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Looking for help diagnosing a Heavy Wing

lr172

Well Known Member
I have a heavy left wing. I suppose that I am good company:D I have read quite a few posts here about the issue and did some investigation today. I examined the trailing edges and they are both very similar. Both are just slightly over-bent, according to the picture on the Section 5 document, but are pretty much identical. If anything the right is more over-bent than the left. I put a caliper on the ends and they are very close in size.

I also put a straight edge on on the underside of the wing skin / aileron skin. on the right aileron, the wing and aileron sit on the same plane (straight edge laying across the two surfaces showed no gaps). On the left aileron, the outboard hinge left the surfaces, as above, but the inboard side had the aileron up (solid parallel gap between aileron skin and straight edge). I didn't measure, but would say it was between 1/16" and 1/8". I called Van's to ask if this type of alignment could cause the heavy wing, as all of the posters I searched found and adjusted mis-alignment on the light wing. The Tech didn't know and said less than 1/8" was in spec. Can this cause the heavy wing?

I ended up putting a 2" tapered balsa block on the light aileron and this eliminated most of the heaviness, but not all of it. I will do more testing tomorrow.

What do you guys think as a next step. I am hesitant to further pinch the right trailing edge given that it seems very consistent with the left.

I also noticed that both of my flaps are about a 1/4" higher than the ailerons at cruise speed. The gap is the same on both sides. I noticed on the ground that I can pull up each flap at least a 1/4" from it's resting position (slop in actuating system). On initial setup, I aligned each aileron using the tooling holes and then set the flaps to the ailerons.

I appreciate any guidance that you can provide.

Larry
 
On my -10, 1/16" made a big difference. (Aileron high = heavy wing) Mine was at the outboard hinge so a longer moment arm. I slotted the bracket so I could move the aileron down, heavy wing went away. Vans sells brackets with no pre-drilled holes for a permanent solution.
 
Bob, and other -10 or -9 builders who have dealt with this, how did you determine that the aileron was high? The top of the wing is not flat, not sure what to use as a reference. 1/16 high is difficult to measure.
 
Yes it is hard to measure. But in my case, standing in front of the wing and sighting down the aft part of the Wing and start of aileron, it was obvious that the left aileron was higher than the right. The right was 'smooth', the left had a very small 'step up' at the leading edge of the aileron. Not sure you'd notice if you only had one wing to look at, but it.'s the difference that matters. And it is easy to measure how much you slot the bracket, after the fact.
BTW, make the measurement with the ailerons AND elevator neutral. Full down elevator induces a small droop in the ailerons.
 
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On my -10, 1/16" made a big difference. (Aileron high = heavy wing) Mine was at the outboard hinge so a longer moment arm. I slotted the bracket so I could move the aileron down, heavy wing went away. Vans sells brackets with no pre-drilled holes for a permanent solution.

Thanks Bob. This was the data point I was looking for. I will slot it tomorrow and cross my fingers.
 
I went thru this last year

I had a huge heavy wing. Had to trim way right and even then it wasn't level.

I monkeyed around with adjusting ailerons and just goofed it up worse. I took a big breadth came back to it after a week and then took the wing tips off and reset the ailerons with the adjustment tool. that cut the heaviness in half. Then I pinched the aileron and made it all right. It doesn't take a lot of pinch. If you can see the deflection from your pinch you applied too much.
 
Today I used the top of the left wing as a guide and found the outboard side was sitting a bit high relative to the inboard side and the right aileron. I dropped this 1/16" and they now all match pretty well. It took about half of the heavyness away. I put the 2" trim tab back on and it is almost gone.

Does it make sense to start pinching the light wing trailing edge now to balance them or should I enlarge the trim tab.

Thanks for all of your assistance here.

Larry
 
How did you figure that out?

Started going through all the alignment checks posted by Van's and on here. In the course of that, sighting lines down the trailing edge, noticed right flap, when retracted, sat slightly lower at the fuselage intersection than the left flap. Was not much (1/8" or so), but, apparently, enough.
 
When I rigged the plane, I aligned both ailerons to the tooling holes. I then set the flaps even with the ailerons. Interestingly, during cruise, I noticed that the flaps were riding about 1/4" higher than the ailerons on both sides. There is a bit of slop in the upward movement of flaps in the retracted state. Obviously the airflow was pushing them up. I changed the retracted position of the flaps to this setting. I then extended the flaps to their original position at cruise with the flap motor. This pointed my nose down a bit and cost me 3 MPH. Obviously the airflow didn't want them there. This makes me wonder if my alierons are pointed too much downward and they are finding an equilibrium that favors a left turn.

Maybe I should adjust both ailerons up a bit to see what happens. I sure wish that I had a wing template, but don't know how to get one.

EDIT: I should add that during our first flight, we slowly lowered the flaps near the stall speed. There was no turning tendency, so we assumed that they were adjusted symmetrically. Maybe that was flawed logic.

Larry
 
Coffee stirrer

I had heavy right wing. I was all set to slot the brackets and/or pinch the aileron trailing edge when I read on here about taping a 2" length of plastic coffee stirrer on the bottom of the light wing. So naturally I thought my wing was so heavy I taped the whole 5.5in length to the bottom of my left aileron. Wrong now I had a heavy left wing. So I cut it back to exactly 2in and plane flies much better. If I keep the right tank 8 gal. fuller than the left tank, that is enough to counter my 210lbs sitting on the pilots side of centerline and the aircraft will fly nice and straight hands off. So I guess I took the lazy way out but I am having way too much fun flying to risk screwing something up and making a big project out of it.
 
Wing template

I have two you can borrow at Bult Field. One of them needs minor repair. But I have to believe and I may be wrong that if you lined up your ailerons accurately with the tooling holes you should be ok and the templates will be unnecessary.
 
Heavy aileron

The most common cure for a heavy wing, is to sharpen the radius [or as you say pinch the trailing edge] of the LIGHT wing. Let's back up and understand why this trailing edge radius makes such a dramatic effect on the aileron....a large radius trailing edge will actually pull that aileron down due to the high speed air flowing under and attached to the aileron, the top of the aileron is in turbulent flow in flight. Another tried and proven method of correcting the problem is to increase the trailing edge using a rubber hammer and piece of wood and gently tapping the heavy wing aileron [tailing edge] to increase the down force trim on that side. I have adjusted roll trim on at least 6 RVs using the method of both decreasing and increasing the trailing edge radius the effect is dramatic so proceed with caution. If your edge has been sharpened excessively during construction, the only alternative is to increase the trailing edge of the HEAVY WING.

Incidentally, it is worth mentioning that the lightest and quickest rolling RV's have a large radius trailing edge aileron [on both sides]. The reason for this is, as the large radius trailing edge on the down moving aileron is exposed to more airflow the trim effect is like power steering, pulling the down moving aileron in the direction intended. Light and quick is nice on a high performance sport plane. CE
 
When I rigged the plane, I aligned both ailerons to the tooling holes. I then set the flaps even with the ailerons. Interestingly, during cruise, I noticed that the flaps were riding about 1/4" higher than the ailerons on both sides. There is a bit of slop in the upward movement of flaps in the retracted state. Obviously the airflow was pushing them up. I changed the retracted position of the flaps to this setting. I then extended the flaps to their original position at cruise with the flap motor. This pointed my nose down a bit and cost me 3 MPH. Obviously the airflow didn't want them there. This makes me wonder if my alierons are pointed too much downward and they are finding an equilibrium that favors a left turn.

Maybe I should adjust both ailerons up a bit to see what happens. I sure wish that I had a wing template, but don't know how to get one.

EDIT: I should add that during our first flight, we slowly lowered the flaps near the stall speed. There was no turning tendency, so we assumed that they were adjusted symmetrically. Maybe that was flawed logic.

Larry

my thinking is...you need to start over with the alignment procedure that
Vans recommends. your post reads as if you are assuming some things and chasing others with fixes after making more than 1 change at a time.

pull your wing tips.
line up the tooling holes
set your ailerons...both sides while the other side is securely in position
make sure the stick is centered
align your flaps and properly fit them to the fuselage so they don't move, when retracted.
reinstall your wing tips...does everything line up?

go fly
ball centered?
low speed effects?
high speed?
what happens if you just let go of the stick? hard left, soft turn, dive, climb?
where do the ailerons end up if you let go? (mine rolled hard left when released)
did you burn off fuel from right or left tank?

I followed the guidelines and found my hinge was drilled a bit off. The outboard of the aileron stuck above the wing skin about 1/16"this caused my aileron to deflect upward causing the roll. after moving the outboard hinge down ~1/16"". it quit rolling. BUT I also found my plane to be twitchy at speed and unstable during the roll tests. it would increase roll oscillation if deflected and released vs returning to wings level.
I squeezed both ailerons a tiny bit...they were already painted and you couldn't even tell I changed them. Flys great!
 
my thinking is...you need to start over with the alignment procedure that
Vans recommends. your post reads as if you are assuming some things and chasing others with fixes after making more than 1 change at a time.

pull your wing tips.
line up the tooling holes
set your ailerons...both sides while the other side is securely in position
make sure the stick is centered
align your flaps and properly fit them to the fuselage so they don't move, when retracted.
reinstall your wing tips...does everything line up?

go fly
ball centered?
low speed effects?
high speed?
what happens if you just let go of the stick? hard left, soft turn, dive, climb?
where do the ailerons end up if you let go? (mine rolled hard left when released)
did you burn off fuel from right or left tank?

I did all of this prior to my first flight. When set this way, with centered ball, I have a heavy left wing that takes my burning off about 10+ gallons with 2 people on board.

I am now looking to either see what went wrong or addressing other areas, such as trailing edge.

Larry
 
The most common cure for a heavy wing, is to sharpen the radius [or as you say pinch the trailing edge] of the LIGHT wing. Let's back up and understand why this trailing edge radius makes such a dramatic effect on the aileron....a large radius trailing edge will actually pull that aileron down due to the high speed air flowing under and attached to the aileron, the top of the aileron is in turbulent flow in flight. Another tried and proven method of correcting the problem is to increase the trailing edge using a rubber hammer and piece of wood and gently tapping the heavy wing aileron [tailing edge] to increase the down force trim on that side. I have adjusted roll trim on at least 6 RVs using the method of both decreasing and increasing the trailing edge radius the effect is dramatic so proceed with caution. If your edge has been sharpened excessively during construction, the only alternative is to increase the trailing edge of the HEAVY WING.

Incidentally, it is worth mentioning that the lightest and quickest rolling RV's have a large radius trailing edge aileron [on both sides]. The reason for this is, as the large radius trailing edge on the down moving aileron is exposed to more airflow the trim effect is like power steering, pulling the down moving aileron in the direction intended. Light and quick is nice on a high performance sport plane. CE

Thanks for your input here. Today I pinched the light aileron a bit and half of my left roll tendency is gone (no heavy wing with 2" Trim tab still on). Before I pinch more, I noticed that the the crispness of aileron has changed. It didn't react as fast. I had read that reducing the trailing edge lessens the sensitivity. I think I will starting making the heavy one fatter and take out what I did today. Both of my ailerons are just slightly over bent according to Van's pictures in the Section 5 document. This tells me that fatting the heavy is probably better than squeezing the light one. Would you agree with this approach?

Larry
 
I have a heavy right wing after adding electric roll trim and a new Garmin roll servo when I replaced the Dynon D100. Prior to this, the plane flew nice and level. Now i have to add almost full left trim to keep the wings level. Where would I start to diagnose the issue? Should I disconnect the roll trim springs to see if the plane flies level again, or could it be an adjustment of the control arms of the autopilot servo? Note that the autopilot servos are powered off, and have not been engaged/tested yet.

Thanks for any suggestion on how to proceed.
 
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