Here is a great tip for installing a bubble canopy from Gerard Goepfert from Scottsdale, AZ. He is a member of the Scottsdale Model Flyers. Thanks Gerard!
1. To begin installing your bubble canopy cut it to shape as you would install it on the airplane, trace the outside shape of the canopy onto a piece of 1/16” sheet balsa. Cut out the shape you traced, but make it slightly smaller so it will fit inside the canopy at the bottom edge, which would rest on the airplane.
2. Use 1/8” square balsa and attach it atop the perimeter edge of the 1/16” balsa piece, which fits inside the canopy. You now have a flat piece of balsa sheet with a 1/8” raised edge (a wall) around the perimeter. Sand and fit to the inside shape of the canopy.
3. Fasten your pilot to the sheet balsa, paint the balsa as this will become the floor of the cockpit.
4. Paint a 1/4” band around the lower outside edge of the canopy. This could match the color of the fuselage or in my case; I painted the lower edge black.
5. After the paint dries, fit the balsa cockpit floor inside the canopy for ta test fit. Sand the edges, bevel the balsa wall, etc.
6. Use a piece of 400A sandpaper and slightly roughen the canopy just under the paint, around the whole perimeter.
7. Epoxy your painted and finished balsa cockpit floor onto the fuselage where the canopy will be placed.
8. After the cockpit floor is firmly glued in place. Apply some 30-minute epoxy around the inside bottom edge just under the painted 1/4″band. Use enough epoxy to cover the plastic canopy edge only. Take your canopy place it over your fastened cockpit floor and press down into place. You’re done!
You will see that the canopy is fastened in place, neatly, without screws, pins or sloppy glue showing anywhere. Best of all it will not come off. One extra step I did was to thin some epoxy and coat the underside of the cockpit floor, let it dry and then fastened it to the fuselage. This was to prevent any oil or fuel form softening the balsa cockpit floor and discoloring it. You will not see the balsa wall since it is covered by the paint on the canopy, and there is no epoxy smeared around the fuselage outside the canopy edge. I somehow devised this on the fly and I was so surprised at the result. I have a beautiful plane and at first, I was worried that fastening the canopy would look poorly, but with this method that did not happen.