Canopy design flaw? Possible fix.

[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....

1) Add a second pin
2) Make the latch face rear.

Let me know what you think.

https://youtu.be/vtHeNaDZuak?si=QI83-Im_K5FsYioF&t=91

[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.

[Tony4aro]

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)

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.

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)

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.

[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.

[Area 51%]

It's too bad the resolution of the video isn't better, but I'm not seeing the alignment pin.

[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....

[Tony4aro]

Check out this thread:
http://www.sonexbuilders.net/viewtopic. ... tch#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.

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.

[Tony4aro]

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)

[Bryan Cotton]

So you think it was just that the latch came undone, and it wasn't a failure?

Yes, that is what I think.

[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....

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.