Wing attach point

dustman · #1 09-07-2007, 06:32 AM

Question to the gallery. I am at the point of drilling the hole to attach the rear spar (RV3), but i need just a little more clearance to be within specs for edge distrance on one wing. At the moment the 2 wings are square the distance to a common point in the rear of the plane are exact. I can fix the problem by pulling the one wing back which will give me the distance i need, but by doing so i will have a slight sweep back on the one wing will this cause problems? Thanks for any info

whifof100ll · #2 09-07-2007, 07:26 AM

First let me urge you to talk to Van's. But here is my opinion anyway.

The slight sweep back will not cause a problem. Lack of clearance is a NO NO.

Since this is important, When I did my 6, I used a transit to set incidence and splay angle. I also used distance to a common point on the tail and plumb bobs reference to the spar. I found that the measuring distance to the tail is not very accurate. Transit can easily set you within millimeters, and plumb bobs work very well.

If you do not use a transit, I suggest referencing the front edge of the wing spar and dropping plumb bobs to the floor. to make sure the wing is square. If you have to sweep back, I would sweep both wings back the same.

I also strongly urge you to set this up carefully, take as much time as is needed to get this perfect, take pictures, estimate the sweep you will have, and talk to Van's to be sure.

Regards,
Dale Lambert
RV-6 finishing kit

Christopher Murphy · #3 09-07-2007, 10:09 AM

That rear spar attachment it critical. I know of one RV-3 owner years ago that tried to correct a rigging problem by drilling the hole over size and without the proper edge distance. He took off made a right turn and the wing folded up killing him. Take the time to correct the problem so the airplane can be rigged per the plans. If you start sweeping the wings you will preload the main spars and also Change the handling characteristics of the plane. This is one area you don't want to experiment with. CALL VAN's.

JonJay · #4 09-07-2007, 10:42 AM

I believe Vans will tell you that wing sweep has at least a 1/2" tolerance or acceptable difference between both sides, both foreward or aft sweep. I had one of the first slow build wings with center section sent in for a QB fuselage. The center section came from the factory built fuselage slightly crooked fore and aft. Hence, I have a slight forward sweep on one wing and the other is straight. My airplane flies as fast and straight as any out there.
Like others have said, the hole clearance is not negotiable. The wing sweep is.
Call Vans

dustman · #5 09-07-2007, 01:36 PM

Thanks everyone I called VAN's i will be making structural changes to fix the problem not taking any chances here.

LettersFromFlyoverCountry · #6 09-07-2007, 02:35 PM

What structural changes will you be making?

dustman · #7 09-08-2007, 08:55 PM

The original builder used angle for the spar carry through im changing it to flat stock as per the plans which will give me more area to work with.

WSBuilder · #8 09-11-2007, 11:16 AM

Quote:

Originally Posted by whifof100ll

First let me urge you to talk to Van's. But here is my opinion anyway.

The slight sweep back will not cause a problem. Lack of clearance is a NO NO.

Since this is important, When I did my 6, I used a transit to set incidence and splay angle. I also used distance to a common point on the tail and plumb bobs reference to the spar. I found that the measuring distance to the tail is not very accurate. Transit can easily set you within millimeters, and plumb bobs work very well.

If you do not use a transit, I suggest referencing the front edge of the wing spar and dropping plumb bobs to the floor. to make sure the wing is square. If you have to sweep back, I would sweep both wings back the same.

I also strongly urge you to set this up carefully, take as much time as is needed to get this perfect, take pictures, estimate the sweep you will have, and talk to Van's to be sure.

Regards,
Dale Lambert
RV-6 finishing kit

Dale,
That's way down the line for me, but could you draw a diagram of how you used the transit? I'll keep that for reference, later. Thanks!

whifof100ll · #9 12-11-2007, 10:07 PM

Quote:

Originally Posted by WSBuilder

Dale,
That's way down the line for me, but could you draw a diagram of how you used the transit? I'll keep that for reference, later. Thanks!

We set the transit up high enough to spot both wing tips. We used the downlooking scope on this transit to locate it over the edge of the spar. With the azimuth on the transit locked, you could rotate the elevation more than 180 degrees allowing survey down each spar from root to tip using the spar face as a reference. Minute variations in splay are very obvious doing this.

Removing the tanks allowed use of a small ladder to see and is required so that the spar is more visible.

Might be overkill but I know it is right on!

Dale
RV-6 finishing kit