Here’s the cutout on the HS spar lower flange. The plans don’t call out any specific dimensions, so I cut the flange to accomodate the elevator control horns with a 1/8″ clearance on both outboard sides. The flanges were trimmed forward until they were just about flush with the spar stiffeners.
With this cutout, elevator down-travel more than meets Vans’ requirements. Next step…drilling elevator control horns to the HS center bearing.
The plans are kinda sketchy on how to check elevator fitment on the HS. After some web surfing and questioning other builders, I came to the conclusion that the elevators seem to be fitting ok. The elevator counterweight arms are parallel to the HS skins, and there doesn’t appear to be any binding – yet. With the counterweight arms clamped to the HS, the elevators also appear to be aligned in trail. The control horns don’t quite line up with each other, but from what I can determine from VAFWWW and the Matronics list, they don’t have to.
After the HS skins were trimmed sufficiently to allow the elevators to swing freely, I used a digital level to check elevator range of motion. Looks like the elevators have a few degrees’ margin of up-travel before they contact the HS skins, and according to Van’s there is no minimum spacing requirement between the elevator skins and HS. So as long as they swing freely, I think I’m good to go. If you’re reading this and know something different, please don’t hesitate to email me!
The next step is to trim some HS flange material away to allow the elevator control arms to reach maximum down-travel. I debated doing this before riveting the HS spar together, and now wish that I had. Some substantial care will now be required to avoid damaging the spar stiffeners.
Ellen and I dusted off the horizontal stab and temporarily mounted the elevators. The rod end bearings in both elevators required some tweaking to get their centers 13/16″ from the elevator spar webs, but that turned out to be no problem. As noted in the plans, some HS skin trimming is required to get the elevator counterweight arms to swing freely.
And after inserting the rod-end bearings, the left elevator is complete.
Ahh…my favorite part of control surface building – rolling the leading edges. I used the same procedure described earlier on this page, plus some liberal application of hand-tweaking to make the overlap as smooth as possible. This one came out better than the other side, I think.
My disease seems to have abated somewhat, so I spent some time downstairs and riveted the trim tab hinge to both the tab itself and the left elevator. The pneumatic squeezer is the weapon of choice for setting these rivets, but I had some problems getting the flush set to fit between the spar web and some of the hinge eyes. If the flush set is too far forward it can push on and bend hinge eyes, not a good thing. And surfing through the Van’s Air Force forum, I found others had the same problem. My solution was to take a spare flush set and grind it down a bit to reduce its radius. Worked great!
Here’s the trim tab, essentially complete.
The riblets came out fine, I think.
Over the weekend, Ellen and I got the trim tab fitted to the elevator and the hinge drilled. After some primer touchup, everything was ready for final riveting. At least that was the plan. I came down with some bizarre stomach bug and didn’t accomplish much. I did manage to get the elevator trim cutout riblet blind-riveted…
Got the trim tab parts primed earlier this week, then riveted the skin to the spar’s bottom flange. A longeron yoke on the squeezer works great for this.
The first attempt at fitting the trim tab to the left elevator…
The last few days were spent on prepping trim tab parts for priming – deburring, dimpling, countersinking, scuffing and alodining. No pictures, but it’s nothing you haven’t seen before.
When countersinking the TT spar upper flange, I match-drilled it to a piece of rectangular pine moulding before applying the countersink. The match-drilled pilot holes keep the countersink pilot centered, thus preventing the countersink from chattering and chewing up the hole.
Another trip during the last week, so only a few things accomplished. First, the new trim tab skin came in. Folding the inboard tabs went a lot easier this time.
Next, I removed the outboard tabs and forged ahead with making another riblet to fit inside the trim tab’s outboard end. Came out pretty well, I think.
The trim tab riblet in place. Until we have the money for a wing kit, there’s plenty of time to fuss over small details like this – so why not?