Tip over canopy jettison design ?

I recently got a forceful lecture from Sam James about the peril of tipover conopies. I have read
here, complicated rail schemes that "might" work for sliders. Dan W at Panther routinely kits a release scheme for his hinged tipover canopy. Does anyone else have a successful design for a tipover hinge side jettison hardware ?

There have been several RV-4 canopies leave the aircraft if not properly latched. I know of one local man who had that happen to him. He found the canopy in a field and was able to recover it and reuse the frame.

There have been at least one RV-3 canopy leave the aircraft. It was documented on VAF some time ago. This one struck the pilot but fortunately did not incapacitate him. He made a successful landing.

It seems as if these airplanes, which all had tip-over side-hinge canopies, can easily shed them. Simply unlatch them while in the air.

Dave

Larry,

I'm not sure what you're asking. What peril is he talking about?

If you let a side tipper unlatch in flight, it's gone. The -4 (and I'd assume, the -3 before it) uses, by design, soft aluminum 'pop' rivets to attach the side piano hinge to the fuselage top longeron. In normal operation, there's never a strength issue. But if the canopy is allowed to go free in the wind, the pop rivets 'unzip' easily.

Biggest danger would be from some of the holders some have added at the roll bar to hold the canopy open. If that piece is too strong, I could see the canopy pivoting around it before departing.

FWIW, if you're thinking about bailing out, getting rid of the canopy might be the easiest step in a -3 or -4. unless you weigh less than ~160 lbs, getting yourself and a parachute disconnected from the airframe will likely be a lot harder.

Charlie

Primary focus is not to get trapped in nose over

Good input thanks. My objective is to get rid of it before a nose over. I has 5 #6 fasteners holding the aluminum hinge to the longeron and my concern is the canopy flailing me to pieces in the wind or perhaps not being gone when upside down. A release scheme like the Panther addresses this condition. I am even more concerned about my -4 that might involve a passenger as well. Any mechanism designs are welcomed...Larry

Larry DeCamp said:

Good input thanks. My objective is to get rid of it before a nose over. I has 5 #6 fasteners holding the aluminum hinge to the longeron and my concern is the canopy flailing me to pieces in the wind or perhaps not being gone when upside down. A release scheme like the Panther addresses this condition. I am even more concerned about my -4 that might involve a passenger as well. Any mechanism designs are welcomed...Larry

Click to expand...

Like Dave said - the design calls for soft aluminum pop rivets to hold the hinge side to the longer on, specifically so that it will jettison of you open it. How come you substituted the #6 bolts? You don't need a mechanism if you build it per the design.

Paul

As has been mentioned, a jettison mechanism was designed in (if the airplane is built per plans) and unfortunately has been accidentally tested numerous times proving that it works as designed.

My Bad

I wanted to be able to take it off for maintenance. Point made, soft rivits can be drilled out and replaced at will...Larry

You can remove it for maintenance in 15 seconds by pulling the hinge pin out. No need to drill out any rivets. I do it all the time..way easier to work on the plane.

To your point about flipover, & the idea of jettisoning it:

There are very few situations where I'd pull my release prior to landing. As you know, when the canopy goes, the windscreen goes, too. I want to see while landing, and I want whatever extra protection the canopy may give, with the hope that damage plus the canopy breaker tool will get me out when things come to a stop.

FWIW; everyone will make their own call on this kind of thing.

Charlie

Here is one of a couple of threads discussing unintentional canopy ejection.

http://www.vansairforce.com/community/showthread.php?t=59391

As mentioned earlier the canopy hinge on Van's tip overs is designed to break away.

If I were doing an off field landing where flipping the aircraft looked very likely and I had a tip over then I might eject the canopy if I was the only person in the aircraft. In discussing this issue with others I kept hearing stories of rear seat passengers being injured. I can tell you from experience that loosing an RV-4 canopy in flight is instantaneous. Your first thought is that a bomb went off and then you have the wind to contend with. The wind will relieve you of your glasses and headset. My method of dealing with the wind was get the airspeed as slow as possible and close one eye then on about 30 second cycles switch eyes. I flew about 15 miles like this. There was some damage to the tail but it did not affect the handling.

Thanks much to all comments

This kind of help is what makes VAF so special !!!

Larry,

If your 4 goes over, the rollbar will make a nice, big hole in the plexi, seen it first hand.

Of greater concern is whether the rollbar will then sink in soft earth... also seen that first hand.

It's not a terrible ideal to put a 4"x4", or whatever you deem suitable, plate on top of the rollbar to increase the rather small area up there. Then put your GPS antenna on top just for convenience.

Also, make sure that you have a canopy breaker... a big Bowie knife... to break out of there.

IMHO, a good rollbar is an absolute.