Home > VansAirForceForums

-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
w/a Donation

VAF on Twitter:

Old 05-13-2023, 11:20 AM
Lucky Aviation Lucky Aviation is offline
Join Date: Nov 2017
Location: Foster Kentucky
Posts: 44
Default Canopy Heat Treating

My friend who is an engineer and in the industrial plastics business guided me with heat treating my canopy to reduce stress.
I carefully measured the frame when installed on the airplane track and installed temporary bracing on the frame to keep things exactly where they need to be. We placed the canopy in an oven which is designed to anneal plastics. We brought the temperature up slowly to 190 degrees, maintained it for 2 hours and brought the temperature down very slowly.
I removed the clecos and the plastic fits the canopy frame perfectly with zero stress.
After going through this process, I believe that a simple homemade oven can be made up with some basic materials to accomplish this without spending a ton of money.
I was just lucky to know a guy who knows what he is doing and has a set up already.
I thought that it may help someone who is worried about too much stress on the plastic when riveting it to the frame, which may invite cracks.
Attached Thumbnails
Click image for larger version

Name:	IMG_1820.jpg
Views:	94
Size:	593.7 KB
ID:	42326  
Roy Schalk
RV-8 building N213RS
C182 N2396R
Reply With Quote
Old 05-13-2023, 12:12 PM
scsmith scsmith is offline
Join Date: Jan 2008
Location: Ashland, OR
Posts: 3,532

It is indeed quite easy to make an oven to do this kind of thing.

We made an oven for post-curing carbon-epoxy composite parts, primarily wing tips made with epoxy that requires a 150F post-cure.

The "oven" is just a box made from 2" styrofoam insulation available at home improvement stores. We pin the panels that form the box together with bamboo shish kabob skewers. Then we tape all the seams with 2" wide aluminum foil tape.

The heat source for the oven is an electric hot plate from Goodwill, and a 6" desktop circulating fan. We use a couple of oven thermometers stuck through the foam to the interior to monitor the temperature.

With the big L-39 "CEllipse" racing tips in the oven, it takes about 2--3 hours to get up to 150F, which is what we want for the post-cure cycle. Adding another hot plate would bring the temperature up faster obviously.
Steve Smith
Aeronautical Engineer

Becoming a repeat offender! Starting another RV-8 that will have the composite tapered wings

RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
Hobbs 725
1/4 share in 1959 C-182B (tow plane)
LS6-15/18W sailplane SOLD
bought my old LS6-A back!!
VAF donation Dec 2022
Reply With Quote
Old 05-13-2023, 03:19 PM
RhinoDrvr RhinoDrvr is offline
Join Date: Jun 2014
Location: Bonney Lake, WA
Posts: 236

I wonder if a completed canopy assembly could be heat treated this way after it was already attached to the frame, or if the differential expansion would just make the assembly more likely to crack during the process?
Evan Levesque
RV-8 / F/A-18A-G / F-16A-D
RV-8 N88MJ (Built by Michael Robbins)
Bonney Lake, WA
Reply With Quote
Old 05-15-2023, 10:00 AM
Paul 5r4 Paul 5r4 is offline
Join Date: Oct 2006
Location: Foley, Al
Posts: 726

EXCELLENT thread. Canopy cracks is one of the things i worry about the most. Especially in cold weather. I thankfully live in the south. I would love to fly up to Massachusetts to visit my son sometimes in the winter but the super cold temps keep me from it.

I would almost rather have a canopy that's in smaller sections or something to eliminate cracking issues. Thankfully none in the 11 years mine has been flying.

I wish I had known about this "stress relief" before installing mine.
Paul Gray
Foley, Alabama
N729PG..... 500+ hrs
RV 7A, Lycoming 0 320 D1A, Sensenich FP propeller
VAF supporter $$$
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -6. The time now is 11:24 AM.

The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.