Ch 14.1: Center Spar

What I've Been Doing In My Spar Time

I'm skipping Ch. 13, Nose Gear, for now because I don't have my nose gear lift yet.  So, while I figure that out, I thought I'd tackle the center section spar.

The center section spar, along with the canard, is one of the most important parts of the airplane.  Aerodynamically it is responsible for carrying about 80% of the weight of the aircraft when in flight.  The canard lifts the remaining 20%.  It's a box structure made mostly of some lightweight and crazy fragile polyurethane foam, but of course it ends up being one of the strongest parts of the plane.

Completed Jig for the Spar

The spar is built on a jig that must be built first using 3/4" particle board.  The thickness of the board helps to ensure a nice straight jig.  The strange part about building it is that you're building a jig using dimension callouts in the 100ths of an inch, measuring with a tape measure in 10ths of an inch, and cutting with a table saw.  Amazingly, I think I got all the measurements as close as one could reasonably get under those circumstances.

Now it's time to start building the spar itself.

Onward!