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Author Topic: control horns  (Read 3833 times)

Offline bill rutherford

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control horns
« on: October 25, 2014, 09:35:45 AM »
I'am getting ready to put 1/8 flap control horns in my new masterpiece . I would like to be able to tweek the later. How should I heat treat them so that I can bend them without risking tearing up the flaps?   Bill

Offline Randy Cuberly

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Re: control horns
« Reply #1 on: October 25, 2014, 11:28:26 AM »
I'am getting ready to put 1/8 flap control horns in my new masterpiece . I would like to be able to tweek the later. How should I heat treat them so that I can bend them without risking tearing up the flaps?   Bill

One of the most important thing in tweaking flap horns is how they are mounted in the flaps.  I always use laminations of plywood epoxied onto the ends of the flaps.  This is easiest to do with at least 5/16 thick flaps.
I also don't like 1/4 inch flaps because they flex too much.  I do not believe in softening the flap horn material for several reasons...first if you do it it must be done before the horn is brazed onto the wire.  Doing it afterwards is impossible without disturbing the brazed joint and weakening it.

When actually tweaking the flaps I always use two pieces of 3/16 in plywood, one of top of the flap and one below (actually two on each flap which makes four pieces total) to hold the flaps.  the plywood pieces need only to be about two inches square.  Have someone hold the airplane nose down so you can see the edges of the flaps and bend away gently and slowly holding the plywood pieces over the flap horn and the flap.

The plywood mounting pieces in the flap are laminated with three pieces of of 1/8 plywood with the center pieces slotted for the horn wire before assembly.  Lamination is done with slow set epoxy.

This system is foolproof.  I've used it for many years on a lot of airplanes and never had a failure...

Randy Cuberly
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Offline Clint Ormosen

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Re: control horns
« Reply #2 on: October 25, 2014, 12:55:22 PM »
Bill, pay close attention to what Randy posted and do exactly that. Works perfectly.

 1/8" horns don't bend easily so you're going need a lot of strength in the flaps. 3/32" horns are a little easier to tweak but my not be appropriate for your model depending on the size. 
-Clint-

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Offline Tim Wescott

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Re: control horns
« Reply #3 on: October 25, 2014, 01:57:25 PM »
My next plane is going to have the Paul Walker-style individually adjustable flaps.  Even though I'm a trimming lightweight, I've still had occasion to waste flights on flap tweaking: I'd much rather be able to do it in a controllable, repeatable and reversible fashion.
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Offline Howard Rush

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Re: control horns
« Reply #4 on: October 25, 2014, 06:28:46 PM »
My next plane is going to have the Paul Walker-style individually adjustable flaps.

Ironically and curiously, Paul's next airplane won't.
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Offline Gordan Delaney

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Re: control horns
« Reply #5 on: October 25, 2014, 06:30:51 PM »
 Bill,
For years now I`ve been useing welding rod 1/8. Works great and you can tweak it.

Gordy

Offline Steve Helmick

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Re: control horns
« Reply #6 on: October 25, 2014, 06:47:49 PM »
Making the flaps (and elevators) removeable completely solves this problem. Use two pairs of ViseGrips, if you want. Also makes repairs, painting and experimenting easier...and more likely!  H^^ Steve
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Offline Michael Massey

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Re: control horns
« Reply #7 on: October 26, 2014, 02:26:21 PM »
Several months ago, I experienced a control horn breaking off while I was trying to make the very first tweak in the flaps.  The plane was just finished and that broken control horn caused a significant repair and refinish of the plane.  The control horn was 1/8" and new.  Obviously, it was too brittle from manufacture.  I now anneal mine before I put them in the plane.  All the rest of the info above is good stuff.
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Offline Allan Perret

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Re: control horns
« Reply #8 on: October 26, 2014, 07:37:22 PM »
1-Use A2 drill rod [8888K181] from McMaster Carr for tweakable horn wire.
2-Make hardwood horn pocket for the flap root.
3-Make a pair of custom tweaking handles for the flaps.
Peace of mind..
Allan Perret
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Offline bill rutherford

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Re: control horns
« Reply #9 on: October 26, 2014, 08:04:01 PM »
I guess my main question is how to anneal the  !/8 wire. The flaps in this latest masterpiece are only 1/4 inch. Might just have to bite the bullet and remove them to adjust. I guess I need to get some !/8th welding rod also.
    Thanks for all the info guys. I guess I could just make the flap thicker with a little ply where the control horn is.  Bill

Offline Howard Rush

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Offline Allan Perret

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Re: control horns
« Reply #11 on: October 26, 2014, 08:42:52 PM »
I guess my main question is how to anneal the  !/8 wire. The flaps in this latest masterpiece are only 1/4 inch. Might just have to bite the bullet and remove them to adjust. I guess I need to get some !/8th welding rod also.
    Thanks for all the info guys. I guess I could just make the flap thicker with a little ply where the control horn is.  Bill
You don't have to anneal the A2 drill rod.  It comes in the annealed state, use it as is.
Allan Perret
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Offline Dan McEntee

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Re: control horns
« Reply #12 on: October 26, 2014, 10:46:10 PM »
You don't have to anneal the A2 drill rod.  It comes in the annealed state, use it as is.

   Does it stay annealed after the horn is brazed in? Or does the drill rod require quenching and drawing to reach it's desired hardness?
    It has been discussed many times over the recent years how today's music wire is pretty inconsistent in quality. As an alternative, could 1/8" be drawn a little softer by gentle heating? That might be easier for some to do in their home shops.
   Type at you later,
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Offline Steve Fitton

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Re: control horns
« Reply #13 on: October 27, 2014, 06:24:22 AM »
Steve

Offline Scott Richlen

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Re: control horns
« Reply #14 on: October 27, 2014, 06:47:36 AM »
Is Derek still flying?  I always enjoyed seeing him at Brodaks, but don't remember seeing him the last few years.

Scott

Offline Phil Krankowski

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Re: control horns
« Reply #15 on: October 27, 2014, 07:34:12 AM »
A2 drill rod is air hardening tool steel.  Since brazing does not heat to "critical" temperature, (about 1650F for most steels, cherry red, non-magnetic) the metal is not going to harden and will remain in the "annealed" state.  It is not possible for the metal to harden because the phase of the steel has not been changed.  (If you want more start reading up on metallurgy)

A2 drill rod in its "dead soft" annealed state is pretty hard and tough due to its alloy content and 1% carbon (compared to mild steel)

If you need more information there are a large number of material data sheets that turn up with a quick internet search. 

Phil

Offline Dan McEntee

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Re: control horns
« Reply #16 on: October 27, 2014, 08:54:10 AM »
A2 drill rod is air hardening tool steel.  Since brazing does not heat to "critical" temperature, (about 1650F for most steels, cherry red, non-magnetic) the metal is not going to harden and will remain in the "annealed" state.  It is not possible for the metal to harden because the phase of the steel has not been changed.  (If you want more start reading up on metallurgy)

A2 drill rod in its "dead soft" annealed state is pretty hard and tough due to its alloy content and 1% carbon (compared to mild steel)

If you need more information there are a large number of material data sheets that turn up with a quick internet search. 

Phil
    Hi Phil;
   Thanks for the explanation. I'm a welder by trade but never got very deep into metallurgy. I like to say I know enough about it to be dangerous! I would have thought brazing temps would get it in the range to harden it. I've worked on build ups of car frame stamping dies made from D2 air hardened steel, and smaller bits for much smaller dies made from similar alloys. At my first job many year ago we had a pretty fair stock of drill rod on hand and tried to make a wing joiner with it, and tried to harden and temper it. I think I remember one of the machinists telling me to quench it in oil, then draw it a bit with a torch. It snapped like a pretzel when I tried it in the airplane! If I remember what little we did study in welding school, the point you are referring to is call the eutectic point, where the grain or molecular structure makes a change. Interesting subject and wish things in life had taken a path where I could have studied it more.
  Type at you later,
   Dan McEntee
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Offline Igor Burger

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Re: control horns
« Reply #17 on: October 27, 2014, 09:07:50 AM »
I use soft steel rod for welding which is realtively easy to bend. However it is lttle bit mechamically hardened, so it is not good idea to heat over 300 dergrees, because it cannot be hardened back thermally, so I use Ag4Sn96 solder. Works well.



  

Online frank williams

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Re: control horns
« Reply #18 on: October 29, 2014, 01:32:42 PM »
Bill
Go to Home Depot.  Go to the metal bin that has sheet metal, aluminum rods and extrusions. steel rods and stuff.  They have a 1/8 steel rod that isn't piano wire and is tweekable.  Plenty firm enough for horns.
Frank


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