Heavy Wing -- Discuss

In my case left wing , requires about 3/8 inch deflection to maintain level flight with ball centered, no leg or wheel fairings. There is little change in deflection with speed.

My thoughts, left roll due to less lift on left wing, so... how is this corrected with vertical aileron position or squeezing trailing edge of aileron.

I am assuming that either of the above options simply allow the aileron to fly in the 3/8 inch low position without any stick pressure.

I would like to fly level with the tip, aileron and flaps in trail without any deflections.

If this is correct then it would appear that I have to adjust the wing incidence or tip twist.

What I have found is a .1 degree higher incidence on the right wing and approx a 1/4 inch droop in the right tip relative to the left tip. Ailerons are equal vertically, there is no twist in the ailerons and flaps. I did go through the Vans check list for heavy wing.

Is this small amount of difference in incidence or tip droop enough to cause this amount of aileron deflection ?

Heavy wing

Petersb, did you check for aileron symmetry? I had a pretty heavy wing and I found that a very small amount of aileron sticking up into the airstream causes quite a bit of roll. Sight down the top of your wing from the leading to trailing edges and check to see if an aileron is sticking up at the hinge. I found that 1/32" could cause a roll at high speed.

fly_vans_rv7a said:

Petersb, did you check for aileron symmetry? I had a pretty heavy wing and I found that a very small amount of aileron sticking up into the airstream causes quite a bit of roll. Sight down the top of your wing from the leading to trailing edges and check to see if an aileron is sticking up at the hinge. I found that 1/32" could cause a roll at high speed.

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Yes, I did check the vertical position of the ailerons. I did find the left inboard was slightly high and slotted the bracket 1/32. Saw no change

Peter

My key question here is, after aileron slotting or squeezing to correct wing heavy condition do the ailerons, flaps, tips line up.

Carefully check the rigging, is the angle of incidence of the wings the same? you may have more AOA on one wing.

Next is flaps? Are they both fully retracted? Flap asymmetry will do this for you.

Once you are sure the wing and flap are in spec, is the deflection referenced to the flaps edge or the wing tip? The wingtips are fibreglass and not a good reference, especially if they are out of shape.

RV10inOz said:

Carefully check the rigging, is the angle of incidence of the wings the same? you may have more AOA on one wing.

Next is flaps? Are they both fully retracted? Flap asymmetry will do this for you.

Once you are sure the wing and flap are in spec, is the deflection referenced to the flaps edge or the wing tip? The wingtips are fibreglass and not a good reference, especially if they are out of shape.

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The angle of incidence is out by .1 degrees, the right tip is 1/4 inch lower than the left, flaps etc are lined up.

Before hacking away at tips and incidence I would like to know if these discrepancies are enough to cause this amount of heaviness

Peter

Of the hundreds of threads I've read no one mentions if the aileron, tips and flaps line up after aileron vertical adjustment or squeezing corrects the wing heaviness.

Could someone that has used these techniques comment on final aileron alignment after correcting heaviness.

Please clarify

I am in the midst of sorting out a heavy wing too.... so if we find answers it will be great.

Are you saying that when flying level, ball centred, that your right aileron is up 3/8 and your left down a corresponding amount?

In my case something is dragging the ailerons out of line, when I push in left stick the ailerons are centered on the flaps and wing tips. I have tried moving the right aileron so its a bit lower with no apparent effect. A trim tab under the left aileron has sorted it but I would like to fix it without the tab.

To answer your question: my RV10 was initially left wing heavy. To maintain level flight required me to hold pressure on the stick to the right, and the ailerons were not lined up with the flaps or tips.
After lowering the left aileron attach bracket about 1/32" - 1/16" the wing heaviness is now gone, and the ailerons do line up with the flaps and tips in level flight. I was amazed how sensitive it is to the attach bracket height.

BobTurner said:

To answer your question: my RV10 was initially left wing heavy. To maintain level flight required me to hold pressure on the stick to the right, and the ailerons were not lined up with the flaps or tips.
After lowering the left aileron attach bracket about 1/32" - 1/16" the wing heaviness is now gone, and the ailerons do line up with the flaps and tips in level flight. I was amazed how sensitive it is to the attach bracket height.

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Bob, thanks, that is what I would like to know, do the ailerons, flaps line up after correcting the vertical alignment.

I have already lowered the inboard left aileron 1/32, although the results are nil. I will try another 1/32.

Thanks Peter

Look at the support section "construction FAQ's" toward to bottom of the page on vansaircraft.com website. It explains the process on analyzing and adjusting for a heavy wing situation.

lowering or raising one flap will change roll. changing one aileron will not change anything except the aerodynamics. raising an aileron will only cause the 2 ailerons to seek a new equillibrium in flight. to exaggerate ......raise the right 2 inches [which would drop the right wing] but the air pressure pushing down the right aileron will raise the left as the right goes down. net effect is ailerons out of rig but no closer to making plane fly wings level.
adding a trim tab to an aileron adds an asymmetrical increase in pressure to one aileron and this will change a ''heavy wing''.

I would start by looking at the wing tips. We have found several wing tips that have been molded with a severe droop at the outboard trailing edge, it appears to be a mold issue as to correct the issue the tip will need to be split and re-glassed. We have found this has fixed the heavy wing syndrome on most planes. Run a straight edge along the Aileron and wing tip trailing edge and see if it is straight before changing anything an the Aileron. On the 7 we have found it is usally the right hand tip that is out of shape and have found it on both the older bat tips and the newer straight tips.

Mick

mick said:

I would start by looking at the wing tips. We have found several wing tips that have been molded with a severe droop at the outboard trailing edge, it appears to be a mold issue as to correct the issue the tip will need to be split and re-glassed. We have found this has fixed the heavy wing syndrome on most planes. Run a straight edge along the Aileron and wing tip trailing edge and see if it is straight before changing anything an the Aileron. On the 7 we have found it is usally the right hand tip that is out of shape and have found it on both the older bat tips and the newer straight tips.

Mick

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Not calling you a liar Mick, but I am highly skeptical.
Even a severely mis-shapen wing tip will have very little effect on roll trim. For the exact same reason that people who went to all the trouble to build a hinged trailing edge on their wing tip to use as a roll control trim tab have found that it doesn't work. Not one little bit. Not saying that a severely misaligned wing tip could have some influence, but if the wing tip trailing edge is even close to aligning with the aileron, I don't believe it would have any noticeable effect.

The very first thing anyone should do if they are working on an RV with folded trailing edges, and they are working to resolve a roll trim problem, is confirm proper shape and symmetry of both ailerons.
The process is explained in Section 5.7 of the recently update Section 5 of the construction manual (located HERE)

bobnoffs said:

lowering or raising one flap will change roll. changing one aileron will not change anything except the aerodynamics. raising an aileron will only cause the 2 ailerons to seek a new equillibrium in flight. to exaggerate ......raise the right 2 inches [which would drop the right wing] but the air pressure pushing down the right aileron will raise the left as the right goes down. net effect is ailerons out of rig but no closer to making plane fly wings level.
adding a trim tab to an aileron adds an asymmetrical increase in pressure to one aileron and this will change a ''heavy wing''.

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I think some confusion is occurring regarding what raising or lowering an aileron is.
Some people believe it is shortening or lengthening the push rod as I think Bob is describing, and he is correct that it wont really change anything.
Many people that have raised or lowered an aileron, have actually changed the elevation of the hinge point of one end or the other (or both). This will have an effect on roll trim but should only be done if careful checking shows that an aileron is positioned incorrectly (vertically).

I was referring to the original post of having to holding in aileron for wings level flight. This is not normally a indication of a aileron that is floating due to a aerodynamic load, say from trailing edges of different radius, twist or hinge geometry.
If you have to hold the ailerons in neutral for level flight then I would suggest it is a aileron issue, but if you need to hold opposite aileron then I suggest it's either incidence, flap rigging or a wing tip problem. Just speaking from experience...

Simple Fix

My IA friend was having the same problem with his RV-8. He clued me in on a quick fix, which an aerospace engineer friend of his told him to solve the same problem. It worked perfectly.

Take a plastic coffee stir stick and cut it in half (2 inch length?). Tape it to the bottom aft outboard edge of the aileron on the wing producing more lift. I just used some packing tape and placed it a quarter inch ahead of the trailing edge radius.

I figured it wasn't going to cost me anything to try this and it worked like a charm. This is basically a simple vortex generator.

I'm flying a 7a with 200 hp IO-360 and constant speed prop and meet all of Vans performance advertised numbers. It stalls straight ahead right at 50 KIAS. I have 80 hours on the airframe so far, and the packing tape hasn't failed yet!

I know this sound Hokey, but you might want to give it a try befor you start pinching your trailing edges.

When testing for a heavy left wing in a side by side, make sure that you have both seats occupied with about the same weights............ fuel also.

But I am sure you already know that..........

having a little trouble visualizing the coffee stirrer. any pics? i want to try it.

I'll second that. Please show pics of the stir stick vortex generator. Sounds like a fun experiment!

Heavy wing

Sorry I didn't reply sooner. I am on the road now but will try and get a pic of something as an example

I had a very heavy right wing on my 7. I had to burn about 13 gallons of fuel to balance it out, I weighed 175lbs at the time. I checked all the alignments and usual recommendations. The wing tips were not painted so I tried splitting and moving the trailing edge which had no effect at all so I flew with a large wedge on the underside on the left aileron.

I tried to fix the heavy RIGHT wing by lowering the outboard end of the LEFT aileron by .080 which is what the measurements lead me to believe needed done but that made it worse. So I returned it to where it was.

I removed the RIGHT aileron and milled the brackets to drop the aileron .060 which was slightly more than it needed but not enough to warrant changing. Flys great, looks great! Bottom line is lower the aileron of the heavy wing.

What is your reference when you say that you have a ?? droop in the right tip? I refer back to the original alignment procedure using the bell crank jig and tooling holes in the tip rib (as shown on Dwg 12A) for setting the aileron tip alignment. This aileron position is then used to mount and position the fiberglas tip. During final assembly, the tip is then typically trusted to align the aileron using the adjustment in the aileron control rod, and the flaps aligned using the aileron for reference. If, as you state, the tip trailing edge is out (again, what reference?) and your aileron/flap configuration was set as I described above (i.e., both ailerons are aligned with the tips) then one or both ailerons would be out of ?design? alignment. It seems this imbalance might easily cause a heavy wing effect.

I found during a double check (measure twice, cut once) of my alignment, before drilling all of the tip mounting holes, that I had not originally managed to correctly align the trailing edge of the aileron with the tooling holes. The problem lay in the way I had set up the reference alignment of the tooling holes. It is, (as you probably remember)) more problematic than the simplistic diagram shown in Van?s drawing because of the necessary stand off of the ?board? as they show it, to clear the skin overhang and aileron bracket. A rethink of my reference mechanism proved that I did not have a good alignment and had to epoxy in the preliminary holes and reposition my tips to realign the trailing edges.

All this may be stating the obvious, but you might start by removing both tips and checking the alignment of the ailerons (and possibly flaps to realign with the ailerons) using the original Van?s prescribed procedure. Then replace the tips and fly. If you had to make any adjustment in the ailerons during this check, you may find that it changed the aerodynamic balance, and that this had more effect than a slightly offset tip. Then you can decide if any adjustment of the tip trailing edge(s) is warranted. At least you will assure yourself that you have the intended aileron/flap alignment and can proceed to troubleshoot from that point.

I currently have 50 hours and have not experienced a heavy wing.

Wing heavy?

For those interested in seeing an example of the simple fix, drop me an email and I will send pix back. I'm on the road but made some example pix on the aileron of a falcon 2000. I'm a bit challenged when it comes to posting pictures on this sight. Amazing, that I can successfully build an airplane but am stymied by this bit of technology.

Stan.magnuson@gmail

Pic of Stan's Coffee straw, kinda like a miniature trim tab.

flaps

make sure the flaps are aligned to the wing not the fuse. measure from a wing rivet to the trailing edge of the flap. make sure both side are equal.

I "fine tuned" my flaps to correct a heavy left wing on my RV-6. The plane now flies nice and level with ball in center with both my feet on the floor in level cruise and a nice straight line from wingtip thru aileron and flap trailing edge on both sides, but if you level the plane on the ground and use a digital level/protractor device to measure the flaps, they definitely do not measure the same number of degrees when fully retracted or fully extended, still the plane flies perfectly wings level with no rolling tendency with flaps in any position... so I really don't care what degree measurement they ended up with, it's how the plane actually flies that matters. I also lost no top speed doing this either. My RV-6 is remarkably fast for only having a lowly O-320 engine.

Neal, can you explain "fine tuned"?

GLPalinkas said:

Neal, can you explain "fine tuned"?

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Adjusted the retracted positions by undoing one of the rod end bearings on the flap pushrod and screwing the bearing in or out a few turns. In my case, I raised the right flap a bit and lowered the left flap a bit. I test flew the plane after each adjustment until it flew level.

Reference material from the source

Vans has a nice two page detailed description of the process the recommend for wing heavy fixes all listed in the order you can follow. It is under the Support tab and FAQ.

I'm curious to know if anyone who'se had a "heavy wing" on their newly completed RV has gone through Van's little troubleshooting guide. It'd be nice to read a good write up on how you went about it and how it worked out.

This thread sounds vaguely like some of the line-shack maintenance debates from my old Huey days.

About halfway through it now, it's also on my build log.

While I'm waiting on my oil quick drain and heat shield to show up in the mail I thought I would dig into the heavy left wing.

Using Van's "How to diagnose and correct a Heavy Wing",
-I now have 12 hours on the plane
-Aileron Trim will take out the heavy wing
-Full right tank and left tank down to 4 gallons lessens the heavy wing but still requires aileron trim to fly level
-Rudder is very close, resting 2 feet on the right rudder pedal in cruise centers the ball perfectly
-Wing sweep is correct
-Aileron neutral is correct using tooling hole jig
(Initially I found the ailerons were each 1/16th high or 1 was 1/8 inch high when the other was neutral. I took a break from the project and thankfully remembered that the ailerons move up with forward stick. When I got back to the hanger I found the elevator full up, when I put the elevator in trail the ailerons were set correctly)
-Aileron hinge height is within 1/64 at inboard and outboard hinges on both ailerons. I used a 12 inch straight edge resting on the top wing skin over a rib to the aileron spar rivet line to check this.
-right flap is about 1/8 high on the right wing relative the aileron in the neutral position (I believe lowering this would make the left wing heavier)
-Left flap is aligned with the aileron in the neutral position
-I also measured the flaps trailing edge from the rear spar and all is the same
-I cannot see any twist in any of the control surfaces by sighting down the trailing edge at the wingtip.

I think I'm going to remove the aileron trim springs and go fly, If I still have a heavy left wing I think I'm going to use a plastic coffee stick/straw taped to the bottom of the right aileron as a temporary trim tab. I can then fly with the wheelpants/gearleg fairings and see if I still need to squeeze an aileron.

A few months ago I flew test a friend's new RV9A. It had a heavy left wing. I followed Van's guide and checked how much fuel burn will remove the problem. It never did (left empty and right full). All rigging were checked multiple times and they were right on. I also tried to tape a wedge to the top of the left aileron and it did not help (wedge not big enough). Fortunately he had another set of RV9A wings. I took the ailerons from that set and mounted them on the airplane and the problem went away. In this case the problem was that the aileron trailing edges were not built straight. They are bowed. (Such imperfection on rudder can cause the ball not to center too.)

There are many factors that can cause a heavy wing: poorly constructed aileron/flap, mis-rigging, misalignment of hings, etc. If you can not find and correct the easy problem, slot the hinge is what Van's suggest and I would have done that.

tc1234c said:

There are many factors that can cause a heavy wing: poorly constructed aileron/flap, mis-rigging, misalignment of hings, etc. If you can not find and correct the easy problem, slot the hinge is what Van's suggest and I would have done that.

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Ted .....please explain what you mean by "slot the hinge". Are you referring to the brackets on the ailerons to move it up. Or down.

Heavy Wing

Here is my fix. RV7 Quick Build Kit. Ailerons and Flaps came prebuilt. On the 1st flight i had to hold left aileron to keep the wings level (heavy Rt wing)(quite a bit of force). After a few hrs my arm got tired of holding wings level so i decided to pursue the Vans "How to Diagnose & Fix a Heavy Wing"Checked rigging, angle of incidence, vert stab. Ball in centre. Went flying with full tanks, burned off most of the fuel in the rt tank. Even with very little fuel in the rt tank and full left manual aileron trim i still had to hold left stick pressure and no one sitting in the right seat. Filled the right tank with fuel and did the calculation. I was over 100 lbs. Whooo. Decided to deviate from Van's list and go to the squeezing of the left aileron trailing edge drill (light wing). Was very careful not to squeese to much. Went flying no change. Squeezed again. went flying. A very minor change. The last thing was to slot the 2 holes in the right outboard aileron attach brakets. I moved the aileron down about 1/8" or a little less. Went flying and would u believe, now i had a heavy left wing. Adjusted the right aileron down by only 1/16th of an inch. Went flying and now it flew level. I wouldn't have believed that a 1/16 of an inch would have made that much difference.

Congratulations Jim. That must have been a huge relief. Now you really can put on that RV grin.

Is the clamp pressure from the 2 attach bolts ample to prevent any possible movement of the aileron down the slot?

Jim
RV9a

jimbo said:

Is the clamp pressure from the 2 attach bolts ample to prevent any possible movement of the aileron down the slot?

Jim
RV9a

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Some get blank hinges from Van's and re-drill to the new position. Others put a rivet in to prevent any movement.