I am trying to understand why my 30% Yak has a tendency to over rotate it's snap roll on the horizontal line. It seems like I need to lead the exit of the snap by an 1/8 or a turn maybe a bit more.
I am entering the snaps at between 1/2 to 1/3 throttle typically, and try and lead the snap with up elevator an instant before I apply full aileron and rudder. Exit is to neutralize the sticks. I am doing the snap on low rates. The snap inself looks good, just over rotates.
While I am new to the gas scene I am not new to pattern just a few years removed so I am pretty familiar with setting up a plane properly.
The other day I flew a freinds EF 110" Yak 100cc and could not believe how well it snapped. Using the same technique when I nutralized the sticks, the snap stopped.
So I am wondering what on the plane will effect snap rolls?? CG, Thrust, Deflection, etc??

Any help would be appreciated.

Thanks.

ChuChuf -

There are several things in could be, in my limited experience. With my models...the over-rotating offenders were all on the porky side. I have come to believe that the weight of the wings themselves have a lot to do with this over rotating tendency. If you think about it...with heavy wings...the built up inertia in a snap is sometimes difficult to overcome. Sadly, again, from my experience, correcting this often required rather drastic measures. My latest offender, a 35% AW Edge 540T, has been decommissioned due to excessive wing weight. It being a composite frame and wing made any lightening project a task I was not prepared to undertake.

Thanks toad for your comments.
Those were my initial thoughts as well so I weighed the plane (since I purchased it second hand and it did require a LOT of rework).
The plane isn't really that heavy coming in at about 17+ lbs. Wings both staticly come in at about the same weight each when weighed on a scale.
I am going to be recovering the plane in the next few weeks to strengthen all the joints as well as put a new finish on the plane and will look for areas where I can lighten, expecially on the tail since I am carrying 11 oz on the nose to balance.
Plan to do some more flying today to see what other tendencies it might have.
Spins as I recall don't seem to over rotate that much. But aster flying the EF 110" Yak, I am spoiled with it's instant stopping when snapping.

Thanks

Terry

Servo strength could play a big part in this also. With lower torque servos you will see the servo giving a little because of all the weight coming around from the snap causing the over rotation. More than likely it is in your servos. The spins arent going to over rotate because you do not have as much air going over the surfaces as you would in a full/half throttle snap.

Originally Posted by TeamFlatout

Servo strength could play a big part in this also. With lower torque servos you will see the servo giving a little because of all the weight coming around from the snap causing the over rotation. More than likely it is in your servos. The spins arent going to over rotate because you do not have as much air going over the surfaces as you would in a full/half throttle snap.

An excellent suggestion!

Ah hadn't thought about servos being an issue, and honestly it is my intent to change the HD DS120 servos I have in this plane when when possible. These servos while strong (I believe they were tested at 170 oz in by TBM) have a bit to much slop in the gear train for me.

But here is a question, are you guys entering the snap rolls on horizontal line at full throttle, half throttle, etc?? How about the use of aileron during the snap? How about CG?? what impact will for or aft CG have on a snap roll?

Terry

Regardless of what he is flying, a pilot learns his/her airplane and provides control input accordingly. The plane does not fly itself in aerobatics, nor is it supposed to. A superior flyer learns and recognizes the nuances of his aircraft and provides the correct control input and the correct times to make effective use of the aircraft's attributes.

In short, it's not the plane, it's the person at the controls.

Often over rotating snaps is caused by too much rudder throw. Try reducing your rudder in your snap rates.

Originally Posted by 1bwana1

Often over rotating snaps is caused by too much rudder throw. Try reducing your rudder in your snap rates.

Yes! Try this first....

Originally Posted by Tired Old Man

Regardless of what he is flying, a pilot learns his/her airplane and provides control input accordingly. The plane does not fly itself in aerobatics, nor is it supposed to. A superior flyer learns and recognizes the nuances of his aircraft and provides the correct control input and the correct times to make effective use of the aircraft's attributes.

In short, it's not the plane, it's the person at the controls.

Uh with this type of answer would be a reason why someone would not progress. Why fly harder and not smarter? Why go through and change the way someone fly's?

Tired Old Man, so what you are trying to say is he needs to stop the snap inputs a half a second before the plane gets level so that the plane will stop in the correct position? If thats part of your thinking that is ONE STUPID way of thinking. When you let go of the sticks the plane needs to stop the second you let go. And yes mine does!!

Chuf, check your rudder throw, this is a cheaper way to fix the problem. But if it continues check your servos and upgrade them if you can. Dont listen to the old man. The old saying goes like this: Work smarter not harder. Some dont understand that concept.

Thanks guys. Checking the rudder throw (which I will try on low since I do leave that on high for snaps) could be the very thing causing the over rotation.
While I agree that one should learn to fly their plane once they get it trimmed out properly, it's the trimming that is important to get the plane to fly the best it is capable of.
Again thanks for the suggestions.

Terry

how about burbing the throttle on snaps. i have seen people do this and i think it is to get more air over the control surfaces to get it to stop.

I agree with the rudder comment. If you you stay on the rudder too long or have to much rudder in it will get difficult to stop it where you want it.

When I finally figured out that I was using to much rudder in my snaps my Yak now stops the instant I come off the sticks. It was just too simple a fix for me to figure out right away.

Tom

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