WING SPAR CONSTRUCTION

The Wing Spar construction is in many ways similar to the fuselage construction.  It essentially is a truss, structurally designed for strength at minimal weight.  Here, two pieces of spruce are glued together to form the top and bottom caps.

Then the truss members are glued to the caps.

The photo above and below show something very important which you must not forget.  A small hole must be drilled through every truss member including the end pieces.  Remember the altitude and pressure changes.  We certainly do not want these things to start popping apart at altitude, now do we.

And finally the top spar cap and bottom spar caps are joined.  Again, there is a need to scarf the plywood to form pieces long enough to skin the spars on both sides.  Plywood grain is oriented the shortway (vertically) for strength.

Again note the holes through each member.