VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Model Specific > RV-7/7A
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-14-2017, 12:12 AM
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 73
Default Elevator/trim tab riblets: Fabricate or chop up Vans parts?

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.
Reply With Quote
  #2  
Old 02-14-2017, 12:22 AM
CubedRoot's Avatar
CubedRoot CubedRoot is offline
 
Join Date: Sep 2013
Location: Ooltewah, TN.
Posts: 434
Default

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.
__________________
Lynn Dixon
RV-7 Slider -
Tail kit Completed - March 2017
Wing Kit Started - June 2017
My Build Log: http://www.theskunkwerx.com

VAF Donation paid for 2017
Reply With Quote
  #3  
Old 02-14-2017, 10:25 AM
wjb's Avatar
wjb wjb is offline
 
Join Date: Nov 2012
Location: Half Moon Bay, CA
Posts: 669
Default

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/displa...=165209&row=27



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... ;-)
__________________
Bill Bencze
N430WB (reserved) RV-7 #74152, tip-up. Avionics and FF underway!
Log at: http://rv7.wbencze.com
Defeating gravity one rivet at a time
VAF 2017 donation happily made

Last edited by wjb : 02-14-2017 at 10:38 AM.
Reply With Quote
  #4  
Old 02-15-2017, 08:33 PM
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 73
Default

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.
Reply With Quote
  #5  
Old 02-15-2017, 09:29 PM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 2,709
Default 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.
__________________
Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/01/2016. Plus a little extra.
RV-7A #73391, N511RV reserved (1,800+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
Reply With Quote
  #6  
Old 02-17-2017, 12:55 PM
longranger's Avatar
longranger longranger is offline
 
Join Date: Mar 2007
Location: 45G, Brighton, MI
Posts: 1,720
Default

Quote:
Originally Posted by Draker View Post
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.
__________________
Miles (VAF# 1238, Paid up as of 12/2016)
RV-7 TU 904KM (reserved)
Wings Structurally Complete!!
SB Fuselage Just Past QB Stage


Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album


1955 Cessna 170B flying since 1982


'To get something you never had, you have to do something you never did.' -Unk.
Reply With Quote
  #7  
Old 02-18-2017, 11:21 PM
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 73
Default

Quote:
Originally Posted by longranger View Post
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!
Reply With Quote
  #8  
Old 02-19-2017, 08:09 PM
truflite truflite is offline
 
Join Date: Aug 2005
Posts: 120
Default

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.
__________________
David Nellis
7A slider finishing kit
2015 VAF dues paid
Reply With Quote
  #9  
Old 02-19-2017, 10:09 PM
Draker Draker is offline
 
Join Date: Jun 2016
Location: Livermore, CA
Posts: 73
Default

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.







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:



Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 11:36 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.