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  #1  
Old 03-14-2016, 11:14 PM
Berchmans Berchmans is offline
 
Join Date: Nov 2009
Location: Anchorage, Alaska
Posts: 457
Default Jettisoning a canopy

In searching the site a bit I couldn't find a real simple way to rig a canopy for jettisoning while performing aerobatics. Below is my solution.


Using a quick release pin I replaced the original fasteners that hold the canopy rollers in place. I put a pull strip on the pin to make it easy to grab onto.


See pin in place on left side roller.

The pin is a 3/16" Dial by .8" usable length. McMaster-Carr carries them, part no. 95255A216. They fit perfectly. I looked at the other styles with "T" and "D" handles but it looked as if they would strike the mid cabin brace sliding the canopy for and aft. There is not wobble in the rollers when secured by these pins.
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  #2  
Old 03-15-2016, 05:42 AM
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WillyEyeBall WillyEyeBall is offline
 
Join Date: Jan 2007
Location: Daleville, AL
Posts: 343
Thumbs up great idea

That will work perfectly by just replacing the bolts with the pins. I assume you had the pull tag custom designed locally?
Thanks,
Bill McLean
RV-4 slider
lower AL
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  #3  
Old 03-15-2016, 06:57 AM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
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Default

My experience with a partially open canopy in flight is there was a load on it, it would not move open or closed. (RV-7 not 8)

That load will be on the pins and they may not come out easily. Or if one comes out, the canopy may become cocked with a greater load on the other.

And there is no way to test it, is there.
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  #4  
Old 03-15-2016, 07:58 AM
Jstov Jstov is offline
 
Join Date: Dec 2014
Location: Melbourne beach, fl
Posts: 190
Smile

Just fly with the Springfield and shoot it off!
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  #5  
Old 03-15-2016, 08:30 AM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

Quote:
Originally Posted by David-aviator View Post
My experience with a partially open canopy in flight is there was a load on it, it would not move open or closed. (RV-7 not 8)

That load will be on the pins and they may not come out easily. Or if one comes out, the canopy may become cocked with a greater load on the other.

And there is no way to test it, is there.
I agree.
That is why I have always recommended to anyone doing this mod., that the procedure they use is to pull the pins before unlatching the canopy. Then pull aft on the handle without inserting fingers.

If you test it let us know if it works
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RV-6A (aka "Junkyard Special ")
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  #6  
Old 03-15-2016, 09:15 AM
pvalovich pvalovich is offline
 
Join Date: Dec 2005
Location: Ridgecrest, CA
Posts: 432
Default Canopy Jettison

I have an -8A with nearly 700 hours on it - 496 flights and counting. After reviewing as much data as I could find, I put canopy jettison/bailout in the "Just something to keep you busy 'til you crash" category.
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  #7  
Old 03-15-2016, 10:18 AM
Berchmans Berchmans is offline
 
Join Date: Nov 2009
Location: Anchorage, Alaska
Posts: 457
Default Agree

I agree with all the comments...but the IAC requirements are that it be jettisonable...not that it necessarily be easy to jettison...of note I did fly the plane and pulled each pin while in flight with the canopy latched...they don't pull as easily as they do on the ground but they do come out...also if tumbling I assume that there will be moments when the canopy will be unloaded...and yes you may wind up on the ground holding on to the pins with a perfectly good chute strapped to your butt...oh and the little flags are keychain fobs from one of the local FBO's. I tested them to 100 lb pull and they did not tear...normal people don't do aerobatics anyway, right? Flying weather in Anchorage has been outstanding for the last few days, severe clear and no winds...
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  #8  
Old 03-15-2016, 10:29 AM
BenNabors BenNabors is offline
 
Join Date: Mar 2014
Location: Alabama
Posts: 127
Default There is one test in the accident database on a RV-7

Quote:
Originally Posted by David-aviator View Post

And there is no way to test it, is there.
Well there was one that was tested the hard way:
I have read all of the accident probable causes in the accident database for the RV-3, -6, -7, -8, -9, -10, and -12's. Have not finished the RV-4.

Out of all the accident reports, this is the one that made me cringe the most, probably because of the unsuspecting nature of it while knowing the inevitability of the outcome while falling from 8500 feet. This accident report would seem to indicate that the sliding canopy for the RV-7 cannot support the body weight of the pilot when inverted when the pilot forgets to attach his seatbelt. Think you have too much experience to do this? This pilot had over 2300 hours.

From the accident report:
FAA records indicated that he held a valid Private Pilot's certificate and had about 2,328 flights hours...
One of the canopy roller tracks was not found. The found roller track exhibited deformations about 8 inches aft of the forward ends on its left and right sides consistent with the attachment rollers being pulled from their tracks in an upward direction.
? Given the location of the pilot?s body and the acrylic canopy parts and the witness?s statement, it is likely that the pilot lost control of the airplane, which then inverted, and that the pilot subsequently fell through the open canopy

The full narrative below:
Accident number: CEN11FA634 http://ntsb.gov/_layouts/ntsb.aviati...11FA634&akey=1

The pilot?s in-flight loss of control. Contributing to the pilot?s fatal injury was his failure to use the available restraint systems, which resulted in him falling through the open canopy when the airplane inverted.

The private pilot was flying his experimental home-built airplane on a visual flight rules (VFR) cross-country flight. While en route, the pilot requested VFR flight following services from air traffic control. A review of radar data revealed that, at the time of the request, the airplane was level at 8,500 feet. About 6 minutes later, radar and radio contact were lost. No distress calls from the pilot were reported. A witness who was working near the accident site reported hearing a very loud revving engine noise. When he looked up, he saw the airplane flying upside down. He also stated that he did not see a cockpit or a pilot in the airplane. A few seconds later, the airplane passed behind a stand of trees and out of sight. He went to the impact site and found the wreckage but not the pilot.
First responders reported that the wreckage was mangled and spread across a soybean field in a southerly direction. Ground scars at the accident site indicated that the airplane impacted the ground at a high velocity in a wings-level, slightly nose-down attitude and inverted. The engine and propeller assembly exhibited evidence consistent with high power at impact. All of the flight control surfaces were accounted for at the main wreckage site. Flight control continuity was established from the cockpit to all of the flight control surfaces, and no evidence indicated that any of the flight controls were disconnected or otherwise separated before impact. The pilot?s body was found about 1 mile northwest of the airplane wreckage. Canopy parts were found about 3/4 mile northwest of the wreckage, and various pieces of the acrylic canopy were found scattered for about 1/2 mile southward. One of the canopy roller tracks was not found. The found roller track exhibited deformations about 8 inches aft of the forward ends on its left and right sides consistent with the attachment rollers being pulled from their tracks in an upward direction. The pilot and copilot lap seat belts were found attached to their respective anchor points with no evidence of overload failures or stresses on any of the latching blades or buckles consistent with the buckles not being latched at the time of impact. The pilot?s autopsy findings did not show any evidence of incapacitation, and toxicological tests were negative for drugs and alcohol. The on-scene evidence indicates that the airplane was likely controllable and that the engine was producing power at the time of impact. Given the location of the pilot?s body and the acrylic canopy parts and the witness?s statement, it is likely that the pilot lost control of the airplane, which then inverted, and that the pilot subsequently fell through the open canopy. The reason for the pilot?s loss of control of the airplane could not be determined.
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  #9  
Old 03-15-2016, 10:39 AM
Berchmans Berchmans is offline
 
Join Date: Nov 2009
Location: Anchorage, Alaska
Posts: 457
Default

Well, what more can you say about that...
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  #10  
Old 03-15-2016, 11:20 AM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
Default

Quote:
Originally Posted by Berchmans View Post
I agree with all the comments...but the IAC requirements are that it be jettisonable...not that it necessarily be easy to jettison...of note I did fly the plane and pulled each pin while in flight with the canopy latched...they don't pull as easily as they do on the ground but they do come out...also if tumbling I assume that there will be moments when the canopy will be unloaded...and yes you may wind up on the ground holding on to the pins with a perfectly good chute strapped to your butt...oh and the little flags are keychain fobs from one of the local FBO's. I tested them to 100 lb pull and they did not tear...normal people don't do aerobatics anyway, right? Flying weather in Anchorage has been outstanding for the last few days, severe clear and no winds...
I've been in touch with my brother who lives near Palmer. He says it is very nice spring, thinking about his garden and the fish are biting at the Legion Club lake.
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RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!

Last edited by David-aviator : 03-15-2016 at 11:22 AM.
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