22 September 2017

First Flight Prep: Elevator balancing.

Van's suggests balancing the elevators separately.  Because my aircraft is not yet painted, my plan was to balance them slightly heavy.

My right elevator was too heavy and needed a few holes drilled in its weight to bring it more into balance.  Oddly, my left elevator was too light.  Here's the only picture I had showing how it likes to rest with the forward edge high.


Thus, it required additional weight.  That weight needs to be as far forward as possible to reduce how heavy it needs to be, thus I aimed for it to be a long, narrow piece.  But it also needs to be wide enough to accommodate a #10 screw.  Using a bag of hardware as a test weight, I was able to determine I needed about 7 - 8 ounces more weight.

I decided to drill out the CS4-4 rivets holding the E-912 Elevator Tip Fairing so that I could add a nutplate just aft of the stock weights.



Then I purchased an "electric ladle" made for melting and pouring lead (the melting point of Pb is 621.5°F).  Both the collected swarf from what was drilled out of the right elevator, plus a 12 oz sinker (also obtainable from an outdoor store) supplied the lead I would need to melt and mold a weight.  Originally, I purchased mold putty to make the mold.  However, using that putty, I found my first pour was not flat enough on two sides (which is necessary to rest up against both the web of the E-903 Elevator Tip Rib and the E-614 Counterweight already in place).


Next I used aluminum angles to re-mold the lead with 3 flat sides.  The mold putty was used to keep the four aluminum angles comprising the mold together.  But I found that the weight from this second melt, though it looked good, wasn't quite the right shape.  It was too long and narrow.


Finally, on my third melt, not using the mold putty but instead just using aluminum angles backed up by bucking bars (to serve both as large heatsinks and to keep my "mold" from moving), I got it right.


This additional weight contains about 7 ounces.


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