bellcrank upgrade

[Steven Kientz]

 It seems the most tedious part of construction for me is attaching leadouts to the bellcrank. Gave it some thought and decided to construct a top plate so I could use the ends supplied in the various leadout kits. As of right now the mockup has a lite ply top and a Brodak 3" BC. I used 2-56 hardware to bolt the two pieces together. I used some plastic leadout tube for a grommet on the 2-56 machine screw that will hold the perfect brand ferrule that the leadouts will ride on.
  Does this sound like it should work/ be safe to fly? I assumed that the 2-56 hardware should take as much if not more abuse that the copper tube and leadout.
  I tried to take some pics , but too much glare(probably needed a dark background).

Thanks
Steve

[FLOYD CARTER]

There are many, many examples of bellcrank installations pictured on this forum  (do a search on "bellcrank", etc).

If you try something new, that hasn't been done before, make sure you do a mock-up and give it a healthy pull test before installing it in your plane.

Your safest plan is to copy what hundreds have already done, with success.

F.C.

[Geoff Goodworth]

Steve, as Floyd said, seach and find what's on the forum.

One option that I know was tried, sounds similar to your description except that the builder had access to strips of 1/16" thick carbon fibre sheet and such a piece was glued and screwed to the Brodak bellcrank to form forked ends.

The one thing I would recommend is that you do not have your ferrule running on the thread and I don't think plastic tube will last very long. I know that they are expensive but Windy did something similar some years ago but he used 4-40 shoulder screws to hold the ends and carry the ferrules. Even though they are expensive, two shoulder screws are worth much less that your finished model.

[Steve Helmick]

Since nothing was posted about how heavy the plane is expected to be, or engine size, it's not possible to say this is a good idea. I would rule out "liteply", first off. And like Geoff said, do not run any eyelet or bushing on threads. I suspect you mean to let an eyelet run on the plastic sleeve. My take is that what you're doing is going to be more work than the standard method, or it's going to be of dubious strength. If I was using a 3" or 4" Brodak (or 3" Sig) BC, I'd just use two of them, because they are cheap and light, and there would be no potential confrontation with an insurance company if something goes bad. When there is an accident, the lawyers go after the manufacturers of virtually every piece of hardware in the plane. Not right, but not good, even if vindicated.
  Steve

[Steven Kientz]

The lite ply was on the mock up only. I had considered 2 BC and using 4-40 hardware. Searching for Bc on here is kinda what led me to try this. definitely like D Moran & B Buck versions.

Steve

[Steven Kientz]

  After thinking about my first mock up today(instead of thinking about work) I've decided to go to Plan B. Two Brodak 3" BCs, 4-40 hardware and some handmade ferrules(delrin). The plane is a Corehouse 500sq" foam wing with a balsa fuse(Bill Bischoff style) warbird. Power will be 35-40 size.Weight will hopefully be under 48 oz. I'm headed to the AMA website to look for criteria for testing my project.

Thanks
Steve

[Steve Helmick]

If you're going to use machine screws for the leadout attachments, I would consider bolting a brass tube spacer (or similar) between the BC arms (so they can't rotate)...OR, I would make the "eyelet" with a threaded hole, so it'd run thread/thread, giving lots of bearing surface. And lubricate them with a wee bit of something like teflon grease. There is some chance that you can find a longer than needed machine screw with the right length of "grip" (the unthreaded part) to eliminate this problem. Remember that threads reduce the sheer strength of the screw quite a lot.  Steve

[EddyR]

Steve   Why are you doing all this?? It is going to be heavy.  Bellcranks with leadouts all ready installed are available from TOM Morris.
Ed

[phil c]

  After thinking about my first mock up today(instead of thinking about work) I've decided to go to Plan B. Two Brodak 3" BCs, 4-40 hardware and some handmade ferrules(delrin). The plane is a Corehouse 500sq" foam wing with a balsa fuse(Bill Bischoff style) warbird. Power will be 35-40 size.Weight will hopefully be under 48 oz. I'm headed to the AMA website to look for criteria for testing my project.

Thanks
Steve

Hey Steve,  not sure why you are agonizing over this.  For a 48 oz. airplane one Brodak 3 in.(I would recommend 4in.  and use longer control horns to keep the control loads low) is more than enough.  Mount the bellcrank on a 1.5 in. wide strip of plywood that goes through a half inch thick center rib.  Pin the mount with a couple bits of 1/8 in. dowel vertically through the rib.  Standard leadout contruction,  a piece of 1/32in. id brass tube on .027 leadout wire to form a ferrule throught the bellcrank and whatever wrap or crimp you want to terminate it.  That will easily pull test 100 lb. per side.

Phil C.

[Steven Kientz]

  Main reason for this is I'm a tinkerer at heart, I assume most modellers are. My favorite part of this hobby is building, flying at least for now is secondary. That might change once I get some more free time to practice. My attempts at wrapping leadouts so far have been really crude. My crimping or swaging is only marginally better. Maybe my time would be better spent building a jig to finish the leadouts on.

Steve

[john e. holliday]

In the planes that didn't out last the bellcrank assembly, I have checked for wear.   Using the SIG nylon or Brodak bellcranks I have found no wear where the leadouts are attached.   I use annealed brass tubing when I can't find copper to put the leadout cable thru.   I think Bob Zambelli had an article on this at one time.   Not only does the tubing hold the cable while wrapping or swagging, no crimps for me.   Even the Fox metal bellcranks have shown no wear.   As stated the Tom Morris units have the tubing over the cable before going into the bellcrank arms.   Remember the old KISS method will cure a lot of problems later.

By the way the only wear I have seen is the pushrod hole on the bellcrank.  That is why I now use 4-40 ball links.

[Steven Kientz]

  Well I can take a hint(finally). Going to build a jig to wrap my leadouts and stay with the "conventional" bellcrank configuration.

Thanks
Steve

[Avaiojet]

Steve   Why are you doing all this?? It is going to be heavy.  Bellcranks with leadouts all ready installed are available from TOM Morris.
Ed

Steve,

Long Thread, great replies and no photos, so not sure what you're up to?

I gotta tell ya this. Early 60's I layered two belcranks together. Did it on a few other models at that time. The 60's. Had to, what else was available then?

Sure, Did the same thing for The New American and The LOSER, soon to be called the Mig-3.

Waste of energy, foolishness, re-inventing the wheel? Could be lable any number of things. I learn the hard way, but I do eventually learn.

Ed said it very well above.

So, I've learned, my next model will have a Tom Morris bellcrank in it. Done!

Here's my photo of what could be considered a waste of time. Extreme waste of time.

I live and learn, the hard way.

Charles