[NSRCA-discussion] [F3A-Discussion] snaps

Mon Jul 5 12:16:10 AKDT 2010

Ken,

In theory...

IF the rotation in pitch is rapid enough, the wing can be forced to stall
before the plane measurably departs from the flight path...and then the
rudder is applied to control the direction of the snap....which produces
biased lift causing rotation in roll axis (even a stalled wing produces some
lift).  Most of our pattern models do not snap well without aileron (which
further biases the lift).

I think most of us read the post on the NSRCA list by Jerry Budd which
concluded the typical modern pattern plane is not capable of snaps as
described in the rules...however..the rules are what they are...and making a
maneuver look as the rules describe is what the event is about.

Completely different discussion point -

A judge observes a square loop with 4 equal length sides, 4 equal radii
corners, and no deviations in distance from the flightline.  Judge scores a
10.  In actuality, a $14 million GPS system shows the square had 4 different
radii, and was wider than tall.  Nothing changes...the judge saw a 10 per
the rulebook..and that is all that matters.  The pilots that perform
maneuvers that appear to be error free as described by the book should get a
10...whether the maneuver is actually correct is another matter.

Regards,

Dave

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ken Thompson
Sent: Monday, July 05, 2010 3:57 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Dave et all,

I am having a bit of trouble understanding how a plane in forward motion can
with 100% certainty rotate on it's CG...when the tail drops or raises,
depending on Pos or Neg snap, the nose goes the opposite direction. I just
don't see how you can stop the CG from moving at all, even the slightest bit
would be a downgrade.

What I think would be very cool is. we get a vid of what we all would
consider as perfect a snap as we've ever seen and generate a line as an
overlay to represent the track...extend that line forward of the planes
position, then we will be able to see if there is an actual deviation of
flight track or path...

I think I'm living in a dream world...LOL!

Ken

----- Original Message ----- 

From: Dave <mailto:DaveL322 at comcast.net>  

To: 'General pattern discussion' <mailto:nsrca-discussion at lists.nsrca.org>  

Sent: Monday, July 05, 2010 1:47 PM

Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

"..break and separation from the flight path..."

and

"...constant flight path through the manoeuvre.."

Seems to me that the definition is contradictory.  A break could occur in
the sense that there is a deviation between attitude and track, but
"separation from the flight path" and "constant flight path" are
contradictory.  I would hope it is clear enough that snaps absent of both
pitch and yaw must be downgraded.

I would point out that a snap that finishes on the same heading, but shows a
minor line displacement has very little effect on the geometry of the
maneuver.  Looking at a straight line of 400'..a snap in the middle of the
line would have to displace 50 feet (8 wingspans) vertically or horizontally
to change the line (from start to finish) by 15 degrees (1 point).  I see no
other guidance in the rulebook applicable to how a line displacement should
be downgraded.

Regards,

Dave

  _____  

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dr Mike
Sent: Monday, July 05, 2010 11:28 AM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Good point, thanks Troy.

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Troy Newman
Sent: Monday, July 05, 2010 10:06 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Ken,

It still has to stay on flight path

"Snap rolls have the same judging criteria as axial rolls as far as start
and stop of the rotation, and constant flight path through the manoeuvre is
concerned."

As Matt suggested this is not a discussion on we think it should be,  rather
it is how the rule is written

Troy

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ken Thompson
Sent: Monday, July 05, 2010 7:13 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Glad for that description...the way I originally understood it the plane was
not supposed to deviate from the flight path...always said that was
impossible...

Ken

----- Original Message ----- 

From: Dr Mike <mailto:drmikedds at sbcglobal.net>  

To: 'General pattern discussion' <mailto:nsrca-discussion at lists.nsrca.org>  

Sent: Monday, July 05, 2010 7:04 AM

Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Yes that is correct, thanks Matt.

Mike 

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
rcmaster199 at aol.com
Sent: Sunday, July 04, 2010 6:22 PM
To: nsrca-discussion at lists.nsrca.org; f3a-discussion at lists.f3a.us
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

The F3A maneuver description may be inadequate and/or inaccurate, however
that doesn't much matter for the judge who has the ardeous task of
deciphering the snap. The description stands as is for this cycle and that's
how the World's judges will judge them to the best of their ability next
year. I urge all judges that judge F3A Semis and Finals at this year's
Nats/Team Selection contest to take heed of FAI description (not AMA) and
judge accordingly.

In essence, Snaps should not zeroe'd as easily as they once were; far cry
from where it was just a couple years ago. I believe that's the main reason
the rule was written as indicated. 

Mike's point I think deals with bringing the Snap back out of hibernation
such that folks get a chance to re-read it and re-hash just in time for the
Team Selection; fresh in one's mind so to speak

Matt K

-----Original Message-----
From: Woodward, Jim R (US SSA) <jim.woodward at baesystems.com>
To: 'f3a-discussion at lists.f3a.us' <f3a-discussion at lists.f3a.us>;
'nsrca-discussion at lists.nsrca.org' <nsrca-discussion at lists.nsrca.org>
Sent: Sun, Jul 4, 2010 4:27 pm
Subject: Re: [NSRCA-discussion] [F3A-Discussion] snaps

Mike, I'm replying from a blackberry without the benefit of the rulebook in
front of me. I thought these were called "Flick Rolls" now? I don't think
any of us are equipped in the context of judging a 0.5 second manuever to
determine if is "stalled" or "unstalled." I think Jerry Budd posted on the
nsrca list the last dissertation on snaps, which from memory, pretty much
proved the planes are not stalled.

Given you posted this, what do you want to see happen? Thx Jim W.

  _____  

From:  <mailto:f3a-discussion-bounces at lists.f3a.us>
f3a-discussion-bounces at lists.f3a.us <
<mailto:f3a-discussion-bounces at lists.f3a.us>
f3a-discussion-bounces at lists.f3a.us> 
To: 'General pattern discussion' < <mailto:nsrca-discussion at lists.nsrca.org>
nsrca-discussion at lists.nsrca.org>;  <mailto:f3a-discussion at lists.f3a.us>
f3a-discussion at lists.f3a.us < <mailto:f3a-discussion at lists.f3a.us>
f3a-discussion at lists.f3a.us> 
Sent: Sun Jul 04 17:11:46 2010
Subject: [F3A-Discussion] snaps 

Given the abundance of snap maneuvers(7 maneuvers, 9 snaps) in the F-11
pattern, I feel compelled to give the exact description via the F3A
rulebook:

A snap-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 rotation, and constant flight path through the manoeuvre is
concerned.

At the start of a 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 I a stalled condition throughout
the maneuver.  If the stall/break does not occur and the model aircraft
barrel-rolls 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 competitors 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. 

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