Control Horns

[Mike Griffin]

When NOT using a bent wire control horn on a profile model for flaps or elevator, what, other than the Nylon Dubro type control horn,  are you guys using? 

Thank you
Mike

[Dwayne Donnelly]

Hi Mike sorry not sure what you mean by a bent wire control horn, but I make my horns from 3/32 aluminum.

[Mike Griffin]

Hi Dwayne,

By "bent wire" I was referring to a 1/8" or 3/32"  wire with horn brazed on to it.  Just the common control horn that as been used forever.  Thank you for posting your aluminum one.  I have used the nylon Dubro horn a lot in the past but was wondering if there was another better and stronger horn on the market.

Mike

[Dan McEntee]

   Nylon tends to dry out and get brittle with age. Sullivan makes some large metal horns, I think, and even some hand made from 1/16" hardware store aluminum angle would last a very long time and you can custom make lengths, offsets and such. No special tools required and a few minutes to make. The only Du-Bro plastic horns that I have trusted are those longer, black nylon units that are pretty beefy.
  Type at you later,
  Dan McEntee

[Mike Griffin]

   Nylon tends to dry out and get brittle with age. Sullivan makes some large metal horns, I think, and even some hand made from 1/16" hardware store aluminum angle would last a very long time and you can custom make lengths, offsets and such. No special tools required and a few minutes to make. The only Du-Bro plastic horns that I have trusted are those longer, black nylon units that are pretty beefy.
  Type at you later,
  Dan McEntee

Thank you Dan.

Mike

[Dave Harmon]

When NOT using a bent wire control horn on a profile model for flaps or elevator, what, other than the Nylon Dubro type control horn,  are you guys using? 

Thank you
Mike

Hi Mike.....
I never have liked putting a couple of screws through a nylon horn then through the balsa even though there was a plywood foot on both sides.
I cut my own horns from green FR-4 ckt board material using an old Du-Bro horn as a template.
You can find it at surplus electronic supply stores or buy a small sheet from the larger distributors.
This stuff is about 1/16" thick and super tough.
Then...I cut a slot in the flap or elevator and glue with Hysol or regular epoxy and use a bent wire to couple the surfaces together.
No brazing...just make 2 bends and that's all.

[Mike Griffin]

Thank you Dave.  I will try and find some of that material

Mike

[John Park]

Dave Harmon's use of circuit board material sounds excellent - I use 'Formica' melamine laminate in the same way on 1/2A models, as (unlike aluminium) it has good wearing properties.  The holes in an aluminium horn, with a steel wire pushrod through it, wear oversize so quickly that I sometimes go to the trouble of bushing them with short lengths of brass tubing, peened over to give a tight fit.  This is a PITA, but effective.

[Dan McEntee]

Dave Harmon's use of circuit board material sounds excellent - I use 'Formica' melamine laminate in the same way on 1/2A models, as (unlike aluminium) it has good wearing properties.  The holes in an aluminium horn, with a steel wire pushrod through it, wear oversize so quickly that I sometimes go to the trouble of bushing them with short lengths of brass tubing, peened over to give a tight fit.  This is a PITA, but effective.

  John;
  I think I know what this is, but describe it more and where you get it. I'm picturing it in my mind in 4' by 8' sheets. I think I have some scraps around here some place left over from a project where I used to work.
  Type at you later,
  Dan McEntee

[Don Jenkins]

When NOT using a bent wire control horn on a profile model for flaps or elevator, what, other than the Nylon Dubro type control horn,  are you guys using? 

Thank you
Mike

I've been using entire control systems from Tom Morris for about 7 years.  I send him the dimensions and he builds to spec using bullet proof systems with 440 ball joints, CF push rods and 3/32" or 1/8" wire horns, you can also get adjustable push rods and horns.  Although I do believe he recently sold his parts business to Russel Honea. His contact info is: (918) 508-9200, russel@okieair.com.  His website is Okieair.com but I've had trouble opening it.

Don

[Avaiojet]

I've been using entire control systems from Tom Morris for about 7 years.  I send him the dimensions and he builds to spec using bullet proof systems with 440 ball joints, CF push rods and 3/32" or 1/8" wire horns, you can also get adjustable push rods and horns.  Although I do believe he recently sold his parts business to Russel Honea. His contact info is: (918) 508-9200, russel@okieair.com.  His website is Okieair.com but I've had trouble opening it.

Don

Absolutely!

Every model I have built has Tom Morris HDWE. Well, except for the Flite Streak. 

And as stated above, you can now order the same quality HDWE that Tom offered including custom made pieces. Russell is quite capable.

I do remember building the Carl Goldberg Shoestring Stunter many years ago. I gave it away to a a guy's son. There's always a guy son's. I should have kept it, gave him the Fox 25 with it also.

It had a plywood horn that slipped over the elevator and you would notch out the stab. Sure, plywood, but with a brass sleeve it might stay healthy for a period of time. Or a Russell "ball link."

Ambiance of yesteryear with an upgrade.

Walter could laser burn them by the dozens.

[Mike Griffin]

   Nylon tends to dry out and get brittle with age. Sullivan makes some large metal horns, I think, and even some hand made from 1/16" hardware store aluminum angle would last a very long time and you can custom make lengths, offsets and such. No special tools required and a few minutes to make. The only Du-Bro plastic horns that I have trusted are those longer, black nylon units that are pretty beefy.
  Type at you later,
  Dan McEntee

Dan after doing some research, I believe the Sullivan metal horns look better than anything else that seems to be on the market for a control horn unless you make them yourself as some people say they are doing. 

Mike

[John Watson]

While we are at it what about control horn shape? Any experimental shapes that worked well.

[Dennis Nunes]

I made this control horn for my Flite Streak from 0.040 mild steel. The horn bolts through the elevator.

However, the stab and elevator are made from 1/4" thick balsa and I recessed a 1" square piece of 1/16" plywood on the top and bottom of the elevator.

With more than a 100 flights I haven't had any issues.


Dennis

[Steven Kientz]

There are some adjustable horns for R/C that I have used on several profiles. Its a 6-32 machine screw  post  with a nylon piece thats threaded on the screw. For the one on the flap I put 2 of the nylon pieces. They are infinitely adjustable.

[John Park]

  John;
  I think I know what this is, but describe it more and where you get it. I'm picturing it in my mind in 4' by 8' sheets. I think I have some scraps around here some place left over from a project where I used to work.
  Type at you later,
  Dan McEntee

Dan:
'Formica' was a British Trade Mark (it may still be in use) for the ordinary kind of melamine laminate that you'd buy in big sheets to glue with impact adhesive onto e.g. a kitchen table.  It could be had in a whole range of colours and designs, and was about 1/16" thick - a darkish brown on the underside, slightly rough to help the glue to hold.  The last time I bought any was over forty years ago, for the tops of some cabinets I was making for my workshop: the offcuts have supplied material for wing-rib templates, control horns and all manner of other applications over the years, and I still have a few bits left!  A very useful resource: my little electric fretsaw cuts it with ease, by the way.
Regards
John

[Lauri Malila]

An even better material would be Tufnol sheet (also an UK product ❤️), either Carp brand (phenolic/cotton) or 6f45 (epoxy/cotton). It’s very easy to machine (especially the one with epoxy resin as it does not smell bad) and glue, and quite ideal as bearing surface. It’s not abrasive like GF plate. L

[Brett Buck]

An even better material would be Tufnol sheet (also an UK product ❤️), either Carp brand (phenolic/cotton) or 6f45 (epoxy/cotton).

   The US proprietary name for "Tufnol" is Micarta (which was patented by Westinghouse) and generates toxic and very memorable smelly smoke when machined. It's phenolic resin/bakelite with some sort of filler, the best of which is a cotton mesh, but is frequently only sawdust.  It is prone to cracking.   The kind with epoxy is is current called G10. Both are used for electronic printed wiring boards (PC Boards). G10 is OK for this purpose, no way on traditional Micarta - way too prone to cracking.

      Brett

[Lauri Malila]

That’s why I specified Carp and 6F45. They use very fine weave cotton and very good fibre/resin ratio.
I use both for engine parts, 6F45 in backplates and RLF1 (same as Carp but rolled tube) for bearing cages. Both are fantastic materials for high precision parts. L

[Brett Buck]

That’s why I specified Carp and 6F45. They use very fine weave cotton and very good fibre/resin ratio.
I use both for engine parts, 6F45 in backplates and RLF1 (same as Carp but rolled tube) for bearing cages. Both are fantastic materials for high precision parts. L

   Even the Phenolic type has some very good characteristics, particularly in high-heat situations. Bakelite (phenolic resin with carbon black and (usually) sawdust) and other phenolic with fillers are still use for handle on toasters, etc, where the low heat conductivity and temperature resistance, and the ability to form it, is still as good a material as exists. Micarta was the high-grade version of that type of material, but there are a remarkable variation, from the original Micarta filled with linen, to the low-ball stuff used in Hong Kong/Taiwan transistor radio PWBs, literally any absorbent fiber that falls apart at the slightest shock.

    Apropos of nothing, as far as I can tell, my *very earliest memory* was of the smell of my dad machining Micarta, to make a vacu-forming mold for some plastic "brick wall" panels - which he used to build a model of our church in New Jersey. I am not sure why, but I know when, it was when I was around a year and a few months old. The completed model was one of my first visual memories, with all the interior lighting (light gray filament transformer running 12V automotive lamps), it was magical. The molds were still in his junk box when he died 56 years later.

    Brett

[Lauri Malila]

I know that smell very well too😷. My memories come from when I made boomerangs from cotton Bakelite with woodworking tools. So usually bad tool geometry and un-necessarily high cutting speeds.
No doubt there is massive variations in quality, partially because people call several different materials with same name.
That's why I stick with Tufnol. It's not cheap but I allways know what I get.
G10 is ok, but in longer run I don't like the glass fibers, if it has to act as a bearing surface.

[Howard Rush]

I used to like that smell.  It also reminded me of childhood phenol— Band Aids, maybe.  Nowadays it portends the failure of something expensive.

[Brett Buck]

I used to like that smell.  It also reminded me of childhood phenol— Band Aids, maybe.  Nowadays it portends the failure of something expensive.

   Band-aid smell is boric acid. It portends the failure of a capacitor, since the electrolyte is still boric acid, just like it was in 1925. So when your flat-panel TV craps out, you might smell boric acid, because the usual cause of failure is the capacitor overheating and venting. Up until the mid-30s, what they put in radios for electrolytic capacitors were literally tanks of boric acid, with some curled-up aluminum plates as the electrodes. They were "sealed" with a rubber plug that had a terminal coming out of it, all crimped in place. Note that this was a closed pressure vessel, usually plunked down next to a bunch of nice hot vacuum tubes.

       That would usually last a few years, before the acid leaked out due to the increased pressure, then, the radio would start to hum, and have to be repaired. I occasionally find one that is still good, even after 90ish years, but they all have some sort of crusty mess where it at least seeped out. Modern aluminum electrolytic capacitors still use boric acid soaked into some sort of paper-like separator and twisted into a spiral. They are sealed differently, and have some crimps in one end to make it vent "safely" before it blows to bits.

    As an aficionado of toxic chemical smells, hot Micarta smells a lot different to me. The the outgassing is nominally poisonous, but not apparently poisonous enough to make sure your 1-year-old couldn't smell it. You get the same smell when you install a new power or rectifier tube in your audio power amplifier, the base is bakelite, and getting it good and hot the first time releases the smell. Its wonderful, it's the best thing about your rectifier tube failing. It's in the ballpark of bacon (Farmer Johns smells better than Oscar Meyer...) or hamhocks as far as pleasant household smells go.

     Brett

[FLOYD CARTER]

FR4 epoxy-glass circuit board material is available from Asian suppliers on e-bay.  Problem is, it comes with copper foil on one or both sides. This doesn't hurt anything if used for control horns or bellcranks. If you epoxy this material to itself, balsa or ply, you should first scrape off the copper to get good glue adhesion. (Ferric chloride will also dissolve the copper).

[Arlan McKee]

I have been cutting and building things from Micarta LE which is the designation for the phenolic/Lenin type for over 25 years. To me it wreaks of formaldehyde when it's cut. It's bad but G10 smells much worse and is much more toxic and irritating. 1/4 thick  or thicker G10 on a table saw glows orange on the leading edge of the cut. I keep a vacuum running while working with any of the G designations.

[Brett Buck]

I have been cutting and building things from Micarta LE which is the designation for the phenolic/Lenin type for over 25 years. To me it wreaks of formaldehyde when it's cut.

   Formaldehyde is definitely part of it, I think phenol is the rest of it.  And I agree that hot/burning epoxy is much nastier.


    Brett

[Serge_Krauss]

I recess the attach points for ply inlays and insert dowel pieces (end-grain) into the remaining balsa to take compression loads. These are epoxied (Edit: after I beef up the balsa by letting it absorb some CA..

Once, when I found that I had drilled my elevator control horn attach holes too close to a profile fuselage, I found a piece of angled-extrusion aluminum to make a new one with offset spacing. It wasn't aircraft-grade aluminum - just soft stuff. So there may be objections here, but it seemed to me that this easy-to-work stuff would be strong enough. I think I ultimately radiused the inner bend slightly. I think it's OK. Here are pictures.

[Brett Buck]

I recess the attach points for ply inlays and insert dowel pieces (end-grain) into the remaining balsa to take compression loads. These are epoxied.

Once, when I found that I had drilled my elevator control horn attach holes too close to a profile fuselage, I found a piece of angled-extrusion aluminum to make a new one with offset spacing. It wasn't aircraft-grade aluminum - just soft stuff. So there may be objections here, but it seemed to me that this easy-to-work stuff would be strong enough. I think I ultimately radiused the inner bend slightly. I think it's OK. Here are pictures.

   I have done that on RC (!) planes a lot a few times, I am sure it will be fine  It's just a matter of how thick and how soft the material is, thin and strong or thick and weak.

       Brett

[Dave Harmon]

FR4 epoxy-glass circuit board material is available from Asian suppliers on e-bay.  Problem is, it comes with copper foil on one or both sides. This doesn't hurt anything if used for control horns or bellcranks. If you epoxy this material to itself, balsa or ply, you should first scrape off the copper to get good glue adhesion. (Ferric chloride will also dissolve the copper).

As far as availability is concerned.....unclad FR-4 is sold by many US based suppliers.
Digi-Key is only one of them.
Here is a looong link to Digi-Key.

https://www.digikey.com/products/en/prototyping-fabrication-products/prototype-boards-unperforated/637?k=&pkeyword=&sv=0&pv128=417738&pv46=81044&pv100=7666&pv70=349187&sf=0&FV=-8%7C637&quantity=&ColumnSort=0&page=1&pageSize=25