[NSRCA-discussion] Snap

Mon Oct 12 08:38:19 AKDT 2009

So, in all seriousness this time, allow me to explain what happens in the knife edge snap.  Here goes:

Short version: Everything works the same as a wings level snap. 

Longer version: The only difference is, the wing starts out completely unloaded and rapidly transitions to being loaded due to the sudden pitch change, and as it reaches the critical angle of attack, the same exact things happen.  The autorotation is due to a wing panel stalling, and it makes no fundamental difference which way the airplane is pointing when you do it.  Now, you do need to perform the correct technique with the rudder before & after to keep it flying on fuselage and propellor thrust vector lift, lest the ground rise up and smite thy model.  

Ed

From: ed_alt at hotmail.com
To: nsrca-discussion at lists.nsrca.org
Subject: RE: [NSRCA-discussion] Snap
Date: Mon, 12 Oct 2009 12:20:55 -0400

Try that knife edge snap without elevator.  Try it near the ground to really get a good look.  Let us know how that works out for you!  :)

Ed

To: nsrca-discussion at lists.nsrca.org
CC: 
Date: Mon, 12 Oct 2009 02:41:56 +0000
From: dunnaway at hbcomm.net
Subject: Re: [NSRCA-discussion] Snap

Just to add more fun to this discussion,   How do you define the "pitch break" on the knife-edge to knife-edge snap in the F-09?  :)   What stalls,  the fuselage or the wing?

Joe

-----Original Message-----
From: "Ed Alt" <ed_alt at hotmail.com>
Sent 10/11/2009 8:21:23 PM
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Subject: Re: [NSRCA-discussion] Snap

What if I add throttle on a 45 downline snap to keep the airspeed constant through the snap? That does not disqualify it as a snap. You can't use your impression of a momentary drop in airspeed as any kind of a reliable indicator that a snap was done.

Pitch break, yawing motion need to be visible.  Some line displacement is guaranteed and really doesn't deserve a downgrade unless it's severe.  Yes, there's the trick of whapping opposite rudder as a lead to the snap onset to help fool judges who need to see the same exact track afterwards, but in reality that should get a downgrade. 

Now, can you guarantee that because you saw some pitch break and yawing motion that it really was a snap?  No, but I guarantee you that without it, it wasn't a snap. I don't mean to make this sound like I'm an expert at flying a perfect snap, but I know darned well what it is supposed to be.

Ed

----- Original Message ----- 
From: John Pavlick 
To: General pattern discussion 
Sent: Sunday, October 11, 2009 7:58 PM
Subject: Re: [NSRCA-discussion] Snap

Yup and I do use that as an indicator. Remember the old Masters Reverse Avalanche? Sometimes the plane would actually almost stop moving right after the snap (if it was done correctly). If the plane cruises right through a "snap-roll" with no visible dissipation of energy, it's probably a twinkle.

John Pavlick
http://www.idseng.com

----- Original Message ----- 
From: Scott Smith 
To: 'General pattern discussion' 
Sent: Sunday, October 11, 2009 8:03 PM
Subject: Re: [NSRCA-discussion] Snap

So why don’t we use speed as a criteria?  A true snap roll will slow the aircraft significantly.  (It’s at least worth a mention the aircraft should decelerate in the description!)  

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ed Alt
Sent: Sunday, October 11, 2009 7:44 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Snap

You can fake a snap just by adding some elevator and rudder, enough to get the tail to cone around.  Fools a lot of judges.

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

From: Dan 

To: General pattern discussion 

Sent: Sunday, October 11, 2009 6:14 PM

Subject: Re: [NSRCA-discussion] Snap

No pitch break = no snap roll.  It's not a matter of anyone's opinion, it's an aerodynamic fact.  If it's truly this hard to judge, they should simply be eliminated.

Ed

Okay if you say so but what is it if it is not a barrel roll or an axial roll?  Certainly it is a snap, and certainly there is a pitch break but it does not have to come before the rotation it can happen simoultaneously.  I can fly level or vertical (up or down) or at any other angle in between and flip my elevator stick repeatedly from one end of a line to another and my plane does not stall (oops I know I should say the wing or wings do not stall)  The arguement for a pitch break is fascious reguarding our models.  I go ahead and do the bump prior to the snap if that is how the judges at that time want it, but to say that a plane did not snap just because there was not an  initial pitch break does not equal actuality.  

Dan

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

From: Ed Alt 

To: General pattern discussion 

Sent: Sunday, October 11, 2009 5:45 PM

Subject: Re: [NSRCA-discussion] Snap

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

From: Dan 

To: General pattern discussion 

Sent: Sunday, October 11, 2009 5:12 PM

Subject: Re: [NSRCA-discussion] Snap

I know better than to enter this conversation but, but, well here goes.  Don, I agree with your post about the three types of rolls.  If it is not axial and it is not a barrell roll the it is a snap roll.  Some one at some time put in the description of a snap the requirement of a ptich break.  Man has this caused problems.  Now tell me if a plane does a snap roll without a leading pitch break then what roll was it, axial, nope don't think so.  Was it a barrel roll, nope not that either so low and behold it must have been a snap roll.  We have all set in a judging chair and watched snap manuevers and we have flown these maneuvers.  We can all say that we have seen and or flown many true snap rolls that did not have a any visible pitch break, some are judged on our 1 to 10 scale and others at times receive the zero.  In the current Masters sequence the 45 degree downline snap for example.  I have flown that manuever many many times and I have thrown in the "required" pitch bump and I have at times neglected to do the bump, but you know what, in either method the airplane performed a snap roll.

I have been flying pattern since the late sixties and going all the way back to then I have know and been able to recognize a stall turn and its difference from a hammerhead turn.  I for the life of me it seems that a stall turn is named very aptly.

Some of us live for the nitpicking discussions of stalls and snaps and wording in maneuver descriptions, others just want a simple description and go out and fly or judge it to our perceived perfection.  Is it any wonder we seem to be decreasing in our numbers. 

Dan Curtis

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

From: Vicente "Vince" Bortone 

To: General pattern discussion 

Sent: Sunday, October 11, 2009 7:47 AM

Subject: Re: [NSRCA-discussion] Snap

Amen....

Vicente "Vince" Bortone

----- Original Message -----
From: "Ed Alt" <ed_alt at hotmail.com>
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Sent: Sunday, October 11, 2009 7:33:56 AM GMT -06:00 US/Canada Central
Subject: Re: [NSRCA-discussion] Snap

Don:

I don't agree with that. You need to see a distinct pitch break and yawing action to accompany the pitch break, otherwise there is no real evidence that autorotation occurred. "Tail coning" alone is not even a reliable indicator of a snap.  You can easily cheat that to sell a "snap".   A snap is a stalled wing, autorotation maneuver. Also, the tendency to downgrade snaps because of any line displacement goes entirely against the physics of what must occur in order for a real snap roll take happen.  I think we should have a rule that most clearly accounts for the physics of what must occur for it to be a real snap, or just take them of sequences entirely.  And of course, educate judges and pilots accordingly.  Also, when you're a judge, don't be afraid to zero or severely downgrade a wiffle snap, or whatever is being presented to you if it's not a real snap. Especially don't be afraid of zeroing snaps when it's a big name trying to sneak a snap cheat in front of you.

Regards,

Ed

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

From: Don Ramsey 

To: 'General pattern discussion' 

Sent: Sunday, October 11, 2009 7:01 AM

Subject: [NSRCA-discussion] Snap

Ok, how about this for the snap?  “If its not a barrel roll and not an axial roll, it’s a snap.” Maybe have the coning of the tail in the description. This eliminates about 90% of the judging differences.

Don

From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob Richards
Sent: Saturday, October 10, 2009 8:09 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] basic judging question (warning 4 letter word)

I think changing the judging criteria, just for the snap part of the manuever, would suffice.

--- On Sat, 10/10/09, John Ferrell <jferrell13 at triad.rr.com> wrote:

? 

I believe "We could fix most of that, by assigning a low K to snap maneuvers" is the only appropriate solution. If you cast them out, it is giving up. 

John Ferrell  W8CCW
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