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Author Topic: A Control System  (Read 1888 times)

Offline Mike Griffin

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A Control System
« on: February 10, 2018, 03:43:34 PM »
Here is the heart of the control system going into the Imitation wing.  This is a bushed, 4" Carbon fiber bellcrank, suspended on the two piece RSM steel swivel post mount and the Carbon Fiber Pushrod has a #304 stainless steel 4-40 capture type threaded push rod end screwed into a DuBro heavy duty ball link.

Mike


Offline Motorman

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Re: A Control System
« Reply #1 on: February 10, 2018, 03:49:29 PM »
Looks like RSM stuff. I would take the bushings out and sleeve the lead outs so it's not metal to metal.
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Offline FLOYD CARTER

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Re: A Control System
« Reply #2 on: February 10, 2018, 04:10:27 PM »
That bellcrank has a brass bushing with rounded edges.  I would expect it to last for a long time, but not forever. 
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Offline Steven Kientz

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Re: A Control System
« Reply #3 on: February 10, 2018, 04:32:57 PM »
Sleeve the leadouts, wouldn't they still be metal to metal?
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Offline Mike Griffin

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Re: A Control System
« Reply #4 on: February 10, 2018, 05:09:06 PM »
Guys you can do it however you please.  If I use a bushed bellcrank, whether it be carbon fiber or nylon, I do not sleeve the lead out wires.  If the bellcrank is NOT bushed, then I sleeve the wire through 1/16" copper tubing.  Of course you can sleeve the leadout wires with a bushed bellcrank if you wish.  Do whatever you want.  What I was trying to show here were the components that RSM offers to put this control system together.

Mike 

Offline Steven Kientz

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Re: A Control System
« Reply #5 on: February 10, 2018, 05:31:56 PM »
Mike I agree. Just wasn't sure how MM would keep that from being metal on metal.
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Offline Vincent Judd

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Re: A Control System
« Reply #6 on: February 10, 2018, 06:07:51 PM »
Mike I agree. Just wasn't sure how MM would keep that from being metal on metal.
Steve

Not sure I understand that logic either Steve.  Bellcrank bushings look fine to me, they'll probably outlive me.  I'll keep track of how many flights I get on my Imitation control system.  If they fail and I lose the plane, well, that's an excuse to build a new one.

Picture's worth a thousand words, thanks Mike.  Loving this kit.

Vince

Offline Mike Griffin

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Re: A Control System
« Reply #7 on: February 10, 2018, 06:58:38 PM »
Thumbs up Vince and Steve.  Its all about having fun.

Mike

Offline Motorman

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Re: A Control System
« Reply #8 on: February 10, 2018, 08:53:39 PM »
Mike I agree. Just wasn't sure how MM would keep that from being metal on metal.
Steve

read my post again.

MM
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Offline Brett Buck

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Re: A Control System
« Reply #9 on: February 10, 2018, 10:42:51 PM »
Looks like RSM stuff. I would take the bushings out and sleeve the lead outs so it's not metal to metal.

   You mean use a sleeve for the leadouts, and have it run on bare carbon fiber? That will slice right through the sleeve and cable.

      Brett

   

Offline Motorman

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Re: A Control System
« Reply #10 on: February 12, 2018, 06:27:50 PM »
I think you're screwed either way, that's why I don't use RSM stuff.   
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Offline Mike Griffin

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Re: A Control System
« Reply #11 on: February 12, 2018, 10:50:29 PM »
I think you're screwed either way, that's why I don't use RSM stuff.

RSM's "Stuff" as you call it, is used by many expert builders and fliers that appreciate quality and value. 

Mike

Offline Brett Buck

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Re: A Control System
« Reply #12 on: February 13, 2018, 01:15:02 AM »
I think you're screwed either way, that's why I don't use RSM stuff.

     Oy vey! And you suggested running a fragile SS wire rope against a material that requires diamond or carbide tools to reliably machine, and is known to wear out hacksaw blades very rapidly. So I think the scoreboard reads Eric Rule 1, Motorman 0.

      The original arrangement, stainless wire rope on brass, will last a reasonable amount of time, while being inexpensive, light, and easy to assemble. It's much better than the partially-sleeved "U-shaped" sleeve/loop and most of the other odd arrangements people use, and in this case you would be running brass against brass or copper, which is unwise unless you can routinely lubricate it.

     An alternative would be to replace the brass eyelet with a much thicker delrin insert, which is known to be pretty good in terms of wear even on the bare cable. Add a full-teardrop eyelet and it's good for 3000+flights. That's also much heavier, requires custom parts, and requires a fair bit of care in construction or it's even more prone to failure (if you don't get the ends of the teardrop even, for instance).

     Brett
   

Offline Howard Rush

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Re: A Control System
« Reply #13 on: February 13, 2018, 10:31:20 AM »
I'd worry that the brass would wear through on the corners, exposing the carbon, which would then cut the cable a strand at a time. 
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Offline Dane Martin

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Re: A Control System
« Reply #14 on: February 13, 2018, 01:00:38 PM »
Interesting topic. Allow me to preface this with, I bought that kit, and that hardware package. I'll let everyone know how many flights I get.

Now on the subject of wear.... when the lead out's are under a load, would there be much "sawing" action at the attachment point? Or would it be more of a side to side  swiping motion? Asking for a friend......

Offline Peter Nevai

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Re: A Control System
« Reply #15 on: February 13, 2018, 05:15:10 PM »
What I do in varying combinations depending upon the parts on hand. Take your bell crank, find yourself a scrap of aluminum and modify. Ignore all the center bushing stuff in the photos. That's a discussion for another day. Fabricate the aluminium piece as shown, add a couple of screws brass tubing and lead outs as shown. Assemble and you are good to go. The carbon bell crank is a RSM 4 inch item. The lead outs are wrapped with some heat shrink slid over the wrap to keep things tidy.
« Last Edit: February 13, 2018, 08:57:40 PM by Peter Nevai »
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Offline Brett Buck

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Re: A Control System
« Reply #16 on: February 13, 2018, 08:47:03 PM »
I'd worry that the brass would wear through on the corners, exposing the carbon, which would then cut the cable a strand at a time.


   Agreed, that is the likely failure mode. But it's better than what a lot of people have used over the years, and certainly better than letting the cable run on the bare carbon as suggested. I have seen 3 leadout failures in recent years using stranded lines and in all 3 cases, the cable failed due to apparent fatigue, right next to a hard sharp edge (two loop and sleeve, and one at a wrapped and epoxied cable serving).

     Brett

Offline FLOYD CARTER

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Re: A Control System
« Reply #17 on: February 14, 2018, 10:43:19 AM »
To settle this, why not wait to see just how many flights it takes for a leadout failure.  I',m guessing it will be much longer than any plane of mine has lasted.  (and I still have one I built in 1963)
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Offline Avaiojet

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Re: A Control System
« Reply #18 on: February 14, 2018, 10:54:23 AM »
What I do in varying combinations depending upon the parts on hand. Take your bell crank, find yourself a scrap of aluminum and modify. Ignore all the center bushing stuff in the photos. That's a discussion for another day. Fabricate the aluminium piece as shown, add a couple of screws brass tubing and lead outs as shown. Assemble and you are good to go. The carbon bell crank is a RSM 4 inch item. The lead outs are wrapped with some heat shrink slid over the wrap to keep things tidy.

Gee.

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Offline Vincent Judd

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Re: A Control System
« Reply #19 on: February 14, 2018, 11:23:55 AM »
If you've ever wondered why more people don't post things on here, you now have a perfect example.  You have the original poster, Mike Griffin, super nice guy, posting a picture of the bell crank assembly for his newest creation, the Imitation.  Over 30 kits sold, one of the most popular new releases in a long time.   Hard work by Mike, Eric and Ted Fancher to bring this thing to us for our enjoyment.

Title of original post was not "give me your opinion on how to build the best bell crank assembly".   Nope, it was just a picture, showing all of us who had purchased a kit how the bell crank is assembled.

Not one person thanked Mike for posting the picture, instead a lot of negativity, perhaps founded or possibly unfounded.  You be the judge of that.

So from me, I want to say thanks Mike for posting that picture.  It will give me something to use as a guide when I'm putting mine together.  I will keep an accurate count of the number of flights I get out of it, and I will assemble it just as you have shown in your picture.

Vince

Offline Avaiojet

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Re: A Control System
« Reply #20 on: February 14, 2018, 11:32:56 AM »
On second thought.


« Last Edit: February 14, 2018, 09:40:33 PM by Avaiojet »
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Offline Jim Mynes

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Re: A Control System
« Reply #21 on: February 14, 2018, 12:53:42 PM »
Gee.

I wish I had thought of that in 1962.  LL~ LL~ LL~

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Offline Brett Buck

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Re: A Control System
« Reply #22 on: February 14, 2018, 02:45:29 PM »
Title of original post was not "give me your opinion on how to build the best bell crank assembly".   Nope, it was just a picture, showing all of us who had purchased a kit how the bell crank is assembled.


  So, Vince, your beef is that I and others came in and defended Mike/Eric while correcting an utterly absurd suggested change that, if implemented, virtually guarantees a failure?  I find it a little hard to apologize for that one.

   Brett

Offline Vincent Judd

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Re: A Control System
« Reply #23 on: February 14, 2018, 08:00:57 PM »
  So, Vince, your beef is that I and others came in and defended Mike/Eric while correcting an utterly absurd suggested change that, if implemented, virtually guarantees a failure?  I find it a little hard to apologize for that one.

   Brett

No Brett, my beef was not with you at all.   I have been getting lots of help from both Mike and Eric on this kit, I guess I'm just defending them.  I'll shut up and mind my own business which is what I should have done in the  first place. 

Offline Mike Griffin

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Re: A Control System
« Reply #24 on: February 15, 2018, 06:05:51 AM »
Good morning everyone.  I thought I might need to say something about my original post.  It is never my intention to post anything to cause controversy when it comes to our hobby and more specifically when it applies to "how to do something."

In most cases when it comes to building a model, there are different ways to accomplish the same goal and I would never imply the way I show something is the "only" way to do it.  There are many far better builders and finishers in the forum than me and when I post something it is not to say this is the way it should always be done but rather this is the way I did it and others may have alternative methods that work just as well or even better. 

Vince I appreciate the very kind words and if I was able to help you or anyone else with anything pertaining to building a model, I assure you it was my pleasure. 

In relation to this post, Again, all I was trying to do was show the components available from Eric to put together a  good control system.  I maybe fly four times a year anymore so the way I rigged this in this photo will last me as long as it needs to before I either die or turn the model into a lawn dart.

Vince did bring up something that I wanted to comment on and that was the number of Imitation kits that were sold.  It was the biggest selling kit I ever produced and I wanted to thank you all for the patronage and I hope you enjoy building the kit and get many hours of pleasure from it.

Kindest reagards,
Mike





Offline Dan McEntee

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Re: A Control System
« Reply #25 on: February 15, 2018, 04:54:59 PM »

Looks like RSM stuff. I would take the bushings out and sleeve the lead outs so it's not metal to metal.


I think you're screwed either way, that's why I don't use RSM stuff.



     This is the offending post, MM putting his foot in his mouth again. Not the first time he has bad mouthed a vendor on this forum needlessly. It all went down hill from here.  Lots of "RSM stuff" out there being used successfully and I don't see any MM merchandise dominating the market!
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Offline jim gilmore

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Re: A Control System
« Reply #26 on: February 15, 2018, 07:05:41 PM »
Some things to consider. 1. the bushing in the carbon bell cranks is held in how ? If it is just a pressed in fit an the ends at both ends are swaged to round the off then I would think that they spin in the bell crank. That would reduce the wear f the bushing from the wire. I guess the real question is what is the expected lifespan of the modelers average airplane.

Offline Motorman

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Re: A Control System
« Reply #27 on: February 15, 2018, 09:15:39 PM »
     This is the offending post, MM putting his foot in his mouth again. Not the first time he has bad mouthed a vendor on this forum needlessly. It all went down hill from here.  Lots of "RSM stuff" out there being used successfully and I don't see any MM merchandise dominating the market!
   Type at you later,
   Dan McEntee

You can call it whatever you like Dan but, you're on my ignore list for a reason. I've seen you browbeat people on here mostly about the search function and you jump on me every chance you get. Like Sparky says, go sand something.

btw I've made many parts for many people over the years and never had a complaint about anything so your argument doesn't hold up to the truth. I give an honest review of vendors and products. If somebody is selling problem products or has bad customer service I give an honest review.

If people like using RSM stuff I think that's a good thing and, I think Eric is the nicest guy in model aviation but, I've had problems with some of the products, so I'm phasing RSM out of my program, it's no big deal, to each his own.

Brett, It seems we both agree this bellcrank will cut through things but, I never suggested bare lead out wire on sharp CF edges. I've seen leadouts with brass tubing horse shoes used on CF bellcranks on this site before so, I though I would suggest it. Maybe there's a difference between a laminate bellcrank and one that's made up with tow?

Motorman
« Last Edit: February 15, 2018, 09:32:45 PM by Motorman »
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Offline Fredvon4

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Re: A Control System
« Reply #28 on: February 16, 2018, 12:49:22 PM »
I loath some of these threads... I try hard to incorporate a lot of the Best Practice...despite my simple fun fly 5 to 10 flight-per year on a any air-frame

Many times doing it right the first time makes sense and is not cost prohibitive

Hell I spent $42 for a full custom control set for a $100 Nobler ARF... that IF I ever get off ass to spend the 10 hours to FINISH the craft will never be flown more than 5 times a year

I have several old skool planes with cruddy and inferior aluminum bell cranks with 0.27 bare wire lead outs and YES the push rod and lead outs have have ovaled the holes and some day will fail...

Every builder must decide for self what is perfect and worth the effort based on USE to incorporate.....

IN my personal flying experience from 1967 to present.... a few bell Crank platform failures.....
I do not fly hundreds or thousands of flights per season... If I did I would simply copy the experts...nothing they do is unique or expensive and to me seems easy to replicate

Just to stay a little bit ON TOPIC

I have one of Mike G's ARF Ring Masters with no way to see how the LOs were done... It flys great and I am confident the total system will last MY life time of Round Up flights
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