[NSRCA-discussion] Snaps

[Rcmaster199 at aol.com]

Jerry and Ed, et al,

Not to belabor the obvious here, Pattern and IMAC models are quite different 
aerodynamically. Where it makes sense for the IMAC model to behave a certain 
way in a snap, the same can't be said or shouldn't be said for Pattern models. 

Regarding tail path during the snap, its appropriate for the Pattern model to 
inscribe the requisite cone where for the IMAC model its appropriate for the 
nose to do as Ed suggests.
It's possible to make a cone shape with rudder-aileron inputs only, except 
the apex will not be the cg (actually the AC, but thats another matter). 

Point taken is that many IMAC people "get" their description but probably an 
equal number of Pattern people "don't get" ours.

The snap roll is not difficult to neither perform well nor to judge 
correctly. I do not subscribe to huge elevator input concept to initiate the snap if 
the model has been designed correctly to begin with. (Here's where the major 
departure between IMAC and Pattern models surfaces since Pattern models start 
with a clean slate but IMAC models are limited). Elevator input is a must but 
only to highly load the wing. Rudder application will do the requisite lift dump 
on the inboard panel. I also don't subscribe to leading rudder in the snap, as 
some rather prominent pattern people have suggested, since that trully 
displaces the model

In regard to getting any maneuver description to Don for certification, that 
would be unfair to Don or the Judging Committee for that matter. We (the JC) 
do not "certify" maneuvers; that's the Contest Board's responsibility. We 
simply try to clarify poorly written yet approved descriptions. We don't have 
authority to approve policy only to write it for CB submittal (which every one has) 
or to clarify it. Sometimes, even clarification gets us in trouble so we 
really don't have that authority either, but have assumed it in an effort to help 
the community.

Matt

In a message dated 7/8/2006 3:09:48 AM Eastern Standard Time, 
ed_alt at hotmail.com writes:
Jerry:
It's all on the AMA website in the Flying and Judging Guide for Scale 
Aerobatics.  See section 8.9.3 and 8.9.4  The presentation being referred to is 
probably from their judging clinics, but you can get the idea from the F&J Guide.  
I attended one of the first judging seminars that Ray Rose put on and there 
was plenty of discussion about snaps and the fact that some displacement was 
inevitable and by itself, not necessarily a cause for downgrade. Yeah, it's a 
conflict with the other criteria about maintaining maneuver geometry, but I think 
there can be descriptions written to deal with that.

Really big displacements are an indicator of other problems that probably 
mean that a snap didn't really happen, such as barrel rolling or only partial 
auto-rotation during the roll.  A slow developing snap will exhibit alot of 
displacement for example.   I haven't seen any updated IMAC judging school 
materials, so whether they still teach that displacements during a snap aren't 
automatically downgradeable or not is unclear.  I think that if you look at what they 
do have in the F&J Guide, it provides pretty good guidance on how to tell 
that a snap probably happened at least.  It points out stuff like watching what 
the nose does re. departing from the flight path, not whether the tail is 
describing a cone shape.  You can get the tail to cone just using aileron and 
rudder alone - that's not a snap.  Snaps are tough to deal with in the rules and on 
the flight line.  It's just my opinion, but I think that the Scale Aerobatic 
rules are better defined in this particular area.


Ed
----- Original Message ----- 
From: Jerry Stebbins 
To: Discussion -NSRCA 
Sent: Friday, July 07, 2006 9:19 PM
Subject: [NSRCA-discussion] Snaps


It would seem that if IMAC has a better "definition" or "presentation" that 
helps shed some sunshine on this quandry---we should get it to Don, and have 
him certify it, or refute it. Should be some common ground in there. At least 
that way there may be more common ground developed to find an approach to 
getting a definable standard.
By the way I am an IMAC member and have never seen this presentation,---maybe 
would have helped my judging perceptions.
Jerry
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