Elev Trim Tab...best method?

s10sakota · Post by **s10sakota** » Wed Jan 18, 2012 4:39 pm

I thought I would ask this question now because this process is coming up soon for me.

What's everyone's opinion on the making the elevator trim tab? Do it like the manual says, or cut off the tabs and make riblets?

From the builders logs I've seen, it seems like bending the tabs and making the trim tab straight and 'bulge free' is nearly impossible. It seems like a lot of people resort to cutting the tabs and making small ribs.

Should I save myself the aggravation and cost of new parts and just cut the tabs and make the ribs right away?

Has anyone actually made a nice trim tab by bending over the tabs??

hydroguy2 · Post by **hydroguy2** » Wed Jan 18, 2012 5:13 pm

I bent mine, turned out fine. I figured if the bending didn't work I could still make riblets and trim the bad bends off. I built a samll wood block to use as a backer for forming the bends. Go slow and careful not to crack it.

newtech · Post by **newtech** » Wed Jan 18, 2012 9:42 pm

I didnt even try the tabs, went straight to ribs. Turned out great.

bruceh · Post by **bruceh** » Wed Jan 18, 2012 10:20 pm

I made some wooden wedges to hold things together while the bends are done. Worked great. It helped to practice on some scrap first. Use some hardwood to get the bend started, then use a hammer to tap the block of wood against the bend to get the seam nice and crisp.

Post by **bullojm1** » Thu Jan 19, 2012 8:10 am

I went through 2-3 trim tab skins trying to get it bent perfectly. I eventually just broke down and made the riblet. Used some flush blind rivets to hold it in and it works great.

Post by **Spike** » Thu Jan 19, 2012 8:33 am

I bent the tabs and it came out great. I used a magnetic brake and was very happy with the result.

John

BSwayze · Post by **BSwayze** » Wed Feb 01, 2012 2:32 am

The trim tab seems to be one of those things that frustrate a lot of builders. But I bent mine, just like the plans call for, and they came out great. It was my first and only attempt, too. I'm not bragging, I'm just saying that if you take your time and follow the suggestions of others here you will do fine. And if not, cut them off and make ribs. Either way, you end up with a functional trim tab.

s10sakota · Post by **s10sakota** » Fri Mar 23, 2012 5:38 pm

I haven't touched the RV project in about 6 weeks. I've been stuck on rolling the leading edges. I need an extra set of hands and everytime there's an EAA meeting in which I could take the elevators for help, I'm at work.

The other part that's been holding me up is bending the tabs on the left elevator. I made a set of wooden blocks, used double sided tape to hold the blocks, And tried to bend the tab. It looked like crap. Plus, even though I trimmed the tabs, they were still too long. So, add me to the list of people that ended up cutting the damn things off.

The problem is that I had to cut on the inside of the bend and it looks like I cut too much off...

Here's a pic of the elevator and the trim tab held in place. The gap I have is about 3/16".

It's going to look stupid, but you know what, the plane won't fall out of the air and I'd rather have a flying RV than a project that is never going to get finished because I suck at building

Jimzap · Post by **Jimzap** » Sat Mar 24, 2012 10:57 am

I finished my trim tab this week. And, yes it was very stressful. I screwed up the first one and ended up buying a replacement skin.
The most important component for the bend, I think, is the form block. It must have crisp edges and be clamped in tight (make sure you don't crimp the skin anywhere else when you clamp it in positon). I also, per another builders advice, riveted the control horns after the bend, not before.
Not sure how to upload a photo but let see if this works.

[img]http://i978.photobucket.com/albums/ae26 ... G_0879.jpg

[/img]http://i978.photobucket.com/albums/ae26 ... G_0878.jpg

Jimzap · Post by **Jimzap** » Sat Mar 24, 2012 11:01 am

Maybe this will work.

s10sakota · Post by **s10sakota** » Sat Mar 24, 2012 5:14 pm

Wow your trim tab looks perfect! You mentioned that the edges of the wood blocks need to be sharp. Yes I learned this the hard way.

I thought I was being all cool and stuff by sanding a very slight curve to the block to give the aluminum a radius. There are minimum bend radiuses right?

Whatever! That's what made mine come out so poorly. It wasn't a nice sharp bend like yours. Your pics will help when I do my trim tab.

But I did fix my elevator today. In fact, just getting my wing kit on Friday has re-modivated me on this project. I moved my workbench from the basement to the garage today and set up a nice shop.

Once set up, I made the rib that will close off the elevator opening. I had to made two of them to get it right, but this will look nice.

Here's a pic here...

http://www.aircraftstickers.com/RV7A/24mar12.htm

RivetBangers.com

Elev Trim Tab...best method?

Elev Trim Tab...best method?

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