Empennage final attach

[Paul Eastham]

Hey guys,
The manual talks repeatedly about temporarily installing the HS, VS, elevators, rudder, and pushrods, but I didn't notice any place where it says to do the final install.

What should I look out for before putting all the bolts and nuts on? The only thing I've thought of so far is to get all the wiring runs squared away for the strobe and trim. I also plan to put the VS and rudder tips on first since I'll need a ladder to put them on once attached to the airplane.

Thanks,
Paul

[Capflyer]

I finished attaching my empanage 2 weeks ago and had the same question. As I looked through the instructions, no where could I find when to do the final install so when everything was drilled and cleaned up and wires run, on it went for it's final tightening. I would recomend attaching the control rod last though so you can get your hands in the area where the elevator control horns are. Also, on my RV7A the rudder bottom fairing needed some considerable trimming to match up with the fuselage so wait putting the fairing on until all else is installed.

[pierre smith]

Hi Paul,
We have a 6A but the same things apply. Be sure to have a disconnect for the tail strobe/nav light before you cap the rudder with tips. Be sure to have a positive ground wire that is screwed (not pop-riveted) to the airframe or you'll be chasing non-working lights occasionally.

I'm assuming that the 9A manual also spells out how to align the stab by measuring from the tips to the center of the fuselage near the cabin, before drilling the attachment holes. The fin may or may not be perfectly vertical if you don't level the airplane left to right before drilling those holes either.

The final attach decision is yours. The empennage gets in the way while you're fitting the canopy so it's better to leave it off until after the wings are fitted and bolted, although it can be attached for good, unless you plan to paint it before flight. (We flew ours for six months, then painted it). If there are shims under tha stab spar, mark and save them showing whether they go on the left or right side, then tie-wrap them to the stab for later use.

By the way, be sure your trim tab moves in the CORRECT direction after it's wired: UP tab means DOWN elevator and vise-versa (quite a few have been wired backwards!). Wrap the tail feathers in a blanket until you're ready for the DAR and mount them. You decide whether the wings or the tail get mounted first.

[alpinelakespilot2000]

Originally Posted by pierre smith

I'm assuming that the 9A manual also spells out how to align the stab by measuring from the tips to the center of the fuselage near the cabin, before drilling the attachment holes. The fin may or may not be perfectly vertical if you don't level the airplane left to right before drilling those holes either.

Just because I've just gone through this, I'm interested in the different ways the -9 manual says to do it, Pierre. They do seem to be pretty close to the -6, but a little different...
1. The manual says to measure from HS tips to the forward corners of the firewall, not the center, although the center would work just as well, of course.
2. Interestingly, nothing in the manaul says to have the fuselage level when you put the HS on. I guess it is assuming that you built your HS accurately, and that the aft deck is already twist free relative to the rest of the fuselage. (Maybe this was harder to do with the non-punched 6). For the -9, you just sit the HS onto the aft deck (on the 1/8" shims) and put a 11/32 drill bit under the rear spar to set the 0-degree incidence. At this point, the HS should be level relative to the fuselage. Mine did down to the 0.0 degree--Van's kit is amazing in this regard! Like you said, though, I think it is a good idea, to make sure your HS is level relative to the rest of the fuselage. My fuse. wasn't level during this process, but I made sure a digital level read the same on the firewall, seat back bulkhead, aft deck, and on the forward spar of the HS.
3. Re: the vertical stabilizer, once the HS is on, we just measure from the top down to the outboard edges of the HS. This will square the VS to the HS. Although Van's doesn't mention where to measure this, it really does have to be from the top at the rear spar since the leading edge of the VS is offset to the left (about 7/16, it seems). Assuming that you've set your HS level relative to the fuse., again the fuse. itself does not have to be level to make this measurement.

Again, just interesting to note the differences in the manuals for the various models. I wish Van's had been better about the empennage attach part (especially the VS) in the manual, but I figured it out in the end after looking a lot of builders' websites.

Regarding leaving them on, Paul. I'd love to because they really look neat up there, but I think it probably depends on your building space and whether or not you want to have to duck around or under them for the rest of the build. Mine will probably be coming off in the next few days after I get the rudder stops finished.