throttle (yes, we're back to lower case letters)

So all I had left to do before I could put this throttle stuff to bed permanently was to figure out how to drill the cover plate for the outboard angle screw holes. I wasn’t quite sure how to do this, but it couldn’t be that bad after everything else, right? Oh, how I make myself laugh sometimes…

The perceived difficulty here was due to the need to cleco the angle in place on the forward side skin, and then figure out some way (in tight quarters) to clamp the cover plate to the angle and drill the holes from below. This promised to be an unpleasant experience, but then I had a sudden bright idea. What if, with the mid side skin still off, I clecoed the original cover plate in place, clecoed the angle to the plate, and then figured a way to clamp the angle in place using the center section bulkhead and gear tower? Then I could simply swap cover plates and drill my holes with ease. What a bright idea, I thought!

So I swapped out the cover plates. Uh-oh, this does not bode well:

IMG 6604

I can’t believe how far above the quadrant this plate sits. It doesn’t even make any sense to me – the quadrant mount holes were predrilled, so there’d be no way to mount this quadrant any higher so it would sit flush against the plate. But the bigger issue was that this implied that when clecoed in place on the side skin, the angle would be too high for my custom cover plate. Guess I’d better cleco the side skin on and verify the bad news.

Yep. Hard to tell from this blurry photo, but the angle sits something like 1/8’1/4” above the top of the quadrant. ARGH

IMG 6605

OK, so now what? I could make a new replacement angle, but with the rivet holes prepunched in the side skin, it might be impossible to move the angle far enough down. To test this idea, I cut up a piece of scrap hardware store angle I had lying around. I used a couple more pieces of scrap angle to create a jig to hold the test angle level with the top of the quadrant for test fitting:

IMG 6607

Next, I went to the outside of the skin and marked the rivet hole locations with a sharpie. After drilling a #40 hole in one of these locations, I was pleased to see that while the hole was close to the vertex of the angle, it seemed like there was enough room to set a rivet head in there. The only possible downside – if I was to make this piece out of actual angle – is that the good angle has a larger radius inside the vertex, which diminishes the available room for a shop head. Worse yet, when I clecoed the angle back in place using my test hole, I found that I’d drilled it a bit too low. Between needing to move the angle down a bit, and the larger radius of the angle stock, I don’t think that’s a viable option for this piece.

So tomorrow I guess I’ll see about forming my own angle piece out of sheet stock. I don’t think this piece needs to be particularly strong, so I may be able to mitigate the issues by using fairly light sheet stock, but I’ll just have to see how that goes. I’ll also throw this tale of woe up on VAF and see if I get any interesting ideas from other builders. Another possible solution – which I haven’t really thought through at all – could be to fabricate an angle piece that rivets directly to the center section bulkhead and gear tower flanges, instead of the side skin itself. Then I could just fill the side skin holes with rivets that attached to nothing – though I wonder if there’d be any concern of the skin flexing and rubbing against the angle mount.

I dunno. I’ll figure something out, as usual…

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