Making cowels and canopies

There is an interesting article showing how to make canopies and radial engine cowels out of plastic pop (soda, cold drink, refresca, gasioso, etc. depending on where you live) bottles in the June 2004 Flying Models. Looks cheap and good. There is a review of Brodak's Olympic MK. VI kit. Also interesting stunt and combat columns. I have to say I think Flying Models is the best general modeling mag going. Cheap and good!

>There is an interesting article showing how to make canopies
>and radial engine cowels out of plastic pop (soda, cold
>drink, refresca, gasioso, etc. depending on where you live)
>bottles in the June 2004 Flying Models.

This is one of the most clever things I've seen in a long time. I didn't realize that the PET soda bottles have thermal memory and will shrink around a plug when heated. Makes sense, since they are blown (stretched) into a cavity. Just think of the possibilities?! How about "shrink molded" fuselages for 1/2 A models? Carve the outside of a hollow log fuselage once, and then produce as many as you like. Tough, fuel proof, and virtually free (you do lose a $0.10 deposit if you live in Michigan ). There are removal issues of course. You would probably have to slit them along the belly like a fish. Currell will probably shoot me for suggesting this one . And paint them from the *inside* like an RC car body for an indestructible finish.

That is waaay too cool! I gotta go to the store tonight to get some bottles. The only real problem that I can see is that soda comes in these kind of bottles, not beer! Now I'll select the beverage based on the color and thickness of the container, not the color and taste of the product?

And the "little guy" magazine continues to provide the great articles. The last two issues have convinced me to re-subscribe.

If anyone tries this out, try to get some photos to post. I want to try a removable pushrod exit cover that actually fits the model....

Making cowls and canopies is tricky. You need about 8 sets of hands to pull the plastic down on your plug. Currell

This is the original article published in RC Modeler Magazine, January 1996 by Dan Simenson.

• 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.

(8) 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.

The 1995-96 Aeromodeller Plans Handbook #1 has an article giving both conventional and pop bottle methods of making canopies. So this technique has been around for awhile. Probably needs to be rehashed every so often.