Control horns, is it just me or... ?

[Rick Wallace]

I use 6-32 mild steel (NOT hardened) threaded rod for all control horns.
Available in multi-foot lengths from the local hardware store. 

An old K-Factor shows how to do this, but here are the highlights (pics
can be available if needed) 

The threaded rod is mounted in a dowel that’s mounted in turn to an end
grain balsa block
 both thick enough to match the control surface
they’re going into. 

Drill & tap a hole lengthwise into a piece of ½” dowel 
 the dowel
mounts into a ¾ x ¾  end grain balsa block set into the control surface.
When dry, sand flush w/ the surface and thread the rod into the hole /
hit w/ a drop or 2 of thin CA and it’s ready for the clevis connector to
be screwed on (tap the clevis connector 6/32 part way if necessary). 

For rudder pull pull, use the same threaded rod, but leave 1-1/2 – 2” on
either side of the rudder. Same mounting technique. 

 

Have hundreds of flights on planes w/ this setup and no looseness/
problems at all. 

 

-Hope this helps – 

Rick 

 

 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of David Wartel
Sent: Tuesday, September 02, 2003 10:14 PM
To: discussion at nsrca.org
Subject: Re: Control horns, is it just me or... ?

 

Check the Sullivan steel horns:

 

http://www.sullivanproducts.com/ContSysAccMainFrame.htm

----- Original Message ----- 

From: Keith Black <mailto:tkeithb at comcast.net>  

To: discussion at nsrca.org 

Sent: Tuesday, September 02, 2003 9:57 PM

Subject: Control horns, is it just me or... ?

 

When it comes to control horns for pattern planes it seems to me that
some of the most commonly used choices have a major flaw.

 

On my last plane I used the MK Aluminum Horns on all surfaces except for
the rudder where I used the IM pull-pull horns. Both of these are nice
horns except they have a major flaw when using a pull-pull setup. The
flaw is that the little black plastic arm that screws onto the horn and
connects to the clevis is so short that it doesn't extend out over the
hinge line. I know that with pull-pull systems it isn't *absolutely*
necessary for the connection to be exactly above the hinge, but the
further back it is the more slack there will be in the cable that is not
pulling.  In my opinion with these horns the connection point is too far
away from the hinge unless the horn is virtually mounted on the control
surface bevel (especially when it comes to rudder). This can easily be
seen in these "instructions" for installing the MK horns
http://www.centralhobbies.com/buildingtips/mkhorns/mkhornsinst.html.
Notice that in this picture there surface isn't beveled yet and the horn
is almost on the edge.

 

On my new plane I wanted to avoid this problem so I did some searching
to find a better solution. To begin with I looked for a longer arm to
connect to the MK horn, one that would extend out to the hinge line. I
found two options from Sullivan but both require too big of a horn
thread (6-32 and 8-32). My search then led me to two other choices that
seem to be good alternatives. The first is the ZNLine aluminum control
horns, but these are apparently only distributed by ZNLine
(http://www.znline.com/produits.php?langue=english
<http://www.znline.com/produits.php?langue=english&cle_menus=1025879382&
cle_data=1025901639> &cle_menus=1025879382&cle_data=1025901639) which
means an international order. The other solution I've found is by RC
Model Enterprises (http://home.att.net/~rc-enterprises/rcme_014.htm) but
these control horns seem very pricey!

 

If anyone could point me to a longer 3mm connecting arm that will fit on
the MK and IM horns I'd be happy (BTW, I've used the MK BB connectors on
the MK horn and they still aren't really long enough).

 

Is it just me, or have others experienced this dilemma as well?

 

Thanks,

Keith Black

 

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