What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Elevator/trim tab riblets: Fabricate or chop up Vans parts?

Draker

Well Known Member
After searching and reading the pros and cons here, I'm strongly leaning towards just going with the "riblet" method from the start rather than horsing around with warping and cracking the elevator skin and trim tab. For those who have gone the riblet way, there seem to be two schools: 1. make your own, or 2. order similar parts from vans and cut them down to size. For $30+shipping I can get 2 E-703 end ribs and a E-709 root rib, and that would appear to cover both the trim tab and elevator. Are there any pitfalls with doing it this way and should I consider forming my own riblets?

Also, when installing, I've seen setups with riblets that faced inwards (and thus allowing you to use solid rivets to attach, and ones where the riblets faced outwards needing pop rivets. Is there a reason besides cosmetics you'd pick one over the other?

I don't want to start a riblet-vs-bend war... looking for opinions from those who have chosen to go the riblet way.
 
I'll be very close to doing the left elevator in a few weeks, and I have been waffling back and forth on doing a riblet, because I don't want to ruin the elevator skin that I have so much work into at this point (stiffeners, primer, edge finishing, etc).

I bought an extra trim tab, so I will probably bend it, but I am thinking about doing a riblet in the elevator itself.

I'm interested to see what others recommend, as I might end up going that route.
 
This is from my log, circa 2012:

OK ... it's time to bend the trim tab and elevator skins. After lots of research on VAF and other places, I decided to go with the "riblet" method. The reasons are these:

1) I don't want to ruin my elevator skin .. seems like Murphy lives here if anywhere.

2) Before bending, I'd do quite a bit of practice, which would take some time, and still not guarantee success.

3) Building the form blocks would take time, and still not guarantee success.

4) Using the time, I can make riblet form blocks, practice all I want and not screw up a skin.

Making the riblet seems like the lowest risk option and not take any more time than it would if I did it the original way... So, riblets it is!

The aviation isle of Home Depot had a nice poplar plank that I used for the block. Made a cardboard template of the rib on the right elevator, transferred it to the block, screwed it down and cut with a compound miter box. A table saw would have been better, but no got one of those. I gave the edge of the bloc a 5 deg bevel to handle springback.

I made two block and clamped them together to do the deed. Worked great the first time out of the gate


Photos and more details here:

http://www.mykitlog.com/users/displ...&project=2206&category=8511&log=165209&row=27

FP03032013A0004B.jpg


However, now that I'm on the finishing kit, with lots more hours of experience under the belt, I'd easily make the bend without thinking about it ... It's a matter of experience working with the metal and knowing how it will react to your "persuasions"

Looking back, though, it was a good learning experience and the end product came out great, but probably added 3-4 hours to the build. No regrets!

And, Murphy actually lives in the canopy... ;-)
 
Last edited:
Thanks, Bill.. I saw those pictures. Which are which? Maybe I'm not visualizing the elevator and trim tab right (they're not in front of me) but I would think you'd have two identical riblets for each side of the trim tab and one longer one for the elevator, all with the same angle. Which of the right elevator's ribs did you use as your guide? Looks like you tried different thicknesses, what did you end up going with?

Looks like these are pretty simple to make and I don't need to order/cut Vans parts to do this job.
 
Bend 'em

I made the blocks from walnut. Basically traced the rib and cut the block in two then radius the bend edge.
The rib block goes inside. The scrap block goes on top.
Put double side tape on every surface. Clamp everything to the bench.
Place additional blocks clamped to the bench so neither block can slide out either way.
Use a block and hammer to fold the tab over and the flush set and gun on low pressure to finish the form.
Sounds harder than it was.
 
Thanks, Bill.. I saw those pictures. Which are which? Maybe I'm not visualizing the elevator and trim tab right (they're not in front of me) but I would think you'd have two identical riblets for each side of the trim tab and one longer one for the elevator, all with the same angle. Which of the right elevator's ribs did you use as your guide? Looks like you tried different thicknesses, what did you end up going with?

Looks like these are pretty simple to make and I don't need to order/cut Vans parts to do this job.

They would be fairly easy to fabricate, but they aren't the same angle. The inboard and outboard ends of the trim tab aren't parallel, plus the tab tapers slightly in thickness in the spanwise direction. A quick measurement of mine with a protractor shows the inboard angle to be about 6-7 degrees and the outboard shows more than 10.
 
They would be fairly easy to fabricate, but they aren't the same angle. The inboard and outboard ends of the trim tab aren't parallel, plus the tab tapers slightly in thickness in the spanwise direction. A quick measurement of mine with a protractor shows the inboard angle to be about 6-7 degrees and the outboard shows more than 10.

Yes, just measured them and verified this is true. Thanks for everyone's input. Just cut some oak wedges and I'm planning to cook some tasty riblets tomorrow! :D
 
I made hardwood blocks milled to the correct angles. There are different angles between these two ribs. I sold a couple sets without complaint so they must have worked for the others.
 
So far so good. If I'm careful I might just join the One-Trimtab club. Glad I did it. All three of them were slightly different.

IMG_1048-M.jpg


IMG_1049-M.jpg


IMG_1045-M.jpg


No idea how I'm gonna set a few of those extremely tight fit rivets, but I'll cross that bridge when I get to it. Trim tab fit looks OK so far too:

IMG_1050-M.jpg


:D
 
Back
Top