### Help Support HomeBuiltAirplanes.com:

#### kent Ashton

I need to make a new canopy for a BD-5 project and they are asking $1000 for the originals. I've bookmarked several construction ideas from the web but if you have blown a canopy yourself, or made one on a mold, post your pics and experience or pointers to them. I like the use of oven-elements mentioned in the second website below. Interesting story in the third reference: The Recumbent Bicycle and Human Powered Vehicle Information Center Q-talk 144 - Creating a Q2 Canopy AeroBike Enclosed Motorcycle: Jan 2012 article DIY Forming Lexan Canopies - Page 2 - Pelican Parts Technical BBS canopies for model aircraft and other The Recumbent Bicycle and Human Powered Vehicle Information Center NextCraft™ Berkut_EZ info http://www.autocycles.org/glass.html -Kent #### TFF ##### Well-Known Member I have not made one except for models, but I did see a manufacturer do it. Low production. Big bubble for for a helicopter. They made a big oven and a hand made mold. Took about five guys on each of the four sides of the sheet of plastic. When it was ready they all have to pull it down and put their weight on it to keep it from springing up until cool. They probably start with a 8X8 piece of plastic for a 45" wide cabin but taller. #### Pops ##### Well-Known Member HBA Supporter Log Member Same there, just models and they were not that good. Would like to make a different windshield for the JMR Special but hate to waste the materials. Dan #### BoKu ##### Pundit HBA Supporter I need to make a new canopy for a BD-5 project and they are asking$1000 for the originals.
Having bought and sold a bunch of acrylic transparencies of about that size, that sounds like a darn good deal to me. You are likely to ruin about that much acrylic before you get as good optics and as good a fit as the original stretch-molded transparency.

My advice would be along the lines of the Japanese proverb "The earliest loss is always the smallest." That is, I'd suck it up, send whomever the money, and not bother buying a bunch of infrastructure and learning a bunch of specialized skills that I would never ever need again.

Thanks, Bob K.

#### kent Ashton

##### Well-Known Member
Hey, post how you made a canopy. Don't post how you didn't make one or how you would buy one instead.

Yeah, I know I can buy one from Alturair or get Todd to make one. Jeesh.

#### BoKu

##### Pundit
HBA Supporter
Hey, post how you made a canopy. Don't post how you didn't make one or how you would buy one instead.

Yeah, I know I can buy one from Alturair or get Todd to make one. Jeesh.
I'm just trying to save you a) time and b) money. I think that, given that transparencies for your application are both available and reasonably priced, you are better off buying rather than making. Considering that a transparency for the ASW15 sailplane that the BD5 cockpit closely resembles costs about $5k by the time it arrives in the US,$1k is a pretty good deal.

As to how I make transparencies, it's simple. I invest about $3k in tooling, send the tooling off to one of the best acrylic houses in the US, send them about$1.5k per copy, and I'm good to go. What I receive fits the fuselage perfectly at every edge, has great optics, and comes pre-trimmed and with the opening for the vent window already cut.

In my direct experience, many if not most of the folks who buy free-blown transparencies to replace their original stretch-molded parts are disappointed by the experience. For airplanes like the KRs and VariEZE that are designed around free-blown transparencies, it's not a problem. Those aircraft already have built-in contour changes at the edges of the canopy, so its no big deal when the location and degree of contour change varies a bit.

But for aircraft like the BD5 and similarly-shaped sailplanes, replacing the original transparency with free-blown often gets you a "twenty-footer" canopy that look OK from about that far out, but when you get close you can see obvious tangency mismatches around the edges. Sometimes it's pretty subtle and you get away with it. Sometimes it looks comically crude. Ya pays your money (or your person-hour equivalents) and ya takes yer chances.

Thanks again, Bob K.

#### Derswede

##### Well-Known Member
It is not easy. We would use a propane heater to soften the plexiglas and would use the old repaired but unusable canopy as a form. We did ruin some plexi. I suggested a vacuum motor to suck it down onto the form, but getting an airtight fit to the form was hard. Used lots of duct tape to try and seal the edges and a shop vac for vacuum...did not work, you need lots of vacuum as the window of time to stretch the plexi is measured in seconds. I built a wood box the size of the plexi sheet, it sat on top in a 2x4form, secured with screws in the corners..the propane heater sat in the box so as to concentrate the heat on the plexi. When it was nice and floppy, the form holding the plexi was lifted off and placed over the form. Wear Good gloves!! Worked ok for windshields, but I don't know if it would work well enough to duplicate a vacuum formed piece. You must be careful...I had some epic burns from hot plexi when we were trying that...don't think OSHA would approve. I was also a 16 yr old kid when we were doing it.
Still have the scars...but was pondering the same for a replacement canopy for a Monerai I am looking at. Hope this might help a bit, and good luck with your project!

Derswede

#### kent Ashton

##### Well-Known Member
use the old repaired but unusable canopy as a form. . . . you need lots of vacuum as the window of time to stretch the plexi is measured in seconds.
Good idea to use the old canopy as a form. Thanks.

BTW, I am patching the old canopy using a water-thin acrylic adhesive for cracks and Weld-on 40 (2 part acrylic) to patch old screw holes. It seems like it will work and will not be too noticable if I paint the edge of the canopy. It is hard to keep bubbles out of the Weld-on 40. I read that before using the mixture, you can hold it on a vibrator but mine must be too cold to allow the bubbles to rise to the top. Sigh. There are always tricks to be learned.

#### Attachments

• 53.6 KB Views: 108

#### Daleandee

##### Well-Known Member
I need to make a new canopy for a BD-5 project and they are asking \$1000 for the originals. I've bookmarked several construction ideas from the web but if you have blown a canopy yourself, or made one on a mold, post your pics and experience or pointers to them.
I only have experience fighting with factory canopies ... that don't count! Here's another thread you may have already seen:

http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/2860-molding-canopy.html

Dunno if this helps ...

Dale Williams
N319WF @ 6J2
Myunn - "daughter of Cleanex"
120 HP - 3.0 Corvair
Tail Wheel - Center Stick
Signature Finish 2200 Paint Job
114.9 hours / Status - Flying

#### Hugh Lorimer

##### Well-Known Member
Lexan 1.5 mm thick bent and a frame from 12 mm dia. alum. pop rivited on, side hinged. Double locked. Hughie

#### Attachments

• 45.8 KB Views: 90
• 55 KB Views: 85