SonexBuilders.net

Greetings,

One thing that worries me about the Onex, and low wing planes in general is getting trapped inside if it flips over. Around here there are very few flat places to land, and often they're rolling field with corn or soybeans, and potentially soggy. The chances of flipping over are fairly significant if you had to make an emergency off airport landing. I've wondered if you could intentionally ground loop the plane to hopefully let one of the wings or tail keep the plane from flipping.

Between the engine, turtle deck, and vertical stab, I think a fairly slow flip over would leave the cabin intact, but you'd have a fairly small area to crawl out to the side. The obvious problem is the canopy, which of course you can't open. You can assume it will break to some extent, but likely not enough to get out.

What tool would you carry to break the canopy out of the way to crawl out? Are there pictures that show flip overs and how the canopy looked afterwards? I'm imagine you'd be pretty motivated to get out, and you'd also end up with some cuts in the process.

In my RV-8, I had an old F4 canopy breaker knife, but those aren't so easy to find. This looks like the same idea in a more generic form, so I ordered one. https://flyboyaccessories.com/product/c ... py-breaker

Ka Bar Usmc style knife. It's basically a knife, hammer and saw all in one.

Yeah, that would probably do it, and could be handy if you had to survive in the woods for a few days :-)

Having a sharp edge could be useful to score a line you'd hope to break. The old F4 wasn't really sharp as I recall, though it was old. Actually I think I still have one of those somewhere, but it will require some searching.

Quickest way to break a Sonex canopy? 8~)



Seriously ... if you have nothing else available, use the seat belt buckle to break the canopy. In most accidents of Sonex aircraft that I'm aware of that have resulted in the aircraft being overturned, the canopy was already trashed. Only problem was getting it out of the way to exit without getting cut ...

Yeah, the drill bit is an old joke for sure :-)

I'm sure there's no single answer to how much the canopy would break, and I'm not really looking find out. Maybe I'll try to find some pictures of overturned aircraft.

I plan to use the small halon fire extinguisher in the airplane to break out of my (factory low wing) if the one door will not open, by using it to break out a window or the windshield.

On November 15, 2021, I had the lovely experience of a desert landing in the 2nd of the two Waiex's I built. I carry a glass break hammer/seat belt cutter. Didn't need either. The Waiex flipped over after a 46mph touchdown and a slide/skid of about 70 feet. The terrain where I touched down was a lot rougher than the area where it came to rest. The turtle deck and tail held up extremely well, the canopy cracked wide open on the port side leaving a gap easily large enough for me to crawl out of after the dust settled. Not easy to tell from the photo, but there was plenty of room for me to get out. A failed $6 valve adjuster was the cause of this mess. I should have bought the $9 ones!

Structurally, these Sonex's have very strong airframes. If you fly them all the way to the accident sight I believe your survival chances are high.
Stretch your glide, cause a stall or spin, and all bets are off. Fly the plane.

The N number is now on the RV7-A I will finish this year.

Hi Lou, Man, I'm sorry you had to answer this from personal experience, but it's exactly the sort of info I was hoping to find. It's encouraging to see how well the airframe held up.

I had wondered if the Waiex tail would be better or worse when it comes to landing upside down. I had figured a vertical stab would maybe let the plan roll more to one side, making more room to get out. Of course that assumes the vertical stab survives.

I totally agree with flying it all the way to the best possible outcome. You'll love the -7A, but you know that if you had an -8. I built two -8's and a -3B. I miss my original -8.

Thanks,
Rusty

I copied this over from the "Lessons Learned" section. Probably should have posted it here first:

I had a habit of not snugging up the lap belt on my 4 point harness in my Thatcher CX4, and the shoulder straps were kept fairly snug but not so much I couldn't reach anything easily.
This placed the buckle somewhat higher than ideal. On a flipover crackup, the buckle struck the stick and was driven into my chest cracking my sternum and cracking fracturing 4 ribs. Just to make things interesting I was trapped, jammed upside down with my head jammed into the ground. It was dark and no way to get out with only a small gap between the ground and the longerons. A clicking sound reminded me that shutting down the fuel pump would be wise. Especially since this was a wheat field. Funny how hard it is to find the master switch when you're upside down in the dark. I decided that I might get into a better position if I undid the harness. It helped but not much.
Happily, help was on the way and after maybe 5 looong minutes I heard my buddy who had been waiting to take off while I was landing, "Are you all right?"
"No, but nothing seems broken. Get me the hell out of here"
His son lifted the wing and he dragged me out. By then I knew my chest was compromised. I lay there a while till the ambulance came, along with police cars, and the fire department.
A week in the hospital, and a long recuperation. My back is still not right 2 years later.
What pisses me off most about the whole thing, and the lesson to be learned is that if I'd had the harness done up properly I most likely would have walked away with some pulled back muscles.
https://youtu.be/XXcU4mfGOtQ

And thus the advantages of having everything in reach when seat and shoulder belts are fully brightened. I could not reach brakes and flaps with shoulder belts tight and converted to toe pedal brakes and electric flaps on my A series. also added panel mounted fuel shut off so could pull that off before off field landings. That also gives visual indication that fuel valve is fully open before takeoff and has not been inadvertently bumped to partially closed.
There have also been significant head injuries incurred when shoulder belts were not tight.

David A.