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Snap Roll (no arguments, please)

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Old 08-30-2011, 09:59 AM
  #1  
Nathan King
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Default Snap Roll (no arguments, please)

This is not a thread aimed at debating the efficacy of the snap roll in F3A competition. I want to understand how the majority of you complete this maneuver and why you perform it the way you do. I fly intermediate and do not routinely practice snaps; however, I do know a thing or two about aerodynamics from my full scale experience.Many people mention a large input of aileron in the context of snap rolls; however, I do not fully understand this practice. To my knowledge, aroll occurs because the airfoil stalls with the airframe in an uncoordinated condition (through the use of rudder), which causes one wing to stall slightly before the other. The aircraft then rolls in the direction of the prematurely stalled wing. Therefore, Iwould think that the proper snap would be made through an initial rapid and authoritative input of elevator followed shortly by the input of rudder the moment before the stall occurs. It seems to me that using aileron to help the roll along incontrovertibly means that the aircraft isn't in a stalled condition, therefore no snap. If anything, I would expect the snap in the opposite direction of the aileron input as the lowered aileron would increase the camber of the wing, increasing AOA, and hastening a stall on that side.

How do you perform a snap?
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Old 08-30-2011, 11:02 AM
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rchotdoger
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Default RE: Snap Roll (no arguments, please)

Well, honestly speaking our models do not actually stall in a snap roll, the best we can do is imitate a full scale snap where in which a wing does stall. The way that i personally snap is to switch to high rate Aileron, then pull all the way back still on low rate elevator and rudder with the aileron slightly delayed, Do Not let go of the sticks and let them go back to center on their own, bring them back to center and tap opposite which makes it crisp, and actually ends where it should.


-Casey
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Old 08-30-2011, 11:37 AM
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Default RE: Snap Roll (no arguments, please)

Casey,

We are in the same page. I use a snap condition using same approach you mentioned. I should add that for my particular plane I just add some power just before the snap. Before initiating the snap I will go to idle and add power during the snap as best as I can. If I do the right timing in adding power during the snap it gets better. The problem is to make my finger move exactly the same every time. This not necessarily work in all planes, pilots and all conditions but it is the best way for me and the Abbra that I have been flying 10 years now. I think we are going to get about 101 ways to do snaps.

Best,

Vicente "Vince" Bortone
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Old 08-30-2011, 12:03 PM
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Mastertech
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Default RE: Snap Roll (no arguments, please)

Hit the button.....................

Tim
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Old 08-30-2011, 12:04 PM
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Nathan King
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: Mastertech

Hit the button.....................

Tim
That would be nice.....if it wasn't cheating.

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Old 08-30-2011, 12:21 PM
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Default RE: Snap Roll (no arguments, please)

I don't think it is cheating.

Volkert
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Old 08-30-2011, 12:29 PM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: wagen017

I don't think it is cheating.

Volkert
Uh.... Am I missing something?

"Examples of control functions not permitted:
1) Snap buttons with automatic timingmode.
2) Preprogramming devices toautomatically perform a series of commands"
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Old 08-30-2011, 12:39 PM
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Mastertech
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Default RE: Snap Roll (no arguments, please)

It's not cheating and widely done. No transmitter has a timing mode in it. That is the difference.

Tim
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Old 08-30-2011, 01:20 PM
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Default RE: Snap Roll (no arguments, please)

ORIGINAL: Mastertech

It's not cheating and widely done. No transmitter has a timing mode in it. That is the difference.

Tim
Tim you must not own a 14MZ

...from the 14's manual.

"The Condition Delay can be programmed for each
channel. The Condition Delay is used to change the
servo throw smoothly when switching conditions."
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Old 08-30-2011, 01:41 PM
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Default RE: Snap Roll (no arguments, please)

Hi Glen,

No I don't own a Brand X.

Are you telling me that you can program a 14 to a preprogrammed snap button on time? IE it starts when you hit the button and shuts off on it's own?

Tim

A timer function on the snap button was in Brand X transmitters 20-30 years ago iirc and that's why that rule came about. Possibly other transmitters but I'm getting old and feeble.
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Old 08-30-2011, 02:39 PM
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Default RE: Snap Roll (no arguments, please)

ORIGINAL: Mastertech

IE it starts when you hit the button and shuts off on it's own?
Tim,

Yes...When a condition is enabled the user can configure a delay to the movement of a servo on a channel or channels. Say for a snap, with a condition switched on a delay can be configured to the way the throttle servos moves to prevent sudden acceleration or deceleration. In the base-case the user still has to move the sticks or as suggested "hit the easy button". Just wanted to point out that a configurable timer still exists in current day transmitters.
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Old 08-30-2011, 03:07 PM
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Mastertech
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Default RE: Snap Roll (no arguments, please)

Thanks Glen, learn something everyday......

Tim
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Old 08-30-2011, 03:11 PM
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Default RE: Snap Roll (no arguments, please)

With a 14MZ, it doesn't necessarily have to be a condition change either, there's some offset mixes with timing functions as well.

I'd suspect the 8fg and 12fg, would have these available??

I'm a bang-the-sticks-in-the-corner style but I try to make the effort to lead with the elevator to show some sort of break (whether it's needed or not). Once the sticks hit the corners, the snap-roll condition takes over and the new AFR/rates becomes active. My aileron throw is greater in the snap condition than in normal.
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Old 08-30-2011, 03:31 PM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: Nathan King
How do you perform a snap?
My snap learnings: Full up (or dn), full aileron, full rudder. As soon as the limit is reached on one input, the next is started. So its 1, 2, 3 (really fast!)

Here's the cheat...full rudder activates a new flight mode that takes about half the elevator throw out.

Always snap away from the judges on single snaps, or towards the judges if 1 1/2. (Heading changes coming in are easier to discern than going out...IMO)

1 1/2 snaps...hang on the rudder for a moment after the rotation stops.
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Old 08-30-2011, 06:14 PM
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Default RE: Snap Roll (no arguments, please)

One thing I learned is that you lead the maneuver with the elevator, and end with the elevator. Use elevator to control speed - you may want to slow the plane down a lot, or try to keep speed through the maneuver using more or less elevator.
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Old 08-30-2011, 07:03 PM
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Default RE: Snap Roll (no arguments, please)

If had the emoticon for popcorn eating you would see it here.
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Old 08-30-2011, 07:24 PM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: RC_Pattern_Flyer

If had the emoticon for popcorn eating you would see it here.
You mean this little guy?

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Old 08-30-2011, 09:01 PM
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Old 08-31-2011, 05:25 AM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: gaRCfield

One thing I learned is that you lead the maneuver with the elevator, and end with the elevator. Use elevator to control speed - you may want to slow the plane down a lot, or try to keep speed through the maneuver using more or less elevator.
Oh crap, forget what I said. Just remembered that came from MAN. Not sure what's worse, that or the smug my g/f reads in the checkout line at the grocery store.
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Old 08-31-2011, 08:52 AM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: Nathan King


ORIGINAL: RC_Pattern_Flyer

If had the emoticon for popcorn eating you would see it here.
You mean this little guy? [img][/img]

Yep that's the one.....Cute, isn't it! And soooo appropriate. Snap discussions, just like all the other discussions on pattern threads (weight, 2x2, noise, u name it) are very very phunny.
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Old 08-31-2011, 09:06 AM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: MTK

Snap discussions, just like all the other discussions on pattern threads (weight, 2x2, noise, u name it) are very very phunny.
Why? Not one right way to do it, or no one really knows? I guess for our purposes, best thing one can do is look at the judging criteria and find the best way to meet it?

I don't like snaps because I don't really know what I'm doing. Don't like being told to bang sticks to the corners, would rather have this discussion and learn what's supposed to happen. If I wanted to hap-hazardly bang sticks, I'd fly 3D.
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Old 08-31-2011, 06:00 PM
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Default RE: Snap Roll (no arguments, please)

Sorry.... I just have to

So what leads when in knife edge configuration like F-13

Mark
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Old 08-31-2011, 06:56 PM
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Nathan King
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Default RE: Snap Roll (no arguments, please)

This thread went south in a hurry, but I did glean some useful insight into snaps. Thank you.
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Old 08-31-2011, 07:04 PM
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Default RE: Snap Roll (no arguments, please)


ORIGINAL: bjr_93tz


I'm a bang-the-sticks-in-the-corner style but I try to make the effort to lead with the elevator to show some sort of break (whether it's needed or not). Once the sticks hit the corners, the snap-roll condition takes over and the new AFR/rates becomes active. My aileron throw is greater in the snap condition than in normal.
I'm curious as to what you are using to trigger the aileron rate/condition change. If you are using Futaba 12/14, I don't know of a way to use two stick positions combined to trigger the condition change. Are you using elevator at +/- max stick to tryigger the change? Do you switch to a snap condition first to prevent the aileron rate change from being active whenever you use max elevator stick(or is that just something that shouldn't happen).
Right now the aileron rate increase is the only change I make for snaps but I use a switch to do it. I would like to get rid of the switch.

Say hi to Paynie for me.

John Gayer

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Old 08-31-2011, 07:59 PM
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Default RE: Snap Roll (no arguments, please)

Hi John,

Depending on your version of software update, the 14MZ supports "logic" for condition selection. In my case I use the elevator and rudder sticks to make the "snap" condition active. With the stick switches set to "Symmetrical hysteresis mode" the snap condition is only activated when the left stick is fairly well "boxed" in either of the 4 corners, Just full elevator or just full rudder won't do it.

By arranging the prority of the conditions, If I have the "spin" condition selected the "snap" condition won't activate because it's a lower priority so I can box the left stick during a spin without activating the snap condition.

There're pluses and minus for using stick switches as opposed to traditional switches or even a snap "button", but pattern setup is all about compromise...

I'm not sure the what the OP hoped to get out of this thread? I don't think it's gone south at all. What control inputs the pilot makes, or how his radio is setup isn't judged, you're only judged on what the plane does and if my plane can perform a textbook snap with just elevator alone then lucky me.
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