• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Fabing Piper(ish) Rudder / Elevator Ribs

Colorado-Cub

MEMBER
Buena Vista, CO
I remember (?) seeing some posts of the process of fab'ing the ribs for the elevator/rudder but can't seem to find them. (Olibuilt? Was that you?)

If not already obvious, I am curious from the experimental fabrication point of view, not a legality/morality/usefulness/"you will shoot your eye out" point of view.

Any links/tips/hints/etc would be greatly appreciated.


elevatorrib.PNG
 

Attachments

  • elevator.png
    elevator.png
    50.8 KB · Views: 730
  • elevatorrib.PNG
    elevatorrib.PNG
    32.4 KB · Views: 278
I think I would bend the slight edges. Then press a die made of Corian into a rubber sheet. Then slide it off die. You must back up the corian with something like hard wood or thick aluminum or it will crack

Other approach do edges slightly on bar folder. Then use press brake for the inner bends. Might have trouble on the small ends using this approach


Sent from my iPhone using SuperCub.Org
 
ever consider making them airfoil shape?

I was considering that for the horizontal stab ala Zenith and lesser so Bearhawk.

Building them straight seemed to be a bit of a challenge without tool dies for the brake, so I was going to start there then work towards an airfoil shape.
 
Thanks for the video links. I never considered attempting a rubber hydro-ish-form for this, but will go watch and learn!
 
I've done it on a regular finger brake. I didn't need any forming block or rubber mallet.

Started with the 2 edge bend, then the 2 90 degrees.
 
My bender won't make the 1/8" edge bend; too small to grab. If you do the edge bend first, how do you do the second bend without flattening the first bend?
Marty
 
My bender won't make the 1/8" edge bend; too small to grab. If you do the edge bend first, how do you do the second bend without flattening the first bend?
Marty
I remember using some bar stock between the finger and the part to bend so it wouldn't flatten the edge.

But it was easier to cut oversize so you could clamp down more for the edge bend, then trim down.

Sent from my SM-J320V using SuperCub.Org mobile app
 
Those ribes are pain to fab. I welded in 3/8 ×.035 in place of those ribes on the elevators and rudder. Powder coated then epoxied 1/2" hard balsa. Sanded to shape. Epoxie varnish, then cover. Been there 12 years and hasn't rotted away yet!. You are building experimental. Those plans are someone elses idea. Experiment!
 
Those ribes are pain to fab. I welded in 3/8 ×.035 in place of those ribes on the elevators and rudder. Powder coated then epoxied 1/2" hard balsa. Sanded to shape. Epoxie varnish, then cover. Been there 12 years and hasn't rotted away yet!. You are building experimental. Those plans are someone elses idea. Experiment!

I was considering taking some .020" 4130 tube, cutting a shallow V down the seam to allow me to make a very slight cone, then welding the seam and ends to the different sized main tubes. Besides being much easier to fab, it seemed like it would already be round so it doesn't cut into the fabric. I thought I was being all sorts of creative...

Are you saying you just welded in tube then used balsa to make the transitions smoother? Genius. Biplanes do that sort of thing all over the place so I should have thought of it myself!
 
I've done it on a regular finger brake. I didn't need any forming block or rubber mallet.

Started with the 2 edge bend, then the 2 90 degrees.

Those must be really narrow fingers on that brake to be able to do those bends??

You make everything look easy with the fab on your airplane, so I shouldn't be surprised you didn't have any trouble with this part. :)
 
If you have access to a regular bending brake making those Piper style elevator/rudder ribs is easy. The challenge is the narrow trailing edge area. When you bend them into a "C" channel the 3/8" trailing edge will deform on a standard leaf. No problem as you can reshape the 3/8" trailing edge part of the rib with some flat bill sheet metal seam pliers. If you use a standard brake then make sure the leaf is set back enough for a acceptable bend radius. I use 20 ga. mild steel for these. Easy to form and cheap enough to make mistakes with for a learning curve. No need to overthink this part, no elaborate tooling needed.
 
If you have access to a regular bending brake making those Piper style elevator/rudder ribs is easy. The challenge is the narrow trailing edge area. When you bend them into a "C" channel the 3/8" trailing edge will deform on a standard leaf. No problem as you can reshape the 3/8" trailing edge part of the rib with some flat bill sheet metal seam pliers. If you use a standard brake then make sure the leaf is set back enough for a acceptable bend radius. I use 20 ga. mild steel for these. Easy to form and cheap enough to make mistakes with for a learning curve. No need to overthink this part, no elaborate tooling needed.

Thanks, I appreciate the details.

I have a small bending brake, but not one wide enough to do these parts...
 
If you have access to a regular bending brake making those Piper style elevator/rudder ribs is easy. The challenge is the narrow trailing edge area. When you bend them into a "C" channel the 3/8" trailing edge will deform on a standard leaf. No problem as you can reshape the 3/8" trailing edge part of the rib with some flat bill sheet metal seam pliers. If you use a standard brake then make sure the leaf is set back enough for a acceptable bend radius. I use 20 ga. mild steel for these. Easy to form and cheap enough to make mistakes with for a learning curve. No need to overthink this part, no elaborate tooling needed.

That's what I was thinking. These were the first parts I made on my project some 2 years ago. I can't remember having any particular trouble. I used a basic bending brake and 20 ga. mild steel too. I think I messed up a couple pieces at first until I got the hang of it.

I do remember using 1/4 square stock to offset the fingers a few times to preserve the little oblique edge bend. You jogged my memory because I later just shaped them up using some seam pliers I had from an aluminum roofing job.
 
The easiest way I have seen, is to use two pieces of Piper "C" Channel per rib. You know, the the material the bird cage is made from. Notch the channel to fit the top and bottom at the leading edge. At the trailing edge, notch and and taper the channel sides to fit the smaller tube. Do not weld, but Braze the channel to the tubes. Fast, light and easy.
 
The easiest way I have seen, is to use two pieces of Piper "C" Channel per rib. You know, the the material the bird cage is made from. Notch the channel to fit the top and bottom at the leading edge. At the trailing edge, notch and and taper the channel sides to fit the smaller tube. Do not weld, but Braze the channel to the tubes. Fast, light and easy.
That is what I intend to use for my rudder and elevators. The C channel can overlap it's mate as an option to tapering the small end.
 
I don't dispute doing your way by any means. The downside is unless you get a smokin' deal on the tubing then 4130 tube in any diameter is 3 plus bucks a foot anymore. 20 ga mild steel sheet stock is much cheaper. Piper channel ain't cheap either.
Those ribes are pain to fab. I welded in 3/8 ×.035 in place of those ribes on the elevators and rudder. Powder coated then epoxied 1/2" hard balsa. Sanded to shape. Epoxie varnish, then cover. Been there 12 years and hasn't rotted away yet!. You are building experimental. Those plans are someone elses idea. Experiment!
 
Last edited:
Back
Top