Jump to content

How safe are bubble canopies?


Recommended Posts

There has been an intense debate about the reliability of various aircraft engines. That got me to thinking about outlandings. Two particular incidents came to mind: the forced landing in Lismore where two people perished and a forced landing at Jacob's Well where two people walked away. In both cases the aircraft landed off field and due to rough/soft ground both aircraft flipped. One significant difference between the two accidents was obviously the fire at Lismore. HOWEVER, I feel that if there had been a post crash fire at JCW, it is still concievable the two occupants may still have escaped. This is NOT the case with a bubble canopy.

 

I know from driving the highways and byways of this great wide land that most of the fields that look suitable for outlanding from 3,000 feet or higher are quite rough and or have very long grass when you get up close to them. I assume that if I have to do a forced landing, my airplane WILL end up on it's back.

 

My question is, given the emphasis on assuming our engines WILL stop at some stage, are bubble canopies really safe for recreational aircraft?

 

I know I'm about to cop grenades from all sides and probably alienate those with bubble canopy aircraft. But still the question remains.

 

 

Link to post
Share on other sites

Or worse if you had to ditch it into water, I just don't know how you could possibly open a canopy that hinges from the front if you were upside down it the water.

 

A mate who is on the RV forums a bit says that there is a couple of RV builders who have put escape hatches in the aft floor of the luggage compartment behind the seats to use in such an emergency.

 

At the risk of starting the 'high wing low wing' debate I feel a lot safer in a high wing although I really do enjoy flying low wings.

 

JimG

 

 

  • Agree 1
Link to post
Share on other sites

They're fine as long as you don't turn upside down on landing. I've heard that it's also better not to have an undercarriage if you're planning to ditch, but what the heck - I've decided to leave the wheels on.

 

rgmwa

 

 

  • Haha 2
Link to post
Share on other sites

It is a point worthy of some thought. Flip overs are common probably with nosewheel planes more that the other. Sitting there with a hot engine and smelling fuel and not being able to get out is grim. A roll bar of some kind would have to be a consideration. Getting out through some other exit seems unlikely. Nev

 

 

Link to post
Share on other sites

Despite my last post, I agree that bubble canopies are not great in a flip-over, either hinged or sliding. This has been discussed a good deal on the RV forums - more particularly how to get quickly. I think a high wing would generally be safer.

 

Even if you could engineer some kind of hatch in the baggage floor, the contortions required to get to it when upside down, even if uninjured, makes me think it would be a waste of time. You might have time to open a slider before a forced landing (but not necessarily enough to get out), and a tipper is always going to be a problem.

 

The best option would be to have something handy to break the canopy enough to get out. If upside down in the water, you would probably have to do that to equalise the pressure to have any chance of pushing the canopy open. Even then, without some kind of training at exiting an aircraft underwater, you'd need some luck on your side to make it out.

 

My RV-12 has a front-hinged canopy and a pretty hefty roll bar, which would/should provide some level of protection, but I hope I never have to rely on it. One of the builders did some testing on an RV canopy to find out what worked best to break it:

 

http://www.europa.com/~swayze/RV-7A/Chapter105Meeting.html

 

rgmwa

 

 

  • Informative 2
Link to post
Share on other sites

rgwma: I watched that video about the canopy breaker tool. If I had an aircraft with a bubble canopy, I'd be looking for one of those. I believe they are readily available as an accessory for cars for breaking the windscreen or side window to escape if the doors are jammed or the car is submerged. That tool seemed to work well on what appeared to be an acrylic canopy. I wonder if it works as well on polycarbonate.

 

 

Link to post
Share on other sites
rgwma: I watched that video about the canopy breaker tool. If I had an aircraft with a bubble canopy, I'd be looking for one of those. I believe they are readily available as an accessory for cars for breaking the windscreen or side window to escape if the doors are jammed or the car is submerged. That tool seemed to work well on what appeared to be an acrylic canopy. I wonder if it works as well on polycarbonate.

Yes, I bought a couple of those gadgets for the plane, but they are fairly light, so I've been thinking about one of those stubby hammers, or maybe a cut-down welding chip hammer. The problem is where and how do you secure it so that it will stay in place during the impact, not be in the way, yet be easy to locate and easily removed from its holder when you need it? My plane has what I assume is an acrylic canopy, but the rear window is Lexan which is a polycarbonate. Polycarbonate is pretty flexible and tough, so something a bit heavier than those safety hammers (but still with a pointy end) might be better.

 

rgmwa

 

 

Link to post
Share on other sites

Scott,

 

As safe as the pilot who makes the landing or the force landing.

 

I have a bubble canopy in the Tecnam and I am as comfortable in that as I am in my car with a "bubble" canopy/cabin.

 

Choice is easy high wing or low wing they both will have pro's and con's just up to you to decide.

 

Alf

 

 

Link to post
Share on other sites
Guest Error404

I'd like to see an average sized man fit out an escape hatch under the luggage area of an RV6 !! A circus performer maybe, but not a normal sized Aussie. Too bad if your luggage was in there too.

 

 

Link to post
Share on other sites

One of the reasons I went from the SportStar to a Foxbat is that I feel like I'm sitting in a roll cage in the Foxbat, and I think it will be easier to push open a door,even if it's warped, than try to lift the whole aircraft off the bubble.

 

However, this would have resulted in low wings being abandoned long ago if it were really a problem. I don't think it's high vs. low wing, and we shouldn't be distracted by that.

 

It's are you in a bubble or a cage? A low wing can be build with metal forming the cage you sit in, so has some strength when on it's back. And it also has smaller windows in metal frames that you could kick out.

 

A true bubble is like a fighter jet (or SportStar) and there is no structure to offer support, and nothing but the entire canopy to try to break.

 

 

Link to post
Share on other sites

A lowing aircraft like a Sonex where the occupants are protected in a roll over by the Fastback type fuselage would IMO be good. A fuselage where the canopy is like a jet ( As Ryan has mentioned) or RV3/4 not as good.Both the RV 3 & 4 have a roll bar, but if the aircraft flips over in really soft, boggy soil, the roll over bar might bury down into the soil so deep as it may be useless for its intended purpose.Not so good.

 

 

Link to post
Share on other sites

Just out of interest. A local engineer (Bill Whitney) ran some ran some light aircraft design courses a few years ago.

 

Bill is very big on building survivable structures, there is some data in his course notes regarding what should be acceptable rollover protection in a light aircraft.

 

 

Link to post
Share on other sites

My Golf has a reinforced rib going over the canopy. In training I was told to release top lock before impact. If inverted kick the perspex out.

 

A lowing aircraft like a Sonex where the occupants are protected in a roll over by the Fastback type fuselage would IMO be good. A fuselage where the canopy is like a jet ( As Ryan has mentioned) or RV3/4 not as good.Both the RV 3 & 4 have a roll bar, but if the aircraft flips over in really soft, boggy soil, the roll over bar might bury down into the soil so deep as it may be useless for its intended purpose.Not so good.

  • Agree 2
Link to post
Share on other sites
My Golf has a reinforced rib going over the canopy. In training I was told to release top lock before impact. If inverted kick the perspex out.

I agree, I fly a golf as well.What I mean is a full blown canopy that isnt supported by a structural frame.

 

 

  • Haha 1
Link to post
Share on other sites

If you flip over in the water any type of canopy or door is not the first problem, disorientation is. You can't push a door or canopy open against water. Once the cabin is full then it can be done if you haven't drowned by then. If you'd been smart & unlatched the door or canopy before impact, so long as you can work out where the door or canopy is you have an equal chance but a bubble canopy is a whole lot bigger than a door so theoretically easier to get out of.

 

If you are upside down on the hard then a roll cage is pretty essential otherwise you will already be squashed by half. If you have a roll cage that has worked then the canopy breaker might work if there's no fire. If there is a fire try to put your head between your knees and kiss your arxe goodbye.

 

 

Link to post
Share on other sites

Just for interest, this is the RV12 roll bar. Although it looks pretty substantial and has a good back-brace, you'd still want to try and keep your head down in a rollover.

 

rgmwa

 

 

 

Link to post
Share on other sites
?..My plane has what I assume is an acrylic canopy, but the rear window is Lexan which is a polycarbonate. Polycarbonate is pretty flexible and tough, so something a bit heavier than those safety hammers (but still with a pointy end) might be better.rgmwa

Forget about breaking lexan/polycarbonate. It won't. Perhaps cutting a hole is feasible, but only with very thin lexan.

If the mounting screws have slots cut to the edge, maybe you could kick the panel out.

 

 

Link to post
Share on other sites
Forget about breaking lexan/polycarbonate. It won't. Perhaps cutting a hole is feasible, but only with very thin lexan.If the mounting screws have slots cut to the edge, maybe you could kick the panel out.

Good point O.K. but it would be pretty difficult to get out through the rear window anyway, due to the roll bar brace and the seat backs being in the way (see photo). The canopy would be the best bet. Just hope I never have try it.

rgmwa

 

 

Link to post
Share on other sites

Getting out of a plastic plane seems to be the hardest. Metal may split apart on impact and you can go through fabric like a bed sheet. How bout taking along a small battery operated power saw. Seen one guy in an ad used his saw invention to get out of a metal box he was sealed in.

 

 

Link to post
Share on other sites
Getting out of a plastic plane seems to be the hardest. Metal may split apart on impact and you can go through fabric like a bed sheet. How bout taking along a small battery operated power saw. Seen one guy in an ad used his saw invention to get out of a metal box he was sealed in.

Our preflight checklist is gonna be humongous. "Escape saw batteries charge? Check..."

 

 

Link to post
Share on other sites
Our preflight checklist is gonna be humongous. "Escape saw batteries charge? Check..."

 

I know a guy who spent hours getting out of a Sapphire when it flipped on it's back. A fire would have saved him the trouble. He would still be there if it was a heavy a/c I think.

 

 

Link to post
Share on other sites

Great discussion. Really makes me think about how I would escape from my plane. In the case of flipping on land I am not sure how I would do that. In the case of water I am not sure it matters if its a low wing or high wing. There is a nice video from AOPA telling the story of a man in cananda that survived a crash in a river with the plane inverted. He went on to start a company that trains people in escaping from planes underwater. http://www.aopa.org/aopalive/?watch=43djhyNzqknG7WzpJR6Jl82jqqEPngZp . In the video he explains how difficult it is to escape from that situation.

 

As to the plane I fly it does have an emergency canopy release. In the water this might help to totally release the canopy from the plane. On land upside down this might not do much.

 

 

  • Informative 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...