I followed the instructions from Vans on mounting the HS and VS. Nowhere in the directions does it tell you to check for square, except forward/backwards square of the HS to the tailcone. HS and VS go on quickly, and make it really look like a airplane.  I did make sure I had the tailcone sitting square on the sawhorses, But then did not check to make sure the HS or VS was also level, just followed the directions. After I finished all the bolts, I thought "I hope it is square", and then made the mistake of checking.  You can't see it well in this picture, but I put a crosshair laser level on pointed at the tail with the HS exactly level, the laser hitting all of the rivets. Unfortuantely the VS did not line up on the vertical laser line.  This shows where it is falling at the top of the VS when it is centered. It is about 3/8" off. This appears to be caused just by different holes being 1/32 or 1/64 off, but over 4-5 feet this causes a bigger change. The out-of-alignment is not noticeable at all without a laser line, but if I ever build another plane, before match drilling the VS I would make sure that it is vertical with a laser level, or by measuring from HS tip to VS tip and other HS tip to VS tip and making sure they are the same. I have been told by other builders to not worry about it that it should not have any adverse flight characteristics. But if you have not mounted yours yet, make sure it is vertical before final drilling the holes. I think because of the small amounts we are talking about if it had been done before the holes were final drilled, the final drilling could have fixed most if not all of the alignment. |