This is part 3 of an article describing the repair of
Thwing! due to damage caused when the motor came loose from its mount in
This is not a typical spar reconstruction in that the spar that broke is not
critical to the strength of this wing.
If a spar breaks in a conventional wing then it should be joined back
together with a piece of plywood on both the front and back of the spar.
The plywood should extend several inches past the break in each direction.
The thickness of the plywood will vary depending on the size of the aircraft
and the location of the break.
For example, on a .40 size model having a spar break near the root I would
use at least 1/16" plywood on the front and back of the break. I would
make the new braces about 6" long. It should be epoxied in place and
clamped securely for the strongest possible joint.