Redundant canopy latching

[John]

Here is another idea for discussion:

Noticed a few cosmetic cracks in the fiberglass surface near the
canopy's hinge area.

Will monitor this area and repair when needed as, of course, if the
hinges fail, the canopy will open at best; fall off at worse.

My particular plane has been flown with open and removed canopy, so
aerodynamically, it does not become unstable. Was thinking, what if
there was a secondary system that kept the canopy closed if the hinges
failed?

Obviously, something simple such as attaching bungees (after you get
in of course) from the canopy rails to the seat might work...but might
also just create a plexiglass parachute when the latch fails and the
bungees do not!

A slightly better idea would be to use four small "c" clamps to clamp
the four corners of the canopy rail once you get in. Maybe those high
tech pistol grip clamps to speed the process. Maybe not convenient,
and also have to check your are clamping to something strutural, but
should work very well in keeping the canopy in place.

This would make it harder to jettison the canopy if you have to bail
out. So, what two independent canopy latching systems?

Keep the current latch (rod pivots and goes thru two posts on my
plane). Add a secondary latch that is closed based on position...like
your car door. In effect, we have automatic canopy latching just like
we have automatic control connects. Shut the canopy, it is latched
automatically, then push the rods thru the posts just like you do now
for a redundant, secondary lock. Add a bailout lever that disengages
both latches and you do not effect egress in emergencies.

When you shut your car door, it is latched shut automatically. To
open, you have to pull the door handle. How hard would it be to
design a canopy that would latch shut automatically each time you
close the canopy?

[Geir Raudsandmoen]

Is 'John >'
a pseudonym for Mario Gladsky ?

Geir


At 21:30 15 March 2004, John wrote:
>Here is another idea for discussion:
>
>Noticed a few cosmetic cracks in the fiberglass surface
>near the
>canopy's hinge area.
>
>Will monitor this area and repair when needed as, of
>course, if the
>hinges fail, the canopy will open at best; fall off
>at worse.
>
>My particular plane has been flown with open and removed
>canopy, so
>aerodynamically, it does not become unstable. Was
>thinking, what if
>there was a secondary system that kept the canopy closed
>if the hinges
>failed?
>
>Obviously, something simple such as attaching bungees
>(after you get
>in of course) from the canopy rails to the seat might
>work...but might
>also just create a plexiglass parachute when the latch
>fails and the
>bungees do not!
>
>A slightly better idea would be to use four small 'c'
>clamps to clamp
>the four corners of the canopy rail once you get in.
> Maybe those high
>tech pistol grip clamps to speed the process. Maybe
>not convenient,
>and also have to check your are clamping to something
>strutural, but
>should work very well in keeping the canopy in place.
>
>This would make it harder to jettison the canopy if
>you have to bail
>out. So, what two independent canopy latching systems?
>
>Keep the current latch (rod pivots and goes thru two
>posts on my
>plane). Add a secondary latch that is closed based
>on position...like
>your car door. In effect, we have automatic canopy
>latching just like
>we have automatic control connects. Shut the canopy,
>it is latched
>automatically, then push the rods thru the posts just
>like you do now
>for a redundant, secondary lock. Add a bailout lever
>that disengages
>both latches and you do not effect egress in emergencies.
>
>When you shut your car door, it is latched shut automatically.
> To
>open, you have to pull the door handle. How hard would
>it be to
>design a canopy that would latch shut automatically
>each time you
>close the canopy?
>

[Eric Greenwell]

John wrote:

> Keep the current latch (rod pivots and goes thru two posts on my
> plane). Add a secondary latch that is closed based on position...like
> your car door. In effect, we have automatic canopy latching just like
> we have automatic control connects. Shut the canopy, it is latched
> automatically, then push the rods thru the posts just like you do now
> for a redundant, secondary lock. Add a bailout lever that disengages
> both latches and you do not effect egress in emergencies.
>
> When you shut your car door, it is latched shut automatically. To
> open, you have to pull the door handle. How hard would it be to
> design a canopy that would latch shut automatically each time you
> close the canopy?

My recollection is most in-flight canopy openings happen to side hinged
canopies. A latch like you suggest would surely be an asset for them.
The Blanik L13 does this already. My forward opening canopies does have
a catch in back that latches like you say, but it's purpose is to
provide the Roeger-hook function.
--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Bob Korves]

Burt Rutan used a canopy safety system on the Vari-Eze and the Long-Eze that
was simple and effective. In addition to the normal canopy latch he added a
thin piece of springy stainless steel with a hole in it, attached to the
inside of the canopy frame. The bottom edge of the piece of stainless was
bent slightly and, as the canopy closed was sprung with a sliding motion
over a post attached to the fuselage until the post entered the hole.
Voila, automatic canopy latch. To open the canopy just spring the stainless
away from the fuselage side with your fingers to clear the post then lift
the canopy.

I thought it was a good idea. It might slow down an emergency exit from the
glider but it would save many canopies and more than a few lives lost to
distraction when the canopy comes open early on tow.
-Bob Korves

"John" > wrote in message
om...
> Here is another idea for discussion:
>
> Noticed a few cosmetic cracks in the fiberglass surface near the
> canopy's hinge area.
>
> Will monitor this area and repair when needed as, of course, if the
> hinges fail, the canopy will open at best; fall off at worse.
>
> My particular plane has been flown with open and removed canopy, so
> aerodynamically, it does not become unstable. Was thinking, what if
> there was a secondary system that kept the canopy closed if the hinges
> failed?
>
> Obviously, something simple such as attaching bungees (after you get
> in of course) from the canopy rails to the seat might work...but might
> also just create a plexiglass parachute when the latch fails and the
> bungees do not!
>
> A slightly better idea would be to use four small "c" clamps to clamp
> the four corners of the canopy rail once you get in. Maybe those high
> tech pistol grip clamps to speed the process. Maybe not convenient,
> and also have to check your are clamping to something strutural, but
> should work very well in keeping the canopy in place.
>
> This would make it harder to jettison the canopy if you have to bail
> out. So, what two independent canopy latching systems?
>
> Keep the current latch (rod pivots and goes thru two posts on my
> plane). Add a secondary latch that is closed based on position...like
> your car door. In effect, we have automatic canopy latching just like
> we have automatic control connects. Shut the canopy, it is latched
> automatically, then push the rods thru the posts just like you do now
> for a redundant, secondary lock. Add a bailout lever that disengages
> both latches and you do not effect egress in emergencies.
>
> When you shut your car door, it is latched shut automatically. To
> open, you have to pull the door handle. How hard would it be to
> design a canopy that would latch shut automatically each time you
> close the canopy?

[Vaughn]

"John" > wrote in message
om...
> When you shut your car door, it is latched shut automatically. To
> open, you have to pull the door handle. How hard would it be to
> design a canopy that would latch shut automatically each time you
> close the canopy?

Exactly! There is no excuse for the canopy latches on many common
gliders. A canopy should latch when it is shut and you should be able to
open it with one motion; just like a car door or the door on the front of
your house. This is not rocket science we are asking for, just normal human
engineering.

For a good read on the problem, just take a look at the accident
history of the Grobe Twin. As I remember, a very significant percentage of
the total accidents (some fatal) for that design involve canopies.

Vaughn

[Robertmudd1u]

>Noticed a few cosmetic cracks in the fiberglass surface near the
>canopy's hinge area.
>
>Will monitor this area and repair when needed as,

If indeed there are cracks in the fiberglass matrix then these need to be
repaired now. If the cracks are in the paint/gelcoat then inspection by a
competent mechanic should be conducted to see if these extend into the matrix.

>
>When you shut your car door, it is latched shut automatically. To
>open, you have to pull the door handle. How hard would it be to
>design a canopy that would latch shut automatically each time you
>close the canopy?
>
It would not be difficult, but it would be a lot more complex, heavier and more
costly.
Pilots might treat their canopies like car doors and just let them slam shut
probably breaking them in the process.

Almost any safety device you can think of can be added to a glider. It just
takes market demand, money, and willingness to deal with the added complexity,
failure modes, and added weight.

Problems with the Grob canopies is a bit more complex. I fly a G 103 and have
looked at a lot of G 103 latching mechanisms. Not all Grob latches are created
equal. Some have a detent, some do not. I have not figured out why yet.

Robert Mudd