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IMAC sequence snap question

Old 08-06-2006, 09:55 PM
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Default IMAC sequence snap question

I have a question about the vertical downline snap in the intermediate sequence. For some reason I cannot seem to stop the rotation cleanly. Typically I end up over rotating about 1/4-1/2 turn no matter how early I let off the sticks and recenter. The only way I can seem to stop it is to reverse the aileron input as it comes around, but when I do it is not a smooth stop, but rather abrupt and cause the plane to pendulum a little for a second. The other two snaps in the sequence are fine, its just this one that is kicking my butt. I bet I have gone though that one segment of the sequence 100 times this week and maybe 5 times it has come out on the mark.

Any suggestions?

BTW, I am flying a 35% Extra 260 that weighs just under 23 pounds. The wings weigh 35 oz each just to give you an idea of the basic setup.
Old 08-06-2006, 10:28 PM
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Default RE: IMAC sequence snap question

There are several reasons this could be happening. Possibly too much throw on the rudder and elevator making it get buried deeper than it needs to be. Another might be cg... for your case if throw isn;t the problem I would guess that the cg is too far aft.

To check throw try doing just aileron and rudder on the down and see if it comes out of that cleanly... if it does remove a lot of your elevator and then try again with elevator. You can also experiment with leading with elevator and unloading the elevator before the snap is finished so it will come out where you want it to.

But basically you just need to make single small adjustments every couple snaps and see if it looks like it is getting better or worse. Also be sure and continue to do your other snaps to make sure they aren't looking any worse when your downline snap is looking better with your adjustments.

Hope this helps

John
Old 08-06-2006, 11:58 PM
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Default RE: IMAC sequence snap question

i have to agree with the previous...it sounds like you have too much of something(s). the wings/airplane are unloaded on vertical downline and should not require a lot of energy to get in and out of the snap. i would reduce the throws on everthing until you cannot get the airplane to snap, then start adding them in small increments until you can. you can also use the torque energy by snapping to the left (when possible) which (compared to snapping to the right) minimizes the initial energy needed to start the rotation, thus the control surface movement. i am guessing the situation you describe is not so much a snap as a initiated spin. not that anyone likes to admit this...but the end of a vertical snap is tough to judge - if you slightly underrotate the snap it is very hard to conclude that the snap finished with aileron. but if you overrotate it...it is obvious and you'll get dinged. i also suspect that if the problem is in your set-up, not only will you benefit in the execution of the snap, but that your entire sequence will present smoother and more controlled.

intermediate? i wonder who thought of that.
Old 08-07-2006, 02:35 AM
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Default RE: IMAC sequence snap question

Reduce or eliminate the rudder for except for the first 1/4 of the snap.
How do you fly the sticks? I am guessing but I am probably using about 20 degree of rudder no elevator except to get the pitch moment, and 15 degree ailerons. You really don't need much on a down line.

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