[NSRCA-discussion] [F3A-Discussion] snaps

Mon Jul 5 11:56:40 AKDT 2010

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 
  To: 'General pattern discussion' 
  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

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  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 

    To: 'General pattern discussion' 

    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.

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    From: f3a-discussion-bounces at lists.f3a.us <f3a-discussion-bounces at lists.f3a.us> 
    To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>; 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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