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  #11  
Old 09-16-2018, 06:08 PM
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az_gila az_gila is offline
 
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With no slots, there might be a good possibility of the aft of the canopy floating upwards as the 'unlatched' folks have reported. Then what happens? The canopy may come straight back at you and hit you in the face.

The way Van originally designed it with the slots would seem to say the canopy would lift up at the front and do a back flip over the top, keeping it somewhat away from the occupants.

I'm sure Van considered the options in the initial design.
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  #12  
Old 09-16-2018, 08:03 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Originally Posted by Hartstoc View Post
Iím still pondering this important comment, and I may yet cut these slots. For now, after studying the various posts on taking off with an unlatched canopy, or having a canopy inadvertantly unlatch in flight, I concluded that changing the bailout proceedure might make the slots unnecessary, especially if there are two people on board to help with canopy jettison.
The newest design from Van's (the RV-14) has slots to allow for jettison of the canopy. I assure you that because of the trouble they cause in designing a fully sealed fwd canopy, etc., they would have been left off if not considered necessary.

This is experimental aircraft after all so if incorporating brainstormed design and modifications makes you feel better when wearing your parachute..... have at it, but if you plan to fly aerobatics with others, your eyeball engineering (in my opinion) would likely be putting them in jeopardy if you ever do have to get out.
There are many others that thought they were smarter than Van's (and at times they have been) but this is not something to be second guessing Van's about, without even doing any testing to prove it is viable.
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  #13  
Old 09-16-2018, 10:04 PM
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Hartstoc Hartstoc is offline
 
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Quote:
Originally Posted by az_gila View Post
With no slots, there might be a good possibility of the aft of the canopy floating upwards as the 'unlatched' folks have reported. Then what happens? The canopy may come straight back at you and hit you in the face.

The way Van originally designed it with the slots would seem to say the canopy would lift up at the front and do a back flip over the top, keeping it somewhat away from the occupants.

I'm sure Van considered the options in the initial design.
Well, given that the original design had slots and no gas springs, and virtually all tilt-ups now have gas springs and no slots, we are all in new territory. Iíve certainly considered the possibility of being injured by the canopy, and Iím concerned about it. There is a good chance that Iíll end up adding the slots to my plane. Until I do, as far as I can see, the exit strategy I described is the best availble. Iím not expecting to jump out of my airplane, but Iím pro-actively considering the possibility. I wonder if that can be said of the thousands of aerobatic hours that have been enjoyed in RVís with unmodified gas springs and no slots by others dutifully wearing the required parachutes?

I guess one additional step should be added to my current bailout proceedures- explore the possiblity of exiting through the unlatched but still attached canopy. Depending upon the condition of the aircraft, that just might work.

This is all intended as a discussion of the problem. Iím not yet suggesting that I have arrived at a reliable solution, but the great value of this forums is being able to include the thoughts of others such as you in the process.- Otis
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  #14  
Old 09-16-2018, 10:28 PM
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Hartstoc Hartstoc is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
The newest design from Van's (the RV-14) has slots to allow for jettison of the canopy. I assure you that because of the trouble they cause in designing a fully sealed fwd canopy, etc., they would have been left off if not considered necessary.

This is experimental aircraft after all so if incorporating brainstormed design and modifications makes you feel better when wearing your parachute..... have at it, but if you plan to fly aerobatics with others, your eyeball engineering (in my opinion) would likely be putting them in jeopardy if you ever do have to get out.
There are many others that thought they were smarter than Van's (and at times they have been) but this is not something to be second guessing Van's about, without even doing any testing to prove it is viable.
Thank you for this, your points are well taken. Iíd add that where the realm of bailouts from homebuilts is concerned, the term ďeyeball engineeringĒ can pretty much be applied to all designs, even Vanís. The military has the rescources to stage meaningful testing and the horsepower to tote a quarter ton of ejection technology, but we donít.

I think most of the points I made in the post just prior to this one apply here as well. I canít imagine anyone smarter than Van- least of all me! This is about discussing an uncomfortable topic, hoping to incorporate the thoughts of all. Iím now seeing slots in the future for my 7A, but once they are there, I have pretty high confidence in my breakaway bolt solution. It is interesting that the RV-14 includes a work-around for the gas spring issue. - Otis
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  #15  
Old 09-17-2018, 08:26 AM
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kbalch kbalch is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
...if you plan to fly aerobatics with others, your eyeball engineering (in my opinion) would likely be putting them in jeopardy if you ever do have to get out.
That was my thought exactly on reading this thread. Eyeball engineering is just that: nothing but a guess and not worth betting one's life (certainly not mine) and that of one's passenger. Whenever I see an "improvement" offered by a builder, my first thought is always show me the math. If that can't be done, it's not worth my time. Others, of course, may feel differently.

As to those who do feel differently, consider this: while we all have the legal right to do as we will in experimental aviation, simply having the right to make a choice doesn't render any choice made safe, sane, or intellectually defensible. We each decide precisely where to draw that line, but at least accept that there is a line - and thoroughly examine every proposed deviation from plans (even our own ideas) critically and with complete dispassion prior to making a decision.
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  #16  
Old 09-17-2018, 08:59 AM
sailvi767 sailvi767 is offline
 
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I think most on here are vastly underestimating how difficult getting out of a out of control aircraft will be. The violent motions, lack of proper restraints and canopy configuration will make it nearly imposssible and to date I have not heard of a successful bailout from a Vans side by side airframe.
If you are going to add anything to a RV to improve your odds of getting out it would be a ratcheting 5 point aerobatic restraint system. This might require beefing up attach points.
G
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  #17  
Old 09-23-2018, 10:14 AM
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Hartstoc Hartstoc is offline
 
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Quote:
Originally Posted by sailvi767 View Post
I think most on here are vastly underestimating how difficult getting out of a out of control aircraft will be. The violent motions, lack of proper restraints and canopy configuration will make it nearly imposssible and to date I have not heard of a successful bailout from a Vans side by side airframe.
If you are going to add anything to a RV to improve your odds of getting out it would be a ratcheting 5 point aerobatic restraint system. This might require beefing up attach points.
G
THANKS to all for your “ruthlessly helpful” suggestions. After a bit of thought, I came up with a way of cutting hinge slots without even removing the canopy. Photos with captions of this process have been added to the same album showing the gass spring mods(in which I have very high confidence.):

https://public.fotki.com/Hartstoc/ca...ase/?view=roll

Now I’m back to the safer bailout drill:
1- Remove headsets.
2- Check center latch to verify that it is fully engaged.
3- Release main canopy latch.
4- Jettison canopy.
5- Release seat harness.
6- Exit aircraft.
7- Visually identify D-ring- insert both thumbs if possible and push away from chest.

I do plan one additional mod, out of concern that cables attached to glare-shield mounted devices like GPS antennae might impede a clean exit of the canopy. I will cut a large hole in the glare shield and install a mount below this to support such devices, then stretch a piece of black fabric over the hole. The devices will remain with the aircraft when the canopy is jettisoned.- Otis
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Last edited by Hartstoc : 09-23-2018 at 10:20 AM.
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  #18  
Old 09-23-2018, 10:35 AM
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Steve Melton Steve Melton is online now
 
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I like it if you are concerned about canopy jettison. Maybe a frangible hinge cover like the RV14 aftermarket? It has enough strength to hold itself and be water tight but easily broken with a push. The thin tabs on the nut retainer shear to release the canopy. It has been tested on the ground but not in flight. The nut retainer is installed by rotating 90 deg to lock in place using a simple supplied tool. If you remove the canopy for service, remove the nut retainers or you will shear them. a couple extra nut retainers are supplied in case you forget or want to test. they can be painted but spray them with a sealer firstly to prevent acetone from reaching the plastic. as an alternative, spray them with a UV enamel clear, such as rust-oleum.



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Last edited by Steve Melton : 09-23-2018 at 12:12 PM.
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  #19  
Old 09-23-2018, 10:39 AM
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Snowflake Snowflake is offline
 
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Quote:
Originally Posted by Hartstoc View Post
Well, given that the original design had slots and no gas springs, and virtually all tilt-ups now have gas springs and no slots, we are all in new territory.
There are other reasons for the change, though. The original -6 tip-up had arms that came straight back from the hinge points to the canopy frame. The slots were necessary to allow the canopy to open.

The design was changed at some point to have hook-shaped arms so the canopy could open without requiring slots in the fuselage. The hooks make ejection more questionable as they prevent the canopy from coming straight out and back... You now have to raise the back of the canopy far enough that the hooks can clear the panel.

Although i've removed and installed my canopy frame a couple of times, I don't recall how far the rear has to be raised to slide it back. Maybe I should try that.
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  #20  
Old 09-23-2018, 12:07 PM
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Mel Mel is offline
 
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Quote:
Originally Posted by Snowflake View Post
There are other reasons for the change, though. The original -6 tip-up had arms that came straight back from the hinge points to the canopy frame. The slots were necessary to allow the canopy to open.

This was only in VERY early kits.

The design was changed at some point to have hook-shaped arms so the canopy could open without requiring slots in the fuselage. The hooks make ejection more questionable as they prevent the canopy from coming straight out and back... You now have to raise the back of the canopy far enough that the hooks can clear the panel.

This change came around 1990 or 1991. My kit was amoung the first to have the "hook shape" hinges. The slots were still required to facilitate canopy jettison.

Although i've removed and installed my canopy frame a couple of times, I don't recall how far the rear has to be raised to slide it back. Maybe I should try that.
See above notes. Just researched builder log. Canopy hinge change to the "hook" style was early to mid 1991.
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Last edited by Mel : 09-23-2018 at 12:20 PM.
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