About at wits end rigging flaperons

[C5Engineer 1170]

I flew a 125 mile round trip this afternoon and my flaperons were driving my nuts. I knew I had a very slight rolling moment to the left but I've just been flying it as is because I'm rarely straight and level long enough to even notice it. I really noticed it today flying a GPS line for an hour straight.

I have a slight rolling moment to the left and my ball stays about 1/2 width to the left. If I center the ball with the rudder it feels like I'm crabbed. However if I put just a tad of right stick in adverse yaw centers the ball and it feels like I'm flying with my butt centered.

After I got to my destination today I did a tweak to them and I went the wrong damn way so it was even worse all the way back. When I got back to my hangar I leveled the plane and set them at +5 and rechecked them a bunch of times. I went flying and it was better but the left roll was still there. I started messing with my flaps and noticed that if I put in just a tiny amount of flaps it seemed to get better.

I left the flaps in and landed and then checked where they were at. The right side was at 3 and the left side was at 1....oooookayyy. So I put the flaps back up and they were both back at 5. I then set the left one at 3 degrees to duplicate the 2 degree difference. This seemed to help some so I landed again and put the left on at 2 degrees with the right side still at 5. It didn't seem to help I'm still holding right stick pressure.

I'm going to double check that I didn't put my F7A's in backwards although my stick pressure is fairly light. Any chance that I'm masking a Yaw issue... sure doesn't seem like it but trim can be weird sometimes. I ran out of time to screw with it anymore.

I did put 2.5 on the hobbs today though...this issue is pretty small but I'm really anal about this stuff..I can't stand it when I drive a rig that pulls either. I can't imagine doing a really long trip with it like this so I'd like to get it resolved...Any thoughts on what I might be missing??

Short vid..kinda crappy but might help

http://s192.photobucket.com/albums/z186/NKAWTG/?action=view&current=MVI_5586.flv

Snapped a few pics along the way but nothing real spectacular

We just had some real heavy rains for a week straight...quite a bit of water

This was a huge cloud of birds..it looked like a moving cloud...you would be in bad bad shape if you flew into something like this.

[Av8r3400 1179]

I've been waiting and thinking on this one, Joey.

Waiting for Leni or Bob to pipe up because they have rigged planes before. My plane too, has a bit of a heavy wing and a heavy nose. I was waiting on some good ideas that may help me, too.

Just a thought (the thinking part) did you level you plane and check the washout and angle of incidence on the wings when you were putting it back together after recovering, to see if your lift struts need to be adjusted?

Also, don't discount the rudder's effectiveness at lifting a heavy wing, too.

[C5Engineer 1170]

Couple of other facts that I'm sure you guys will ask. I leveled the airplane at the third rib hinge outboard which is just inside where the strut attaches. BOTH wings are level in this place. I also confirmed the washout while the wings were on sawhorses before reinstalling them after the recover. Not an exact measurement there but they were both really close.

I set my flaperon angle using a Warp Drive prop pitch tool. I measured the angle on the inboard ends of the flaperons.

I've been pondering this all day and came up with a theory... somone tell me if I'm being silly.

When you ad reflex i.e. more negative angle the airplane pitches up right?

Right now I have -5 degrees on the right and -2 on the left and it's still rolling left. If the flaperons worked exactly like ailerons then this correction should have caused it to roll right.

I'm thinking that because there is more reflex on the right that maybe the right wing is creating more lift and that is what is causing the roll to the left. This would partially explain that the roll tendency diminshes some when I add a tad of flap because it's getting rid of some relex.

Either way I don't know why it has a rolling tendency with them both set to -5 anyways. I guess every airplane needs some trim to fly level though right?

My next move is to take out some reflex on both sides and make the left one or two degrees more than the right to prove or disprove my theory.

Currently Left -2 Right -5

Going to try Left -4 Right -3... I like the stick forces better at -3 than -5 anyways.

I will report back with the results of this test. Also just to verify can someone please take a picture of their F7A's just so I can idiot check that I have mine in the right way??

Thanks as always

[C5Engineer 1170]

A pretty good discussion from Backcountrypilot.org

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.

[akflyer 1427]

without trim tabs on the flaperons all you are doing is moving the stick position. The flaperons will fly level side to side, but will be neutral, reflexed or extended... The only way to correct roll is with trim tab on flap, or as designers inteneded, adjust the one strut end to add washin or washout.

[dholly 718]

While I don't have the practical experience to say with certainty, I think wing twist may be the issue as well... even if your quick measure suggest they are in spec and equal on the sawhorses, that strut adjustment can be crucial. I had an offline chat about this when I was building my old Mk-IV wings with another gentleman from the Yahoo Avid Group. I would break out the laser(s).

Back in the 80's, when lasers first came into use, I built some fixtures for checking the angle of incidence and other related wing geometries. Amongst the first candidates for alignment was a Pitts S1-B. When we were finished (about two hours later) the owner took the plane on a test hop and came back very excited. "It's almost 7 knots faster in cruise and no longer needs the exaggerated trim settings. And, when I stall it, it stalls straight ahead." Before the month was over, I had about a dozen owners on a waiting list. Biplanes were the ones that showed the greatest improvements. Fabric covered monoplanes were a close second. Composite aircraft, for whom I'd developed the process, showed measurable improvements too but not as dramatic. (I don't know why) The process is quite simple. Band saw two identical profiles from 3/4" plywood that match the upper camber of the wing so that the fixtures, when placed on the top surface, are parallel to the streamline. Add screw in eyes at each end so a bungee chord can be used along the bottom of the wing to secure them. Attach a pair of plastic clips to the top planar surface of both fixtures so that a laser can be moved back and forth between them. Lasers were expensive then, today you can probably afford to buy two. However, it's important that the two lasers be collimated to intercept the wall in an identical fashion. Park the plane in front of a large hanger door and, using blocks and jacks, level the aircraft so the center spar is perfectly horizontal. Using a transit or long carpenter level, scribe a horizontal line on the hanger door, long enough to match the wing span. Attach both fixtures, one on each side and at equal distances from the center axis and turn on the lasers. Measure the height of each beam's impact spot, relative to the horizontal datum line. Adjust the wings as per the manual. The father away you are from the hanger door, the more sensitive the adjustments and the more precise the results. I had used a long, colored alcohol based leveling system with 35 feet of flexible plastic tubing and graduated glass columns to rig the wings on my Long Ez. When I went back and checked my work with the laser test rig, I was shocked at how far off the wings were and the degree of asymmetry I'd created. I wish I'd thought of this while I still owned the Decathlon. It flew beautifully. Still, I can't help but wonder how much better it might have behaved. I know this answer doesn't address the saw horse part of the question. It will, however, provide a degree of accuracy difficult to achieve with bubble devices. Are we having fun yet? Art Bianconi www.vortexgenerator.net

[Av8r3400 1179]

without trim tabs on the flaperons all you are doing is moving the stick position. The flaperons will fly level side to side, but will be neutral, reflexed or extended... The only way to correct roll is with trim tab on flap, or as designers inteneded, adjust the one strut end to add washin or washout.

With the flapperon design that we all use, you can trim them without a tab by tweaking the trailing edge with a large flat sheetmetal pliers. This was recommended to me for my heavy wing situation by my CFI/1600 hour Kitfox buddy.

I've seen this done, but as Leni and Doug have said, adjusting the wing angle sounds better and more effective.

[C5Engineer 1170]

Sounds like all I need are wings with "Freaking Laser Beams attached to their heads"....Austin Powers Thanks for the info. I'm going to double triple check my wing alignment and maybe put a turn or two on the rod end and try that. I never thought about just tweaking the trailing edge of the flaperon. Out on the tip I bet that would be pretty effective. I know the Cessna guys do this on the corrugated trailing edge of their flaps and ailerons for rigging issues.

So I need more lift in my left wing..that would mean more washout correct? To pull the trailing edge down I should SHORTEN the rod end??? Can anyone verify or am I thinking back ass wards.

[Av8r3400 1179]

That would work, theoretically.

[akflyer 1427]

Sounds like all I need are wings with "Freaking Laser Beams attached to their heads"....Austin Powers Thanks for the info. I'm going to double triple check my wing alignment and maybe put a turn or two on the rod end and try that. I never thought about just tweaking the trailing edge of the flaperon. Out on the tip I bet that would be pretty effective. I know the Cessna guys do this on the corrugated trailing edge of their flaps and ailerons for rigging issues.

So I need more lift in my left wing..that would mean more washout correct? To pull the trailing edge down I should SHORTEN the rod end??? Can anyone verify or am I thinking back ass wards.

Ahhh grass hopper, you be tinking creary shorten the reft rear and you will find ritenment on the stick

[C5Engineer 1170]

Called Dean today and he said the same thing..shorten the rod end a turn and see what it does. Going to re rig my flaperons and focus my attention on the washout.

[C5Engineer 1170]

When I went to pull the bolt the to adjust the rod end there was a ton of pressure on it and I had to whack it out with a punch. I went one turn and had to have buddy wiggle the wing tip to get the bolt back in. It didn't really do much so I went one more turn. This time it was able to wiggle the bolt out with my fingers and there was a noticeable difference. I went one more turn and it was better yet so I went one more turn for a total of 4 turns and the bolt slid right in easily. It now just barely rolls right instead of left so next time I fly I'm going to back it back out a half of a turn. What a difference it made! It is easier to make a coordinated turns to the right now too. I did some stalls both power on and off and it didn't want to drop a wing at all.

Now though when I pull on a few degrees of flap it wants to roll right which makes sense now why when it was rolling left it would stop when I pulled on a little flap. I'm guessing that my flaps must not be coming on perfectly symmetrical. It's not a huge issue but I often pull on a little bit of flap to get rid of some reflex and decrease the stick forces when I'm canyon flying or landing in gusty winds. Anyways with 5 degrees of reflex and 5800 rpm it will fly hands off which is what I was looking for. Like I said at 5 degrees the stick pressure is a little heavy but just a small crack of flaps gives me a slight nose down trim and gets rid of the forces.

[dholly 718]