[NSRCA-discussion] Judging the Snap

[Jeff Worsham]

Hi Larry,

I appreciate your opinion here: “IMHO… It is a fallacy to state that, “because the tail displays a conical rotation, it must be that the heading did break from the flight path”.
But I don’t understand.  How can the tail get into a conical rotation about the CG unless there was a pitch break? 
Thanks in advance,
Jeff


> On Mar 25, 2017, at 10:32 AM, Larry Diamond via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
> 
> Earl,
>  
> Yes I have read your article a few times. I believe it supports what is in the rule book and that a pattern plane can actually perform a snap.
>  
> My concern is more related to how are we actually judging, I don’t think we are locked into judging the snap at contests the way it is intended because of pushback when, in my opinion, it is scored based on the presentation… a low or zero score.
>  
> One can easily argue that if the tail displays a conical rotation, therefore the nose must have displayed a conical rotation. This is clearly a fact. Except a fast barrel roll the tail and the nose are on the same plain in reference to CG, thus “No Stall” condition. It is just that, a fast barrel roll. If you are only looking at the CG and not aware of the Nose/Tail orientation, you would deduct “5” because the CG barrel rolled around the flight path. However, the correct application to the rule is a zero, because there was no clear break in heading and the nose/tail is on the same plain in relation to CG.
>  
> IMHO… It is a fallacy to state that, “because the tail displays a conical rotation, it must be that the heading did break from the flight path”.
>  
> What am I missing?
>  
> Best Regards,
>  
> Larry Diamond
>  
> From: NSRCA-discussion [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Earl Haury via NSRCA-discussion
> Sent: Saturday, March 25, 2017 6:57 AM
> To: mups53 <mups53 at gmail.com>; General pattern discussion <nsrca-discussion at lists.nsrca.org>
> Subject: Re: [NSRCA-discussion] Judging the Snap
>  
> Larry, take a look at this: http://www.ckaero.net/blog/2014/11/23/anatomy-of-a-snap-roll/ <http://www.ckaero.net/blog/2014/11/23/anatomy-of-a-snap-roll/>
>  
> Earl
>  
> From: mups53 via NSRCA-discussion 
> Sent: Saturday, March 25, 2017 1:53 AM
> To: Larry Diamond ; General pattern discussion 
> Subject: Re: [NSRCA-discussion] Judging the Snap
>  
> Good post. Thanks Larry
>  
>  
>  
> Sent from my Verizon, Samsung Galaxy smartphone
>  
> -------- Original message --------
> From: Larry Diamond via NSRCA-discussion <nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org>> 
> Date: 3/24/17 8:25 PM (GMT-06:00) 
> To: General pattern discussion <nsrca-discussion at lists.nsrca.org <mailto:nsrca-discussion at lists.nsrca.org>> 
> Subject: [NSRCA-discussion] Judging the Snap 
>  
> Since getting back into Pattern and based on last year’s observations at a couple of contests, it seems to me that through evolution it has changed a little over the last 10 years with the Snap Roll downgrades (as it is flown and judged not by the rule book).
>  
> Yes, I took the AMA judging test. However, being a lowly Intermediate since 2004… I do not want be in a position where I scored a maneuver low/zero because I didn’t understand what it’s supposed to look like in the air today.
>  
> Also after a couple of discussion with people in different districts there are differing opinions about what a Snap is and isn’t; and, when an Intermediate/Advanced pilot should or shouldn’t score a zero to higher skill level pilots.
>  
> Set aside the rule book, as I think it is very clear… I’m asking what is being applied in the actual Judging of contests today. I keep hearing about a little relief because a Pattern Planes can’t actually Snap (stall) properly.
>  
> The Snap is a fast rotation, which is very difficult to see every downgrade. What visual cue should we look for when a very shallow break may/may not be present, but to the eye it looks like a rapid barrel roll.
>  
> At what point does the Snap maneuver earn a zero?
>  
> Let’s be honest with ourselves as to what is actually being practiced (judged)… With the underlined verbiage, are we zeroing the maneuver; or, simply downgrading to prevent conflict because a zero was scored.
>  
> The Rule from 2016-2017
> Snaps: A snap roll is a rapid rotation where the fuselage nose makes a detectable break in heading from its track in pitch and yaw for the duration of the roll but the track follows the line of the maneuver (straight or arced):
> 1. 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. For example, it the model pitches its track 15 degrees nose up and the wings rotate 15 degrees before the yaw is applied, 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 rotate through opposite helical arcs around the flight path. Lack of these helical arcs (or coning) is indicative of an axial roll and is scored zero.
> 3. If the track corkscrews or barrel rolls, it is severely downgraded (more than 5 points).
> 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 heading does not remain deviated for the entire roll it is downgraded 1 point per 15 degrees.
> 6. Airspeed is not a criterion 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.
>  
> Larry Diamond
>  
> P.S. I am hoping this will be an above board and honest discussion. I just want to make sure I am doing the right thing here.
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