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Building Tips and technical articles. => Building techniques => Topic started by: ChrisSarnowski on February 23, 2011, 02:15:50 PM

Title: What to do about metal bellcrank
Post by: ChrisSarnowski on February 23, 2011, 02:15:50 PM: I'm trying to rehab an old Shoestring for trainer use or maybe more.

It's got a metal bellcrank in good condition but the leadout cable is not bushed or anything. They're looped through the bellcrank holes 2x.

I can get at the bellcrank ends to replace the leadouts. Ideally I would remove the bellcrank and replace it with say a Sig 3" nylon, bush with copper tubing etc. It looks like much more trouble to remove the bellcrank though since the pivot bolt appears to be right under the wing spar.

Any suggestions / photos on redoing the bellcrank & leadouts to be more durable?

Thanks
Chris
Title: Re: What to do about metal bellcrank
Post by: Howard Rush on February 23, 2011, 03:00:48 PM: I'd dab a little grease on the joints and inspect it from time to time.
Title: Re: What to do about metal bellcrank
Post by: PJ Rowland on February 23, 2011, 06:06:38 PM: Im not sure if its under enough strain to worry about it breaking. Perhaps 4000 flights but will it get that many?

As Howard mentioned - grease it up inspect it from time to tim and go have fun.

( Great advice not just for planes either ) ~>
Title: Re: What to do about metal bellcrank
Post by: ChrisSarnowski on February 23, 2011, 07:02:56 PM: Thanks guys.

I believe it is a Goldberg Shoestring so it has a built-up wing. Not the easiest to inspect as there is currently no hatch.

It might not have a long life if it gets used as a trainer - we'll see!

-Chris
Title: Re: What to do about metal bellcrank
Post by: Howard Rush on February 23, 2011, 08:31:48 PM: After a dozen flights or so in a combat plane, the bellcrank assembly got transfered to a new airplane, so it was easy to inspect. I used Veco, then Fox bellcranks. I think I used .024" cable, but it might have been .027". It lasted awhile.
Title: Re: What to do about metal bellcrank
Post by: Ward Van Duzer on March 05, 2011, 02:22:54 PM: Cable will saw through a metal BC (especially if it is a PERFECT BRAND BC), solids will not. But, some folks don't like solids...

W
Title: Re: What to do about metal bellcrank
Post by: Bill Little on March 10, 2011, 03:04:59 PM: Quote from: Ward Van Duzer on March 05, 2011, 02:22:54 PM
Cable will saw through a metal BC (especially if it is a PERFECT BRAND BC), solids will not. But, some folks don't like solids...

W

Hi Ward-O,

We had the unbushed metal bell crank saw through the lead out cable........ ;D Aaron did save the plane, at least enough that only minor repairs were needed (we were flying over grass). he had just seen Bobby Hunt do the "broken lead out 2 step" at the NATS. LL~

Big Bear
Title: Re: What to do about metal bellcrank
Post by: BrianW517 on March 14, 2011, 03:26:34 PM: n~ :o When my cable "down" lead out wire, wore through the metal bell crank, on my Old Golbburg Shoestring, I was able to save the plane, by belly flopping it, on the grass, as I ran towards the plane, on it's sixth inside loop. Lost only the wooden prop & landing gear. http://stunthanger.com/uploads/bellcrank%201.pdf ^ <= y1 D>K H^^
Title: Re: What to do about metal bellcrank
Post by: dennis lipsett on March 15, 2011, 10:04:59 AM: When I used metal crank back in the day I did as many and used solid L/O wire. only when i returned and started using plastic and other types did I switch to flecable. I still like solids, just that flex is more convenient when transporting a model.
Dennis
Title: Re: What to do about metal bellcrank
Post by: Bill Little on March 16, 2011, 01:58:42 PM: HI Dennis,

I guess my main reason for the "changeover" from solids to cables is that Tom Morris' bell cranks come with the cables attached. ;D

I, fortunately, learned form the guy who was my "mentor" about using short pieces of brass tubing, flanged over to stay in place, back about 1963. The single lead out failure we have experienced since then was from building the Fancy Pants straight out of the box, as a product review, with no mods added. Brodak's kits now come with nylon BCs so that problem is eliminated.

Big Bear
Title: Re: What to do about metal bellcrank
Post by: Howard Rush on March 16, 2011, 06:00:10 PM: Quote from: dennis lipsett on March 15, 2011, 10:04:59 AM
When I used metal crank back in the day I did as many and used solid L/O wire. only when i returned and started using plastic and other types did I switch to flecable. I still like solids, just that flex is more convenient when transporting a model.

If you are used to solid leadouts, nothing else sounds quite right in the car on the way to the contest.
Title: Re: What to do about metal bellcrank
Post by: Dennis Moritz on March 16, 2011, 07:34:26 PM: Depends on whats worth it and what is not. Perfect cranks were soft aluminum. They sawed through, definitely. Fox cranks are tempered better. IMHO. How long will this trainer be flying and will it be honking. Cut a couple of inspections hatches in the bottom, CA them back in. If the plane is o.k at the end of the season, not likely if it's a trainer, cut the hatches out again, take a look and replace. One of the most frustrating things about other people's builds and ARFs is the darn controls. Usually the worry is not worth the time.

Howard is funny.