What's a good method for attaching braided lead outs to an old-style, stamped aluminum bellcrank? They've been used for decades with success, we've all seen them, they're about 1mm in thickness, stamped out of aluminum with a ~1/4" brass bushing pivot.

I've got a few of them that I would like to place into service but every time I pick one up it seems woefully inadequate for the job, then I chicken out and use a Sig nylon BC. Won't the braided LO simply saw through the thin aluminum? Or, just as bad, could the aluminum fatigue the lead outs where they loop through the ends of the BC?

Here's what I did, not from experience mind you, but because I couldn't think of another solution. 1/32 ply was glued on both sides and an appropriate sized piece of brass tubing was pressed in for a bearing surface. The braided LO will be sheathed where it goes through the bellcrank similar to the way it's shown in the second pic.

Seems like WAY overkill. If you have a simpler and better way I'm all ears.

Thanks, Bill

I do not know how much flying you do, but I have NEVER had the problems that you are fearfull of. First you want to not make a large loop through the bellcrank. Pass the lead out through the crimping tube, then through the bellcrank, back through the tube, now bring the leadout back around the tube and through the tube again. Pull the tube tight to the bellcrank and pinch the crimping tube in two places. You will notice that there is VERY little sawing of the cable or even movement. You want to pull not move up and down.

Thanks Larry, I was over thinking it.

Go to http://www.mbsmodelsupply.com, get 4 Sig 3" nylon bellcranks for $3, and throw the old Veco, Fox, and Perfect bellcranks in the junk bin where they belong.

The Fox bellcranks are the hardest aluminum bellcranks out there, and the leadout and pushrod holes will still wear out very quickly. If you plan to get more than about 50 flights out of a plane, use better hardware.

Thanks for direct answer and link!

And welcome to the forum! Your info bar indicates you signed up back in 2006,
feeling a little guilty that my question caused you to break your silence.

Bill

Hathaand, thanks for the above link. I wish I had seen it last week. I just ordered a couple of BC from Tower H and spent a lot more. I’m building a Peace Maker and just need the BC installed so I can cover up the wing.

Bill, I still like your above idea, but I’ll take the simpler suggestion. When I was a kid I used flexible picture hanging wire for led outs thinking it was strong enough. It lasted about 5 minutes before breaking.
John

It is indeed true: Braided leadouts will saw through aluminum bellcranks.

"Back in the day" I had combat planes set up with braided leadouts and an aluminum bellcrank. Perhaps I would have a dozen flights on it.. and after a crash/mid-air you could see where the braided leadouts were already sawing through the aluminum bellcrank.

Originally Posted by LA Ming

It is indeed true: Braided leadouts will saw through aluminum bellcranks.

"Back in the day" I had combat planes set up with braided leadouts and an aluminum bellcrank. Perhaps I would have a dozen flights on it.. and after a crash/mid-air you could see where the braided leadouts were already sawing through the aluminum bellcrank.

Correct! At 120+ MPH there is a lot of force exerted on the lead outs/bellcrank. I found a nice Sig 3 inch nylon bellcrank eliminated wear and gave a wonderful, precise and silky smooth feel to the controls. I bushed with brass the eyelets. There may have been an improvement in the last 40 years, however. But I'll have to see/feel it to be convinced.

Thanks for your input guys. Just found this pic on Stuka Stunt, didn't say how many flight this plane had (this looks like an autopsy photo) but based on the experience of a couple members here it sometimes doesn't take long!

I have used hand made wooden bell cranks on up to 09 size airplanes. I make brass bushings for them after the first one I made sawed through the cable leadouts after a half dozen flights, I was amazed to see that.

Bill,

The method you used on the phenolic bellcrank should work on the Veco ones. I would STILL radius the aluminum a bit.

Those old bellcranks were OK for older engines up to ~.35, and today would handle up to a modern .15, but I would not use them for anything larger.

A lot depends on what you are flying and how many flights you expect to get out of that airplane. Also, modern thinking would say that a 3" bellcrank is minimal for many applications. That said, the SIG nylon you mentioned looks good and their 4" one should handle almost anything.

Another option is to use solid leadouts with the old aluminum bellcranks.

Of course these are only opinions, your choice.

George