emergency chute

Jack wrote:
One in four is no kind of "probability" at all, let alone a high one.

Actuqally, it's 3 of 11. But that's not exactly a statistical
powerhouse either. That's why I said "informal survey suggests" rather
than "study shows."

I'd be much more interested in seeing even an informal analysis of
unsuccessful attempts to bail out.

The attempts were not unsuccessful. These people all bailed out and
saved their lives. The injuries were sustained on landing. They were
not life-threatening. In every case, the parachute loading was more
than I would recommend for a middle aged person wearing shoes with no
ankle protection, and the training was less than what I would recommend
for anyone (none, actually). But that was the case for the other 8 as
well. They got by with bumps and bruises.

I think the informal analysis reads like this:

Round parachute loadings are based on the old military tables. These
presuppose several factors, none of which are true for the average
glider pilot bailing out:
Healthy, strong, conditioned soldiers, usually in their 20's.
Jump boots providing ankle protection.
Very intense, very regular training in parachute landing falls.

Maximum allowable TSO loadings are even higher - they're based on the
ability to sustain opening shock at maximum altitude/airspeed, and
descent rate doesn't figure into it at all.

For the average middle aged (or older) glider pilot wearing typical
soaring footwear, using a round parachute at anything close to the
manufacturer's recommended maximum loading is asking for a landing
injury. That weight should be derated by at least 30%. Note that the
weight includes the weight of the rig.

For those who are light in weight, a 26 or 28 ft diameter canopy is
adequate. Round emergency parachutes are not made in sizes larger than
28 ft. In fact, I wouldn't know where to get a 28' rig anymore. For
those who are over 200 lbs (including the rig), there are no
appropriately sized round rigs. Their options include using a reserve
that is likely to put them in the hospital, or getting a square rig and
the training required to use it.

Michael

Michael wrote:
Jack wrote:

One in four is no kind of "probability" at all, let alone a high one.


Actuqally, it's 3 of 11. But that's not exactly a statistical
powerhouse either. That's why I said "informal survey suggests" rather
than "study shows."


I'd be much more interested in seeing even an informal analysis of
unsuccessful attempts to bail out.


The attempts were not unsuccessful. These people all bailed out and
saved their lives. The injuries were sustained on landing. They were
not life-threatening. In every case, the parachute loading was more
than I would recommend for a middle aged person wearing shoes with no
ankle protection, and the training was less than what I would recommend
for anyone (none, actually). But that was the case for the other 8 as
well. They got by with bumps and bruises.

I think the informal analysis reads like this:

Round parachute loadings are based on the old military tables. These
presuppose several factors, none of which are true for the average
glider pilot bailing out:
Healthy, strong, conditioned soldiers, usually in their 20's.
Jump boots providing ankle protection.
Very intense, very regular training in parachute landing falls.

Maximum allowable TSO loadings are even higher - they're based on the
ability to sustain opening shock at maximum altitude/airspeed, and
descent rate doesn't figure into it at all.

For the average middle aged (or older) glider pilot wearing typical
soaring footwear, using a round parachute at anything close to the
manufacturer's recommended maximum loading is asking for a landing
injury. That weight should be derated by at least 30%. Note that the
weight includes the weight of the rig.

For those who are light in weight, a 26 or 28 ft diameter canopy is
adequate. Round emergency parachutes are not made in sizes larger than
28 ft. In fact, I wouldn't know where to get a 28' rig anymore. For
those who are over 200 lbs (including the rig), there are no
appropriately sized round rigs. Their options include using a reserve
that is likely to put them in the hospital, or getting a square rig and
the training required to use it.

Michael

Funny, I have a Pioneer tri-conical (round) chute of 29' diameter. It is 19
years old and never been open except in the riggers for checking. Pretty much
the way I like it.

At 235lbs with an already weak leg It's going to hurt if I ever use it...

On Sat, 09 Apr 2005 21:27:13 +0200, Bruce wrote:

Michael wrote:
Jack wrote:

One in four is no kind of "probability" at all, let alone a high one.


Actuqally, it's 3 of 11. But that's not exactly a statistical
powerhouse either. That's why I said "informal survey suggests" rather
than "study shows."


I'd be much more interested in seeing even an informal analysis of
unsuccessful attempts to bail out.


The attempts were not unsuccessful. These people all bailed out and
saved their lives. The injuries were sustained on landing. They were
not life-threatening. In every case, the parachute loading was more
than I would recommend for a middle aged person wearing shoes with no
ankle protection, and the training was less than what I would recommend
for anyone (none, actually). But that was the case for the other 8 as
well. They got by with bumps and bruises.

I think the informal analysis reads like this:

Round parachute loadings are based on the old military tables. These
presuppose several factors, none of which are true for the average
glider pilot bailing out:
Healthy, strong, conditioned soldiers, usually in their 20's.
Jump boots providing ankle protection.
Very intense, very regular training in parachute landing falls.

Maximum allowable TSO loadings are even higher - they're based on the
ability to sustain opening shock at maximum altitude/airspeed, and
descent rate doesn't figure into it at all.

For the average middle aged (or older) glider pilot wearing typical
soaring footwear, using a round parachute at anything close to the
manufacturer's recommended maximum loading is asking for a landing
injury. That weight should be derated by at least 30%. Note that the
weight includes the weight of the rig.

For those who are light in weight, a 26 or 28 ft diameter canopy is
adequate. Round emergency parachutes are not made in sizes larger than
28 ft. In fact, I wouldn't know where to get a 28' rig anymore. For
those who are over 200 lbs (including the rig), there are no
appropriately sized round rigs. Their options include using a reserve
that is likely to put them in the hospital, or getting a square rig and
the training required to use it.

Michael

Funny, I have a Pioneer tri-conical (round) chute of 29' diameter. It is 19
years old and never been open except in the riggers for checking. Pretty much
the way I like it.

At 235lbs with an already weak leg It's going to hurt if I ever use it...

I have landed under the same canopy at 230#. It hurts unless you do a
good PLF.

Bruce wrote:
Michael wrote:
Round emergency parachutes are not made in sizes larger than
28 ft.

Funny, I have a Pioneer tri-conical (round) chute of 29' diameter. It
is 19
years old

I am well aware of the Pioneer. It's a fine canopy. My understanding
is that none have been manufactured this century. I could be wrong.

At 235lbs with an already weak leg It's going to hurt if I ever use
it...

Yes it is.

Michael