Snap rolls (long) - the ins and outs...

[Adam Glatt]

Keith, one popular way to manage throws is with conditions in your expensive computer radio.  JR calls it flight modes.  That allows throws that are perfect for regular manuevers (lots of time I use full deflection of my sticks because I have the condition's throws set up so that I can't go more throw, because it is never needed in consistent flying).  Doing it this way you would turn on the snap condition just before the snap and turn it off just after.  Some guys flip the switch at the start of the manuever and turn it off once they exit the manuever - it gives you more chance to think about the inputs, but the rest of the manuever probably won't be smooth.
Conditions/FlightModes, at their most basic, are only used to have different end point throws on all three channels triggered by one switch.  Often different expotential is used as well, but the main thing is end point throw.


Throw is dependant mainly on wing size, shape, airfoil, and horizontal stab size.  Usually it involves LOTS of aileron (20-30deg), little elevator, and medium rudder.  IMO, most people below FAI are trying to do snaps with too much elevator and not enough aileron.  They see that if they use less elevator it doesn't snap, but I've found that you can actually substitute more aileron for that elevator throw.  Elevator tends to speed up the snap, but it does it violently and it takes a while for it to get going.  If you notice your plane winding up through the first 180deg of rotation or so, you probably have too much elevator (or slow aileron servos).

Which of course brings up servos.  Not much to get into here, it's really just a budget thing.  Spending more money will get you better snaps and more accurate exits.

Inputs are really where the masters show themselves.  You have to really understand exactly what each control service does to a snap and its role in a snap, and from there you can try to come up with a sequence that makes the snap as 'good looking' and accurate as it can be (good luck finding perfection on this one).

The other problem is that there are very few judges who can properly judge a snap, imo.  Take a look at the judges from the recent Team Selection Finals - these guys know what they are doing.  Unfortunately, we can't have these guys with us every day and at every contest.  I think the best way to learn what a good snap is is to watch the top pilots.  Muncie is an AWESOME place to see snap after snap from a lot of world-class pilots.  You can't go wrong copying these guys.

I can guarantee you others will have different opinions about everything I wrote here, so don't take it to be the 'right' answer.  You have to go flying and just do flights with lots of snaps.  Take a look at all the snaps in the different schedules, maybe have someone call all these snap manuevers for a few flights.  Play around with different inputs and throws, because besides the airframe, there's nothing else to it!
  ----- Original Message ----- 
  From: Keith Black 
  To: discussion at nsrca.org 
  Sent: June 23, 2003 11:26 PM
  Subject: Re: Snap rolls (long) - the ins and outs...


  This is a great thread on the anatomy of a snap! 

  What I'd like to hear are techniques for executing good positive and negative snaps. I'm interested in things like what's the best direction to snap (left?), what are the necessary stick movements for positive and negative snaps, timing of stick movements, what should be done differently on down-line vs. horizontal vs. up-line snap, etc. 

  I've heard that the top fliers don't just jam the sticks at the same time but they break the snap into multiple components to keep it true and on heading. This is a complete mystery to me and I'd love to understand it more.

  Also, of great interest to me is how much throw is necessary for good snaps and how to fly smoothly with that much throw. Obviously each plane will vary but I'm looking for some basic guidelines on throws, maybe with specific planes just as a idea. And how do the top level fliers deal with having enough throw to execute snaps AND keep their other maneuvers from being jerky? Dual rates, huge expo, snap switch, or just REALLY steady fingers? 

  This weekend at the Nederland, TX contest FAI flew F03 in the sixth round. All of us mortals sat around in amazement watching snap after snap in every conceivable attitude and direction. And Earl you're correct, these snaps looked nothing like a lot of snaps in the other classes. They were extremely crisp, quick and solid. 

  So please, someone share your secrets so we can improve on those mediocre snaps that everyone keeps referring to! :-)

  Thanks,
  Keith Black

  (snip due to size limit)
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