Balancing the Elevator

The elevator and ailerons are generally required to be balanced to improve stick feel, longitudinal stability and reduce the potential for control surface flutter while in flight.  The Bearhawk is no different.  The method I chose to use to balance my elevator differs slightly from the Bearhawk plans.  The plans show clamping plywood to the leading edges of the elevator then pouring molten lead into a form, as shown here...

Since my Bearhawk kit is the Model B with airfoil shaped ribs on the horizontal stabilizer and elevator, I am working with compound angles where it would be quite difficult to form up and seal the leading edge of the elevator.  Therefore, I chose to take a different approach and form the lead into bars that I could attach to the inside of the forward ribs of the elevator.  Here is an example of the outcome:

This location isn't ideal in terms of balance effectiveness meaning that I really should be placing the lead as far from the fulcrum (pivot point) as possible, as the plans indicate.  This will still work, it just requires more lead to balance the elevator.  2.75lbs per side to be exact.  

To create the two lead slugs for both sides, I took a piece of 1.5" square tube and cut it to approximately 6" in length.  I then removed one of the tube walls with a metal band saw.  Finally, I welded caps to both ends to create a steel form.

I lined the form with three layers of heavy duty aluminum foil.  The lead I used came from eBay.  I purchased six 1 pound bars.  You can probably find cheaper (free) lead from a tire store.  

Using an oxy/acetylene torch I held each lead bar with channel locks and gloves and melted the lead over the form allowing it to drip in.  I couldn't hold the torch too close or it would melt the aluminum foil.  

I ground the square shoulders off 1/4" SS carriage head bolts so I could get a flush fit.  

Using fender washers and nyloc nuts, I attached the lead weights to the inside of the ribs.

Overall I am pleased with the results.  

It is important to remember that when balancing the elevator to account for the weight of the fabric and paint AFTER the elevator has been covered.  At this point in the picture the elevator appears to be perfectly balanced when it is actually clamped into position for the picture to demonstrate the clearance of the carriage head bolts.  This elevator is actually slightly forward heavy and should balance nicely after it is covered and painted.