Mounting Vert. stab. RV-9A

Looking for clarity in mounting the V/S. I trimed VS-702 as shown on
DWG 27A. The bottom of the forward nose of the V/S sits about 3/4" below 709 bulkhead. Vans drawing shows it in line with the top of 709. It looks like it should mount ok. I just dont like that it's not an exact fit. Does anyone have any pictures showing the mount to the aft end of the fuse. What concerns should I have in the alignment of the V/S?
Thanks, Mark C. 9A

The critical part of mounting the VS is to make sure that the rear spar with the brackets for the rod ends is absolutely straight. Prefit the rudder and make sure all of the holes in the rod ends lines up. I had a bit of an arc in the VS rear spar at first and had to keep moving the top forward. The attach plate F-981 needs to be in front of the forward VS spar so you can move the top of the VS forward to keep the brackets on the aft spar in line. Make sure to follow the little note in detail View A-A about adding and gluing on the single washer on the left side of the fuselage to help with setting the VS offset.

Click each pic for a larger version and a brief description...

IIRC, I trimmed the forward VS spar per plans, but could have left it a little long. It will move up and down slightly as you adjust for a square VS rear spar. I had plenty of edge distance for the lower rivets, but could have left a little more material.

Straight edge

Put a straight edge vertically touching the
mounting brackets for the rudder. Don't need the rudder
on. Drill and cleco the bottom of the vert. Stab. First. With one hole.
When you put a straight edge on the brackets, clamp the
forward mount in position. Plump bob down to make sure it's plump.
Final drill all holes when plump and straight on the aft edge.
Use the measurements given on the plan to locate the bottom of stab.

V/M Mounting...

guys excellent response, ok Nate on your picture you show VS 702 in front of the attach plate 981, I also had it that way... Looking again at the drawing Bruce is correct 981 is in front of 702. Also what is the purpose of view A_A glueing the washer on the left aft side elevator stop 912D....?? Is it for P-Factor balance? Mark C.

Mark C. said:

guys excellent response, ok Nate on your picture you show VS 702 in front of the attach plate 981, I also had it that way... Looking again at the drawing Bruce is correct 981 is in front of 702. Also what is the purpose of view A_A glueing the washer on the left aft side elevator stop 912D....?? Is it for P-Factor balance? Mark C.

Click to expand...

Mark,

[EDIT: VS 702 and 981 orientation is correction: See Next Post]

The purpose of the washer is to eliminate twist in the rear spar and doubler due to the offset in the 981 bracket...

Actually, you guys had me worried, so I had to go look.

The attachment plate does sit behind the VS front spar, so the image I posted is correct.

Nate, thanks in re-reading the work book either in front or back is ok depending how it interfaces with the 981 bracket. As with yours having 981 behind 702 seems to work best for me.. Whats killing me is the directions talk about measuring from the top of the VS to the end tips of the horz. stab. and I cant get it better than 1/8" tolerence for true verticle off the horz. stab. Thoughts? Thanks for the feed back.. I know when completed one hard landing and I'll be an 1/8" off everywhere.. Mark C.