Fatal Towplane Accident 5-9-20

On Sun, 17 May 2020 15:08:51 -0700, Tom BravoMike wrote:


I think a simple mechanical device like a lever arm or cage that
extends behind the towplane for a few inches may enhance safety
significantly. Something that the tow rope would press against at a
particular angle that would activate a lever arm that automatically
opens the tow hook and releases the ring. How hard would that be to
make? It would be independent of the tow pilot, where if the tow rope
under tension pulled at greater than a particular angle to the
towplane, it would move the lever back and open the tow hook, releasing
the ring.

See what I wrote early in the thread and what response I got:

"We all know how the self-release works on the glider side at winch
launching: at a certain angle the rope puts a pressure on a lever which
causes the release. Isn't it technically simple to have a similar
solution on the tow plane side, a lever above the rope, which pressed at
kiting would release the rope immediately? Where am I wrong?"

Nobody has yet referred to the series of experiments carried out in 1978
and 1982 by Chris Rollings at Booker in the UK. I've just put a copy of a
summary report he wrote some time after 2000 on my website:

https://www.gregorie.org/gliding/kiting_on_tow

This describes both sets of tests as well as a his explanation of why, in
his opinion, an automatic release based on line angle is unlikely to
work.

IIRC this is not the original report, which I've never seen. If anybody
reading this has seen an earlier version, especially one with diagrams or
photos in it, please post a link or give a reference if its in a gliding
magazine.


--
Martin | martin at
Gregorie | gregorie dot org

On Sunday, May 17, 2020 at 7:24:19 PM UTC-4, Martin Gregorie wrote:
On Sun, 17 May 2020 15:08:51 -0700, Tom BravoMike wrote:


I think a simple mechanical device like a lever arm or cage that
extends behind the towplane for a few inches may enhance safety
significantly. Something that the tow rope would press against at a
particular angle that would activate a lever arm that automatically
opens the tow hook and releases the ring. How hard would that be to
make? It would be independent of the tow pilot, where if the tow rope
under tension pulled at greater than a particular angle to the
towplane, it would move the lever back and open the tow hook, releasing
the ring.

See what I wrote early in the thread and what response I got:

"We all know how the self-release works on the glider side at winch
launching: at a certain angle the rope puts a pressure on a lever which
causes the release. Isn't it technically simple to have a similar
solution on the tow plane side, a lever above the rope, which pressed at
kiting would release the rope immediately? Where am I wrong?"

Nobody has yet referred to the series of experiments carried out in 1978
and 1982 by Chris Rollings at Booker in the UK. I've just put a copy of a
summary report he wrote some time after 2000 on my website:

https://www.gregorie.org/gliding/kiting_on_tow

This describes both sets of tests as well as a his explanation of why, in
his opinion, an automatic release based on line angle is unlikely to
work.

IIRC this is not the original report, which I've never seen. If anybody
reading this has seen an earlier version, especially one with diagrams or
photos in it, please post a link or give a reference if its in a gliding
magazine.


--
Martin | martin at
Gregorie | gregorie dot org

Thanks, Martin - excellent reference! It confirms my suspicion why an automatic release would be problematic!

Uli
'AS'

On Sunday, May 17, 2020 at 4:24:19 PM UTC-7, Martin Gregorie wrote:
On Sun, 17 May 2020 15:08:51 -0700, Tom BravoMike wrote:


I think a simple mechanical device like a lever arm or cage that
extends behind the towplane for a few inches may enhance safety
significantly. Something that the tow rope would press against at a
particular angle that would activate a lever arm that automatically
opens the tow hook and releases the ring. How hard would that be to
make? It would be independent of the tow pilot, where if the tow rope
under tension pulled at greater than a particular angle to the
towplane, it would move the lever back and open the tow hook, releasing
the ring.

See what I wrote early in the thread and what response I got:

"We all know how the self-release works on the glider side at winch
launching: at a certain angle the rope puts a pressure on a lever which
causes the release. Isn't it technically simple to have a similar
solution on the tow plane side, a lever above the rope, which pressed at
kiting would release the rope immediately? Where am I wrong?"

Nobody has yet referred to the series of experiments carried out in 1978
and 1982 by Chris Rollings at Booker in the UK. I've just put a copy of a
summary report he wrote some time after 2000 on my website:

https://www.gregorie.org/gliding/kiting_on_tow

This describes both sets of tests as well as a his explanation of why, in
his opinion, an automatic release based on line angle is unlikely to
work.

IIRC this is not the original report, which I've never seen. If anybody
reading this has seen an earlier version, especially one with diagrams or
photos in it, please post a link or give a reference if its in a gliding
magazine.


--
Martin | martin at
Gregorie | gregorie dot org

Interesting read. It still leaves open the possibility of using acceleration and rotation sensors (MEMs) to profile a kiting incident and cut the rope (as mentioned earlier in this thread). It would be easy to record those values (at altitude) with a simulated kiting.

Then we need a reliable rope cutting device, triggered electrically by the MEMs circuit. I just did a conceptual exploration of a guillotine that uses a .22 cal short blank to actuate the blade. I know nothing about guns or munitions, but I am sure someone here has better suggestions for a firing mechanism, released by a melting fuse wire. The firing pin mechanism should be modular and sealed, so replacement is simple and reliable.

Please see screen shots here. As I said, it is all conceptual, and I am looking for input/suggestions. Fire away... https://www.dropbox.com/sh/8o6sbwho3...yO9ts-Voa?dl=0

Matt

On Sun, 17 May 2020 18:40:10 -0700, Matt Herron Jr. wrote:

Interesting read. It still leaves open the possibility of using
acceleration and rotation sensors (MEMs) to profile a kiting incident
and cut the rope (as mentioned earlier in this thread). It would be
easy to record those values (at altitude) with a simulated kiting.

I have distinct feeling that simpler (to operate) is better, so wonder if
full up elevator on the tow plane would trigger it, i.e. trigger mounted
just behind a spring loaded stick backstop. The spring should be strong
enough that holding the stick back 'normally', e.g. for taxiing in wind,
would not trigger the guillotine but a "we're all about to die!" yank on
the stick would override the spring.

Disclaimer: I am not a power pilot, let alone a tuggie who's been upset
by a glider, so have no idea whether this might work or is just plain
stoopid.

Then we need a reliable rope cutting device, triggered electrically by
the MEMs circuit. I just did a conceptual exploration of a guillotine
that uses a .22 cal short blank to actuate the blade. I know nothing
about guns or munitions, but I am sure someone here has better
suggestions for a firing mechanism, released by a melting fuse wire.
The firing pin mechanism should be modular and sealed, so replacement is
simple and reliable.

Please see screen shots here. As I said, it is all conceptual, and I am
looking for input/suggestions. Fire away...
https://www.dropbox.com/sh/8o6sbwho3...wkUoyO9ts-Voa?
dl=0


Looks good, but something similar using a gas cartridge would
be more acceptable in parts of the world where ammo is relatively
difficult to come by. A solution that got worldwide use would be better
than a US-only solution simply because the market would be bigger and
cost less per unit fitted.

FWIW, the guillotine on most winches are rather strong springs that work
on the chisel on anvil principle - and that were developed back in the
day when the standard rope was 4.5mm steel cable.


--
Martin | martin at
Gregorie | gregorie dot org

On Monday, May 18, 2020 at 9:09:38 AM UTC-4, Martin Gregorie wrote:
On Sun, 17 May 2020 18:40:10 -0700, Matt Herron Jr. wrote:

Interesting read. It still leaves open the possibility of using
acceleration and rotation sensors (MEMs) to profile a kiting incident
and cut the rope (as mentioned earlier in this thread). It would be
easy to record those values (at altitude) with a simulated kiting.

I have distinct feeling that simpler (to operate) is better, so wonder if
full up elevator on the tow plane would trigger it, i.e. trigger mounted
just behind a spring loaded stick backstop. The spring should be strong
enough that holding the stick back 'normally', e.g. for taxiing in wind,
would not trigger the guillotine but a "we're all about to die!" yank on
the stick would override the spring.

Disclaimer: I am not a power pilot, let alone a tuggie who's been upset
by a glider, so have no idea whether this might work or is just plain
stoopid.

Then we need a reliable rope cutting device, triggered electrically by
the MEMs circuit. I just did a conceptual exploration of a guillotine
that uses a .22 cal short blank to actuate the blade. I know nothing
about guns or munitions, but I am sure someone here has better
suggestions for a firing mechanism, released by a melting fuse wire.
The firing pin mechanism should be modular and sealed, so replacement is
simple and reliable.

Please see screen shots here. As I said, it is all conceptual, and I am
looking for input/suggestions. Fire away...
https://www.dropbox.com/sh/8o6sbwho3...wkUoyO9ts-Voa?
dl=0


Looks good, but something similar using a gas cartridge would
be more acceptable in parts of the world where ammo is relatively
difficult to come by. A solution that got worldwide use would be better
than a US-only solution simply because the market would be bigger and
cost less per unit fitted.

FWIW, the guillotine on most winches are rather strong springs that work
on the chisel on anvil principle - and that were developed back in the
day when the standard rope was 4.5mm steel cable.


--
Martin | martin at
Gregorie | gregorie dot org

A nail-gun (ram-set) that shoots steel nails into concrete is powered by .22 cal blanks and they should be readily available everywhere.
However, why cut the rope if you can have a parallel actuation of the already existing release mechanism?

Uli
'AS'