I put the final layer of wood glue on, then sanded it when it was drying. I then put a single coat of white on the glider. It'll get another coat tomorrow; the main body, where weight is less of a factor, will get a coat of primer first.
I brushed on white paint to cover the grey epoxy clay, plus a few spots on the trailing edges of the wings and tail fins that weren't covered in the original finishing.
I got lots of work done. First, my dad cut out two of the 8 triangles that make up the main body. I sanded them and butt-glues them together with wood glue. It's currently drying.
Next, I started work on the motor mount. I decided to go with the conventional design used in commercial pyramid kits, where inside the pyramid is a square bulkhead with a large tube in the middle. Inside the large tube goes the motor mount tube with centering rings attached to it to fill the large gap. The parachute(s) goes between the inner and outer tubes and is pulled out when the motor ejects.
By pure luck my dad had a 54mm hole saw that precisely matched a 2" cardboard mailing tube I had lying around saved for something like this. I cut out 3 circles from my 1/4" plywood. Through one, I drilled 2 1/8" holes through. Through the other 2, I drilled 1" holes which I sanded (using a dremel disk on a drill) to 1.25". I cut a 5" length of mailing tube and a 6" lenght of 29mm tubing, plus 3' of 1/8" kevlar string.
I tied the kevlar string through the 1/8" holes in the bulkhead disk, then put a drop of CA (superglue) on the knot to hold it. I then glued the bulkhead into one end of the 2" tube. The 2" tube will be permanantly attached to the main body of the pyramid and will hold the motor mount and parachute during powered flight. The kevlar will tie around the motor mount and hold the whole thing together.
I wood-glued the two centering rings to the 29mm motor mount tube, which is 6" long - just big enough for the 5.994" length of the 29/40-120 casing I intend to use with it. Tomorrow I'll put fillets on the other side of the centering rings, the bulkhead joint, and the middle of the one assembled pyramid side, plus of course cutting out and gluing the other sides of the pyramid. First flight will likely be in November on a G53 Black Max reload.
The Boston Projection
17 hours ago