Tip of the week - 130


Going to gear this one towards foam models since that is what I am most familiar with, but please add your input for control horn installation regardless of model material or style. The most important aspects of installing a control horns are the alignment and the strength of the install. Having a control horn pull away during flight is going to have nasty results. To get the throw of the control surface to move properly and equally in each direction requires proper alignment.
To properly align a control horn you want it to be installed so that the holes in the horn are directly over the hinge line. I searched google and this is the first image I found.



Notice that the holes in the control horn are always in a straight line from top to bottom. This allows you to install the pushrod into any hole and maintain alignment over the hinge line.



I am a big fan of the Dubro Micro Razor Control Horn for my EPP models



http://www.allerc.com/product_info.php?products_id=3211
On my most recent build I measured the distance from the holes to each peg. The distance is 11mm and 22mm for the front and rear pegs from the center of the holes. I then measured 11mm and 22mm from the edge of the control surface to the location the horn would be installed and drilled holes for the pegs. I then did a test fit and viola, perfect alignment!
Now to make sure it stays in place I put a good coating of Welder Adhesive on the pegs and underside of the horn, and dripped some thin CA in the holes of the foam. Be sure you install the horn quickly after dripping the CA into the foam since thin CA will set quickly. After I inserted the horn, I put a lite coat of Welder (hot melt glue works also) around the base of the horn and let it all cure. This was an EPP build, and you should not use CA or Welder when building with foams like Depron or Cellfoam as the glue will attack and melt the foam. The “Andrew Jesky takes RC to a Higher Plane” DVD shows him using foam safe CA for this step while building a depron model.
I typically try to install control horns at some point in the build where the control surface is not yet attached. This allows me to work on a flat level surface and not have to work around the entire model. I also do this so I can let the glue set while I work on another portion of the build. I hope that info helps a few folks out there and please feel free to post questions or additional tips.

ATTF

Love these tips! Keep 'em coming!

Excellent tip! This is another one of those things that seem so simple, yet messing it up can have such dire consequences.

For Depron surfaces, I like to squirt a drop of the White Gorilla Glue into each hole. It makes for a very rigid bond. Remember that the stuff expands, so don't go smearing a bunch on the surface!

I prefer medium CA on EPP surfaces myself. It's penetration stiffens up the area nicely to reduce control slop.

- Jim

Thanks Guys! I like the CA / Welder cocktail on EPP. CA down the holes so it gets in there well, then the Welder under the horn and on top of it so you have something to hold the top and bottom of the horn to the foam. Seems pretty strong and none have failed on me yet. I have a few EPP models with some wicked throws that really puts strain on the servos and they stay in place.

Diggs

OH, and I didn't know that Gorilla Glue was Depron save, but I never really thought about it... Great to know!