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General control line discussion => Open Forum => Topic started by: Dennis Toth on October 14, 2022, 07:40:46 AM
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Guys,
Anyone doing custom vacuum formed canopies? Dave Migley (sp?) use to do them, anyone know if he is still in the stunt game? Anyone else doing them?
Best, DennisT
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Sig used to do them if you sent them a proper plug. You might call them.
Dave
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If you cannot find a source there are some very informative videos out there on vacuum forming canopies and larger hobby related items. It doesn't require that unique a skill set to build the equipment for home use and doing it yourself. Brodak sells the poly material of different gages, some use empty bottles. Once formed over the plug you fabricated next is to trim it to fit the fuselage.
Steve
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Check with Nick Zirelli at:
https://ziroligiantscaleplans.com
I sent him a plug and the canopies he did for me were fine.
Also, Keith Sparks with Park Flyers has dozens of canopies, all types and all sizes. Suggest you contact him to see if he will form a canopy from your plug. I think he can send instructions on how to prepare your plug.
His website:
https://parkflyerplastics
Sig would be a good alternative. They have done canopies for me also.
Let us know what you end up doing.
Keith
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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.
(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.
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Try parkflier plastics, they might have something close enough.
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Try parkflier plastics, they might have something close enough.
This! I dealt with them a couple years ago, needing a canopy for a PT-26 that no one seemed to make. He explained what he needed for a plug to make me one. I made the plug to his requirements and for a pretty small fee I got 3 canopies back in the mail. I must have done a good job on the plug because he asked if he could copy it to add the item to his list of offerings.
Gary
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Tom,
Very interesting information. I assume that what happens is that the bottle plastic thickens as it shrinks down around the plug and you get a reasonably solid canopy out of it? I tr ied using a sheet from a report cover to make the Barnstomer sewn canopy but it is only about 0.008" thick and feels very flimsy. I want a canopy that if someone grabs it will not pull lose from the glue joints. I think something around 0.015 or 0.020" would work. Is there a video on YouTube for doing the bottle canopies?
Best, DennisT
Update: I found this YouTube video on doing the Pop Bottle mold method, looks like it might be worth a try: https://www.youtube.com/watch?v=UwsqUccbZws