Elevator tab bending

Okay, mostly I just want to vent right now. @#$% tabs on the left elevator skin!

I did the wood block thing and I thought it turned out "okay" - not cosmetically great, but acceptable. Then I looked at it closely and saw the big (5/8") crack in the top side, right at the trailing edge. It seems the length of the little flaps you bend to close out the skin in the trim tab area was too long - I trimmed them up some, but apparently not enough - and the bottom tab dug into the top skin, the pressure of which caused it to crack as I was going over it with the rivet set to flatten out the bend.

The crack is too big to live with, and I don't want to have cracks in my airplane anyway. It's also too deep into the skin to just cut it off and replace, so now I am drilling out the rivets that hold the elevator stiffeners and other stuff to the skin, and I'll order a new skin from Van's tomorrow. Sixty bucks plus shipping, ouch.

This next time around, I'm going to be smart and ignore the instructions - my new plan is to use the hand seamer to make the elevator tab bends first thing, before I complete the trailing edge bend. Or, maybe I'll fabricate a little rib to put in there instead. At least I'll have plenty of scrap aluminum available to use!

I think I'll also do the trim tab the same way, because this wood block and folded tab stuff is completely lame. I wonder why Van's doesn't just offer a little rib to put in there... I know from searching various list archives that I'm not the only one to have trouble in this area. Yet another aspect of this airplane project that makes no sense, I guess. It seems like the times when I've gotten into the most trouble with the empennage so far is when I've done exactly what the plans say and in the prescribed order, instead of throwing them out and using my head instead. I wonder how many fuselages I'll have to build before I get it right? Grr.

Okay, rant over - thanks for listening...

mcb
RV-7 emp
QB wings & fuse scheduled for October
http://www.rv7blog.com

make a little rib

Let me see if I can save you 60 bucks. Just make a little rib. If that's the worst thing that happens to you during the building process, you'll have a showplane for sure! Put the little rib on, and if you really still don't like it a year or two from now, you'll have plenty of time to change it.

I know that whatever it is that you are working on always seems like the most important part of the aircraft, and if it's not perfect it will ruin your impression of the entire project, but take the advice you get from Van's all the time:

"Build on".

I agree with Mickey. I did the same thing. After building a new end rib with a little fiberglass & filler, it doesn't show at all.


derrell
7aA
(Still fighting the canopy)

Update

Thanks for the advice, guys. I went ahead and drilled all the stiffeners and so forth off of the skin, and I'll order a new one tomorrow. I'm probably too picky, but I'd rather spend the money and do it right the second time. I did go ahead and bend the tabs on the trim tab skin before completing the trailing edge bend, and they turned out great. That's definitely the way to go for the elevator skin, and I have no idea why the plans have you mess around with the wood block thing when there's a much easier way.

cheers,
mcb
http://www.rv7blog.com

I made a closeout rib

I tried it by the plans, hated the results, and ended up making a little end rib. Took about 15 minutes.

Don't Pre-bend

MBurch,

Just in case someone picks up on your idea to bend the tabs before squeezing the elevator skin shut (or the trim tab, for that matter) - that presents a difficulty. If the tabs are bent, they prevent closing the skins enough to account for springback. The result could be a very bulgy trailing edge. Not good.

Making ribs is probably the least skill-intensive solution, but Lions, and Tigers, and BEARS!, this means more blind rivets in the trailing edge!

John Siebold

Argh - you are right. Well, end ribs it is then.

thanks,
mcb

Elevator tabs

RV7ator said:

MBurch,

Just in case someone picks up on your idea to bend the tabs before squeezing the elevator skin shut (or the trim tab, for that matter) - that presents a difficulty. If the tabs are bent, they prevent closing the skins enough to account for springback. The result could be a very bulgy trailing edge. Not good.

Making ribs is probably the least skill-intensive solution, but Lions, and Tigers, and BEARS!, this means more blind rivets in the trailing edge!

John Siebold

Click to expand...

You can still bend the TE skin with the tabs bent. I bent the elevator tabs per the instructions (bad idea). I bent the Trim tab tabs before bending the TE with much better results - and no problems getting the TE bent. I definitely recommend bending the tabs on both skins before bending the TE.
I ended up locally squeezing the TE by putting pieces of angle just forward of the TE bend and squeezing them with a pair of pliers to get the flatness correct. My wooden brake never got the flatness right.
If you end up putting in a little rib you can use a bit of filler on the pop rivets and no one will ever see them. I saw lots of them at OSH (I had just finished my elevators so I looked at every RV elevator I could

Dennis Glaeser
7A Wings

Follow-up

Hi folks,

Thought I'd post a follow-up here in case somebody runs across this thread while searching. I ended up buying a new skin, cutting off the bendy-tabs, and fabricating a little rib, as others had suggested. It turned out so good I may go ahead and do the same thing on the trim tab.



cheers,
mcb
RV-7 emp almost done, QB wings/fuse arriving next month

mcb,

thanks for posting that pic! it's exactly what i was looking for, and i knew where to go to find it...VAF.net, or course!! i tried bending my elevator tabs tonight, and i hate how it looks. i'll be fabricating a rib tomorrow to fit in there.

great resource, this site...yet again!!

elevator trim tab bending

(apparently) like many others, i screwed up the elevator trim tab bending. mine was probably airworthy, but cosmetically, ahem, unappealing. so i ordered a new skin and rib (about $22, iirc.) by the time it came, i was well into the wings, so i put the trim tab aside and continued working on the wings.

when i had pretty much finished the wings, and was waiting on the fuse kit, i went back to tie up a few loose ends, and then tackled the trim tab again. it was amazing how much of a non-event it was. worked fine, and looks pretty darn good, if i do say so myself. my guess is the additional experience of working with aluminum, even though not directly related to the task of "tab bending" helped me out.

so, if you don't like the looks of yours, my advice would be to give it some time before you re-do it.

john

So, mburch am I understanding you correctly that since you put the rib flanges facing inboard that you ended up using fiberglass to fill the hollow end?

Lance

tabs

This was a problem for me as well. I have made forms for ribs that replace the tabs. The forms were made on my mill. If anyone is interested they are $20.00 shipped for three ribs. One for the elevator and two for the trim tab. Sorry for the shameless plug in this forum, but it seemed pertainant.

[email protected]

Dave

Dancer said:

So, mburch am I understanding you correctly that since you put the rib flanges facing inboard that you ended up using fiberglass to fill the hollow end?

Click to expand...

Actually I bent the flaps on the trim tab per the plans. The only place I used a riblet instead of bending the flaps was on the cut-out part of the elevator. I'm currently planning just to leave it as-is... I don't think it looks too bad at all!

mcb

Just went there.

I just went through this same process. Another riblet for '07. Like somebody else said, bending these tabs before the stiffeners go on is a GOOD idea.

BTW, what's the favored procedure for fabricating the bending blocks? I don't have a table saw, sliding compound miter saw, or anything else I can imagine would cut a straight line in a piece of wood big enough to make the angled one.

Me too

Count me in for the 07' riblet parade. My elevator tabs went great, but the trim tab tabs were another issues. I screwed with them to the point I cracked the skin and said enough is enough. I recieved my wings, so I shifted gears and started on those and I'll order my replacement trim tab and do the riblet thing with I order my landing lights and pro-seal from Vans sometime in the near future.
Also if you are lazy like me, someone on here said that the tail end of a couple of E-709s works great for a riblet, just cut off the ends and instant riblets.