Spectra leadouts

[Ara Dedekian]

      Started a 1/2A stunter and will make the leadouts out of 100# Spectra. Pulled the setup shown to 25 pounds(+), the limit of my fishscale. The easiest setup I've ever done stringing up leadouts. The idea was to save weight in ways other than messing with the structure. It's an equal span wing so I'm attempting to compensate with Spectra leadouts,flying lines and RC nylon links for a lighter inboard panel.

     Ara

[Robert Zambelli]

VERY CLEVER!!!    
Neat and light.

Bob Z.

[Ara Dedekian]

Thanks Bob. Now let's see if it works.

Ara

[Pat Chewning]

Yes very clever.  But I'm not sure I'd trust that thin little nylon pin in the clevis to hold my airplane to the flying lines. 

[Ara Dedekian]

Yes very clever.  But I'm not sure I'd trust that thin little nylon pin in the clevis to hold my airplane to the flying lines.

      Pat

        I considered that too, but this setup is for a 1/2A stunter. Also, these nylon clevises connect the upper and lower ailerons on a 68" RC biplane I have. Not my idea since I didn't build it, but they hold. I haven't seen any signs of wear.

     Ara

[Steve Helmick]

It wouldn't take much to slice off the pin and drill holes for a metal pin or screw of some sort. Perhaps a 1/16" rivet with a dab of JB Weld on the ends to retain it would work.

I think the bellcrank itself is the place I would look to reduce weight, because there's a lot of metal in that one. We had somebody up here using wooden bellcranks, but I can't recall who it was. Maybe Rich Porter? I think I'd be happy with a 3" TF/Brodak nylon bellcrank. Basically, my philosophy is that the control system is a place where strong, solid and smooth are THE most critical things in the airplane. You want the biggest bellcrank you can fit in the wing on a 1/2a plane.

FWIW, fishermen generally say that "braid" (i.e., Spectra) is not very good with abrasion.  I have not had a problem with it in that regard, and I fish quite a bit with braid from 15 lb test to 40 lb test. I would avoid wear points as much as possible in your application.    Steve

[L0U CRANE]

Ara, nice...!

I don't see how the Spectra is attached in the clevis... I wouldn't trust a bulky knot, alone. (Agreed, for 1/2A the clevis pin should not be a strength problem.)

On metal bellcranks, I'd accept the few grams "extra weight" to gaining a more familiar 'feel' with a, say, 3" bellcrank's dimensions and matching control horns.

Luck!

[phil c]

Clever solution Ara.  I'd suggest pull testing a couple of  the couplers to destruction.  Even if you don't have a big scale I think you can make a pretty good estimate if it will take say 50 lbs before breaking.
Make sure the holes in the bellcrank are polished smooth with slightly rounded edges.  I think the metal is more likely to wear the pin than a halfA stunter is likely to break it.

[Dane Martin]

It wouldn't take much to slice off the pin and drill holes for a metal pin or screw of some sort. Perhaps a 1/16" rivet with a dab of JB Weld on the ends to retain it would work.

I have done this with great success on an electric RC delta wing. The little metal pin is captured by both sides, so it's very strong.

[bob whitney]

Du Bro makes almost the same piece ,a little heavier with a removable pin in it.