Someone came along and asked, "Can we hide the belhorn INSIDE the winglet?" They did, and came up with the "internal rudder belhorn".
The problem with implementing the internal rudder belhorn into my airplane is that I had decided to not install a lower winglet. This meant that I didn't have the luxury of milling out a pocket (as indicated in the "internal rudder belhorn" plans) since my rudders don't extend as far down if I would have installed lower winglets.
So I came up with the following workaround...
First, I positioned the belhorn onto the bottom surface of my rudder and drew an outline onto the foam...
Looking at the belhorn from the side, I estimated how deep this pocket needed to be. This was extremely tricky... (keep in mind the wing is up-side-down... so the following references are based so you can follow along in the pictures) I wanted the belhorn to be below the wing's bottom surface... but it needed to be above the winglet pocket. Look closely and you can see my depth line of how much foam to mill out...
I double checked my marks.. and it was time to mill the foam pocket out...
Using a dremel, I slowly removed the foam...
This pocket gives the belhorn a perfect place for it to be floxed into...
Here I am double-checking to make sure the belhorn won't hit the bottom surface of the wing after I complete the wing tip ends...
Also, I made sure that when the rudder cable gets pulled, it would give me the necessary rudder deflection needed (22 deg min : 26 deg max)...
Also made sure that the belhorn would not touch the outside skin of the winglet...
Happy with the pocket, I then used the dremel to remove any micro to get a nice flox and glass-to-glass bond...
Ensuring that the belhorn cures in the exact spot so that the belhorn tip ends up at the rudder conduit when the rudder is deployed is crucial! So the best way I could think of to achieve this was to hold the belhorn in that position as it gets floxed in...
Making sure the belhorn is below the winglet's bottom surface...
With everything checked out... it was time to flox this belhorn in! I started out by painting plain epoxy onto the belhorn (only the portion that will get flox in of course!)...
Painted plain epoxy on the side walls....
Added a ton of flox into the pocket...
And positioned the belhorn in place... noticed I had inserted a bolt through the tip of the belhorn with a spacer under it so that it would hold the belhorn at the perfect height!
Made sure all the holes were floxed in...
I then prepregged 3 plies BID... and placed it on top.
After cure, I trimmed up and sanded the sides flush. This however does NOT complete the belhorn install. The "internal rudder belhorn" plans say to lay 2 plies of BID @ 45 lapping 1" onto the rudder skins on both sides. This layup was simply to "lock" the belhorn in the correct position.
Before moving forward, I did check that the belhorn cured in the correct position...
And that I did get the full travel of the rudder as required... perfect!
In order to lay the plies of BID 1" onto the rudder skins, I first had to mill out some foam... so I removed about 1.5" to make sure I had enough room... and deep down all the way to where the belhorn started...
I made sure to remove all the micro for a nice glass-to-glass bond... and protected the rudder hinge so that epoxy would not get into the loops...
I painted the sides with plain epoxy... added flox to the belhorn surface... and micro on the foam walls...
I then prepregged 3 plies of BID... and tucked it into the pocket.. creating like a "C".. touching the belhorn.. and then going up 1" onto the walls of the rudder... I then added a smaller ply to complete the exposed foam of the pocket...
After cure, I trimmed everything flush.. and sanded everything smooth...
I used liquid X30 foam and filled the pockets in... noticed the release tape to protect the belhorns from the expanding foam...
Sanded the foam flush with the rest of the rudder's pocket...
Cut one ply of BID at 45....
Poured micro into the foam... and laid one ply BID over it.. lapping into the rudder pocket's walls...
And there you have it!! Rudder belhorns are installed!
It was now time to fill the bottom of the rudder..
I zip-tied them up-side-down to stands to make it easier to work with...
I sanded the belhorn "dish" layup..
And used pour foam over the dish... boy, that foam sure likes to expand!
Mmmmm... looks like pound cake!
Using a knife, I cut the pound cake (foam) flush with the rudder bottom...
And sanded it flush...
I then made flox channels for flox corners using a dremel and a sanding cone...
Applied flox to the corners... and slurried the foam...
I then installed 1-ply BID... wetting it out with a brush...
After cure, I trimmed up the edges all around...
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