The FireFly Re-Visited

Last night, I had a little spare time on my hands, so I sat down at the rocket bench to repair the Firefly glider, which had suffered a broken attachment pin on its May 5^th maiden flight.

As I was gluing the piece back on, I took a closer look.
This little piece of balsa is certainly required to do a lot.

In fact, it’s the prime focal point that takes the brunt of all the glider’s flight stresses.

First, it has to bear the G-forces acting on the glider at liftoff.

Next, it handles the weight of all the drag forces acting on the glider during boost and coasting phases of flight.

Then, it has to withstand any shock forces associated with engine ejection and glider separation.

Finally, it is always the first point of contact on the ground after gliding flight, i.e., the model’s ‘landing gear’.

That’s an awful lot to ask of a little sliver of balsa wood.

I realized that, if I didn’t want to be repairing this attachment pin after each and every flight, some engineering needed to be done to remedy this weak point.

Drawing on pop-pod boost/glider technology, I decided that the best course would be to apply some reinforcing sides on the pylon/pin assembly.

For this, I cut out a couple pieces of 1/32” thick plywood.

After sanding down the dowel pin to match the thickness of the glider’s nose, I wrapped a piece of sandpaper around a ¼ “ dowel and carved out a little hollow in the nose to make a cavity for holding a glob of trim clay.  This will cut down on the amount of clay that normally has to be molded around the outside of the nose for proper flight trimming.

The plywood sides are then glued on, shape sanded, and finished to match the rest of the model.

With this new design modification, it is hoped that the firefly will log many more flights without losing its nose every time!