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  #1  
Old 05-30-2018, 07:32 AM
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Strikefinder Strikefinder is offline
 
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Default Elevator Trim Tab Fold -- Acceptable?

Hey all,

I'm working on the LH elevator and trim tab and have gotten the bends on the elevator itself and the outboard tab pretty well done, but the inboard tab has turned out somewhat "less perfect". That said, I'm not certain that another go at it will necessarily produce a much better outcome, and considering that it will be covered in paint and such, my gut is to just build on. That said, I thought I'd ask your collective opinions before doing so:







The trailing edge isn't very pretty, I know, but otherwise the tabs seem to come together fairly nicely (when cleco'ed to the spar, the come together even better).

{Also: I'm familiar with the "riblet" method...not looking to change gears at this point, just determine if I should live with what I've got...}
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  #2  
Old 05-30-2018, 07:47 AM
NavyS3BNFO NavyS3BNFO is offline
 
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Default Build on!

Looks good to me.
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  #3  
Old 05-30-2018, 08:18 AM
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It will fly, but what I would not accept are the poor edge finishes and an obvious crack in the trailing edge radius.
The empennage is your practical practice piece. You can learn quality and carry that level through your build.
I would swallow hard and do this again, perhaps with some guidance from an experienced builder. That tab can be tricky but shouldn’t show hammer marks when done although it doesn’t affect air worthiness.
Edges should not show mill marks.
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Last edited by JonJay : 05-30-2018 at 08:20 AM.
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Old 05-30-2018, 08:54 AM
David Paule David Paule is offline
 
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Your next one will be considerably better.

You can avoid the hammer marks by using a wooden block to spread the load.

What I did for the end rib folds was use a 3" metal hand seamer, like this one. It didn't do the bend at the trailing edge well, for that I tapped it locally with a hammer against a block of wood.

The trailing edge can be bent by using the tool that Van's recommended in my RV-3B plans. I don't seem to have a picture of it, but it's two 2x6s, straight, next to each other held together with door hinges. Think of it as an open book, with the hinges located farther apart than the width of the trim tab, so they don't interfere. You simply place the trailing edge in the fold and press the pieces together. Be careful to bend it evenly (it can cause local unevenness) and not to go too far. If you go too far, I've been able to open it up a bit by pressing a dowel in there and unbending it as needed.

With both the wooden tool and the dowel, the key is to work slowly and carefully.

If you don't mind a further comment, you should clean up all the edges. What's shown are not as smooth as you'd like and might well lead to cracks later.

Incidentally, for me, it was the fifth one that will fly. The first four were scrap.

Dave
RV-3B, skinning the fuselage
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  #5  
Old 05-30-2018, 09:34 AM
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Strikefinder Strikefinder is offline
 
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It seems like my unease was justified. I'll put in an order for another two (they're cheaper than the shipping, after all) and give it another go--or two.

I hadn't cleaned up all the edges yet and was probably too eager to try the bends to have done enough job even on those parts...I sort of figured based on everything that I read that I wasn't going to get it right the first time, so I almost mindlessly jumped in figuring it would end up as a learning piece of scrap. But the other side came out so well I felt like I wanted to "make it work". Fortunately, other than time lost in shipping, this isn't a big cost or time in rework to get back to where I was.

The edge bend was done with the 2x6s, but it wasn't quite enough in one spot, so I tried making a small adjustment using a pair of pliers, which led to the roughed up and dimpled end.
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Old 05-30-2018, 09:55 AM
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Mark Dickens Mark Dickens is offline
 
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Quote:
Originally Posted by Strikefinder View Post
I'll put in an order for another two (they're cheaper than the shipping, after all) and give it another go--or two.
It took three tries for me....don't feel bad! You're just getting started on buying replacement parts from Vans
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Old 05-30-2018, 10:12 AM
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Don’t be afraid to “relieve” the corners at the trailing edge. You are doing two bends here that intersect: the trailing edge bend and the bend in the tab. That induces stress. This is a bit exaggerated but the corner is well relieved.
Keep swimming!
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Old 05-30-2018, 10:31 AM
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Quote:
Originally Posted by Mark Dickens View Post
It took three tries for me....don't feel bad! You're just getting started on buying replacement parts from Vans
If only that were the case.
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  #9  
Old 05-30-2018, 10:48 AM
David Paule David Paule is offline
 
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I should have added that for the tip flanges, I made a tapered block of hardwood and clamped that inside the trim tab for backup. I'd put a radius on the edges.

I reserve a large shelf in my garage attic for scrap. I felt bad about the amount that was going up there, until another local builder said that when he was done, he took his scrap to the dealer and got $136 for it.

I figure Van's breaks even on the kits and makes their money on our replacement parts.

Dave
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Old 05-30-2018, 11:39 AM
mturnerb mturnerb is offline
 
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If you're not on a first name basis with everyone in the order department at Vans, something is wrong....
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