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Heavy Wing?

pilot28906

Well Known Member
I have read and continue to read about the heavy wing fixes both here and on Van's web site. Seems it can be caused by several things.

In straight and level flight the ailerons are in trail but when I let the stick go, the left aileron deflects up 1/2-1" and of course starts a left turn.

Does this symptom indicate which particular problem I have that would point me to the correct fix?

RV7

Thanks
 
I have read and continue to read about the heavy wing fixes both here and on Van's web site. Seems it can be caused by several things.

In straight and level flight the ailerons are in trail but when I let the stick go, the left aileron deflects up 1/2-1" and of course starts a left turn.
RV7
Thanks

Did this happen with a passenger of your size? Was the fuel balanced between tanks?
 
What about on a rv9 where you can’t squeeze the ailerons?

After you do all the stuff gasman mentioned and you are certain that all other variables have been eliminated, you can put a trim tab on the aileron. Not a big deal.

hopefully other 9 owners chime in with other options.
 
What about on a rv9 where you can’t squeeze the ailerons?

On the 9, 10, 14, put the aileron in trail and sight down the wing. Repeat for the other wing. Is one aileron vertically higher than the other? 1/16” makes a difference. High aileron=heavy wing.
 
Yes, the left wing is still heavy with a passenger and with more fuel on the right side. Not as bad, but still heavy. Not too bad at slower speeds but worse at high speeds.
 
John,

I’ve help server also RV builders/owners fix heavy wing problems. In every case, there existed a rigging problem needing to be discovered.

I’ve posted on this in the past, but here is the short version of how to go about checking your rigging:
- Are the flaps really all the way up and trailing edge flush with he fuselage - and both sides the same? I found one RV-4 that had a low flap for 20 years.
- Taking a straight edge over the wings and extending out over the flaps, do you have the same gap over both flaps, and over the length of both flaps (as in no twist)?
- After you address the flaps, now look at the ailerons. With the trailing edge of one aileron lightly clamped to the trailing edge of the flap, is the other aileron trailing edge lined up with the other flap? If not fix this before moving on.
- With the ailerons now lined up with the flaps, measure the aileron to wing skin gap across the length of the aileron. Is it the same? Are both flaps the same. Typically this is the problem area. The fix is to re-hang the offending aileron - either with replace it the hinge with a “no hole” hinge from Van’s and drilling a new hole in the right spot or elongating the hinge to aileron bolt holes to have an adjustment up or down.
- After you do all this, then look at the wingtips on how they line up.

For builders, this last point is why I strongly recommend deferring wingtip fit up until after the wings are on the plane and this rigging is done.

Carl
 
I fixed my heavy wing by taping a coffee stir straw at the trailing edge of the back/bottom of the aileron of the non heavy wing.

I’m sure there are other options and bigger straws for heavier wings too.

X
 
John,

"The fix is to re-hang the offending aileron - either with replace it the hinge with a “no hole” hinge from Van’s and drilling a new hole in the right spot or elongating the hinge to aileron bolt holes to have an adjustment up or down.
- After you do all this, then look at the wingtips on how they line up."

Carl

AH HA !!!!- - this sounds like more than "rigging" , not that I am the arbiter of such language but rigging always seemed to imply adjustments available without component modification, i.e. new hinge pivot points.

As part of the process, I used coffee straws to continue phase one until it was time to fix. Amazing what that straw will do with a rudder too. Very effective. Just adjust effect with the length of the straw.

YES - I had a heavy wing, did all the things you mentioned and had to elongate my hinge several times until it was neutral. Then made a new one.
 
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I fixed my heavy wing by taping a coffee stir straw at the trailing edge of the back/bottom of the aileron of the non heavy wing.

I’m sure there are other options and bigger straws for heavier wings too.

X

Kinda like a Gurney flap (or wicker) on a race car wing or spoiler.
 
My left flap was not all the way up against the fuse. The left flap was 1/8"+ low. I adjusted it so it is up against the bottom of the fuse and now the left and right flaps are the same.

Then I removed the left wing tip and attached the wing end rib template for neutral and installed the bell-crank jig on the left wing. I noticed the left aileron TE tip was about 1/8" high of neutral at the OB tip compared to the end rib template. I adjusted the left aileron by lengthening the aileron push rod bringing the left aileron TE tip to the template neutral position. This was done with the elevator locked in the neutral position.

I have not flown yet but does this seem like a correct adjustment?

Thanks
 
My left flap was not all the way up against the fuse. The left flap was 1/8"+ low. I adjusted it so it is up against the bottom of the fuse and now the left and right flaps are the same.

Then I removed the left wing tip and attached the wing end rib template for neutral and installed the bell-crank jig on the left wing. I noticed the left aileron TE tip was about 1/8" high of neutral at the OB tip compared to the end rib template. I adjusted the left aileron by lengthening the aileron push rod bringing the left aileron TE tip to the template neutral position. This was done with the elevator locked in the neutral position.

I have not flown yet but does this seem like a correct adjustment?

Thanks

It will likely yield some improvement, but fly and check. After doing all the checks in the Vans document, slotting the hinges and finished by drilling, I used squeezing the TE as the final trimming. Many of the adjustments made it feel a little better.

I think I had more than 9 changes and flights. Be sure to fly the same settings, note W&B and definitely note fuel levels. Sometimes I found it hard to quantify the"heaviness" so topped tanks and flew on the heavy side until it was balanced. trim was neutral. Then after a few changes did the same again to "measure" improvement. When done, 3-5 gallons was easily trimmed either direction.
 
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Aileron Measurments

Adjusting the ailerons per above did not help. I have taken some measurements from the top of the aileron hinges to the top of the aileron skin. I did this for both Left and Right aileron Outboard and Inboard. Is the difference from OB to IB too much; causing the left heavy wing? Left and Right seem to be consistent.

Left
OB=.254" IB=.141"

Right
OB=.248" IB=.136"

Thanks
 
While I have never flown an RV, I did production test fly a couple of hundred Crop Dusters over about 14 years and of course have had to trim a few heavy wings.

First does it stall evenly and not drop one wing every time? That pretty much means it’s not the wings slight angle of incidence or maybe a difference in wash out.

Then are RV’s ailerons identical? can you swap the left and the right? If so, do so and see if the heavy wing follows the aileron, if it does then of course it’s likely the aileron, but many times I’ve swapped them only to have the problem go away.

Then I have had to replace an aileron very rarely, and we never figured out what was different about the “bad” one.

it’s normal for ailerons to fly high in flight, if there is any slop at all in anything, sitting on the ground of course gravity pulls them down, and in flight they get sucked up by lift. Now I’m not talking much, but there is some slight difference.


Oh, and on edit we would set the flaps using a straight edge on the bottom of the wing, unsure if that would work for an RV or not, or of course use a good level.

I tried using flaps to correct a wing heavy, but it screwed up the stall
Now this was a Crop Duster, but I think an airplane is an airplane
 
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