Aileron "tuning" or "trimming"

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Hi all,

I have a PW-5 that requires side pressure on the stick at all times to correct a tendency to bank to the right. More pronounced at higher speeds, of course. Wing tape helps a little but doesn't eliminate it. But there is a visible tiny difference in aileron position from one side to the other when the stick is neutral.

Planning to pull out the manual and figure out how to make length adjustments to the control rods, but is there any counterintuitive thing I should know before attempting to fine-tune?

Cheers,
Chris

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On Sunday, May 27, 2018 at 8:03:36 AM UTC-4, wrote:
> Hi all,
>
> I have a PW-5 that requires side pressure on the stick at all times to correct a tendency to bank to the right. More pronounced at higher speeds, of course. Wing tape helps a little but doesn't eliminate it. But there is a visible tiny difference in aileron position from one side to the other when the stick is neutral.
>
> Planning to pull out the manual and figure out how to make length adjustments to the control rods, but is there any counterintuitive thing I should know before attempting to fine-tune?
>
> Cheers,
> Chris

A few things to start with:
First-Before doing anything look in the maintenance manual to see if there is any information on how ailerons should be rigged.
Next, align one aileron in "neutral". Then check to see if the other is in neutral. Stick position does not matter.
If they do, fly the ship and see if it flies straight. Again stick position does not matter for this test.
If it flies straight, then adjustments to the control mechanism may be made to get stick centered.
If they do not line up, the mechanism may need adjustment to make them line up.
If it does not fly straight with ailerons even and in neutral the problem likely is in the rigging of the wings. There may be a way to correct this. See the manual.
All this should be done with the help of your mechanic.
Good luck
UH

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It could be a warped wing, there was an article years ago in Australian Gliding detailing a similar problem with a Mosquito, which was cure by heating the wing in a large oven whilst twisted back
allowing it to cool a couple of times.
Ige seen small aluminium tabs on ailerons used to correct minor issues.

[Dan Daly[_2_]]

Is there play in the aileron when the stick is held steady?

How many hours on the glider?

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There is a useful tool on the iphone compass, if you swipe the compass, a rather good inclinometer is there.
Very easy to check such things as aileron and flap positions and travel.

[Matt Herron Jr.]

On Sunday, May 27, 2018 at 5:03:36 AM UTC-7, wrote:
> Hi all,
>
> I have a PW-5 that requires side pressure on the stick at all times to correct a tendency to bank to the right. More pronounced at higher speeds, of course. Wing tape helps a little but doesn't eliminate it. But there is a visible tiny difference in aileron position from one side to the other when the stick is neutral.
>
> Planning to pull out the manual and figure out how to make length adjustments to the control rods, but is there any counterintuitive thing I should know before attempting to fine-tune?
>
> Cheers,
> Chris

this is counter intuitive. Check that the horizontal stab is properly aligned. I had the same problem in my Ventus. At high speeds it would need stick pressure to keep the thing flying level. Rex at Williams Soaring Center suggested the stab, checked it with a laser, and it was indeed out a little bit. He trued it up (somehow) and the problem went away.

I don't think ailerons out of alignment would cause this. The stick will just find a neutral position that is not perfectly centered, but it shouldn't cause bank. warped wings would though. Does it always drop the same wing when you stall it?

Matt

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> I have a PW-5 that requires side pressure on the stick at all times to correct a tendency to bank to the right.
>

I have exactly the same problem in my PW-5. Also to the right. Our mechanic looked over the ailerons and couldn't see anything wrong with their alignment or any looseness.

My PW-5 has about 300 hours TT.

Obviously I'm interested in how you finally solve this one.

[[email protected]]

I'd look for anything causing drag on the right wing, could be loose aileron gap tape where the leading edge is forced up under air loads or poorly seated spoiler on the right wing. As noted, right turn has nothing to do with zero ailerons or stick position. If unable to find the cause, a small aluminum trim tab (bent up) placed on the trailing edge of the right aileron will make the aileron fly slightly down and counteract the right turning tendency...........but this remedy will add some drag!
Hope this helps,
JJ

[Mike the Strike]

On Monday, May 28, 2018 at 6:25:23 AM UTC-7, wrote:
> I'd look for anything causing drag on the right wing, could be loose aileron gap tape where the leading edge is forced up under air loads or poorly seated spoiler on the right wing. As noted, right turn has nothing to do with zero ailerons or stick position. If unable to find the cause, a small aluminum trim tab (bent up) placed on the trailing edge of the right aileron will make the aileron fly slightly down and counteract the right turning tendency...........but this remedy will add some drag!
> Hope this helps,
> JJ

I think JJ's answer is most likely to be correct. I had this symptom on my ASW20 and everything looked fine until I did winter maintenance to polish the wings and replace gap tape. I discovered one lower gap tape had come partially unglued and lifted a little in flight, acting like a little flap. Replacing the tape with fresh cured the problem.

Mike

[Nick Kennedy]

JJ
What size trim tab would be good for a slight turn?
What proportions that stick out in the wind is your wild ass guess?
Nick

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The tabs I have seen were about 100mm long, and them bent to the correct amount.
Pretty simple.

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Trim tab size is the smallest that'll do the job, I'd say 6 or 8 inches long by a couple of inches wide, bent up in the middle about 15 degrees.......then fly and see if that does the job. Glue it to the aileron with Shoe-Glue.........great stuff.
JJ

[Avron[_2_]]

In Pik20, the plastic tube that leads the wheel brake cable, comes to the stik fron one side.
Sometime it actualy push the stik aside and cause a slight roll.

[[email protected]]

On Sunday, May 27, 2018 at 10:03:05 AM UTC-5, wrote:
> It could be a warped wing, there was an article years ago in Australian Gliding detailing a similar problem with a Mosquito, which was cure by heating the wing in a large oven whilst twisted back
> allowing it to cool a couple of times.
> Ige seen small aluminium tabs on ailerons used to correct minor issues.

Boy, am I hoping it's not a warped wing.

Wing tape is already in use, cleanly applied.

Taped up the inspection ports and am next going to figure out how to seal the apertures around the control rods (it has has the first edition push-pull rods instead of the snap-together twist rods). Will see if that makes a difference and report back. Not going to mess with turnbuckles until we determine that it's not a differential air leak or vacuum.

Cheers,
Chris

[Charlie M. (UH & 002 owner/pilot)]

The next question to ask (if the wing is warped) is one tip twisted up or the other twisted down vs. what the original was?
Guess wrong, the glider may fly straight but have other "less than desirable attributes".
I remember one 2 seat glass trainer that was fine at lower speeds, but the polar nose dived at speed due to the factory wing twist (that helped with stall/spin). Drag went really bad at speed.

Heck, a bad "broken tail boom repair" could have the vertical fin slightly skewed, this can impart a yaw that can show up as you see.
All control surfaces are centered/equal, but the fin is adding yaw.

Has it always been like this, or has it developed over time?

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Well, given that I have only owned the bird for less than a dozen flights, and the first place I noticed it was on the ferry flight home, I have no idea how long it's pulled to the right. Will have to ask the prior owner.

[Charlie M. (UH & 002 owner/pilot)]

Understood.
Just some additional items to think about and look at.

Hope the resolution is an easy one.