Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 8:49 am
by Tony4aro
Hi All.
OK… I know the canopy on our planes is part of the lifting body, and there have been a few sonex go down because of the canopy coming open. I’m assuming its a combo of loss of lift, and drag. In the safety section of this forum, the latest crash from this… the discussion was about the guide pin. I totally understand that it can get sloppy, and allow the canopy to slide back. SO… since it’s so critical, why not have 2 pins?
I am current starting to work on my canopy on my “A” Waiex… and I have been thinking about this. And I watched a video of a canopy opening after takeoff, and in that vid… you can see it is closed, but it slides back, lifting the canopy up. (I will link it below) AND… from anything I have read… this is how it happens… it starts with a slide back. In turn… the pin gets blamed.
With that in mind… why does the canopy latch face forward? If we simply turn the latch around… if the pin was lose, and the canopy shifted rearward… it would push the latch tighter into the body rail, and it would never lift.
Since I’m new to this… can you guys chime in and give me any reason this wouldn’t work, and more importantly… save planes, and potentially lives?
To sum it up…
- Add a second pin
- Make the latch face rear.
Let me know what you think.
https://youtu.be/vtHeNaDZuak?si=QI83-Im_K5FsYioF&t=91
Re: Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 10:02 am
by Bryan Cotton
Tony,
Interesting thoughts! I’m not sure the alignment pin is the culprit. And even with a good alignment pin, if the latch is not locked to the frame, it can move and allow a release. I think if I forgot my locking pin the spring would still hold it. And if my alignment pin failed, my canopy could only move back a little before it hit the turtledeck bulkhead.
The spring is a good secondary safety. Good use of the checklist is crucial. An updated locking system like the one John Monett shared, or the one Peter Anson sells seem like a good idea.
I believe if you turn the latch around, but don’t pin it, the canopy will still open.
Re: Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 11:48 am
by Tony4aro
Bryan Cotton wrote:Tony,
Interesting thoughts! I’m not sure the alignment pin is the culprit. And even with a good alignment pin, if the latch is not locked to the frame, it can move and allow a release. I think if I forgot my locking pin the spring would still hold it. And if my alignment pin failed, my canopy could only move back a little before it hit the turtledeck bulkhead.
I’m not 100% sold that it was a bad pin either… but it’s what the discussion seams to lead to on other threads. BUT… I can see how critical it is, and to a certain level, it has a “Single point failure” possibility. On the right side of our canopy, is a long hinge… very unlikely to fail. But if the guide pin fails… it will allow the canopy to distort and flex… and move to the rear on the left side. And I guess that is the second part of all this. Our canopies are VERY flimsy. If they were rigid, they wouldn’t flex, and the guide pin wouldn’t even be needed. (just my random thoughts and observations)
Bryan Cotton wrote:The spring is a good secondary safety. Good use of the checklist is crucial. An updated locking system like the one John Monett shared, or the one Peter Anson sells seem like a good idea.
Sure… the spring will help to keep us from forgetting something. (our lock pin) If the canopy is down… the spring will pull the latch forward for us. But this comes back to my original thought… we can have a spring, and a latch pin, but if the canopy distorts… it’s motion in flight will be a twist, and to the rear. From what I can tell… there is a lot of force on the canopy in flight.
But, do you have a link to the updated latch? I’ve see a “Short” video on something, but I believe it was a B model canopy. They are already more rigid with the machined bows.
Bryan Cotton wrote:I believe if you turn the latch around, but don’t pin it, the canopy will still open.
Sure… if there is no spring, and there is no “Lock”… the canopy could be popped open in flight. BUT… the flight forces couldn’t open it. (wind pushing back, and lift pulling it up)
Bryan Cotton wrote:even with a good alignment pin, if the latch is not locked to the frame.
This wording from you actually sparked a new thought. AND… is part of the problem. The latch is locked to the canopy frame, (A weak point in itself) but it is NOT locked to the fuselage. If the lock pin went through the latch, and into a hole in the fuselage… that would lock the canopy down in a real way.
I guess this is all in my head because in the video I posted… it very much looked like a latched canopy, but it was twisted away. AND… it seems like a failure point that can be solved and made more “Idiot Proof” (so to speak) with a little rework of the design. If the door on my warrior comes unlatched… it’s not a fatal issue.
Thanks for the input… it really helps getting feedback like this.
Re: Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 12:34 pm
by Bryan Cotton
Check out this thread:
viewtopic.php?f=21&t=6718&p=53311&hilit=Simple+latch#p50839
Regarding the Waiex video, there was no twisting until the canopy lifted. Then it was game over. The canopy is flimsy when open, but plenty strong when latched. If they had pinned it, or even if they had the spring to prevent the latch from migrating back, that would not have happened.
Re: Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 2:39 pm
by Area 51%
It’s too bad the resolution of the video isn’t better, but I’m not seeing the alignment pin.
Re: Canopy design flaw? Possible fix.
Posted: Mon Oct 09, 2023 11:50 pm
by tps8903
My over center Canopy lock. I also added a safety pin for the forward portion with a flag that says “Install before Flight”
I don’t know why the picture is upside down…
Re: Canopy design flaw? Possible fix.
Posted: Tue Oct 10, 2023 7:00 am
by Tony4aro
Bryan Cotton wrote:Check out this thread:
http://www.sonexbuilders.net/viewtopic. … tch#p50839Regarding the Waiex video, there was no twisting until the canopy lifted. Then it was game over. The canopy is flimsy when open, but plenty strong when latched. If they had pinned it, or even if they had the spring to prevent the latch from migrating back, that would not have happened.
So you think it was just that the latch came undone, and it wasn’t a failure?
I know I’m overthinking all of this, and there are thousands of flight hours on the original design… but we are al human, and things get missed. I’ll go look at the other thread now.
EDIT
OK… That’s the latch I’ve seen. But it’s a b-model. I guess it’s concept can be adapted.
Re: Canopy design flaw? Possible fix.
Posted: Tue Oct 10, 2023 7:03 am
by Tony4aro
tps8903 wrote:My over center Canopy lock. I also added a safety pin for the forward portion with a flag that says “Install before Flight”
I don’t know why the picture is upside down…
Interesting. I like the idea of a large handle that has an obvious visual that it’s not latched. Do you have any pics on how it actuates? FYI… it’s the right way when you click on it. (Not upside down)
Re: Canopy design flaw? Possible fix.
Posted: Tue Oct 10, 2023 8:15 am
by Bryan Cotton
Tony4aro wrote:So you think it was just that the latch came undone, and it wasn’t a failure?
Yes, that is what I think.
Re: Canopy design flaw? Possible fix.
Posted: Tue Oct 10, 2023 11:15 am
by tps8903
Tony4aro wrote:
tps8903 wrote:My over center Canopy lock. I also added a safety pin for the forward portion with a flag that says “Install before Flight”
I don’t know why the picture is upside down…
Interesting. I like the idea of a large handle that has an obvious visual that it’s not latched. Do you have any pics on how it actuates? FYI… it’s the right way when you click on it. (Not upside down)
I’ll take some pictures at the plane tomorrow if folks are interested. The lever locks over center, and slides the Canopy bar forward. I added a safety pin as a double back up to the over center lock.
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 7:26 am
by AlexZ
Canopy_latch.jpg (57.35 KiB) Viewed 3333 times
This is a simple latch at the rear.
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 7:56 am
by peter anson
Lots of good ideas here so I may as well plug mine. There are more than 80 of these out in Sonexland and I have not heard of one failing. They lock in two ways:
- The handle goes over center.
- The handle is locked in place by a ball into a recess in the housing. It can only be released by pressing a button on the outer handle or pulling the release knob on the inner handle.
It’s also pretty intuitive to operate. For more information check http://www.ansoneng.com/sample-page/products-summary/canopy-safety-latch/
It won’t prevent your alignment pin from falling out but my canopy is a pretty neat fit. I think that once the canopy is closed it wouldn’t be possible for it to move enough for the hook angle to slip out of the holes.
Peter
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 9:42 am
by Scott Todd
I agree with Peter. With his latch closed, its not possible for the canopy to move enough to become dis-engaged. Well at least on my Onex installation 
I’ve flown several Sonex’s and think Peter’s latch is almost a must-have. It’s so positive, locks in place, and allows access from both sides. Here is the thread with a few more details on mine:
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 5:40 pm
by GLENDSMITH
Interesting topic. My ONEX was built per plans and the canopy has seemed fine. One thing I have in my emergency checklist is to pull the safety pin so the canopy can be opened from the inside or outside easily. I have also been pulling the safety pin on final during normal landings just incase something goes wrong. Do you guys think I may be making a mistake?
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 6:24 pm
by Bryan Cotton
Glen,
That seems like a bad idea to me. Maybe on short final of an emergency landing makes sense, but for a normal landing I’d vote no. What if you have to go around and the canopy opens?
Re: Canopy design flaw? Possible fix.
Posted: Wed Oct 11, 2023 7:42 pm
by Dave Wolfe
If you crash the canopy will likely break anyway.
Re: Canopy design flaw? Possible fix.
Posted: Sat Oct 21, 2023 5:06 pm
by phenry
Here is my solution to the canopy lock problem.
Used it for eights years with no issues.
Yes, I know it can not be opened from outside.
