Elevator mass balance

The Roncz canard plans shows us how to install the elevator mass balances. Each elevator gets an inboard and an outboard mass balance.

Let's start with the outboard weights... page C-1 gives us jig "J"...

I purchased my mass balances from the Cozy Girls...

I then cut a few blocks out of 1" thick H100 Divinycell foam (6 lb/cu ft)... butted it up against the elevator... and traced out the outline...

Took it to the bandsaw and did the best I could... but it was difficult to get a nice smooth radius...

So I took it to my router table and smoothed it out...

Perfect fit!

I then positioned it along side the "J" jig and weight... and traced out the aft edge of the weight onto the foam...

This let me know precisely where to trim the foam piece...

Taaaaa-daaaaaa! Perfect!

I noticed the two weights were not identical.. so I labeled the two and made sure I worked with each one separately...

I then measured 7.5" from the outboard edge (as indicated in the plans)...

Notice the mass' inboard mark at 7.5" from the elevator's outboard edge... and the mass' outboard mark at 6.7"...

I then had to trim the width of the foam spacer...

That's much better!

I then test fitted everything together... squaring it up with the leading edge..

Looking good!

The plans say to bond everything with 5-min epoxy... so I covered the elevator hinge slot with blue tape (to prevent any epoxy run off from getting in)... and sanded the surfaces dull.. including the weight..

I placed plastic wrap between the weight/spacer and the J jig to prevent it from getting stuck to the jig...

I mixed up some 5-min epoxy and bonded everything together...

Verifying everything is squared... perfect!

I repeated it for the other elevator and let cure.. I then cut a "V" into foam blocks to prop them up...

Sanded the lead weights so the wet flox would bond, sanded the foam spacer flush with the weight, and sanded the elevator area aft of the spacer for a good glass-to-glass bond...

With everything prepped, I painted plain epoxy on the weight, spacer and aft of the spacer...

I then smeared wet flox on the weight and spacer (not on the sides)...

I wrapped the first UNI ply and stretched the fibers tight...

Wetted the UNI ply out...

Then applied the 2nd UNI ply...

And wetted the 2nd ply out...

I finished it off with peel ply for a nice transition..

I let both cure overnight...

Next day, I had to remove the peel ply and trim up the edges flush..

I used the dremel first and then sanded everything flush by hand...

Taaaa-daaaaa!!! Outboard elevator mass balance installed! The sides get micro'd during finishing...

Are we done?! NOOOOO... now we have to make the elevator mass balance pockets! How else is the elevator going to fit?!

Started out by bringing the elevator into position and marking the location of the weight onto the canard...

I used the canard contour checking template to help me draw a straight line down to the trailing edge..

Looking good!

Multi tool to cut the lines...

And a smaller blade to cut the fwd and aft lines...

I then used a blade to pop the fiberglass off...

Then the dremel to remove the foam and trim the sides...

A metal file to make everything straight...

Notice the notch goes all the way down to the top of the canard...

I then test fitted the elevator to see if the notch needed opening...

Since I figured I would be test fitting many times, rather than installing the elevator hinge pin all the way through, I simply slid a long AN bolt on the inboard end...

And the elevator piano pin on the outboard hinge only...

The plans say to have a minimum of 0.6" spacing on all sides... so I needed a little more trimming...

There we go!

Elevator trailing edge up... (the canard is upside down)

Elevator trailing edge down... (the canard is upside down)

No binding! Looking great!

No binding! Looking great!

Are we done now?! NOOOOO!!! Now we have to apply 1-ply BID to the pockets.. and while we are at it, lets put that 1-ply BID on the outboard rib...

Flox corner all around the rib...

Plans don't really say anything about how to apply the 1-ply BID into the pocket.. but I went ahead and put a flox corner all around the pocket as well.. I would hate for this 1-ply BID to come off in flight and jam my elevator!

Repeat for the other end...

Better pic of the flox corner around the pocket...

I then cut the 1-ply BID pieces... and taped the outboard hinge to protect it from any epoxy...

Painted plain epoxy inside the flox corners... then put flox... then slurry on the foam..

Same for the end ribs...

Wetted everything out with a brush... and peel plied for a nice transition...

 Now are we done?! NOOOOOOO!!! We still have to install the INBOARD weights! I placed them against the NC12...

And marked the holes...

I took the weights to my drill press and drilled away! This was my first time drilling through lead.. it's so malleable that it forms all these spikes!

I had to let it cool and use a hacksaw to remove it!

After cleaning it up, it's ready to be installed!

The original plans say to use AN509-10R14 bolts (counter sunk into the CS12)... but since I am using the offset torque tubes that are spaced further apart, I don't think the AN3 bolt head will interfere..

These are AN3-12A bolts...

Ok, now we are done!! Elevator mass balance weights are installed! I will check for proper elevator nose down later (as I still have to trim the elevator's inboard ends and layup those ribs).