My Safety Concerns About Bubble Canopies

Discussion in 'Rules and Regulations / Flight Safety / Better Pil' started by JayKoit, Oct 17, 2018.

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  1. Oct 17, 2018 #1

    JayKoit

    JayKoit

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    Hi everybody,

    My boys and I are finally at a place where we can start a build, and this topic has been on my mind.

    We've been looking at Zenith 650s for a long time, and also like the Sling 2, Sonex and the RV-12. Problem is, they're ALL bubble canopy planes, and I just can't get comfortable with the fact that if we ever have to put it down in a field somewhere and it flips...we're trapped in the aircraft.

    I know there are canopy breakers, and have read what I can in several forums (however I haven't found much, almost like this is sort of taboo), but how effective are they, and do they really make it possible to get yourself extracted from an inverted plane? Are there other methods/tools/ideas that address this issue?

    I'd love to hear from bubble canopy owners and non-bubble canopy owners alike...and has anyone ever let a bubble canopy design dissuade you and steer you in a different direction? Because of this we've started considering the 750 CruZer instead...even though the boys like the 650 more.

    Thoughts? Thanks!
     
    Last edited: Oct 18, 2018
  2. Oct 17, 2018 #2

    Twodeaddogs

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    As an Inspector, I always insist that my builders fit a canopy breaker/harness cutter, regardless of canopy design. I have tested the breaker against Perspex (bench test in a hangar) and found that it will break the stuff but you need a good vigorous swing, which you might not have room to do in an inverted aircraft. I know one builder who had to kick his way out as his hammer made only a small hole but he was able to wriggle around and make room to kick the Perspex and it finally broke but it left jagged edges, which made egress difficult. Also, the harness cutter tends to be quite sharp and will cut harnesses but again, it needs a bit of room to effect the cutting action. I'm not a fan of the forward swing up canopy on Zeniths as there is no ability to slide it open prior to touchdown. I did see an RV invert and the canopy warped a lot but didn't break, despite the windscreen being bent well out of shape and they had to be helped out by an airshow rescue team.
     
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  3. Oct 17, 2018 #3

    blane.c

    blane.c

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    I've always preferred the looks of the Razorback P-51 to the bubble canopy. Perhaps a Razorback customization would work on a Zenith?
     
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  4. Oct 17, 2018 #4

    JayKoit

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    Thanks, these are precisely the things that have me concerned about flying a canopy aircraft. Interesting point about the sliding canopy, though. At least those can be opened prior to landing, which would help in the event of going inverted.
     
  5. Oct 17, 2018 #5

    JayKoit

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    Yeah, I suppose that could be done. Might also look pretty cool, too. :) And the areas along the side of the canopy in between the metal frame could be designed to pop out, or you could build a sliding mechanism for easy egress.
     
  6. Oct 17, 2018 #6

    Sprucemoose

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    It might help, or it might make things worse. The canopy provides a lot of protection for the old noggin in the event of a nose over, on land or water. Hard to fight your way out if you’ve been knocked unconscious.

    15 years flying my RV6 has given me a lot of time to ponder this. I do have a small backpacking axe mounted within reach.
     
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  7. Oct 18, 2018 #7

    lr27

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    Clearly you have to build a Breezy!

    More seriously:

    How easily does Plexiglas break if you score it with a knife first? My experience with the stuff suggests this would help a lot. I suppose you could score it with a hatchet just as easily. Also wonder if a sliding hammer/chisel arrangement might be easier to deal with in cramped quarters. I also wonder if a scared guy with a knife could cut through sheet metal. I'm certain it could be done with offset aviation snips, but how fast?

    Do any of these designs have a baggage door? If so, do they have seatbacks which could be made removable?

    I suspect even high wing planes are susceptible to jammed doors, though maybe not if they just flip over.

    I wonder how these two guys got out?:
    http://www.kathrynsreport.com/2016/11/vans-rv-6-n224ga-eureka-municipal.html
     
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  8. Oct 18, 2018 #8

    BBerson

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    My canopy has a 4"x6" mecaplex vent hole on the side from the factory. I have a small adjustable wrench to pry a bigger hole like a can opener if needed.
     
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  9. Oct 18, 2018 #9

    JayKoit

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    Good point. In thinking more about this all afternoon, the idea of doing a custom canopy that retains good rollover protection and has some sort of custom side window that can be opened in an emergency might be the way to go.
     
  10. Oct 18, 2018 #10

    JayKoit

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    I'm thinking a custom canopy that has a hinged emergency window built into the side might be a good solution. I don't think any of the designs mentioned have baggage doors or removable seat backs, but I'm sure those could be engineered. High wings generally don't trap you near as badly, all things being equal, so long as you open the doors just before impact...at least that's what I've heard. ...and that RV in the report, man those are two lucky guys based on the looks of the plane! They must have had help from airport personnel/other pilots nearby
     
  11. Oct 18, 2018 #11

    Sprucemoose

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    I've often looked at the sheet metal sides of the cockpit and thought that the quickest way out (using the axe) would be through the metal rather than the canopy. Even going through the floorboard is an option. The plexiglass is not the only means of getting out.

    I have no such concerns on the Breezy, but it does create it's own set of challenges, like picking bugs out of your teeth.
     
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  12. Oct 18, 2018 #12

    wsimpso1

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    With a one piece front hinged canopy, I would rig a way to pull the hinge pins, the way that the sailplane guys do. They use a hook that does not release the canopy until the canopy swings up and away. I would rig the hook to retract with the aft catch so the canopy can come free for ground escape. That would allow bailing out at altitude and if you end up inverted on the ground you have two ways out depending upon how things come to rest;

    If you have some room between canopy and ground, you yank on the pull-pin handle, then the aft catch releasing the canopy and dropping it to the ground. Shift it to one side and squirm out;
    If your canopy is bearing weight or close to the ground, break the overhead part of the canopy, eject the canopy and shove one or both big pieces laterally to escape.

    I have gull wing doors. The A and B pillars and the roof are sturdy, so it will carry weight if the whole thing is upside-down. Pullable hinge pins on the doors finish the egress plan. Pull the handle to yank out pins, pull the latch handle, and the door is free. Shove it out of the way and out you go.

    Bill
     
    Last edited: Oct 18, 2018
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  13. Oct 18, 2018 #13

    blane.c

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    Many accidents cause fractures to the human skeleton. Being able to extract yourself with a broken arm or leg should be considered in any scenario about crash survivability. Feet and the lower legs frequently become trapped by a distorted fuselage and aircraft controls as well. Nobody likes thinking about being toasted while trying to extract their feet from a wreck but it happens.

    Many accidents are from engine loss, think more smaller engines, then you can land at an airport in the event of losing one. Sure airplanes have a glide ratio but usually it isn't a good one when you really stop to consider it. Problems are much better dealt with in the hanger rather than in the "field".
     
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  14. Oct 18, 2018 #14

    VP1

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    Very valid concern. If I were to build something with a bubble I'd consider making it jettisonable and consider ditching it should I ever need to make an off airport landing.
     
  15. Oct 18, 2018 #15

    Twodeaddogs

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    A lot of canopies are big and heavier than you think and a jettison system requires careful thought, as a jettisoned canopy could foul the tail and take off a horizontal stab or fin, changing a gliding aircraft to a tumbling one, from which escape is much more difficult. Also, an opened canopy, especially if it hinges aft can act like an airbrake. Military aft opening canopies are designed to break off and often have a weak link in their hinges (see Fouga) or have a springloaded jettison device (see Me 109) or a 20mm cartridge to blow the entire canopy off (see FW 190). Even the humble Cessna 172 can have a jettison cable fitted to it's doors. Also, reclined seats make getting out into a howling gale to bale out difficult unless you have handholds in convenient places..............the problem with ditching is that the aircraft will invariably float nose down for a period of time, once it settles after ditching and it will start to fill with water. So, you have to get out, find your flotation devices, stand on the inclined wing or sit on the fuselage and attract the attention of boaters or lifeguards or local fishermen, all of which is not that easy if you are hurt or disorientated or are trying to drag out your friend. Getting out of a damaged aircraft is bad enough, without adding the chance of drowning or dying of exposure to the odds against you.The act of ditching is violent, even in the best conditions and the aircraft will stop, violently, in a few lengths, compared to a landing on grass or even concrete. So, a ditching pilot risk getting banged about to a greater extent than a pilot force-landing on grass or concrete.The risk of inverting is much higher, severely reducing the odds of getting out, as the aircraft is inclined to come back to the vertical, which makes it sink quicker. Inverting also tumbles all those items in the cockpit that you thought you had stowed safely.
     
  16. Oct 18, 2018 #16

    Dana

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    A friend of mine sold his Sonerai partly because of concerns about getting out if it nosed over.

    One of the many things I like about biplanes, they have a built in roll cage. :)

    I believe the USAF survival knife has saw teeth on the back so you can cut your way out of an aluminum skinned aircraft.
     
  17. Oct 19, 2018 #17

    Twodeaddogs

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    Ironic that you should say that, especially since you are flying a Hatz. Two friends had an accident landing one and it rolled over and my friend in the front seat had a bit of a job getting out, despite being as thin as a rail.
     
  18. Oct 19, 2018 #18

    Riggerrob

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    Consider slide down side windows (Globe Swift, Ercoupe, Anderson Kingfisher).

    Definitely install a roll bar - or stout windshield frame - in any low-winged airplane.

    My everyday carry includes a fold-blade knife with a seatbelt cutter and a sharp point for cracking glass. The blade is strong enough to reduce steel cans to hobo stoves.

    Consider smaller crash axes - as used by firefighters - because they are purpose-design to tear large holes in automobiles.
     
  19. Oct 19, 2018 #19

    Twodeaddogs

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    I've also seen automatic centre punches used to break perspex; no swinging or hefting required.
     
  20. Oct 19, 2018 #20

    Dana

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    The front cockpit on a Hatz is difficult to get in and out of when when the plane is right side up...
     
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