I've am in the middle of the testing phase of my Experimental. During the rebuild I replaced some bellcranks with an updated set that helps eliminate some adverse yaw. As I result I had to completely re-rig the Flaperons. This airplane uses a full span "Flaperon" that is below the wing.

I flew my first X-country yesterday and noticed that I have a very slight left roll. After getting back I made an ajustment to the rigging. If it's rolling left and required right stick pressure then the left aileron should be rigged a little down and the right one a little up correct??? This is what I did and it didn't seem to really fix it. With my feet on the floor and the slight right stick pressure to maintain wings level my ball is centered so I don't think it's a rudder issue. The flaperons actually have some positive incidence in them. It gives you a little better cruise speed and the ability to pitch trim the aircraft by adding or taking out a little bit of flap.

Do we have any rigging experts that might be able to shed some light on this. Right now my left flaperon is at +2 degrees and my right is at +5 and it's still wanting to slightly roll left. I have verified the washout is the same on both wings and when the airplane is leveled per the manual both wings are level. Am I missing something? Thoughts?? Here's a shot of the airplane if your having a tough time with the Flaperon concept.

I have full span flaperons on my Zenith 801... They are a different beast to set up and trim...

If you adjust one side down, or one side up or both, the plane will meet an equaliberum and still fly heavy on the same wing. All it will do is change the location of your control stick. The way to fix it is to attach a small trim tab to either flaperon and dial it in that way. I have seen people who attach that trim tab to the wing but it took alot bigger tab to achieve the same result. YMMV

Tailwinds.

Ben.

Another thing to check is that the horizonal stab, and elevators are rigged properly as a "twist" on either item will cause a roll.

Stol wrote:....If you adjust one side down, or one side up or both, the plane will meet an equaliberum and still fly heavy on the same wing. All it will do is change the location of your control stick. ....

This has been my experience also. In my case (cessna), there are a couple of options:
1) re-rig wing AOA at the aft spar attach - lower the heavy side and/or raise the light side.
2) Adjust the flap lower on the heavy wing, & higher on the light wing.
3) You can lightly tweak the traling edge of the ailerons between the beads-- up on the heavy side and down on the light side. It doesn't take much, if you can easily see the tweaks farther than about 12" away, you've tweaked them too much. This is the same as adding trim tabs, and makes a surprising amount of difference.
I don't think any of these 3 are applicable to your Avid. But you should have some sort of AOA adjustment for the wings-- generally with V struts it's a threaded clevis at the upper end of the aft spar.
Good luck.

Eric

But you should have some sort of AOA adjustment for the wings-- generally with V struts it's a threaded clevis at the upper end of the aft spar.

I believe this sets the washout of the wing, not the overall AOA. Important for predictable stalling characteristics.

I had the same problem on my Tundra. Hands off roll to the right. Ailerons are not the problem. They will always work opposite each other and find neutral to the wing air flow by themselves. Return the stick to center and readjust the aileron cables to that position so you have the ailerons neutral with the trailing edge of the wing and the same stick movement both left and right. You need to check the washout.

On a two strut aircraft that has washout in the wing you will need to adjust the rear strut length to equalize the washout with the other wing. Unequal washout (twist) creates unequal lift on each wing causing the hands off roll. On my stepdads L4 I can just count the threads in the adjustable clevis at the bottom of the rear strut to see they are the same. They were not and it had just been annualed when he bought it. One wing would stall before the other and drop a wing at landing. Also note that the front strut length on a two strut aircraft is only for setting the dihedral but that is another discussion.

Since yours is an experimental you might actually have to measure the washout on each wing then adjust the rear strut length accordingly. Raise the tail until the aircraft is level and block it. The bottom of the inner rib of the wing should also be level at that point. Then put the level on the last full outer rib on the underside of the wing. When the bubble centers measure the distance in the gap from the end of the level up to the bottom of the wing. Check the other side, then adjust the rear wing strut length with the clevis until that distance is the same.

If after adjusting the washout it flies level but flies in a crab with nose left or right, then adjust the flaps to be sure one is not down in the airflow more than the other creating unequal drag on one side more than the other. That should take care of it. If it doesn't take all of the crab out don't feel bad. You will then have to put a trim tin on the end of the rudder and it will be just like a lot of Cessna's and other certified aircraft out there. With patience you will get it adjusted out. Good luck.

I forgot to mention that due to differences in construction of experimentals, from one wing to another, it is not enough just make the washout equal. You may have to over adjust one side slightly to compensate for differences in the construction of each wing.

I have a threaded rod on the left wing aft strut only. I verified all of this when I leveled it for the weight and balance but I'll double check it. It stalls straight ahead. The tail of this airplane is a very simple welded chromoly frame with no adjustments unless it got bent somewhere along the line. Thanks for all your info!

The L4 dropped a wing on landing, it was off that far but the Tundra did not. It stalled straight ahead too. I counted the turns on the rear struts this afternoon and I have nine threads showing on the left and eight on the right. A little bit at the strut makes a difference when extended to the end of the wing.

Avid, I built and fly a kitfox so am familiar with flaperon rigging. I agree with Stol's post. Put the flaperons back to neutral with the stick centered.

If it was me I would first try turning that threaded rod end on the left rear wing spar in one full turn. That is to shorten that strut to give a little less wing twist which will increase the angle of attack at the wing tip. One turn should be enough to see if it helps and you can go back a half turn if it was too much. Be sure to test the stall characteristics again to see if it still stalls normal.

If that doesn't help or you want any easy way to fix it here's what I have seen on some kitfoxes. Make a wooden wedge (balsa is good) about six inches long and an inch or so wide. About a quarter of an inch thick on the thick edge tapered to a sharp edge on the thin edge. Tape it to the top inboard trailing edge of the left flaperon, sharp edge forward. Go for a test flight. When you find the size and shape of wedge you need, epoxy it on and paint. No one will ever notice it.

Just thinking about this some more. Have you test flown with some weight in the right seat yet?

tcj,
Good point about weight in the passenger seat. I think you have the adjustment of the washout right too.
I had a 701 and they use flaperons too but I hesitated to complicate the discussion with bringing that up since the 701 is a straight wing with no washout. Instead the flaperons are split to inboard and outboard sections. The inboard section is adjusted lower than the outboard to stall the inboard section first. That arrangement replaces the function of washout in the wing. Adjusting one inboard section more than the other causes drag differences from one side to the other and can produce both a roll, like washout can, and a crab the same as unequal setting of flaps. Since the Avid has washout in the wing it is more similar to standard aircraft and the flaperons act more like ailerons until they are dropped to use as flaps. The purpose of them being below the lower wing is only to increase their effectiveness especially if the wing is stalled and when they are dropped for flaps the gap between them and the wing lets them behave as slotted flaps, lowering their stall speed.
Just about all light planes have rigging issues from time to time and so few AP's tweek the rigging unless pressed for it.
Good discussion on rigging.
Good luck Avid.

Yes very good discussion on rigging. I knew there would be some guys much smarter than me on here. I have a much better understanding now of how all these things work together. My wings were recovered during the restoration of this plane and it's very likely that tip got tweaked slightly during the shrink process. Thanks for everyone's responses and thoughts! I'll try to keep this thread updated as I mess with it. It's sounding like it's going to be trial and error.

Avid,

I think tcj might have hit the nail on the head, IF the roll is to the left as described, and IF the roll is very slight. These are pretty light airplanes, and having the weight of pilot/pax off center is going to induce some slight roll. If you are comfortable carrying a passenger in the plane, I'd try that before I started messing with the rigging to see if that fixes the "problem". OR, try a flight with the pilot in the RIGHT seat, and see if the left rolling tendency turns into a right rolling tendency. I think I'd be careful changing the rigging, especially if the plane stalls really straight right now, unless the rolling tendency is really annoying or problematic.

MTV

MTV I tried putting 10 more gallons of fuel in the right tank and it didn't not effect it all. I'll be flying solo 90% of the time. I'd rather have a slight right roll the 10% of the time if having a pax would effect it. My fuse is only 39 inches wide.. I don't think that's enough of a moment to really cause a roll.

Rigging is what I do weather small electic R/C's airplanes up to and including P210-R's. Specialized tools for each application. Airframes that have damaged by whatever means may NEVER fly hands off ! I specialize in Cessna products but have done pipers,Maules and Taylorcrafts. Cables to flight control's stretch and change position most of the time.

182 STOL driver wrote:Rigging is what I do weather small electic R/C's airplanes up to and including P210-R's. Specialized tools for each application. Airframes that have damaged by whatever means may NEVER fly hands off ! I specialize in Cessna products but have done pipers,Maules and Taylorcrafts. Cables to flight control's stretch and change position most of the time.

No cables in an Avid except the rudder and they are straight line pull directly to the Rudder horns. The rest are pushrods. Makes for a sweet flying little airplane. Most of the time it's two fingers and thinking about where you want it to go. I have not flown a Cessna since I got this thing flying. I'm afraid how heavy it's going to feel.

Here's a short video of how much pressure it takes to stop my roll

http://s192.photobucket.com/albums/z186 ... I_5586.flv

Could you take a digital level and see if one wing has different washout than the other?

This is good stuff Joey. I'm bookmarking this thread for when I rig the Rans.