My Fight With A Heavy Wing

I thought that my experience in resolving a heavy right wing after my build might be helpful to someone else. First, all during phase one, I was experiencing a slightly heavy right wing. After studying all of the posts on the subject, and reviewing Van?s suggestions on the subject, I decided to order the rudder trim tab, and install it first, because, the suggestions were to get the ball centered first, and mine was running a little right of center. Sure enough, after installing the trim tab, the ball was dead center, and with no adjustments to the factory bend, I might add. But, I still had a heavy right wing.

Next, it was ?pinch the trailing edge of the light wing?. I did this and it helped, but I still had a heavy right wing. The next suggestion was to take a hammer and a block of wood to the trailing edge of the heavy wing. Wow! That seemed a bit brutal, and I decided to make that a last resort effort in fixing the problem.

Next, I read where one of the builders fixed his heavy wing by taking a turn on the flapperon rod ends. I had carefully measured mine, and had put them in with Loctite, and I wasn't excited about disturbing them. I again took vary precise measurements and found my rod ends were positioning both flapperons in precise duplicate locations on each wing. Now what??

While making all of these measurements of the flapperons, I did notice a slight variation in the trailing edge of the top wing skins, where it trails past the rear spar, and approaches the flapperons. The top skin on the left wing was perfectly flat, whereas the right wing skin was drooping all along the span, just slightly; from a 1/32? to as much as an 1/16? in some areas. This was determined by extending a straight edge, chord wise on the wing skin, and seeing a slight bit of daylight under that last half inch of the top wing skin. So, I carefully reshaped the trailing edge of the right wing top skin to also make it perfectly flat, just like the left wing. The following test flight rewarded me with a beautifully flying, hands off, airplane.

Hopefully, this long post will help another builder who has been working on a heavy wing like I was.

Tom

I have also noted that, as can be expected, the lateral trim of the RV-12 is sensitive to the cockpit loading (i.e., pilot-only versus with passenger, low fuel level versus high fuel level, baggage, etc.). Since much of my flying these days is me alone with about 15 gallons of fuel, I have laterally trimmed the plane hands-off for that specific flight condition. Fortunately, the RV-12's flaperons are light and effective enough to easily handle other loading conditions. And you can always turn on the SV AP to hold the wings level for you! ;<)

Heavy right wing

So, I carefully reshaped the trailing edge of the right wing top skin to also make it perfectly flat, just like the left wing. The following test flight rewarded me with a beautifully flying, hands off, airplane.

Please tell me how you did that. I have an S-LSA so I can't take the airplane apart.

Thanks,
EBB

Ex Bonanza Bucko said:

So, I carefully reshaped the trailing edge of the right wing top skin to also make it perfectly flat, just like the left wing. The following test flight rewarded me with a beautifully flying, hands off, airplane.

Please tell me how you did that. I have an S-LSA so I can't take the airplane apart.

Thanks,
EBB

Click to expand...

I just lowered the flaps, and used a section of thin plywood, about 1' X 2'. I slid it in under the drooping trailing edge of the wing skin and gently lifted, bending in small increments until it was level. as measured with a straight edge. You will find it really quite easy to do.

Good luck...............Tom

Thanks Tom

A big shout-out to Tom for posting his observation about his RV-12 wing skins aft of the rear spar not being flat. During early flight testing, I discovered a heavy left wing and followed Van?s suggestion of flattening out the aft edge of the flaperon on the light wing (right wing in my case). After flatting the aft edge just a little, went for a test flight and still had a heavy left wing but seemingly slightly better.

Before bending more metal, decided to have a look here on the VAF forums to see what others have done. I knew the rod end bearings were set correctly, so was looking for other options. Fortunately, I ran across this thread and read where Tom discovered the upper wing skins aft of the rear spar were not flat ... and after Tom flattened them, his RV-12 flew hands off without rolling.

Decided to have a look at mine and discovered I too had places where the skins were either low or high on the same wing. The skins aft of the rear spar on both wings were tweaked to be level and that made a HUGE!!! difference ? no more heavy left wing!!

So I would suggest other RV-12 builders that have a heavy wing to first take a very close look at the skins aft of the rear spar ? drop the flaps, then adjust the skins flat using a straight edge and block of plywood using the method Tom pointed out. Fly the RV-12 and if it is still not right, then look elsewhere ? possibly getting draconian with the aft edge of the light flaperon or adjusting rod end bearings.

Thanks again Tom for bringing this to our attention.

Happy Flying,

I've been scratching my head for some trying to resolve a heavy right wing. Not that it's a big problem as it just takes light pressure on the stick to fly straight, but having flown the plane across Australia and back, it's definitely annoying. Will check the skins next time I'm at the hangar. Thanks Tom.

As soon as I flew off the PAPs I riveted trim tabs to my rudder and ailerons. Makes it much easier to adjust trim if you have to.

You shoudnt need trim tabs to get it to fly hands off.take your time tweaking the flaperon trailing edges,a little goes a long way. No rudder trim tab here,must of had a level table some day building. She is a sweetheart!!!

Bob,

Glad it worked for you, but I really like the simplicity of trim tabs and they are easy to adjust if needed.

Rich