Sliding Canopy

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JeffB

Filing Flight Plan
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Feb 25, 2018
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JeffB
Any thoughts on the safety of a sliding canopy for a small, single engine piston low wing plane? At first glance, it would seem that planes like the Sling 2 and Tecnam Astore would offer some advantages, but it's not clear. Specifically, for off-field landings or ditchings, is there any advantage to the sliding canopy when making an emergency egress? If left "partially open" wouldn't the canopy just slam shut / shatter on impact?
 
When I had my Grumman Tiger, I kept a piece of PVC pipe, with a cutout down the center the width of the canopy rail. Thinking was, when placed over the rail, it would keep the canopy from slamming shut. The Grumman canopy would pretty much stay where you left it if opened in flight or taxiing, unlike my Sling 2. The Slings canopy unlike the Grumman, likes to ride forward to the closed position, in the air or taxiing. My 21st Century’s fix is a Pool Noodle, slit down the center like the PVC pipe of the 80’s and 90’s. I keep just behind the passenger seat, very accessible.
 
Like C-1, many of my Grumman pilot friends use the pool noodle.
 
I have had this discussion with a couple of the more prominent Grumman shops and their guidance was the same. Neither one had ever seen or heard of the Grumman honeycomb "bathtub" where the seats are located deform in a forced landing in a way that prevented the canopy from opening. And that a closed canopy provided support to resist the windscreen from caving backwards. So their recommendation was to keep the canopy closed and locked during a forced landing.

This works unless the airplane flips over and the canopy is immobilized by the ground. In my Tiger the drill would be to kick out one or more of the side windows (which are the original thin variety), or to exit via the baggage door (which has an inside unlocking tab). And I guess that even if the advice I got was wrong and my canopy jammed closed on a forced landing, the options of kicking out a window or going through the baggage door still work.

I'm not sure how the plane would behave on ditching. I can only find one instance of a Grumman water landing and that was in shallow conditions where the plane was resting inverted on the bottom. That pilot crawled out the baggage door once water pressure equalized after a few minutes.

If it stays upright on ditching, then I expect that the canopy could be opened in a normal manner before the plane submerged above the bottom of the canopy. If the plane flips over with the canopy closed, then things will be worse. Like a plane with conventional doors, the cabin would have to fill with enough water to equalize pressure with the outside before the canopy could be opened. I would probably kick out (in??) a window again to expedite water entry, but it's not going to be a pleasant experience.

I have no idea how a full bubble canopy would behave (sorry).
 
A sliding canopy might open if the airplane flips on its back. A clamshell canopy will not open if the airplane flips on its back. I’ll take a small chance over no chance.
 
Thanks for the fast reply posts. All useful information.
 
I fly an RV with a sliding canopy. Used to fly a Tiger and loved to open the canopy for aerial photography. According to Vans you are NOT supposed to ever open the canopy in flight, so I don't. Instead, I keep a pointy hammer tool in the cockpit and plan to break out if necessary. :)
 
Lots of variations on an inverted 'crash' landing, of course, but is the vertical stabilizer typically strong enough to be a roll bar and keep the canopy off the ground?
If the aircraft is resting on the canopy, I see no way to get enough grip to slide it.
Kicking out/breaking windows or exiting through the baggage door would require no significant injuries, which also seems very optimistic (especially if you end up on the roof).
 
G-Man said:
Lots of variations on an inverted 'crash' landing, of course, but is the vertical stabilizer typically strong enough to be a roll bar and keep the canopy off the ground?
If the aircraft is resting on the canopy, I see no way to get enough grip to slide it.
Kicking out/breaking windows or exiting through the baggage door would require no significant injuries, which also seems very optimistic (especially if you end up on the roof).
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a fair amount of crash pictures I see where the plane flipped after landing show the vertical still fairly intact. There isn’t a lot of weight to crush it and not a lot of energy left by the time it makes contact.
 
G-Man said:
If the aircraft is resting on the canopy, I see no way to get enough grip to slide it.
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If the airplane ends up upside down on the canopy, chances are the plexi is all busted up already.

But, rather than take chances, my policy is always takeoff and land with canopy open (assuming that is an option).

Whether flipping is fatal or not depends a lot on the particular design and whether or not there is built in structural support to keep your head from touching the ground. That is something I like about the T6; there is a steel king post between the two cockpits to keep the pilot’s head from being ground down. A T28, on the other hand doesn’t have that and most off airport landings that flip are fatal.
 
edo2000 said:
I fly an RV with a sliding canopy. Used to fly a Tiger and loved to open the canopy for aerial photography. According to Vans you are NOT supposed to ever open the canopy in flight, so I don't. Instead, I keep a pointy hammer tool in the cockpit and plan to break out if necessary. :)
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Wow! I found my twin brother! Exact same previous history, current ride and window break hammer between the seats ...;)
 
I fly a Grumman w/ a sliding canopy.

I am aware of one incident where a Grumman botched a landing and everyone survived that but the canopy wouldn't open and the fire got them all.
Horrific. Absolutely unfathomable.

I have been hit by lightning before and that's no joke. I bet the odds of the lack of being able to get the canopy open are lower than being hit by lightning.
I survived the lightning strike by the way. Point is, all planes have a feature that will kill you in a 1 in a million incident.

I wouldn't let the potential egress issue prevent you from getting a plane you like. Odds are there are 20 other ways aviation will kill you before a stuck canopy.

Get what you want but keep a hammer close by. They work:
 
Grumman procedure is to just kick out the glass. If you land in an attitude where the canopy will jam, you are in bigger trouble anyway.
 
Since I fly a canopy aircraft I have similar concerns about ending up inverted. Kicking out the window is an option (especially in the original Navion design where they hardly hold in there in normal operation). I figure I'd go through the baggage door if I could. The canopy will latch open in the Navion about 11 inches, but that's a tight squeeze. The problem is you probably can't open it in flight even that far. The airflow works against you. You can usually only open it up enough to make a lot of noise. The few times I've flown with it open, I've latched it open before takeoff.

Of course, any low wing that ends up inverted may have problems getting the door open
 
If she ends up on her back, its unlikely you'll be able to get the canopy open. You can open it before touchdown and wedge something in the track but, if you flip all bets are off. Once you flip, its likely staying where ever it is. So if its partially open and stuck, egress becomes even more difficult because now the frame is in the way. Keep it closed and keep a good egress hammer securely fastened within reach.
 
I have a tip up RV. The support is behind the passengers, so if it's flipped it will collapse "less" and that's what the hammer is for. Well, the hammer is probably to enlarge the hole.

On the slider RV's, the support is above the glare shield. Unlikely it will slide when inverted, and as stated previously they are not intended to be open in flight.
 
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I would counter that egress hammers are meant to be used on glass, not plastic....of doubtful utility in an aeroplane.
 
wrbix said:
I would counter that egress hammers are meant to be used on glass, not plastic....of doubtful utility in an aeroplane.
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I'm pretty sure I could get through plexiglass with a hammer.
 
SixPapaCharlie said:
I fly a Grumman w/ a sliding canopy.
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That means you got to join the "stud" club ...many other pilots think they're real pilots, but Grumman pilots or those flying with a sliding canopy know otherwise ... having flown and owned both for years, makes me a SUPER STUD and I rake in millions in endorsements:cool:;)

SixPapaCharlie said:
I have been hit by lightning before and that's no joke.....I survived the lightning strike by the way.
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Now if you had NOT told everyone for several more pages, you could have made Super Stud as well:confused::confused:;);)

Got to be like the old "Lost in Space" series in the 60's ... cliff hangar, keep them wondering ...
 
how many times an accident would occur with out time to open the canopy?
 
Ravioli said:
Here you go @wrbix

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Uh....did you see the effectiveness on the 172 windshield? Nada.

My plan in the event of stuck canopy is use fire extinguisher as battering ram against side window (AA5B).
 
wrbix said:
Uh....did you see the effectiveness on the 172 windshield? Nada.

My plan in the event of stuck canopy is use fire extinguisher as battering ram against side window (AA5B).
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You should practice this, just to make sure it works:rolleyes::rolleyes:;)
 
I have a 24 oz ball peen hammer velcroed to the tower between the seats in my slider canopy RV 6.
 
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