From RCM Modeler Magazine:
• Shrink Form Your Own Canopies, RCM, January 1996, Dan Simenson.
How to "Shrink Form Your Canopies" was worked up as a simple way of making canopies for scratch-builders. It utilizes the plastic in 2 liter pop bottles, either clear or green tinted. With essentially free material and your hot air gun, you are ready to try it. It works well for canopies up to about 8-1/2" long and with the Alternate Method up to 11-1/2" long. That seems to the practical limit, as an opened up and rolled out 2 liter bottle gives a piece of material about 13-1/2" long. They are fuelproof and are not affected by acetone, MEK, or dope thinner. RC-56 cement works good for installation. Currently, I have several in use: an 8-1/2" on a .10 sized "Turbulent City," two 5"x3"x2-1/2" deep units on .40 sized models and an 11-1/2" on a .65 sized sport model. This process works for making engine cowlings also, but that's another story.
The canopy pattern or "plug" can be carved from any clear wood: balsa, pine, cedar, poplar, etc.. For best results, the plug should extend about 1/4" beyond the edges of the desired canopy. Final sanding of the plug should be with 220 grit paper. Do not paint.
(1) Mark a trim line and center tics on the plug with a felt tip permanent marker. Remove the label and cut both ends from the 2 liter pop bottle.
(2) Slip the plug and a scrap block of wood into the bottle, positioning the plug in the center of the bottle. Wedge a small block between the plug and block of wood to make a snug fit.
(3) Start shrinking the bottle around large bottom block first. Keep the gun moving. Next shrink the sides, then around the plug at the ends. Avoid too much heat at the very ends or they may curl up.
(4) When almost shaped, go over the whole surface carefully to get the last ripples out.
(5) Trace trim line and center tics on the plastic with a felt marker. Marks can be cleaned off later with acetone or thinner.
(6) Cut canopy along the trim line. After final fitting and cleaning, attach with RC-56.
Alternate Method for Canopies Up To 11-1/2" Long.
(7) Cut ends from bottle as before. Split down one side. Pull Sheet snug from front to back over the plug, placing tacks at each end beyond the trim line. Then pull down at the sides and tack or nail in place. Tacks or small nails about 2" long and can be used and need not be driven all the way in. There will be large "billows" along the sides, but they will shrink up.
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Apply heat to the large wrinkles first, alternating sides as you work from the center towards the ends. Finally, go over the entire surface carefully until it is smooth. Trace the trim lines and center tics before cutting out the canopy.
Topic: Canopies (Read 1039 times)