What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Wing twist

G

ge9a

Well Known Member
I have my QB wings inserted into the fuse for the first time. All is going very well, except tonight when I began to set the incidence on the right wing, it appears there is a 0.3 deg twist between the root and the tip. The left wing appears to be straight throughout. I'm not sure what I can do about it at this point, but should I be concerned? I just thought I'd ask before proceeding.

Thanks.
 
Build On!!!!

If you are really concerned go and have a beer. Then build on tomorrow.

In fact I think those are the directions from Vans.
 
There is a lot of RVs flying with more twist that you are talking about and most don't even know it
 
split the difference

If you're convinced about the twist then split the difference in the angle of incedence on the twisted wing.

0.3 degrees doesn't sound bad at all.

Dave
 
Really

All above are great answers. Chance is its a measurement error. WHICH WAY IS it twisted? How are you measuring it? What is your refrence point? What wing? Both? Chill and get back to it later. G
 
Set the incidence per Van's Procedure

I would just set the incidence per Van's procedure and work with what you end up with in the flying airplane. There are so many variables that no two RVs are exactly alike. On mine I had to raise the trailing edge of the left wing root to get the correct incidence angle but the right one was correct with no angle adjustment. I had assumed that the design was such that at the proper incidence angle the lower flap skin would extend straight under the fuselage providing a clean gap seal but this was not the case. The quickbuilt fuselage is not square and I had to form a step down "Z" on both flaps to achieve the gap seal and the one on the left is larger than the one on the right. Further, I had to develop a small tab expension to completely cover the flap pushrod opening. I'm not sure how you measured the twist angle but it sounds quite small and I doubt that the aileron deflection to compensate will be a conscious effort. You will have to trim for the forces in flight (certainly right rudder) and if there is any residual effect from the measured wing twist it will get lost in that activity. My RV-6A flies has no roll-off in flight and consistently achieves 171-173 kts TAS with an O-360-A1A, non-blended airfoil Hartzell C/S prop, at full throttle, leaned for max power, at 2450 rpm.

Bob Axsom
 
Bob - it sounds like I'm starting out to have the exact opposite experience as you. My left wing required no adjustment to correctly set the incidence, and the entire wing is straight (or appears so with my measurements). But the right wing was initially about 0.3 degrees low on the rear spar, so I jacked it up until it was correct. I will hang the flaps tonight to see how they fit.

Judging from the responses (thanks for all of those, BTW), I should not worry about the 0.3 or 0.4 degrees of 'apparent' twist in my right wing, and I won't. But for clarification, I measured the angle of incidence per the plans (with the correct block over the rear spar). I found the rear spar to be consistently 0.1 degrees lower at the mid-point of the wing than at (near) the root, and 0.3 degress lower at (near) the tip than the root - I'm talking about the right wing only. I'm sure there are measurement errors in the way I'm doing this. If I were just using a bubble level instead of the digital model, I would still notice the twist, I just wouldn't have an accurate measurement of the 'delta' between the root and the end of the wing.

For reference, when measuring and setting the wing incidence, I am aligning the forward edge of the 4-5/64" block with the centerline of the rear spar rivets. Then I am setting the forward edge of my straight edge exactly 1" forward of the leading edge/wing skin overlap, so it is aligned with the forward edge of the front spar. That is how I interpreted the instructions from Van's. Am I on the right track?

Thanks for all of the help, as usual!

Greg
 
You must log in or register to reply here.
Back
Top