Hey folks,

I am trying to get this thing dialed in. I am really enjoying this aircraft so far with the exception of 2 issues. I am hoping that some of you may have some experience with this A/C combo. It does well except in slow flight and hover. Man, no matter what I do it wing rocks like a SOB in slow, high alpha flight. I have tried more/less elevator, slightly more speed even inverted and I can't get the f****** wing rock to stop. I thought about putting some SFG's on it but other than that I am out of ideas. The other issue is it seems very difficult to hold in the hover. My 50cc yak 54 that I used to have behaved way better in the hover. Power seems fine but it just seems to fall over to easy. I have tried every DR setting I can program and it just gets to wobbly? Any help would be appreciated.

im not going to offer much help but it sure sounds just like my AW yak55

Sealing the hinge gaps migh help, also did you try an inverted 45 climb to check your cg to see if is neutral .

Maybe add in a mix for spoilerons?

Tony

The hinge gaps are sealed. No I haven't tried the 45 degree climb yet.

Sorrrrry for the long post but wing rock can be any number of things,

I am not sure how much you have read, but when I have a problem plane I start reading over things like Now to Trim a Pattern plane, or any help forms for IMAC to
Watch videos of the same plan doing 3D to see if it has the same tendencies.

But this is what I would check,
Lateral balance win tip to wing tip
Twist in wings and stabilizer, rudder.
Get them ALL out, even to the point of removing the covering and steaming out the twist, every ARF has something that is twisted. Almost all twists are fixable just from heat even wings.

I have planes with big gaps unsealed and for 3D don’t see one plane rock more or less but it is a good practice to seal all gaps.
Setup is everything
Once the plane is true move on to hoe the stabilizer moves in relation to each other. They must track the same (not easy to do) use long carbon stick taped on the surface pointing at each other just past the rudder.

Then check to make sure the ailerons viewed from the tip to be at O degrees to the center line of the airfoil.

CG, try this after checking all other things, move CG back, then you will need less elevator and do not over control the ailerons (add some expo to help)

Change the Prop DIA and or Pitch. Try a lower pitch.

Last try mixing, the new add on 3 axis stabilizers may help prove the plane can fly but will just make you feel bad.

Hang around pattern or IMAC guys to try to pick up tricks to trimming. Have someone you trust to fly it that is good at harriers. One problem is the anti rotating pins on the wing and stabilizer, they may be off in relation to each other and you may have to file the holes. Most good precision planes have adjusters to help with this.

Sell it and get another YAK like you had. Kidding!!! But it may come to this if all this extra work is overwhelming. On all of my ARF's I check all the surfaces and fixed parts for trueness before hinging.

Start with the stab, the ailerons I am betting it will be there.
Hope this helps

Try adding a degree of up thrust. This should help it lock into a hover better as well as help in reducing the wing rock.

It sounds like you have not yet done anywhere near "complete" trimming out of your plane. Use the attached chart to go step by step to help determine what your plane needs to fly nearly perfect. Then you can adjust rates for 3D. The chart is a condensed from the Peter Goldsmith text on trimming.


BTW don't go past the CG step until it is perfect for the way you like to fly!

Thank you for all the pointers and that check list. I will be checking all those for sure. Atleast when it warms up here in ol Kansas anyway LOL

Lots of good opinions but what I have found for me is usually wing rock is from nose heavy. I also have adjusted my ailerons to sit almost as though they look like spoilerons, Just up enough and it stabilizes the plane. Those two simple things have always corrected wing rock for me.

Originally Posted by Spats

Lots of good opinions but what I have found for me is usually wing rock is from nose heavy. I also have adjusted my ailerons to sit almost as though they look like spoilerons, Just up enough and it stabilizes the plane. Those two simple things have always corrected wing rock for me.

I agree. Sounds nose heavy. One of the first things you should do is check the CG in the air.

Originally Posted by ericb

I agree. Sounds nose heavy. One of the first things you should do is check the CG in the air.

I'm fairly new at this, but your symptoms are classic nose heavy in my limited experience. Especially "falling" out of a hover. I'm just getting into 3D, but the difference between nose heavy and just right for me is the difference between a locked in hover and torque rolls or not being able to get into a hover at all.

Again, in my limited experience, the best CG for 3D is one that's completely neutral...meaning inverted flight without any down elevator. My understanding is that setting your CG using the 45 degree upline method is more for precision aerobatics. As soon as I get a new 3D plane trimmed for level upright flight the first thing I do is roll it onto it's back to see what I need to do with CG.

Don't get me wrong, my advice is not to be taken as gospel, but this is what has worked for me.

Good luck and let us know what you find!

OK, I will certainly check the CG because I do need some down elevator to hold the inverted. I will also check the ailerons. You say that they are slightly up....do you have this status programed to a switch for high alpha flight or is your ailerons like this for just jamming around or take off even?

I set them about 1/16 - 1/8 up. They are not on a switch, I don't recommend this until you check CG. Most everyone will give a reason why not to do this. It's just something I have done on two of my planes.


Putting them on a switch would be the best way to experiment with the setting.

Why would you not want to do that. I mean I am a real world pilot so I can think of a few aerodynamic reasons but models don't always see to follow the real world entirely