How to use the word level 10 times.

jim_geo · Post by **jim_geo** » Sun Feb 04, 2007 1:15 am

I have noticed on a few builder sites the use of wooden blocks duct taped to a level when setting the incidence of the wings. That didn't seem like a very good way to setup a level to me since many different areas need to be checked as the wing is set in place. The thickness of tape will cause an error in the read of the level large enough to be a problem if the back side of the level is used and the tape encircles the level, for instance when cross checking for level on the fuse. With the level set up as shown in these pictures both sides of the level can be used without needing to disturb the spacer block or otherwise undoing anything. It can also be adjusted easily for left wing right wing use if you happen to have a digital level that only reads on one side.

RVNewsletter · Post by **RVNewsletter** » Sun Feb 04, 2007 10:21 am

Dick Martin used a pretty interesting -- and simple setup. Given his penchant for squeezing every knot out of an RV, I thought it made sense. It was just a piece of angle with the whole screwed to it. He's holding in the picture here.

I admit, though, I didn't do either. I just put the block where it was supposed to go. Put the level across it, and made sure the height of the bottom of the level above the rear spar rivet line was exactly what was called for in the plans, which is the important part.

jim_geo · Post by **jim_geo** » Sun Feb 04, 2007 12:42 pm

If I did it again I'd do Dick Martin angle jig shown in your link. It's such a no brainer.

Dan A · Post by **Dan A** » Sun Feb 04, 2007 6:26 pm

The key item here is to make sure both sides (wings) are set exactly the same! That way you should experience no heavy wing.
Dan

jim_geo · Post by **jim_geo** » Sun Feb 04, 2007 7:08 pm

That's exactly why I cross check everything three times before drilling. What I found was that as I made a change in one place the reading at another would change. So I fine tuned everything until I had side to side front to back level on the fuse then cross checked the wing to the fuse. I found that as the wing moved, even though at first I was only off by less than 1/2 degree, that change was enough to throw the level of the fuse out. All in all it took about three hours of fiddling with it to get evrything set in a position I felt confident of. Once that bolt hole is drilled it's pretty much a done deal.

RVNewsletter · Post by **RVNewsletter** » Mon Feb 05, 2007 9:16 am

Three hours? Man, you got off easy.

I think it took me two days to get everything to agree.

Of course, that included multiple beer breaks.

Post by **Spike** » Mon Feb 05, 2007 11:28 am

Beer makes everything better.

jim_geo · Post by **jim_geo** » Tue Feb 06, 2007 10:44 pm

I think I'll have to have a few beers tonight then. Don't use my information from this thread. At least don't use it with a digital level without knowing the level really well. Much to my dismay I discovered that my digital level doesn't flip over and retain accuracy. I started wondering about this when my flap didn't just kiss the bottom of the fuse but missed it by what looked to be about an 1/8”. While setting up the right wing today I decided to use the Dick Martin (see link above) method using the fence from my Unisaw instead of AA. Starting with my finished wing I checked the incidence of the left wing and an error of .3 degree jumped out at me. That error works out to be .28" in 3.5'. The distance from the spar to the trailing edge. I don't know what to do now, of all the things I want to be right on my plane this item was number 1 on the list. I'll be calling [gulp] Vans in the morning to see if I can do anything.

Dan A · Post by **Dan A** » Thu Feb 08, 2007 11:49 pm

If you didn't drill the attach hole in the rear spar full size, you can just re-set the incidence and drill the hole larger. Good luck!!
Dan

jim_geo · Post by **jim_geo** » Fri Feb 09, 2007 2:05 am

It's a done deal. I called Vans and talked to ken. What he said was that the most important thing was edge distance of the bolt and spar tabs. Second most important was symmetry and third was the actual angle of the wing. So my plane will likely trim out just a fuzz differently from another. I was able to accept that answer. So I moved on to the right side. After lining everything up and copying my error to the right wing I drilled and set that wing. Once I attached the flap and set it to the aileron which was set at the neutral control position I noticed the flap trailing edge extended down ¾” below the fuse

. I was totally shocked since the flap on the left side was at least center lined with the bottom of the fuse. I walked away from it Wednesday night and got back to it this morning (Thursday). I marked up some stations along the longeron in the cabin area left and right and measured to the top surface of the wing. All measurements were dead on the same from side to side. At that point I started sighting from the leading edge of both wings over the top surface back to the flap. As I dropped down I noticed the inboard portion of the flap disappears several degrees before the outboard end. That was the right wing, on the left wing the flap vanished evenly. Checking further revealed a definite twist in the flap starting between the second and third outboard flap rib. Anyone have an idea about correcting it?

Post by **Spike** » Fri Feb 09, 2007 9:27 am

I am the king of warpage. The first and biggest question to ask is "will this truly effect the flying characteristics of the plane?" The next question to answer is "Do I really care?"

If so, then start drilling rivets out of the spar & end ribs until it starts to relax. Go slowly and keep comparing, hopefully you will find out the specific area that causes the warpage. It can be as simple as an end rib not being flanged correctly, or the surface that you were using to rest the part on while riveting/clecoing.

It can be done, though it might not come out "perfect" since you have lots of holes already drilled. By the way, a really really good way to find out if something is warped is to use a pool table as a flat surface. A properly setup slate pool table will be about as flat as you can get.

- Spike

RVNewsletter · Post by **RVNewsletter** » Fri Feb 09, 2007 11:58 am

I think when I mated, I took two measurements. From the tip of the wing (the same spot on the outboard wing back to the edge of the skin (at the same point) on the 712 bulkhead (the very end of the side skin, basically).

And, of course, the straight line with the plumb bobs off the leading edge.

I ended up not doing anything with the longerons as a reference because they're subject to building error. I used the center section to establish level.