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Author Topic: 1/2A control horns?  (Read 1647 times)

Online Target

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1/2A control horns?
« on: October 02, 2017, 12:02:43 AM »
Does anyone have a source for scaled down flap and elevator horns, that look like miniatures of the full size units?
Thanks,
Target
Regards,
Chris
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Offline wwwarbird

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Re: 1/2A control horns?
« Reply #1 on: October 02, 2017, 06:08:54 PM »

 Du-Bro has some good ones, most decent hobby shops usually have them in stock...

 https://www.dubro.com/collections/control-horns/products/1-2-a-control-horns
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A. IC C/L Aircraft Modeler, Ex AMA member

Online Target

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Re: 1/2A control horns?
« Reply #2 on: October 02, 2017, 07:11:01 PM »
Hi, Wayne-
No, I'm talking about full on full fuselage stunt horns that are inside the fuse, with a wire and a brazed metal horn, just like the big boys use. But probably made with 1/16" music wire instead of 3/32" or 1/8"....

Seemingly they must only be fade to fill kits like the Tercel or the 1/2A Pathfinder; real 1/2A stunters....
I have some ideas on how to make my own, without brazing or silver soldering.

R,
Target
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Chris
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Online pat king

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Re: 1/2A control horns?
« Reply #3 on: October 02, 2017, 09:36:02 PM »
The horns for my Baby Bi-Slob are made with 1/16 music wire and 1/16 ply arms epoxied to the wires. The wires must be roughed-up using sandpaper or emerypaper before epoxying the arm. There is not a lot of load on the control system of a 1/2A airplane.

Pat
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Online Target

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Re: 1/2A control horns?
« Reply #4 on: October 02, 2017, 10:04:50 PM »
Thanks Pat.
Maybe for extra insurance, a second wire bound and bonded to the area where the horn resides, so no round shape?

I'll give it some thought. I have a couple possible strategies to pull from as well.

At least I know that there isn't some stash or mini horns somewhere, seems you confirmed that.
Regards,
Chris
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Online Target

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Re: 1/2A control horns?
« Reply #5 on: August 12, 2018, 05:19:45 PM »
I'm still looking for 1/2A sized miniature flap horns, if anyone has a source.
Thanks!!
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Chris
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Online Dave Hull

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Re: 1/2A control horns?
« Reply #6 on: August 25, 2018, 01:52:38 AM »
Chris,

They are not hard to make. Use some K&S .062x.250 brass strip and drill three holes. The hole for the joiner should be about .002 to .004" larger than the wire. A close fit, but not a press fit. Some heat and a touch of solder and you're done. Even soft solder is good enough for a 1/2A ship. An easy way to increase the strength is to use Stay-Brite silver bearing (96Sn-4Ag) solder. Just use the same iron as you would for rosin core 60/40. If you want even more insurance, slide a Formost brass washer up against the horn on each side. These have close-fitting IDs. The finished horn should pull test to around 4 in-lb with 60/40 solder and the washers and about 6.5 in-lb with Stay-Brite. I will try to attach a photo of a couple I made to the dimensions I wanted. I make just about all of the ones I use any more regardless of the size or type of airplane.

Dave

PS--The "gorilla horn" in the photo was a purchased item. You can see it has 3/32 wire. It was probably a Brodak item and was overkill for what I was building. If you look close, you can tell that the two horns I made for this plane are elevator horns--there is only one control linkage hole.

Offline L0U CRANE

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Re: 1/2A control horns?
« Reply #7 on: August 25, 2018, 01:56:22 PM »
I, for one, recommend larger horns and bellcranks for the smaller models.

Our flying handle has to use a reasonable separation distance between the lines. Too large, used with a 2" 'span' bellcrank, will CAUSE the dreaded 1/2A model twitchiness. Our comfortable 'tilt' angles to input controls, with a handle large enough to fit our hand, will send a 1/2A bellcrank too far, too fast.

We COULD learn to use much smaller input motions, if the model lasts long enough. We COULD learn to adjust lines for a comfortable 'neutral,' which is also more finicky with a small line separation. A bit larger - I'm not saying put a 4" span bellcrank on a Little Wizard!

Longer control horns help slow response. A 2.5" 'span' bellcrank is much easier for our existing motions to fly than a 2" - the angles are reached a bit slower, and the line can be separated a bit more at the handle. It all becomes more familiar, more like the response feel of larger models.

The points about HOW you make your horns, and possibly  bellcrank as well, are excellent.

Appearance of "being 1/2A" should be secondary after choosing things that improve the enjoyment of flying a little one.

Interested to follow your progress!
\BEST\LOU

Online 944_Jim

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Re: 1/2A control horns?
« Reply #8 on: August 25, 2018, 05:05:57 PM »
If you choose to run a smaller bellcrank, may I recommend one of these? I run a two inch line spacing to go with two inch bellcrank. The various plates allow for quick line spacing changes without affecting centering. The construction even offers a bit of exponential-ism, which can be removed by cutting/sanding off the hard angles in the handle.

Online Dave Hull

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Re: 1/2A control horns?
« Reply #9 on: August 25, 2018, 10:14:57 PM »
I find that using a modified Renger handle (like Porsche Jim's) set at 1-5/8" spacing when matched to a 2" bellcrank and standard horns works well for me on pretty much everything for stunt and sport in the 1/2A range. For my trainers, I move to the outer hole on the elevator horn. The stunters I move in until I get the response I need. For goofy stuff like the Flettner/autogyro the same handle and control geometry still works fine. The Flettner and on all my Mouse planes have homemade .062 aluminum bellcranks with buttons for direct line attachment. All 2" spacing. In my opinion, having a low friction control setup is more important than trying to overcome friction with a large bellcrank. And crucially, not just low friction but zero spring rate. It should not go back to any particular position except due to gravity orientation! I suppose it would not be difficult to get a larger bellcrank into something like a Baby Pathfinder, but on things like a Baby Clown or Baby Flite Streak or even a Pinto you are just making new problems to solve.  I get it that Rich Porter made outrageous 1/2A airplanes with huge bellcranks. But that was in a VooDoo platform which of course had a lot of room. And he probably used huge line spacing on his coathanger handles to match....

One other thing to mention is that the control stiffness and slop should be pretty small in 1/2A planes as far as I am concerned. Pushrod guides (especially if using weight-saving .047 wire for pushrods), hole slop in horns and bellcrank, bent and springy leadouts (if solids), stretchy lines (Dacron, boo, hiss), and stiff cable in your handle all degrade the controls. Using giant bellcranks and correspondingly giant horns has the sole advantage (in my opinion) of tolerating a lot more slop and still resulting in minimal control surface free play. If you build a closely toleranced system you get rid of the need for giant components.

I suppose that the final reason that some might like "oversized" components is to retain control upwind in a gust when line tension goes away. The line tension is generally so small to begin with on many planes that I am back to the low friction solution. And flying one downwind in a strong breeze and running out of control force seems kind of unlikely. If there is that much wind, a 1/2A is not going to track well anyway. For example, with a Baby Clown in strong breeze I find that a loop at 60 degrees is tough because there just isn't enough mass and lift and the loop size is going to get squashed down by the wind. At least that is what I have attributed it to so far--not to control ineffectiveness or stiffness.

Half-A's are fun and you can do a lot with them. You can have a whole flock of experimental planes and still fit them in the house. And you don't need a second mortgage....

McDivot

PS--Perhaps an interesting comparison of control geometries would be to look at F2C racing planes. These babies are going 120+ mph on 52' lines. They are not twitchy or you'd be in the ground faster than you knew what happened. And you can't watch your plane all the time. You need to be watching for the plane in front of you and your pitman. All the ones I took apart or built had bellcranks smaller than 2". The one in the photo is less than 1-1/2". The wood planks in the bench are 1-1/2" wide. This goes with a standard handle spacing of 1-3/4".
« Last Edit: August 26, 2018, 12:14:59 AM by Dave Hull »

Offline Larry Renger

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Re: 1/2A control horns?
« Reply #10 on: September 03, 2018, 09:24:31 AM »
I have used brass tubing,open at the bottom to get double the solder joint and squished flat at the top and drilled for the pushrods. Never had a failure.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Online Dave Hull

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Re: 1/2A control horns?
« Reply #11 on: September 04, 2018, 01:19:00 AM »
Larry,
How was your pushrod attached to the brass tube-horn? (Sounds like a musical instrument, doesn't it?)

The reason I ask is that we had a imminent failure on a brass tube-horn due to rapid wear from a metal clevis. Granted, it was in a Goodyear racer, and maybe the vibration levels were higher....   Also, did you anneal the tubing before you squashed it flat?

Dave


Offline Larry Renger

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Re: 1/2A control horns?
« Reply #12 on: September 04, 2018, 09:18:29 AM »
As I recall, it was a simple Z bend end. No the tube wasn’t annealed.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Online Dave Hull

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Re: 1/2A control horns?
« Reply #13 on: September 04, 2018, 11:55:07 AM »
Thanks for the info!


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