Sunday October 30th, 2005|
Mated The Wings; Problem With Wing Sweep
Big day today. My friend Bryan came over to help me and Jaime get the wings on. Bryan was my CFI and taught me to fly...so it was neat having him here for this milestone in the project. Here Bryan is removing the flap from the wing (yes...I removed the flaps a couple of days ago for fitting but I had to put it back because there was literally nowhere to store it).
Anyway...we slid the wing into place without too much fuss. It really wasn't that big of a deal. Just get it close, use the drift pins and it lines right up!
Same thing with the right wing...
Ok, because the fuselage w/ wings mated is very tight in the garage, we actually mated the wings with the fuselage too far to the left (fuselage-wise) in order to have working room. Here we are moving the setup back into the corner and I'm sliding the main sawhorse. I'm willing to sacrifice myself if this thing falls. ;-)
Ok, now for a couple of vanity shots for posterity.
One from the back of the truck...
Next I set out to set the sweep of the wings. Jaime and I dropped two plumb bobs along the tank leading edge, marked the spots then dropped a plumb bob off each end of the wing and snapped a chalk line..
Doh...got a little forward sweep (forward is bottom left of image and aft is top right of image). The distance here is about 1/2 inch. No big deal, right, just slide the wings back a little....then it rained on my wing mating parade.
The rear spar attach points are all the way in...so I can't sweep the wings back at all. ARRRRGHGHGH. Both wings have about 1/2 inch sweep and both are flush. If you look carefully, you can see that the problem is the AN470AD4 rivet just at the top there. The difference at the tips is .5 inches, but that translates to very little at the rear spar. I'm gonna work the trig to figure out how far it has to move. I'm also going to call Van's and post a message to the Vansairforce forums tonight to see what the deal here is.
Here's the drawing for the rear spar attach point. The RV-7(A) and -8(A) wings are identical except for this part. It comes from the factory cut for the -8 but for the -7 you have to trim it. Anyway...was back when I built the wings I had to take the drawing from the preview plans to cut the rear spar. The problem is the plans on the preview plans are much smaller. You can read all about that here. I remeasured the rear spar as best as possible (it's hard to reach) using the full scale drawing and it looks like it's right on the money.
Anyway...I fiddled with this for quite some time...looking at the drawings...measuring the spar....looking at the mark on the floor...resnapping the chalk line...checking the plumb bobs again.....scratching my head, etc. Gotta call Van's tomorrow, I guess. Anyway, you can see here that the wing cradle BARELY fits in the garage. And if you're curious I have about 4 inches clearance from each aileron to the door/wall. Very tight in there, but obviously workable.