Balance Weights

Step 6 INSTALLING THE PITCH TRIM BELLCRANK AND THE ELEVATOR MASS BALANCE WEIGHTS

Here's a shot of the CS10 lead weights being installed onto the front of the elevators. These foam pieces are pretty straightforward to make. I used the J templates underneath, per plans, and added a piece of waxed paper to prevent them from becoming a permanent part of the elevator assembly. I didn't like the bump on the elevator behind them, so, I made some extra foam pieces later on.

While those pieces were curing, I went ahead and drilled the pitch trim bellcrank. I used a piece of conduit to stabilize the piece while it was drilled, plus back support the aluminum to prevent problems on the inside of the bellcrank when installed on the spool piece. I located these holes with a small piece of paper - wrapped around the bellcrank - that on which I had printed a CAD drawing with equal spacing for the six rivets. I'm not sure what dimensions those would have been, but, I wasn't into measuring them. I just let the CAD package divide the diameter into 6 equal portions.

After installed the extra foam pieces. I used a hack saw blade to rough cut them to size then sanded to shape. Maybe my CS10s are too small, or, my elevators are too thick - either way, they didn't look like the plans so I fixed 'em.

Here's a shot of me cutting the foam out of the balance weight slots. A nice upgrade for this plane would be to make the balance weight wider, then, use a shorter moment arm and have the weights be entirely hidden inside the canard. I'll do this on my next plane.... I want to finish this one.....

Here's the slots all finished and ready for glassing. You can't see it here, but, I cut a piece of foam for the "back" of the slot on a band saw with a pivot installed. This made for a completely smooth, correct radius cut. I then glued this into the slot. You won't see it, but, it might keep some wind or bugs out of there.

I made my slot a little wider than called for. I didn't want to end up with too close a tolerance after paint and etc. I may also put a layer of BID on the side of the weights just for strength reasons.

To make sure my weights fit properly through the complete range of elevator travel, I made some wood mockups of them, drilled them for the hinge pins and installed them. This was much easier than installing and removing the elevators 20 times. Sure, I'm sure these are not identical to the real ones, but, I still saved taking the elevators off and on 20 times.

My son James took this shot of me working on the second balance weight slot once the first one was complete. You can see how much the weights will stick out into the wind when the elevator is at full up travel. I'll wait until the plane is being finished to make little covers for these.

To set the .65" distance on the pitch trim bellcrank, I assembled the spool piece to the offsets and measured from the table. I wish there was an easier way to locate this piece, there doesn't appear to be.

Here's a shot of the tip fairings getter their 1 ply BID covers for the ends. You can also see the finished carbon fiber tube I installed. I'm not sure having the bottom of it open is a good thing, maybe I'll stuff some soft foam in there to prevent that. I think smaller tubes might have helped. I used what I had!

Here's the other side. Same issue with the tube. The inside end of it will be sanded flush with the BID once cured.

Last, here's the balance weight slots with their 1 ply BID covering. I didn't put any BID on the bottom, it's pretty much down to the top skin of the canard so I just microed it. I'll sand it smooth and once it's painted you'll never know. I also didn't put any BID on there to make sure I still got all the elevator travel I needed.

Here's the elevators, with the mass balance weights installed (and the 2 ply UNI layer added) re-assembled onto the spool piece, with the CS11 lead weights also installed. For the record, I wish I would have made a slight recess in the elevator foam before skinning them. That way, the 2 ply UNI layup wouldn't have caused a bump I'll have to fill in later.

A better shot of the spool piece with the bellcrank and CS11 lead weights installed.

A close up of the CS11 lead weight. No big deal here, drill the offset and the lead weight, install with some AN hardware and washers.

My elevator assembly balances nose down big-time. Better yet, if disturbed from nose down, it quickly goes back there. Don't believe me? Check out the video..... click here to view it

Here's the canard, ready for finishing and painting. I've re-installed the elevators now that they are complete with balance weights. I will leave the hinge pins "sticking out" for now. I think I have an idea on how I want to do the ends - left-hand threads, 4-40 in size, on the inside. That way, if I want to remove them, I can install a 4-40 screw and turn them out using an allen wrench or drill/driver. Want to see the canard "fly" - check out another video - click here to view it

My canard is now (almost) complete! I made up some nice straps and hung it from the floor joists in my basement workshop.

Oh my gosh - an empty jig table! Time to level it, then, move the fuselage onto it for Chapter 13!

The elevators (and canard) are now complete. On to Chapter 12!