Ch 11.1-3: Elevators

Building the Elevators...

Like the canard, I built my elevators with foam cores from Eureka CNC.  They are perfectly shaped to contour and makes the job so much easier.

Do You Do Impressions?

Canard Jig impression made
in the bottom of my elevator core

I did have one problem...  Eureka packed my canard jigs in the same box with the elevators and they were so tightly packed against the elevator cores that they ended up causing some impressions in the core foam.  You can see the impression in the pictures at the right.

Normally this wouldn't be a big deal but balancing elevators and ailerons is difficult and I'll have to add micro fill to fix this which means unnecessary extra weight.  You have to use a minimum of micro, resin, etc. when making these control surfaces for them to balance properly.  It becomes that much harder when you have to do any micro contour filling like this.  I did contact Eureka and Steve offered to send me a section of elevator to replace the damaged section if needed.  In this case however, I think it will work out.  You can see that when the end is trimmed to the end of the torque tube, much of the problem is eliminated.  Added to that, since I made sure to place the damaged area on the inboard side, it will be further trimmed to an angle to match the fuselage so about 80% of the damaged area will probably end up being cut off after it's all said and done.



Torque Tube Hinges

Left elevator about to be mounted onto
the torque tube

First up is installing the hinge mechanisms into the torque tubes.  This went pretty much to plans but I would offer a few Tips.

1st, I've probably said this before but I purchase all the hardware I can from the Cozy Girrls.  Their workwomanship is first rate!  I like to build but I don't like it so much that I'm willing to manufacture my own metal parts.

2nd, it wasn't obvious to me in the plans which direction the NC-2 inserts are installed into the torque tubes...hinge pin hole up or down?  I didn't think any of the drawings made it perfectly clear.  The best picture was Figure 4 where you can see that the hinge pin hole is at the bottom of the insert relative to the interior flat portion and with the elevator upright.

3rd, before you secure the inserts with rivets, place the hinge pin through the NC-2 inserts.  This will help ensure they are aligned and help you end up with fewer problems getting the hinge pin in and out later.

And lastly, there have been some questions about which side of the NC-2 inserts do the torque tubes get the notch filed.  The archives have different answers, the most recent being that the drawing on Ch. 11 pg 2 is incorrect in showing dotted (hidden) lines for the notches (indicating the notches are only filed on the bottom side of the torque tubes) and that both sides should be filed.  When you go to mount the elevator with the NC-7 jigs, you realize the top (side furthest from the hinge pin hole) must be filed for that jig to work correctly.  The bottom side, doesn't end up needing to be filed at all to obtain full movement of the elevator.


Skinning the Elevators

Right elevator bottom skin (far) curing
while the left elevator (near) torque tube
mounting is curing.

Glassing the elevators is pretty straight forward however you need to do your best work getting all the excess epoxy out of the layup.  This will help you be able to balance them.  I wet out my glass on a sheet of plastic and leave the plastic on when applying to the part.  Leaving the plastic on makes it easy to eliminate air and squeeze out as much extra resin as possible.  I then remove the plastic and apply peel ply which soaks up more of the excess...more than I would have thought it would.

Glassing the bottom skin

Tip: Leave the trailing edge glass a bit long so you have room to cut and sand it to the correct length before the top skin is applied.






Before glassing the top skin, the plans have you remove some foam at the trailing edge, layup the top skin, trowel micro  in the void left on top of the glass-to-glass trailing edge and then leave to cure.  I did everything in the same order however I let the top skin cure before applying the micro at the trailing edge.  I had a slight twist in the aileron and wanted to weight down the trailing edge nice and flat while it cured.  I couldn't do that if the trailing edge was wet with micro...so I simply performed that step after the top glass cured and I had trimmed the trailing edge to the proper length.









Now that I had a left and right elevator, it was time to assemble them into one piece.

Onward!