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Frustrating wing heavy

Space Cadet

Space Cadet

Well Known Member
I'm about out of ideas on my left wing heavy problem, which requires the full electric trim setting and even then seems marginal and requires nearly continuous right stick force. I've checked and adjusted the aileron vertical heights more than I think is reasonable and it didn't help much (about a 1/2 bolt hole diameter). I've adjusted a minor difference in elevators, and checked the horizontal stabilator's squareness to the fuse. I don't see any issues with the rudder or vertical stab, and I've fixed a ding in the wing tips. I've flown with and without the fairings and wheel pants, and it makes no difference. Rudder trim is just slightly right at cruise. Quick-build wings and fuse, so hard to believe wing incidence angles would be off.

So, could it be the wing tip's trailing edge shape, one of which seems to have more curve upward than the other? Everything was in alignment (flaps, ailerons, tip) when I set it up, but have had to make some changes so no longer in alignment. But it sure doesn't look like a lot of difference.

Any other ideas? I'm going to call Van's Monday if nothing else comes to mind.

Dwight
 
Heavy Wing

Space Cadet said:
I'm about out of ideas on my left wing heavy problem, which requires the full electric trim setting and even then seems marginal and requires nearly continuous right stick force. I've checked and adjusted the aileron vertical heights more than I think is reasonable and it didn't help much (about a 1/2 bolt hole diameter). I've adjusted a minor difference in elevators, and checked the horizontal stabilator's squareness to the fuse. I don't see any issues with the rudder or vertical stab, and I've fixed a ding in the wing tips. I've flown with and without the fairings and wheel pants, and it makes no difference. Rudder trim is just slightly right at cruise. Quick-build wings and fuse, so hard to believe wing incidence angles would be off.

So, could it be the wing tip's trailing edge shape, one of which seems to have more curve upward than the other? Everything was in alignment (flaps, ailerons, tip) when I set it up, but have had to make some changes so no longer in alignment. But it sure doesn't look like a lot of difference.

Any other ideas? I'm going to call Van's Monday if nothing else comes to mind.

Dwight
Click to expand...

Dwight

We had the same issue on our Saratoga. What we found was a Flap was jist a bot out of rib. A few turns on the Actuating rod and not in perfect harmony.

The easiest way to test is use a digital level and check the bottom flap skin angle on the same rib and check the angles. ours was out a few degrees.

I know the RV-10 is rigged with the flaps up firm the the reap spar. But you could have one a bit off and not know it.

You might also want to confirm the angle on incidence on each wing to make sure it is set right.

It does not take much to be off amd have a heavy wing.

Good luck.
 
how to change

I've already rigged the flaps a second time, pretty sure they are set properly. I can check the angles to be sure.

If it is the wing incidence angle, how do you fix it? I would think that would be a massive change.

D
 
My -10 was initially left wing heavy, but lowering the outboard end of the left aileron by one or two 32" made a significant difference. Are you sure that when you elongated the attachment fitting holes that it didn't slip back to its original position when you re-assembled?
This "fix" is so common that Van's sells attach brackets with no holes pre-drilled. They're for the -7 but will fit the ten with a bit of trimming.

I'm not sure the "squeeze the aileron trailing edge" trick works on the ten.
 
No squeeze

Sorry, the squeeze does not work on ailerons with the trailing edge riveted.
This trick works well on bent aileron skins.
I know, no one wants a trim tab but you could at least stick one on with tape and see if you can correct it with a tab and then decide if it might be acceptable to rivet it in place for good.
It is said that Van's personal RV-10 has a small trim tab on the aileron.
 
The apex wedges on the RV10 ailerons are a little tough to squeeze :rolleyes::rolleyes:

Verify your entire aircraft alignment and rigging by triple checking everything, all components. Start at the beginning and be systematic, check off each component one by one and you'll find your problem.

RV7Guy said:
Simply squeeze the trailing edge of the LIGHT wing aileron. There is countless discussions on this. It a 5 minute deal, a flight to evaluate and maybe a little more squeezing.

I had this on my seven and went through all the rigging set up. It was right and I knew it. Called Van's and they said, "squeeze the light wing aileron."

Done deal. Dead nuts straight and true. Wasted hours!!!!

FYI, this is an imperceptible squeeze. I think it is black magic myself. But it worked!!!
Click to expand...
 
We had the opposite problem :confused:

we put a trim tab under the left aileron, YOU WILL NEED ONE under the right aileron.

This is VERY NORMAL.

Vans will tell you this too.. No two machines are the same or perfect.

If you have electric trim this may be a subtle difference to the spring forces V stick forces.

Get flaps rigged right, go from there with a tab. Tape one off at first and test. Then rivet it on later, put it under the aileron, that way nobody see's it nor hits their leg on it!
 
fly straight.

I took a heat gun and heated the wing tip trailing edge and gradually tweaked a slight change in the profile. Now it flies straight. best if you do this before that fancy paint job.
 
I tried everything to avoid the trim tab. In the end I added one. It is 1/4 wide and 5" long with a small bend. It does not take much. I just wanted no trim with equal tanks. Check out how big some of the trim tabs are on most certified:eek: You wil not feel bad for having one. Rv's get built very straight.
 
Thanks all. I'll go check the measurements and angles again. I have not tried to check wing incidence, but will just to see. I did double check all my slots after the first adjustment, I'll confirm this latest adjustment didn't move. Was surprised that moving the left had no impact, so I have pretty much given up on that solution (unless it did slip).

Troy, I assume you're imbalance was small, say within the range of a fuel imbalance?

So no one seems to think it's the tips, that's interesting at least.

Who's got some pics of their tabs handy? Or where's the instructions for it, I've been ignoring it thinking I'd not need it :rolleyes:

Dwight
 
Our right wing was heavy so we lowered the wing tip slightly which helped to where it was close enough. We cut out some material and was able to flex the tip down some.
 
wingtips

My wingtips had a bad bow on the trailing edges both sides and were way out of line to the aileron/flap neutral setting. I had to split them open along the trailing edge (with a hacksaw blade) and grind out material to get a flat fit. I packed them again with flox and resin and made a board clamp extending on to the aileron (in neutral position) and clamped them till cured. that was before first flight. a small amount of flex in the trailing edge of those wingtips will act like a trim tab.
 
Double checked

Okay, I've double checked most of the things. I noticed: Wing incidence angles appear to match within 1-deg, or my ability to measure them. That's a relief. Ailerons held their previous adjustment, but one could do with a bit more change. Flap (up) angles are pretty darn close, but the left side is up about 3/32" relative to the fuse bottom, while the right is pretty much even.

So, now that I've vented and gotten more advice, I think I'll try the following and see if/what makes the difference.

1) Adjust one aileron further
2) Lower left flap slightly to be even with fuse bottom like the right
3) Adjust left wing tip upward curvature

I'll report back next weekend after testing those in order.

Thanks,
Dwight
 
Space Cadet said:
Troy, I assume you're imbalance was small, say within the range of a fuel imbalance?

Dwight
Click to expand...

I could just trim it out with full tanks. If I burnt fuel out of the heavy tank first I needed less trim. I cut and moved all my tips trailing edge as well (they were a mess as stock) but it just was not quite enough. Next step was the hinges but I opted for the trim tab.
 
Space Cadet said:
Okay, I've double checked most of the things. I noticed: Wing incidence angles appear to match within 1-deg, or my ability to measure them. That's a relief. Ailerons held their previous adjustment, but one could do with a bit more change. Flap (up) angles are pretty darn close, but the left side is up about 3/32" relative to the fuse bottom, while the right is pretty much even.

So, now that I've vented and gotten more advice, I think I'll try the following and see if/what makes the difference.

1) Adjust one aileron further
2) Lower left flap slightly to be even with fuse bottom like the right
3) Adjust left wing tip upward curvature

I'll report back next weekend after testing those in order.

Thanks,
Dwight
Click to expand...

Well I would start by getting the flaps exactly even. 3/32 on the rt side lower then the left side would make a large lt wing heavy. I have been there more then once. I would start there. Let us know what worked for you.

John
 
I have the same issue (heavy right wing), which is solved by placing a 6" long and 1/4" thick trim tab on the bottom of the left aileron. I checked, rechecked, and triple checked everything, but couldn't get it fixed, so am just using the tab. Van's says it's normal and no big deal and told me that the prototype RV-10 and Van's personal RV-10 both have aileron tabs. The plane flies straight otherwise.

Don't bother messing with the flaps--it makes little difference (I tried), and you want the flaps up against the spar in reflex; otherwise, you're stressing the flap actuation components at cruise speeds.

-Rob
 
No joy #1 and #2

Flew short test flight today after fixing #1 and #2 (more aileron adjustment and flap adjustment). No real noticeable change, maybe slightly better. I now doubt #3 (adjust wing tip angle) will do anything either, but I've got the fix in place and epoxy drying, so will test it later in the week. I'm nothing if not obstinate.

Rob, thanks and good comment on the flap adjustment, I think the one I adjusted is indeed off the stop now so will set it back again, especially since it made almost no difference.

Can someone post a link to a picture of the tab (or where to find the instructions) so I know what I'm doing?

Thanks,
Dwight
 
Speed fairings?

Do you have speed fairings on? If these are not aligned just right, you can have asymmetrical drag that might cause the symptoms you are describing. There are a few other threads describing this condition. Good luck in solving your problem.
 
wing heavy

One degree diference in incidene is alot I typicaly try to get them witin one tenth of a degree
good luck ,Jerry
 
I agree

RV Jerry said:
One degree diference in incidene is alot I typicaly try to get them witin one tenth of a degree
good luck ,Jerry
Click to expand...

One degree is a big difference, how are the stall characteristics, one wing dip when things are coordinated.

Randy 8A
 
How to change it

RV Jerry said:
One degree diference in incidene is alot I typicaly try to get them witin one tenth of a degree
good luck ,Jerry
Click to expand...

How would one change this on a quick build if they find a slight discrepancy (2/10ths inch)?
 
Sweep and incidence

Wesael said:
How would one change this on a quick build if they find a slight discrepancy (2/10ths inch)?
Click to expand...

I have a QB -10 and when drilling for the wing attach, I thought I would simply follow the plans (cleco the hole in the rear spar, clamp the periphery, remove the cleco, and enlarge the hole). A very experienced builder helped me and said he wanted to confirm the sweep and incidence prior to simply following vans per-drilled hole. So, we did the formal measurements. Turns out, the sweep was significantly off (in the 1-2" range) and the incidence was also off (we measured to a 10th of a degree). Once things were set and prior to enlarging the pre-drilled hole in the rear spar, I looked through the hole and the holes were about three quarters of a diameter off. It surprised me, and confirmed the suspicions of the builder I was with. I would imagine that this could have caused a heavy wing if we simply took the pre-drilled hole and ran with it. I'm wondering if anyone else noticed this or heard of this or if it could explain the heavy wing here.
 
Agree but...

I agree 1 deg is probably significant, but I don't think I can measure that accurate. There was about 1-deg variation just measuring out along the same wing. Have not done stalls yet, still breaking in an engine and keeping speeds high. Will try it this weekend maybe.

Anyway, I don't think I will mess with trying to change the incidence even if it is off, as long as using the trim tab will fix it. Hope to test that tomorrow if weather holds out and I'm not getting more sick than currently feel.

No one's got a picture or link to a typical trim tab?

Dwight
 
It seems to me I remember a post by Pierre, that he had to re-drill his rear spar attachment hole to fix a wing heavy. The plans allow for a slight enlargement if required. As I recall, there is an edge distance specified.
When we drilled the hole we followed the Vans instructions, and did not measure the incidence prior to drilling. I wish I had. We help Wayne G. drill his and measured first, his was within 1oths of a degree.
 
Test Results

Ok I share the same situation (Heavy wing and dont want to do the trim tab).

I started looking real close at both wings to try to find the cause of the heavy wing.

If I looked real close at the wing tips I could see a very slight "dip" in the top rear section of the heavy wing tip. You can see it in this pic.

IMAG0536.jpg


The other wind did not have this dip.

I decided to try getting the dip out and while I was at it maybe rais this area a little to create a little more lift on the heavy wing by carving some 2" foam into a wedge to make a stiffining rib inside the wingtip.

The problem that I ran into was by doing this the tip skin wanted to wrinkle when I raised it with the rib but I went ahead and epoxied the rib in place and while I was installing it I would guess that I saw it raise this area 1/4" or so.

The tip now lookes like this.

IMAG0538.jpg


I test flew it and with everything equal. (Both tanks full) It is now only slightly right wing heavy. I would guess that I equelized aprox 1/2 of the imbalance

The result is, It is now close enough that If I start burning fuel from the right tank it will balance within 45min or so. I will leave it like this for a while to see if this will work for my likeing.
 
Interesting one

That's an interesting one. I noticed that on the wing tip as well. Since all my other "adjustments" have done very little in general to improve things, I figured it wasn't worth trying.

If weather cooperates, I'll be flying a lot this weekend. I think I'm done experimenting with a fix and am just moving on with a tab for now. Need to finish Phase 1 to make OshKosh, and June is pretty full up with non-flying stuff.

Dwight
 
My experience with elevator misalignment

I had an obvious mislignment between the elevators (I still don't know how to get it perfectly straight following the plans). It was giving me a 'heavy' left wing condition that required almost full right trim to correct.

I was able to significantly reduce the amount of right trim required for level flight at cruise by adjusting the relationship of the two elevator trim tabs. I would estimate 1/3 of the condition was relieved.

I then went and fixed the elevator alignment. This removed 80% of the heavy wing condition though some trim is still required.

Still some analysis required here but I thought I'd share in case it helps.
 
Additional trim spring

Here is something I have done to my 10 and it works beautifully.

Although my left wing was only slightly heavy with full fuel and quite balanced
at half full, it required right trim especially with passengers loaded in the back
and even more with full baggage.
Based on what I read in this thread I adjusted the elevator trim tabs to aid
the aileron. However, the trim tabs are already kind of weird the way they travel and adjusting them to where one is up on one side, and down on the other, is just not right.
Instead, I added a spring hooked up to a hose clamp around the aileron push tube in the wing. The other end of the spring is attached to a rib. Assuming you have electric aileron trim, this will aid the spring that is fully extended and increase trim effectiveness on the one side where you run out of trim.
The clamp allows you to adjust it to where this spring is neutral with just a tiny bit of pull to the one side that needs trim.
I installed this in the second inspection bay.
Result: Trim to the right is now twice as effective.
There is no perceptible resistance to the control stick especially not in flight.
I do have to add, that I use the right tank fuel first (mogas) before I resort to using the left tank making the slightly heavy right wing condition worse than it would be under normal tank switching conditions.
 
Update

Well I did quite a bit of flying and testing this weekend finally. A trim tab built per the previous comments worked. Still bothers me, but I can get on with things.

On the wing incidence angles- Of interest to me was that during my first stall tests, there was no discernible tendency for one wing to stall over the other. In fact, one of the first stalls I did had the left wing breaking sharply first, which would indicate to me that the incidence of the left wing was higher than the right, despite the left wing heavy flying characteristics otherwise. But, it only happened the one time that I could tell and more testing is required.

I also suspect the elevator trim tabs may be a contributing factor, but not going to mess with it until fall.

Anyway, thanks for all the inputs, and I'll keep testing and trying to get rid of that trim tab (after I get through Phase 1)!

Dwight
 
dmaib said:
Here is an old elevator trim tab thread on the Matronics list. It comes up every year or two as folks finish and fly their airplanes. I set mine by this method and have never had any heavy wing problems. I have no idea if this has any relevance to your issue, but it is an interesting thread on the RV-10 elevator trim system.

http://forums.matronics.com/viewtopic.php?t=20576&highlight=elevator+trim+tabs
Click to expand...

Thanks David. That will help me when I am ready to align my trim tabs.
 
Smart level

Wesael said:
Question here.

What did you use to get measure that accuratly? I am looking into checking mine.
Click to expand...

The smart level from Cleveland is accurate to 0.1. It worked very well and has come in handy numerous times. Obviously, you don't need that kind of accuracy for most parts of the build.
 
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