pierre smith

pierre smith

Well Known Member
Mornin' everybody.
We set our wing incidence on our RV6A recently, using a transit. After levelling the airplane fore and aft and side to side, we stood a yardstick on the spar at the skin butt joints. a mark was made at that point, then another 3 1/32" higher, as per Van's. The stick was then stood on the rear spar and the wing raised/lowered until the new mark was centered and the rear spar clamped and drilled after double and triple checking. Now our wing underside does not lay against the skin that protrudes out of the fuselage sides (quickbuild) but is 1/4" higher at the trailing edges on both sides. We again double checked the incidence angle, this time with a level but find that's OK. Ken at Van's said that usually, the wings lay flat against the skins but, hey, it's a homebuilt and they all vary. As long as both wings are at the same angle it's OK.
Have any of you guys had a similar problem/situation regarding the incidence angle?
Thanks in advance, Pierre Smith
 
Belly skin overlap

Hi Piere!
Had the same problem on my -6A, and most recently on the -8. Didn't prove to be an issue in either case. After the screws were in, the skin laid surprizingly flat to the wing.
As Van's would say, drive on!!
By the way, the -8 is in the air and flying good. Got the usual couple of minor issues, but overall doing real well. Biggest disappointment is the Van's gauges, have several that just don't work.
Oh well! Try to get down soon.
Bill Waters
 
pierre.
I used a machinists level on top of a carpenters level. the skins fit tight on my "9" probably just lucky
Frank
 
Yes!!!!!

Mine was so bad that I went through exactly the same anxiety and self doubt that you did -- after all this is the pride if the homebuilt industry and everything is automaticly perfect --- right? NO! Stick to your alignment process and don't compromise to some perceived truth. Align everything to a real truth that is constant for all flying surfaces - the canopy deck - force yourself to accept it as the reference plane for alignment of all flying surfaces. My "Quick Build" kit was number 62 I believe and the two sides of the fuselage are not the same. If you get sucked into matching what you think the thing should look like, you will be aligning to multiple references and the two wings and tail will not be aligned properly with each other. The plane will probably fly OK but you will lose performance (flies great but I have a heavy right/left wing - sound familiar). My flap gap seal skins had to be formed with a significant step to reach the bottom of the fuselage and the one on the left is more than the one on the right. Then I had to add an extension (easy to do) to cover the flap actuator hole. I also had a problem with the front (tank) attachment angle bracket mounting. Where it had to go to mate the tank fitting was not compatible with the structure placement inside the fuselage. I had to make the angle bracket out of much heavier angle stock and attach it at a point forward of the design fuselage station attach point. There are many other obsticles that needed to be worked through but the airplane is flying great. With your extensive background I know you want the plane to be perfect and conflicts like this drive you crazy - me too. I was so concerned about it that I asked Mike Seager about it when I went for my transition training and he just said it will fly fine - that if you walk the line you will see twisted wings (like a propeller) and they all fly fine. Sticking with a single reference plane for all of the rigging will give you the truest airplane and these quick builds do have errors that have to be accommodated. I have now spent 4216.1 personal hours building my "quick built" RV-6A (I worry a lot I guess) and I log every hour that I put in taking the plane to full completion (maintenance, etc. time is not logged). I have thought I had the plane done several times but there are still things that have to be done to make it the airplane I want to fly.

Bob Axsom
 
wing incidence 1/4" high at rear...

Same problem on mine...QB fuse and slow build wings. Required a joggle in the flap to fuse transition. But the incidence is correct to the cabin longeron, and the HS is flat. Do what the instructions say and the plans show and it will be fine.

On the same note - It also helps to look at "newer" designs (7,8,9,10) to see if Van's may have 'improved' the design. Example: set the VS straight or angled left? In this situation the -6 plans say straight, while newer plans say left a little bit. I choose to go left a little bit (1/4") on my -6A. I also highly recommend the Van's -7 'improvements' to the -6 fuse & FWF.
 
Incidence

Thanks.....WOW, you guys are a great group of guys/gals :):)
I went back and used a four foot carpenter's level with the airplane sitting on it's gear, with the usual nose-up attitude of 6A and drew a line on the fuselage side, just under the canopy rails with a magic marker on the level. I found that the airplane's rearward "tilt" amounted to 1 1/2 inches of difference between the back end (above the rear spar) of the line and the front (over the front spar) of the line. This means 4 1/2 inches of incidence with the airplane's nose pointing skyward. The incidence is still correct this way too. Yep, it's gonna fly this way and I'll keep you all posted.
Thanks so much,
Pierre
 
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