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01-30-2014, 08:48 PM | #1 |
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Snap Roll ... How to?
In my quest to become more of a rounded flyer, I have decided to conquer the snap roll.
Any and all opinions/ comments are welcome. I figured if anywhere I could get information on this topic is here A video of a proper snap would be most beneficial Thanks in advance Btw My latest radio doesn't have spring loaded switches (yet). So I got to fly these every time |
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01-30-2014, 08:50 PM | #2 |
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Re: Snap Roll ... How to?
In my readings, it seems that one should lead with rudder and end rudder ?
From an old discussion on the iac site. " On a 35%, ..... start with 18 degrees of ailerons, 10 degrees of elevator and 2-2.5" of rudder at the TE." Is this a good formula to start with ? Last edited by Old School Flyer; 01-30-2014 at 10:05 PM. Reason: Misread the initial discussion |
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01-30-2014, 09:46 PM | #3 |
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Re: Snap Roll ... How to?
What the heck, I'll be the first to jump into this "mess" hehe
First, it's important to understand what a snap roll is. I found this on the wikipedia site..... Snap Roll A family of rapid autorotational or "horizontal spins," not unlike spins. Rotation is induced by a rapid pitch input followed by rapid yaw input, thus stalling one wing further than the other. This imbalance in lift causes the high speed roll. So, I'm not sure where you are reading that you lead with rudder but, I'd suggest that's incorrect. To keep this discussion simple(r) we'll just talk about from upright, positive horizontal snaps. A friend of mine who flies full-scale and has done some aerobatics told me that the inputs for a snap roll in a Decathlon is to pull full elevator pitching the nose up rapidly then when the stick hits the stops, to stomp on the rudder which yaws the aircraft thus stalling one wing and thereby initiating the autorotation. This follows exactly the snap as described on the Wikipedia page. Things are a bit different in the modelling world. I've tried snaps with zero aileron input and it just looks funny and is hard to stop the autorotation consistently and cleanly. In "our" world, we often add some aileron to help the roll. You didn't specifically ask what the inputs would be but, essentially they are: 1: pull full elevator 2: input rudder and aileron in same direction 3: neutralize inputs to recover That's probably over-simplifying things. How much rudder, aileron and elevator you want is up to you. Some like more aileron to help speed up the snap but, then it's difficult to recover from the snap on heading and/or with the wings level. Less aileron, the plane will rotate slower and sort of "wallow" around a bit which has another set of issues on recovery. Too much yaw, same thing. Too little elevator and the plane doesn't really stall, thereby not really autorotating. Too much elevator can bleed off too much energy etc etc etc. I don't have the IMAC rule book handy but, to paraphrase the judging criteria for snaps, there must be pitch deviation then autorotation. Again, over-simplifying. ** Rick will correct me, I'm sure ** There are a couple of snaps in the 2013 Int sequence demonstrated here... I also find it interesting watching vids like this.... http://www.youtube.com/watch?v=jYF-O...ature=youtu.be There are several snap elements in Rob Hollands flight and what I find interesting is after he initiates the snap he goes full OPPOSITE elevator. Check out the snap at about :45 seconds into the vid. Interesting stuff. As the full scale aircraft become more powerful, stronger and lighter, I think we'll start seeing the full scale guys copying what we do in our overpowered, lightweight models Anyway, not sure if that helps or confuses but, there ya go, anyway!
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01-30-2014, 09:43 PM | #4 |
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Re: Snap Roll ... How to?
Never thougt about the movments hanes lol. Just smash the sticks it still looks cool on take off lol. I'm. Curious to see what others say.
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01-30-2014, 09:49 PM | #5 |
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Re: Snap Roll ... How to?
Brodie. I had a plane that must have been set up just right. It would snap anywhere anyhow. Perfectly, no speed loss or altitude or anything. But after that bird left. So did my perceived ability to snap. So in doing my homework I have found that I'm snapping to "hard" So figured I'd try and learn to do it right.
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01-30-2014, 09:56 PM | #7 |
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Re: Snap Roll ... How to?
Been a while since I flew but I prefer opposite looks better seems to swing the tail around better. For a tighter snap same rudder and aileron. Like I said been a few months lol I could have my motions backwards. I don't fly imac just to have fun and mess around
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01-30-2014, 10:05 PM | #8 |
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Re: Snap Roll ... How to?
bhughes, yep, just flying around and having fun should be the first priority
That said, and I don't mean to be an a**, but technically speaking, rudder and aileron in opposite direction is NOT a snap roll. I've often heard that referred to as a "shoulder snap" Now, if you initiate the snap by PUSHING the elevator (a negative snap) then aileron and rudder should be opposite. I'm sure we've all had airplanes that have snapped at times when we didn't want it to. On final approach, letting the airspeed drop too much and with a bit of rudder input in, one wing will stop flying which initiates autorotation and snapping into the ground. Been there, done that! Another excellent example is pulling out of the bottom of a loop when the ground is coming up fast and we pull a whole bunch of elevator and stall. Often one wing stalls before the other, now we've got autorotation again and the dreaded snap into the ground. Again, been there done that! Anyway, hope some of that helps, hopefully some others will chime in here and correct my mistakes.
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01-30-2014, 10:04 PM | #9 |
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Re: Snap Roll ... How to?
My initial readings took me here. http://www.mini-iac.com/Forums/tabid...c/Default.aspx
As per anything else on the internet, I have taken it with a grain of salt. BUT I don't have the time in to this hobby. To know if that information is correct either. Hence this thread. Thanks again Last edited by Old School Flyer; 01-30-2014 at 10:11 PM. |
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01-30-2014, 10:11 PM | #10 | |
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Re: Snap Roll ... How to?
Quote:
as I noted earlier that the rudder begins and ends autorotation, the ailerons change the rate of autorotation He says the AUTOROTATION begins and ends with rudder. Not the beginning of the snap. A snap will always begin with pitch, then yaw which initiates the autorotation.
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