Page18-06 Flaperon trailing edge bends

[BigJohn]

I'm posting this for the newer builders. When I put the skin on my flaperons I was way too timid (lazy?) about squeezing the skins down so they would lay flat on the ribs. See Figure 2 on page 18-02. I did not discover the error of my ways until my first flight, when I noted a very heavy right wing and a "dead spot" - some Van's write-ups call it "aileron snatch" - in the ailerons with stick near the center of travel.

Yesterday I corrected the situation using a pair of heavily padded seaming pliers. It would have been easier to do before putting the skins on for sure. But at least I got the job done without messing up the paint.

Correcting the heavy wing was easy. Correct for any rudder trim issues first. I used a temporary trim tab. Then squeeze the light wing flaperons SLIGHTLY more than the heavy. Trial and error. Adjust and fly, adjust and fly. A good excuse to get in some landing practice.

For more details see my blog.

N37JP now cruising in roll and yaw trim. At least close enough for now. Might have to readjust a bit after wheel pants go on.

But - my main message here is to take the time to form the skins down flat before riveting them to the the ribs. I suspect this is just a good practice for any of the parts that have a bend at the trailing edge, such as the Anti-Servo Tabs, and the rudder, although I don't think those parts are as critical as the flaperons.

 

[JBPILOT]

Hey John - -

I have stated this before, but I had a heavy wing, and the ball half out. When I corrected the heavy wing, the ball moved back into correct position also. I have NO rudder correction. I would suggest solving the heavy wing first, before rudder trim. My experience certainly could be different from others, but it might save time messing with the rudder first.

Glad you are up and going now. Have the cabin sealed up yet ? Essential in 'our' colder climates.

John Bender

 

[Mel]

But - my main message here is to take the time to form the skins down flat before riveting them to the the ribs. I suspect this is just a good practice for any of the parts that have a bend at the trailing edge, such as the Anti-Servo Tabs, and the rudder, although I don't think those parts are as critical as the flaperons.

Actually all these trailing edges are critical. The aircraft was designed for a specific "airfoil". If the trailing edges are not properly formed, you do not have the "designed" airfoil.
Another factor is that if the trailing edges are not formed completely, you are asking for cracks at the aft most rivets.

 

[BigJohn]

Mel, thank you for that clarification. I suspected that but wasn't sure. I will now go back and do the sqeeze modification to all those trailing edges. Seems to be fairly easy to do with the padded seaming pliers, without damaging anything or cracking the paint.

I hope this thread will be helpful to builders who are in progress or just starting.