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-   -   RV-4 Canopy Conundrum (https://vansairforce.net/community/showthread.php?t=163767)

FinnFlyer 10-01-2018 08:47 AM

Quote:

Originally Posted by rv7charlie (Post 1291504)
What kept it attached? The per-plans pop rivets will 'unzip' as soon as the canopy goes open far enough to stress the ones at the front end of the hinge. I discovered that fact right after purchasing my 1st -4, when I was replacing the simple lanyard that kept it from going too far, but did nothing to keep it from slamming shut in a wind gust.

Charlie

Sequence in my RV-3B: Canopy opened 90 degrees, held by strap, then strap broke and opened 180 degrees and rested on right wing. I remembered "fly the airplane" and added throttle to safely make it around the pattern and land. It's very possible that had I been a cooler pilot and only used enough power to climb and fly the pattern near minimum required airspeed, the canopy would have stayed attached. It only tore off when adding full power and getting above maybe 100 mph.

Finn

RepmikeBrown 10-03-2018 08:09 PM

Canopy Release
 
Roger, bummer on the first flight!
When I built my latch, I made sure it was a tight fit when the pin/ rod inserted into the nylon block. I still have to pull a second time to fully latch down. Something to consider when you build another is the extra safety latch lock.
I?d also join your closest EAA chapter that has some RV builders. That?s a resource that?s priceless.

Billvt 02-18-2020 07:41 AM

RV-4 Canopy Strap Concern
 
My RV-4 is 90% done, 90% to go and I am working the canopy.

Question is, what to use for the canopy strap to keep canopy from opening all the way on the ground.

If the need arises to jettison the canopy in flight, seems tp me that a strap that is too strong, like paracord, may not break and the canopy would be dancing around on the right side of the aircraft.

Need something that will break when canopy departs but is strong enough to keep canopy open on the ground without breaking.

What are you folks using????

Bill Morelli - A&P I/A - EAA Tech Counselor
Up North Aviation
CNC Instrument Panel Fabrication
Web www.upnorthaviation.com
E-Mail upnorthaviation@gmail.com
- RV-4 build in progress !!!

fixnflyguy 02-18-2020 08:52 AM

My solution and thoughts.
 
I built my -4 as are you, and I have maintained and inspected many others. No two are alike. Everything from parachute chord to steel chains I have seen. Van did a great job of KISS, and the whole canopy jettison idea is great, however after I flew mine a few hours with a chute, I was pretty sure the conditions I (and a PAX) would need to be in for a bail out where far less a worry than keeping the canopy LATCHED in flight and keeping it open on the ground. I have the standard configuration latch mechanism per plans, along with the additional "knife blade" safety latch. I cant imagine any way to have an accidental blow off with this set-up. I also have a very bright LED on my panel with a micro switch that is illuminated if my latch handle is 1/32" off the latch position. For a hold open, I have a 10-12" gas strut simply connected to the canopy cross former and a simple bracket on the R/H roll bar weldment. It holds it exactly where i want it, dampens the close and isn't in the way. I have it attached with a single bolt and large area washer on each side. I'm certain either the strut would fail or the attachment would rip out in event of an in flight opening, but really no way to prove it. ..Hopefully, you will get yours done soon and join the "flying RV-4" group soon..they are a blast!

David Paule 02-18-2020 09:19 PM

Quote:

Originally Posted by DeeCee 57 (Post 1291494)
?.the canopy of the -4 opened right after take-off rotate, and fell on the right wing, remaining attached for the remainder of the flight. Pilot lost headset and prescription glasses but not the nerves, and brought the aircraft back to a safe landing?.

Quote:

Originally Posted by FinnFlyer (Post 1292454)
Sequence in my RV-3B: Canopy opened 90 degrees, held by strap, then strap broke and opened 180 degrees and rested on right wing. I remembered "fly the airplane" and added throttle to safely make it around the pattern and land. It's very possible that had I been a cooler pilot and only used enough power to climb and fly the pattern near minimum required airspeed, the canopy would have stayed attached. It only tore off when adding full power and getting above maybe 100 mph?.

Question - if the canopy can, if mounted more strongly, remain attached long enough to permit a landing, and if the airplane flies well enough for that, what?s the advantage in having it depart?

If it?s open and the lift force on the canopy will tend to hold it open, and if the airplane remains under control, that sounds better than having it leave. The pilot can still leave if he wants to parachute.

Dave

FinnFlyer 02-19-2020 06:27 AM

Stay attached
 
Yes, seems it makes sense to have a strong tip-over attachment.

However, at higher speeds I don't know if it could start ripping apart at the hinge and trash around held by the tip-over attachment.

Then why have the "weak" piano hinge riveting?

Perhaps the whole idea comes from fighter jets where you want to get rid of the canopy so you can eject. Not having ejection seats in the RVs, and having tip-over canopies that open widely enough for easy egress while in all flight conditions, that idea may be flawed.

Question would be if there are any uncontrolled flight conditions where the tip-over canopy would not stay open?

I forget, are there any actual cases of egress in flight with a parachute from RVs?

Or any reported flight conditions where the canopy did not stay open?

Without real world data, or some engineer doing computer simulations, I'm beginning to think it's all up in the air :)

Finn

Christopher Murphy 02-19-2020 06:33 AM

I think better if it separated?
 
Watch this video. Not sure if the oscillating was PIO or from the canopy.

I know its not a tandem RV


https://youtu.be/BVTnp6fk7oM

Scott Hersha 02-19-2020 07:13 AM

Wow!! It looks like his helmet may have saved him.


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