Snap Roll(s) Question?

[Cessna150C]

So I have started trying to perfect my snap rolls. Timing seems to be one of the most important parts. It looks like I have my work cut out, but I guess practice makes perfect. Well make that practicing with the correct technique.

So here is my first question. When executing a positive half-snap on a 45 degree up-line, how do you keep a constant heading through the entire snap? My half-snaps always end off heading about 20 degree toward the direction of rotation.

Second question. When trying to execute a series of snap rolls I can only get about two full rotations before the snap looses energy and gets "buried". I am unloading most of the back pressure on the stick. After reviewing my flight video I noticed that I am subconsciously adding and sustaining pro-rotation aileron through the snap. Is that causing the snap to get "buried".

Thanks in advance for any input!

 

[CFI AandP]

For the half snap on a 45 up line, use canopy references for your bank and attitude. Some people draw a line with tape, marker, etc. on the canopy to match the horizon when inverted on a 45 up line.

Are you snapping left or right? Stick position is different between lefts and right.

 

[djpacro]

Consider a full snap - halfway round you will be off the original heading but back to it after the full rotation. Stopping it halfway results in you finishing off heading. Some refinements to minimise that amount but think about: as soon as the snap has stopped - boot the other rudder to slide the nose back on heading.

We're flying CIVA's Yak 52 sequence as Intermediate this year - level half snap followed by two of a four to upright.

Currently in an S-2A and haven't flown an S-1 for ages so better not comment on the other question.

 

[whifferdill]

There are several things you can do to minimize your heading error after half snaps...and not just those on 45 uplines. Snap left. Gyroscopic precession during the initial pitch up of the snap causes a yaw to the right. Snapping left can minimize the initial heading displacement. But this is less of an issue with your lightweight Catto prop. Gyroscopic effect for any maneuver is much more noticeable when swinging a metal prop.

Also, learn to use as little aft stick as possible to initiate the snap. I see a lot of videos of folks using full or nearly full aft elevator. With proper technique and timing it can be a fairly small elevator movement. The more elevator you use to initiate the snap, the more the nose will pitch up, which translates into heading error as you start to rotate.

And unload the half snap very quickly with some forward stick to keep the nose from pitching up. The gyroscopic consequence of a left rudder yaw is also a pitch up of the nose. Left snaps take more forward unloading of the stick than right snaps do. And for half snaps, you will want to unload slightly more forward than you would for a full snap. Again, to reduce the pitch change and heading error after 1/2 rotation.

Lastly, do not apply full right rudder to stop the snap. You should really only need to neutralize the rudder to stop a half snap. If you apply excessive right rudder to stop the snap, that's only yawing you further off heading.

And even after all that, you may still be off by a few degrees stopping the snap. I've found that they still require the re-application of a small amount of left rudder simultaneous with the snap stopping. You should also notice that you have a slight pitch error after the half snap as well, requiring a slight amount of aft stick upon stopping the snap. And these left rudder and aft stick movements should be quick enough and measured to the point where nobody sees you actually make much of a correction after the snap stops.

A perfect half snap is quite a challenge, given so many inputs taking place in the span of about a second. Feels good to nail a perfect one. Regarding the half snap on the 45 up, are you practicing this year's Intermediate Known? I've also been flying these in this year's Advanced Known.

Regarding multiple snaps, if you are doing them level, yeah you will run out of energy after a couple and will fly out. If you want more rotations, you must do them on some degree of a downline so that gravity helps counter the natural decay of energy associated with snaps.

Eric

 

[Cessna150C]

There are several things you can do to minimize your heading error after half snaps...and not just those on 45 uplines. Snap left. Gyroscopic precession during the initial pitch up of the snap causes a yaw to the right. Snapping left can minimize the initial heading displacement. But this is less of an issue with your lightweight Catto prop. Gyroscopic effect for any maneuver is much more noticeable when swinging a metal prop.

Also, learn to use as little aft stick as possible to initiate the snap. I see a lot of videos of folks using full or nearly full aft elevator. With proper technique and timing it can be a fairly small elevator movement. The more elevator you use to initiate the snap, the more the nose will pitch up, which translates into heading error as you start to rotate.

And unload the half snap very quickly with some forward stick to keep the nose from pitching up. The gyroscopic consequence of a left rudder yaw is also a pitch up of the nose. Left snaps take more forward unloading of the stick than right snaps do. And for half snaps, you will want to unload slightly more forward than you would for a full snap. Again, to reduce the pitch change and heading error after 1/2 rotation.

Lastly, do not apply full right rudder to stop the snap. You should really only need to neutralize the rudder to stop a half snap. If you apply excessive right rudder to stop the snap, that's only yawing you further off heading.

And even after all that, you may still be off by a few degrees stopping the snap. I've found that they still require the re-application of a small amount of left rudder simultaneous with the snap stopping. You should also notice that you have a slight pitch error after the half snap as well, requiring a slight amount of aft stick upon stopping the snap. And these left rudder and aft stick movements should be quick enough and measured to the point where nobody sees you actually make much of a correction after the snap stops.

A perfect half snap is quite a challenge, given so many inputs taking place in the span of about a second. Feels good to nail a perfect one. Regarding the half snap on the 45 up, are you practicing this year's Intermediate Known? I've also been flying these in this year's Advanced Known.

Regarding multiple snaps, if you are doing them level, yeah you will run out of energy after a couple and will fly out. If you want more rotations, you must do them on some degree of a downline so that gravity helps counter the natural decay of energy associated with snaps.

Eric

Thanks for the info. After reviewing the flight video it looks like I am using a LOT of opposite rudder to stop the half snap. I'll have to have to give the new technique a try.

 

[whifferdill]

If you hit a clean snap with lots of roll rate...and the S-1 can snap over 360 deg/second...the half snap is pretty much a quick rudder, release, and re-apply (slight amount of original rudder) movement. It all happens faster than you can say it. If you're oversnapping slightly, your subconscious might be causing you to use too much opposite rudder on recovery. Get in and out with the aft stick as fast as possible, and try neutralizing the rudder as soon as you feel the snap break. In the Pitts, if you have time to actually track the horizon much before starting recovery, you may be burying the snap and getting a slow roll rate. Because it happens so fast, the half snap is more of a timing maneuver than a visual maneuver. Don't worry about stopping perfectly after 180 degrees of roll at first, just get the feel for getting in and out quick with the rudder. The rest is just timing and of course lots of practice. And Alan Cassidy's book describes snaps and snap fractions better than anything out there. And this also goes for aerobatics in general. It's a must own book for the acro pilot if you don't have it.

Be cool to see your videos too. I've found the ones I've shot are the next best thing to ground critiquing. I've picked up lots of little things reviewing them.

And one last thing - if you have competition aspirations, get in the habit of NOT correcting small errors in heading and especially roll. If you over or undersnap a few degrees, DON'T correct it. Fly what you have and blend your heading or roll correction into either the pullout, pullover, or the next figure. It's easy to flinch and reflexively make a quick correction back to your precise roll heading, but that will be seen by the judges and you are broadcasting your error. Better to hold what you have, since if you're only off a few degrees, the judges may not notice. If you correct immediately, they'll definitely see it and downgrade.

 

[whifferdill]

Speaking of half snaps, it had been a while since I've done any level half snaps. Made a run through the British Intermediate sequence just for fun on Saturday to knock off some rust. Last figure is a half level snap. IMO, Figure 1 requires a little too much aircraft performance to be a good Intermediate figure, but I do like the 2-roll roller, inverted spin, and snap fraction. Adds a little more complexity compared to the way the IAC Intermediate category has been structured for a long time. Although this year is the first time in a long time that the IAC Intermediate Known has contained anything other than a single full snap.

http://www.youtube.com/watch?v=uEWm7wt71ZU

Flew this as an Unknown and I've got a number of self-critiqued notes on this flight. See what else y'all can find.

 

[redtail]

Speaking of half snaps, it had been a while since I've done any level half snaps. Made a run through the British Intermediate sequence just for fun on Saturday to knock off some rust. Last figure is a half level snap. IMO, Figure 1 requires a little too much aircraft performance to be a good Intermediate figure, but I do like the 2-roll roller, inverted spin, and snap fraction. Adds a little more complexity compared to the way the IAC Intermediate category has been structured for a long time. Although this year is the first time in a long time that the IAC Intermediate Known has contained anything other than a single full snap.

http://www.youtube.com/watch?v=uEWm7wt71ZU

Flew this as an Unknown and I've got a number of self-critiqued notes on this flight. See what else y'all can find.

That was awesome!

Damn, I just want to get a grip on aileron rolls & loops. I kept releasing stick pressure and rolling out too soon.

Gotta get back up there soon, I've only had one lesson so far.
Your videos inspire me. Sorry this noob couldn't find any imperfections for ya

 

[flhrci]

Speaking of half snaps, it had been a while since I've done any level half snaps. Made a run through the British Intermediate sequence just for fun on Saturday to knock off some rust. Last figure is a half level snap. IMO, Figure 1 requires a little too much aircraft performance to be a good Intermediate figure, but I do like the 2-roll roller, inverted spin, and snap fraction. Adds a little more complexity compared to the way the IAC Intermediate category has been structured for a long time. Although this year is the first time in a long time that the IAC Intermediate Known has contained anything other than a single full snap.

http://www.youtube.com/watch?v=uEWm7wt71ZU

Flew this as an Unknown and I've got a number of self-critiqued notes on this flight. See what else y'all can find.

Is the half snap the one that sounded like you broke the airplane towards the end? It was quick.

I always like your videos. I lack a lot of clues about what you are doing but it looks fun and challenging.


David

 

[whifferdill]

Is the half snap the one that sounded like you broke the airplane towards the end?

LOL. Yep. The right air vent pops open when you snap it, and combined with the whistle of air, that's what you're hearing.

 

[Hiperbiper]

Speaking of half snaps, it had been a while since I've done any level half snaps. Made a run through the British Intermediate sequence just for fun on Saturday to knock off some rust. Last figure is a half level snap. IMO, Figure 1 requires a little too much aircraft performance to be a good Intermediate figure, but I do like the 2-roll roller, inverted spin, and snap fraction. Adds a little more complexity compared to the way the IAC Intermediate category has been structured for a long time. Although this year is the first time in a long time that the IAC Intermediate Known has contained anything other than a single full snap.

http://www.youtube.com/watch?v=uEWm7wt71ZU

Flew this as an Unknown and I've got a number of self-critiqued notes on this flight. See what else y'all can find.

Brithsh intermeDate huh?:

(1)I didn't see any oil dripped in flight. (-10x1.0024K)
(B)No Crumpet Roll of Tea Cup Swizzletwist included. ((1.2xsquareroot of whatdayisit)
(6) The French Roll was not included. An easy one to miss since it starts nowhere, ends nowhere and no one gives a damn what it looked like.


In Future if you insist on doing British stuff you MUST have either a Picture of the Queen or a banner of "Kate is Preggers" somewhere easily seen in the video.

Other than that it was another outstanding video...!

Chris