[SPAM] Re: Displacement during snap rolls (was Why is it so quiet?)

[Ed Alt]

Hi Bob:

Hmm, you are right, the guide doesn't say anything explicitely about track shift.  I've been to their judging class and this got talked to death.  The outcome was that Ray Rose instructed us that there ought to be some track displacement and that there was no particular downgrade for the displacement itself.  Different event, different rules I know, but the physics are the same.  A real snap is going to have some displacement, so we ought to be expecting it and not downgrading when we see it happen.  I think it's hard to see the displacement in many cases and we ought to be much more focused on the pitch break at the onset of autorotation and rotating motion of the tail during the autorotation to tell that a snap really happened.

Ed
  ----- Original Message ----- 
  From: Bob Pastorello 
  To: discussion at nsrca.org 
  Sent: Wednesday, December 29, 2004 7:27 AM
  Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


  Ed - I checked the IMAC Flying and Judging Guide;  couldn't find a comment to address this question of lateral shift of track.

  Anywhere else to look?

  Bob Pastorello
  NSRCA 199  AMA 46373
  rcaerobob at cox.net
  www.rcaerobats.net


    ----- Original Message ----- 
    From: Rcmaster199 at aol.com 
    To: discussion at nsrca.org 
    Sent: Tuesday, December 28, 2004 11:17 PM
    Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


    I am interested in what this Scale Aerobatics Judging guide has to say. Is there a web site?

    MattK
      From: Ed Alt 
      To: discussion at nsrca.org 
      Sent: Tuesday, December 28, 2004 11:04 PM
      Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


      Good topic Bob.  If the model really did a snap roll, it had to displace somewhat.  If not, and if you could actually tell that it did not, that could be an indicator that a snap roll did not actually happen. Generally, the model has to displace to a new track, however slight, from the yawing and pitching moments introduced.  The criteria should perhaps be that you are able to able to maintain the new track exactly in parallel to the pre-snap track.  How much offset is OK is hard to say, but things generally start looking suspicious whan it's much more than a couple of wingspans.  You would generally start to see other obvious problems, such as barrel rolling, if the displacement were really large.  For another perspective, I think the Scale Aerobatics Flying and Judging Guide does a decent job of describing how to grade a snap.

      Ed
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