then double to ~ 1 degree (again, for level, steady,
1-g
flight). Velocity is a little trickier to account for because it's a
non-linear second order function in the lift equation (remember Qbar?
Reference: <a moz-do-not-send="true"
href="http://en.wikipedia.org/wiki/Dynamic_pressure">http://en.wikipedia.org/wiki/Dynamic_pressure</a>,
Qbar = 1/2 * rho * V**2) where rho is air density and V is the
velocity).
Essentially, the lift doubles every time we increase Qbar by 2, or
velocity by the square root of 2 (or 1.414). So if you're flying along
in
level flight at 60 mph (88 feet per second), and you speed up to 85 mph
mph
(124.45 feet per second), you've doubled your dynamic pressure (Qbar)
and to
stay at level 1-g flight, you'd have to retrim your plane in pitch to
1/2 of
what your AOA was before (or you'll start climbing). In this case the
AOA
would be ~ 0.25 degrees (as would the pitch attitude). One last bit of
info for the point I'm about to make is that the lift curve slope for
our
airfoils at the Reynolds Numbers we are operating at is linear out to
around
~15-16 degrees alpha, with separation of lift occurring above that,
closer to
18-20 degrees alpha (Reference: <a moz-do-not-send="true"
href="http://www.aerospaceweb.org/question/aerodynamics/q0136.shtml%29">http://www.aerospaceweb.org/question/aerodynamics/q0136.shtml)</a>.
Note that the onset of separation is independent of airspeed, it's
purely
a flow angle phenomenon, i.e. you can stall an airfoil at any airspeed,
or
attitude (if you can get to a high enough angle of attack). That's
essentially what Chris is saying below.<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">So what does this all mean?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">If you look at the numbers, for our planes, you
can't get to
stall from steady level flight (at any reasonable cruise speed) without
inducing a significant G-loading on the aircraft (which will cause a
noticeable, and very observable, change in the flight path angle),
BEFORE the
airfoil stalls.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Here's some more numbers to help you connect the
dots:
from level 1-g trim flight at 1/2 degree AOA, you'd have to induce
nearly
30 g's to get to ~ 15 alpha, not likely you'd be able to do that
without seeing
it. Even starting at 2 degrees AOA (which is a lot for our models),
you
have to generate nearly 5-6 g's to reach stall (think you'd notice
that?).
Don't believe me? OK answer this: Have you ever quickly but
smoothly from level upright 1-g flight at a normal cruise speed input
full aft
stick for a second or two and then release it but no lateral input?
What
happens? Unless something is grossly wrong with your airplane you're
likely to see a rapid pitch up and a corresponding change in flight
path angle,
probably to something approaching a near vertical attitude, but not
much else.
Why? Our planes are so lightly loaded that only at spin entry and
landing speeds can we induce enough angle of attack to approach stall
on the
airfoil on the plane without inducing significant g's and grossly
altering the
flight path angle (and flight path angle is what we really see when
we're
flying at cruise speeds BTW, not so much the pitch attitude until we're
at much
lower speeds. That's because we mentally integrate the velocity vector
in
our minds but that's a topic for another time/day). Full scale
aerobatic
planes (and to a lessor degree IMAC planes) don't suffer this problem
nearly so
badly since their wing loadings and inertia's are much higher (dynamic
stability is somewhat more complex than static stability so I'm not
going to go
much further than this on this topic). The bottom line is this:
we're not stalling the wing when we do our snaps, not even a portion
of
it (unless you're VERY low on airspeed at entry such as a spin). We're
too lightly loaded to get to stall at any reasonable airspeed, the
airplane
will respond too quickly in the pitch axis resulting in a rapid change
in
flight path angle, effectively unloading the AOA during the response.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">So what are we doing to make the plane present
what appears
to be a snap roll when we can't actually be stalling the wing
asymmetrically to
induce autorotation like many claim? Lots of control power in pitch
and
roll coupled with additional rolling moment induced by dihedral effect
(sideslip driven by rudder input). Pretty much everyone knows that at
higher AOA you can command/control roll with rudder, well that's due to
dihedral effect (roll with rudder), it gets more powerful with a little
AOA.
That's where you get the part of the dynamic that visually emulates a
full scale snap roll but physically is quite different (you can make it
look
like a full-scale snap, but it really isn't).<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">So the bigger question is should emulating a
full-scale snap
roll be a pattern judging criterion or do we even care? (we know what
the
answer is for full scale aerobatics and probably IMAC too but we are
neither of
these). Until we decide the answer to THAT question, we're really just
debating "how many angels can dance on the head of a pin"...<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">OK, it's really, really late out here on the
left coast,
I've gotta get to bed. Shoot away.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Thx, Jerry<o:p></o:p></p>
</div>
<div>
<div>
<div>
<div>
<p class="MsoNormal"><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><br>
Budd Engineering<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><a
moz-do-not-send="true" href="mailto:jerry@buddengineering.com">jerry@buddengineering.com</a><o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size: 10.5pt; font-family: "Helvetica","sans-serif"; color: black;"><a
moz-do-not-send="true" href="http://www.buddengineering.com">http://www.buddengineering.com</a><o:p></o:p></span></p>
</div>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Oct 13, 2009, at 8:54 PM, Chris Moon wrote:<o:p></o:p></p>
</div>
<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<div>
<p class="MsoNormal"><span
style="font-size: 13.5pt; font-family: "Helvetica","sans-serif"; color: black;">Ahhh.
angle of attack is not the same as the aircraft
attitude.Websters defines angle of attack as "the acute angle between
the
chord of an airfoil and the line of relative air flow". The relative
wind flows parallel and opposite the direction of the wing's movement
through
the air.The wing's attitude as we see it from the ground is NOT the
same as
angle of attack. If you are in a vertical climb is the wing stalled?
After all it is 90 degrees ATTUIUDE from your perspective on the
ground, right?
But the wing is not stalled because the relative wind is coming
parallel and
opposite the direction of flight. You can be in a nose low descent and
stall a
wing. Now take a straight and level pass and give it an instantaneous
large amount of up elevator. What happens? First, the plane continues
in the
direction it was going (straight ahead) for a short time, but what is
important
is that the angle between the relative wind (straight ahead) and the
wing which
is now pivoting up increases until it reaches the critical angle of
attack and
it stalls. Without knowing the specifics of that wing design, we can't
know when exactly this will occur, but it can be extremely fast and at
a
relatively low ATTITUDE in relation to the ground. Hence, you do not
need
a high nose ATTITUDE in order to have a high angle of attack. There are
too
many variables for one to say that they need to see a nose high
attitude in
order to define a high angle of attack and thus a stall. Remember
also,
that different wings have a different critical angle of attack where a
wing
will stall. How does anyone know where that angle is without a wind
tunnel and testing? and who am I to say it did not pitch up enough to
stall
therefore I giveth the pilot a 5 or zero even though I cannot possibly
know the
particulars of the wing that I am watching.<br>
My comment of the 1-2 degrees was to say that we do not know how
closely any
particular wing is flying from it's critical angle of attack. If it is
in
fact close, a change of only 1-2 degrees can cause a stall. We are
trying
to be aerodynamic engineers from the ground and deciding for ourselves
what the
angle "should" look like and downgrading accordingly. Now throw
in the conceptual difference between angle of attack and aircraft
attitude, and
it is easy to come to the wrong conclusion about stall or no stall. Are
we
fling only 1-2 degrees from the critical angle most of the time, no but
the
point it that there is absolutely no aerodynamic requirement for a very
nose
high ATTITUDE to be a requirement in order to get a high angle of
attack on the
wing.<br>
<br>
Chris<br>
<br>
<br>
Vicente "Vince" Bortone wrote:<o:p></o:p></span></p>
<div>
<div>
<div>
<p class="MsoNormal"><span
style="font-family: "Arial","sans-serif"; color: black;">Chris,<o:p></o:p></span></p>
</div>
<p style="margin: 0in 0in 0.0001pt;"><span
style="font-family: "Arial","sans-serif"; color: black;"> <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span
style="font-family: "Arial","sans-serif"; color: black;">I
am copying from the first sentence FAI rule book: "</span><span
class="apple-converted-space"><span
style="font-size: 10pt; font-family: "Arial","sans-serif"; color: black;"> </span></span><span
style="font-family: "Arial","sans-serif"; color: black;">A snap-roll
(or flick roll/rudder roll) is a rapid autorotative
roll where the model aircraft is in a stalled attitude,<span
class="apple-converted-space"> </span><strong><span
style="font-family: "Arial","sans-serif";">with
a continuous high angle of attack</span></strong>" The question: Is
1-2 degrees consider a good amount to define a high angle of
attack? <o:p></o:p></span></p>
</div>
<p style="margin: 0in 0in 0.0001pt;"><span
style="font-family: "Arial","sans-serif"; color: black;"> <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span
style="font-family: "Arial","sans-serif"; color: black;">Vicente
"Vince" Bortone<br>
<br>
----- Original Message -----<br>
From: "Chris Moon"<span class="apple-converted-space"> </span><a
moz-do-not-send="true" href="mailto:cjm767driver@hotmail.com"><cjm767driver@hotmail.com></a><br>
To: "General pattern discussion"<span class="apple-converted-space"> </span><a
moz-do-not-send="true" href="mailto:nsrca-discussion@lists.nsrca.org"><nsrca-discussion@lists.nsrca.org></a><br>
Sent: Tuesday, October 13, 2009 3:07:01 PM GMT -06:00 US/Canada Central<br>
Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC)<br>
<br>
I think what this goes back to is the erroneous belief that you need to
see an
exaggerated pitch departure or it should be severely downgraded. Keep
reading the maneuver description. It needs "A" pitch break, and
depending on the current aoa (angle of attack) that can be a difference
of just
a degree or 2 if you are near the critical aoa. Please don't tell me
guys, you are looking for MORE than a simple exceeding of the critical
aoa and
resulting stall. An exaggerated pitch break just to prove to naysayers
that you make a break is wrong, wrong, wrong. It says it needs
"A" break. Please keep re-reading it. Same for spin
entry. It needs to stall, not go 30 degrees nose up to "prove"
a stall. We are getting wound up over a misunderstanding of the
mechanics
of a stalled condition. As Don and Verne are alluding to, it really is
not that complicated.<br>
<br>
Chris<br>
<br>
<a moz-do-not-send="true" href="mailto:verne@twmi.rr.com"
target="_blank">verne@twmi.rr.com</a><span
class="apple-converted-space"> </span>wrote:<o:p></o:p></span></p>
</div>
<blockquote style="margin-top: 5pt; margin-bottom: 5pt;">
<pre><span style="color: black;">Or you could just write in "DNO".... I always seem to see the break as in, nose up, tail down, and my 56 year old eyes are lousy. Verne ---- "Vicente "Vince" Bortone" <a
moz-do-not-send="true" href="mailto:vicenterc@comcast.net"
target="_blank"><vicenterc@comcast.net></a> wrote: <o:p></o:p></span></pre>
<pre><span style="color: black;"> <o:p></o:p></span></pre>
<blockquote style="margin-top: 5pt; margin-bottom: 5pt;">
<pre><span style="color: black;">Verne, Following AMA description: if we don't see the break is 5 points downgrade. That is 1/2 of the snap roll maneuver. Therefore, if we see the snap roll but don't see the break the judge has the right to write down 5 points score assuming that all other components are perfect. Therefore, base on the rule book the snap roll without a break has a value of 5 points. Vicente "Vince" Bortone ----- Original Message ----- From: verne @ twmi . rr .com To: "General pattern discussion" < nsrca -discussion@lists. nsrca .org> Cc: "Don Ramsey" <don. ramsey @ suddenlink .net> Sent: Tuesday, October 13, 2009 2:14:02 PM GMT -06:00 US/Canada Central Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC) Is there anybody involved in this discussion that honestly can't recognize a snap when they see one? I'm just asking..... Verne ---- Don Ramsey <don. ramsey @ suddenlink .net>
wrote: <o:p></o:p></span></pre>
<pre><span style="color: black;"> <o:p></o:p></span></pre>
<blockquote style="margin-top: 5pt; margin-bottom: 5pt;">
<pre><span style="color: black;">Vince, What about the next sentence in the FAI definition, “If the stall/break does not occur and the model aircraft barrel rolls around, the manoeuvre must be severely downgraded (more than 5 points).” How about if the break does not show and the model does NOT barrel roll around. Do you still downgrade by 5 or more points? I don’t know what the intent of the rule was but I can tell you for a fact that the judges that only score FAI in Europe do not downgrade it by 5 or more points. I believe they use the “If it’s not a barrel and not an axial roll then it’s probably a snap, so judge it that way” because they have been instructed in the past to do it that way. Don rom: nsrca -discussion-bounces@lists. nsrca .org [mailto: nsrca -discussion-bounces@lists. nsrca .org] On Behalf Of Vicente "Vince" Bortone Sent: Tuesday, October 13, 2009
12:10 PM To: General pattern discussion Subject: Re: [NSRCA-discussion] How I became an expe<o:p></o:p></span></pre>
<pre><span style="color: black;">rt Snap Judge (TIC) Matt, I am copying the snap description from the current FAI and AMA manuals. I don't see the AND you mention in the FAI rule book. See the important portion in bold. I see that the AMA description is better in this respect. You are correct in regard the downgrade in FAI . 5 or more points if you don't see the break and the model barrel rolls. Therefore, what is the downgrade in FAI if the judge does not see the break and there is autorotation? I will say 5 points since it says 5 or more points if the model barrel rolls. Again, it appears that AMA down grad descriptions are better. FAI : SNAP-ROLLS A snap-roll (or flick roll/rudder roll) is a rapid autorotative roll where the model aircraft is in a stalled attitude, with a continuous high angle of attack Snap-rolls have the same judging criteria as axial rolls as far as start and stop of the rot
ation, and constant flight path through the manoeuvre is concerned. At the start of a <o:p></o:p></span></pre>
<pre><span style="color: black;">snap-roll, the fuselage attitude must show a definite break and separation from the flight path, before the rotation is started, since the model aircraft is supposed to be in a stalled condition throughout the manoeuvre, If the stall/break does not occur and the model aircraft barrelrolls around, the manoeuvre must be severely downgraded (more than 5 points). Similarly, axial rolls disguised as snap-rolls must be severely downgraded (more than 5 points). Snap-rolls can be flown both positive and negative, and the same criteria apply. The attitude (positive or negative) is at the competitor’s discretion. If the model aircraft returns to an unstalled condition during the snap-roll, the manoeuvre is severely downgraded using the 1 point/15 degree rule. AMA: Snaps: A Snap roll is a simultaneous, rapid autorotation in the pitch, yaw and roll axes of flight in a stalled wing attitude. The following criteria apply: 1. Since the
maneuver is defined as a stalled maneuver, initiat<o:p></o:p></span></pre>
<pre><span style="color: black;">ed by a stall of the wing induced by a rapid change in pitch attitude, the nose of the fuselage must show a definite break in pitch attitude from the flight path in the direction of the snap (positive or negative) while the track closely maintains the flight path. The lack of a discernable pitch break is downgraded by 5 points. Large deviations from the flight path, indicative of a delayed stall, are to be downgraded using the 1 point per 15-degree rule for each axis of the excursion before stall. For example, it the model pitches 15 degrees nose up and the wings rotate 15 degrees before the stall, the maneuver should be downgraded 1 point for pitch and 1 point for roll. 2. The track visualized as the path of the Center of Gravity (CG) should closely follow the geometric flight path of the maneuver while the nose and tail auto rotate through opposite helical arcs around the flight path. Lack of these helical arcs (or coning) is indica
tive of an axial roll and is scored zero. <o:p></o:p></span></pre>
<pre><span style="color: black;">3. If a stall does not occur and the model barrel rolls, the score is zero. A barrel roll can be identified when the CG, the nose, and tails scribe the same helical path through the required rotation of the maneuver 4. Snap rolls have the same judging criteria as axial rolls as far as start and stop of rotation, constant flight path through the maneuver and centering on lines. 5. If the model returns to an unstalled condition during the maneuver, such that the autorotation is not visible and the model rolls or barrel rolls to complete the maneuver, it would be downgraded using the 1 point per 15 degree rule. 6. Airspeed is not a criteria which should be used to judge this maneuver. The wing of the model is stalled during this maneuver; therefore a significant decrease in speed may occur and is not a cause for downgrade. Vicente "Vince" Bortone ----- Original Message ----- From: "Matthew Frederick" <a
moz-do-not-send="true" href="mailto:mjfrederick@cox.net"
target="_blank"><mjfrederick@cox.net></a> <o:p></o:p></span></pre>
<pre><span style="color: black;">To: "General pattern discussion" < nsrca -discussion@lists. nsrca .org> Sent: Tuesday, October 13, 2009 9:47:30 AM GMT -06:00 US/Canada Central Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC) ? While speaking with Don Ramsey about the nuances of judging snaps at a recent contest I found that he agreed with my interpretation of the FAI snap rule. The severe downgrade should only be applied if there is no break AND there is no autorotation (this is exactly what the rule says). Basically, lack of a break is not substantial grounds for the severe downgrade in FAI . If the break is not seen and autorotation still occurs at some point during the roll the one point per 15 degree rule applies. Since the snaps happen so fast, for me it's usually not more than 1 or 2 points unless it was blatantly obvious that the plane rotated a while before the snap truly began. It's the same as if you stop the snap before comple
ting the rotation and do an axial roll to<o:p></o:p></span></pre>
<pre><span style="color: black;"> finish. This nonsense of people being so quick to apply a severe downgrade has gone too far. One element of a maneuver (because I can't think of any sequence that has just a snap roll) should not ruin a whole flight, or eve n that one maneuver unless it just wasn't a snap. I like the idea of "if it's not a barrell roll and not an axial roll, it's probably a snap." Matt ----- Original Message ----- From: Vicente <a
moz-do-not-send="true" href="mailto:vicenterc@comcast.net"
target="_blank"><mailto:vicenterc@comcast.net></a> "Vince" Bortone To: General pattern discussion <mailto: nsrca -discussion@lists. nsrca .org> Sent: Monday, October 12, 2009 5:12 PM Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC) I believe that the current downgrade is severe. AMA 5 points. FAI 5 or more points if my memory is correct. In local contest I have been using 3 points downgrade. I know that is wrong but it has been my best way for me to take into account the break issue. It used to be zero and it was changed to 5 points (IMAC still a 10 points downgrade or nada). Therefore, Ron is correct. Probably makes sense to go 2-3 points downgrade if the judge can not see the break before rotation. Vicente "Vince" Bortone ----- Original Message ----- From: "John Fuqua" <a
moz-do-not-send="true" href="mailto:johnfuqua@embarqmail.com"
target="_blank"><johnfuqua@embarqmail.com></a> <o:p></o:p></span></pre>
<pre><span style="color: black;">To: "General pattern discussion" < nsrca -discussion@lists. nsrca .org> Sent: Monday, October 12, 2009 1:51:00 PM GMT -06:00 US/Canada Central Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC) Ron makes valid observation which I came to many years ago at the TOC when Mr. Bill graciously funded for full scale pilots like Patty Wagstaff do demo flights to entertain us. The one thing that I came away with in comparing full scale to our airplanes is the speed of the snap/rotation. In the full size aerobatics types that I observed there was plenty of time to see the nose pitch and then after somewhat of a hesitation yaw and rotate. In our pattern planes, especially when using a snap switch, it all gets to be a blur due to sheer speed. I have no solution to this issue but to MAKE the pilots show a break by having severe downgrades. Otherwise the concept of a snap will be ignored. &n
bsp;Yes it's hard to see which makes it incumbent on the pilot to<o:p></o:p></span></pre>
<pre><span style="color: black;"> present it to the judges. -----Original Message----- From: nsrca -discussion-bounces@lists. nsrca .org [mailto: nsrca -discussion-bounces@lists. nsrca .org] On Behalf Of <o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="mailto:ronlock@comcast.net" target="_blank">ronlock@comcast.net</a> <o:p></o:p></span></pre>
<pre><span style="color: black;">Sent: Monday, October 12, 2009 1:26 PM To: General pattern discussion Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC) Here is a description that shows technically correct snap execution, and valid, consistent judging is possible. (Half of the District One guy need not read this, they have already heard it) <G> At a small airport airshow, one of demos was an in-trail formation of four full scale AT-6 Texans. As each plane got to stage center, it did a single positive snap roll. Spectators saw four snap rolls in a row, about 5 seconds apart. The flight of four went around, and repeated the maneuver. Some spectators are getting bored - even a pattern guy could get bored with a string of 8 nearly identical maneuvers. And then, they did it yet again!! What's in this for us? The snap maneuver by each AT-6 appeared to take a second or so, from initiat
ion to completion. By the time the fourth plane did a snap, you could start s<o:p></o:p></span></pre>
<pre><span style="color: black;">eeing.... - there is a nose pitch up, - then a yaw, - then plane rolled in direction of yaw, - plane returned to straight and level flight. By the time the flight came around for another four snaps, you could see more details.. - there is a nose pitch up, (somewhat sudden, at least sudden for an AT-6) - then a large amount of yaw, - then rapid roll in direction of yaw, (rolling faster than it could with ailerons) - plane returned to fairly close straight and level, nose slightly high. By the time the flight positioned for yet another four snaps, (Yawn, spectators headed for cotton candy) the four distinct elements of the snap roll maneuver were easy to see, and there was time to evaluate (judge) each element. 1. there is a nose pitch up, (somewhat sudden, at least sudden for an AT-6, with little rise in altitude) 2. then large amount o
f yaw, (the yaw proceeds the upcoming roll) 3. then autorotation at rate faster than it could do an ail<o:p></o:p></span></pre>
<pre><span style="color: black;">eron roll) 4. plane returns to level flight track, with nose lowering to level flight attitude. We can all be expert Snap Roll Judges! Ahhh, at least for AT-6 snaps. What I take from all of this- The problem is not snap descriptions. It's the application of them; observation, discrimination and judging of elements in the split second observation time we have. Is the task beyond reasonable expectations of most of us as a judging community? I suppose we will continue work started over 10 years ago to improve in these areas. In the meantime, shall we reduce the impact of inconsistent judging of snaps by limiting the downgrade of the snap portion of a maneuver to say..two points2? Ron Lockhart _______________________________________________ NSRCA-discussion mailing list NSRCA-discussion@lists. nsrca .org <o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="http://lists/" target="_blank">http://lists</a>. nsrca .org/mailman/listinfo/ nsrca -discussion _____ _______________________________________________ NSRCA-discussion mailing list NSRCA-discussion@lists. nsrca .org <o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="http://lists/" target="_blank">http://lists</a>. nsrca .org/mailman/listinfo/ nsrca -discussion _______________________________________________ NSRCA-discussion mailing list NSRCA-discussion@lists. nsrca .org <a
moz-do-not-send="true" href="http://lists/" target="_blank">http://lists</a>. nsrca .org/mailman/listinfo/ nsrca -discussion No virus found in this incoming message. Checked by AVG - <a
moz-do-not-send="true" href="http://www.avg.com/" target="_blank">www.avg.com</a> <o:p></o:p></span></pre>
<pre><span style="color: black;">Version: 8.5.421 / Virus Database: 270.14.9/2428 - Release Date: 10/13/09 06:35:00 <o:p></o:p></span></pre>
<pre><span style="color: black;"> <o:p></o:p></span></pre>
</blockquote>
<pre><span style="color: black;">_______________________________________________ NSRCA-discussion mailing list NSRCA-discussion@lists. nsrca .org <o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="http://lists/" target="_blank">http://lists</a>. nsrca .org/mailman/listinfo/ nsrca -discussion<o:p></o:p></span></pre>
<pre><span style="color: black;"> <o:p></o:p></span></pre>
</blockquote>
<pre><span style="color: black;">_______________________________________________ NSRCA-discussion mailing list<o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="mailto:NSRCA-discussion@lists.nsrca.org" target="_blank">NSRCA-discussion@lists.nsrca.org</a><o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion"
target="_blank">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></span></pre>
</blockquote>
<p class="MsoNormal"><span
style="font-family: "Arial","sans-serif"; color: black;"><br>
_______________________________________________ NSRCA-discussion
mailing list<span class="apple-converted-space"> </span><a
moz-do-not-send="true" href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><span
class="apple-converted-space"> </span><a moz-do-not-send="true"
href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></span></p>
</div>
</div>
<pre style="text-align: center;"><span style="color: black;">
<hr align="center" size="4" width="90%">
</span></pre>
<pre><span style="color: black;"><o:p> </o:p></span></pre>
<pre><span style="color: black;">_______________________________________________<o:p></o:p></span></pre>
<pre><span style="color: black;">NSRCA-discussion mailing list<o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><o:p></o:p></span></pre>
<pre><span style="color: black;"><a moz-do-not-send="true"
href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></span></pre>
<p class="MsoNormal"><span
style="font-size: 13.5pt; font-family: "Helvetica","sans-serif"; color: black;">_______________________________________________<br>
NSRCA-discussion mailing list<br>
<a moz-do-not-send="true"
href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a><br>
<a moz-do-not-send="true"
href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a><o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
</div>
<p><span style="font-size: 10pt; font-family: "Arial","sans-serif";">Internal
Virus Database is out of date.<br>
Checked by AVG - <a class="moz-txt-link-abbreviated" href="http://www.avg.com">www.avg.com</a><br>
Version: 8.5.420 / Virus Database: 270.14.3/2415 - Release Date:
10/05/09
06:19:00</span><o:p></o:p></p>
</div>
<pre wrap="">
<hr size="4" width="90%">
_______________________________________________
NSRCA-discussion mailing list
<a class="moz-txt-link-abbreviated" href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</a>
<a class="moz-txt-link-freetext" href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion">http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</a></pre>
</blockquote>
</body>
</html>