Results of changing incidence on one wing

[petersb]

I require about 3/8 down aileron on the left wing to fly level.

Measurements showed approx 0.1 degree too much incidence on the right wing.

I raised the right wing railing edge by 1/16 inch which should be approx 0.1 degrees.

Result, no change

Thought this might be interesting info for those working on wing heavy issues.

 

[GLPalinkas]

I require about 3/8 down aileron on the left wing to fly level.

Measurements showed approx 0.1 degree too much incidence on the right wing.

How are you measuring the incidence? Sounds like a digital level. That may not always be the most accurate way of measuring. A reading of .1 could be off 1/8" or more. A machinist level (like those used for a drill press, etc. is very accurate and I used mine to get my incidence the same. The measurement is not as important as both wings being the same and keeping proper edge distance on the rear spar bolts.

 

[petersb]

How are you measuring the incidence? Sounds like a digital level. That may not always be the most accurate way of measuring. A reading of .1 could be off 1/8" of an inch or more. A machinist level (like those for a drill press, etc. is very accurate and I used mine to get my incidence the same. The measurement is not as important as both being the same and keeping proper edge distance on the rear spar bolt.

I used a bubble level, digital level and the most consistant was my iphone app.

I checked the measurement numerous times

However the interesting observation was, no change in wing heaviness when the incidence was changed.

Just thought , you might be suggesting that a change was not made due to inaccurate before and after measurement errors. There was a positive 1/16 inch displacement change of the rear spar attach point, using my calculator I figure that is approx 0.1 degrees

 

[bret]

Android app level, paid a couple more bucks so I could calibrate it, back up measurement confirmed with bubble level. Did you check down the length of the wings to check for twist? Then there is the straw taped on aileron for trim trick?

 

[Toobuilder]

My Rocket was way out of trim in roll despite the fact that the whole TE of the wing lined up and was equal. Turns out the airplane suffered a (poor) repair on the left outboard aileron hinge and the pivot point was .150 too high. So despite the fact that the TE appeared correct, the section of wing represented by the aileron span had an effective higher camber airfoil section and produced a rolling moment. I fabricated a new hinge bracket, located with the aid of a laser through the tooling holes in the tip rib and all is good now. I'm guessing the -7 has pre drilled holes in everything so is unlikely to be out of alignment, but it's easy to check with the tip off.

 

[JonJay]

I raised the right wing railing edge by 1/16 inch which should be approx 0.1 degrees.

Result, no change

Thought this might be interesting info for those working on wing heavy issues.

That is interesting. I am curious, how did you raise the trailing edge? Normally, once the rear spar is drilled to the carry through, what's done is done....

Since you previously owned a 6, I probably don't need to mention the obvious, but for others, in a side by side, all things equal, fuel etc... you will have a slightly heavy left wing when solo, unless you sit on the right side, then you will have a slightly heavy right. When I fly with my wife, much to her dissatisfaction, I guess her weight within a few pounds by how much fuel I have burned from the left tank. She is not impressed.

 

[g zero]

Heavy wing

Take a look at the elevators , make sure the are both inline , I have seen more than one that was off . I think builders line up the steel weldment before they drill not the trailing edge of the elevators . The left and right weldments do not line up perfect if drilled properly .
Tom

 

[Ralph Inkster]

Another thing that could possibly cause a 'heavy wing' is if the gear leg fairings do not same incidence.

 

[Veetail88]

I'm curious as to how you raised the trailing edge as well.

There are lots of warnings about how critical that rear spar attach hole is and I hope you didn't elongate it.