Puchaz spin - now wearing 'chutes

Bill Daniels wrote:
OK, crank these numbers. Consider my Nimbus 2C (Experimental, so I
could
install a BRS) at 650 Kilos with water (which takes 5 minutes to dump). The
gear strut will give 30mm on impact and the tire will give 50mm more. The
cockpit shell is just fiberglass with no crush structure.

I pop a BRS at 300 meters AGL with the surface wind at 15 knots. What are
my chances? Give BRS weights, 'chute diameters and descent rates.

My understanding is the "whole glider" German rescue systems will lower
the glider nose down at about 40 degrees or so. If it is more level, it
is likely to oscillate wildly so much the descent and impact can't be
controlled. So, the landing gear is irrelevant, but the cockpit
structure is extremely important. The nose must absorb the "landing".

A Nimbus 2 might be a poor candidate for installing a system that won't
be tested, except when you really need it. Your safety might be better
served by selling the Nimbus and buying newer glider with a more crash
tolerant cockpit. At least in the US, crashing while landing (meaning
the last 100' of altitude) still claims more pilots than unsuccessful
bailouts.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

"Eric Greenwell" wrote in message
...
Bill Daniels wrote:
OK, crank these numbers. Consider my Nimbus 2C (Experimental, so I
could
install a BRS) at 650 Kilos with water (which takes 5 minutes to dump).
The
gear strut will give 30mm on impact and the tire will give 50mm more.
The
cockpit shell is just fiberglass with no crush structure.

I pop a BRS at 300 meters AGL with the surface wind at 15 knots. What
are
my chances? Give BRS weights, 'chute diameters and descent rates.

My understanding is the "whole glider" German rescue systems will lower
the glider nose down at about 40 degrees or so. If it is more level, it
is likely to oscillate wildly so much the descent and impact can't be
controlled. So, the landing gear is irrelevant, but the cockpit
structure is extremely important. The nose must absorb the "landing".

A Nimbus 2 might be a poor candidate for installing a system that won't
be tested, except when you really need it. Your safety might be better
served by selling the Nimbus and buying newer glider with a more crash
tolerant cockpit. At least in the US, crashing while landing (meaning
the last 100' of altitude) still claims more pilots than unsuccessful
bailouts.

Eric Greenwell
Washington State
USA

OK, good info Eric - now we are getting down to it.

To summarize the thread so far:

The BRS requires a reinforced cockpit to absorb the non-trivial landing
impact forces. Most accidents involve premature termination of tow or
landing errors where a BRS 'chute wouldn't help anyway. Or perhaps,
mid-air collisions at an altitude where a personal 'chute is the equal for a
BRS for survivability.

A BRS is likely to require non-trivial pilot training and discipline in its
operation and maintenance. Injuries should be expected with the used of
either personal or BRS 'chutes.

On the other hand, taking the 'chute off the back of the pilot and putting
it on the glider adds significantly to ergonomics and comfort. The BRS can
be deployed at low altitudes where a pilot with a personal 'chute is
unlikely to make a successful egress. This altitude band favoring a BRS
probably expands where the pilot is old or infirm.

Maybe it's something to think about on a new glider but retrofitting an
older glider is problematical. A BRS is perhaps a useful option but not a
panacea. I remain skeptical but open to ideas.

Bill Daniels

Bill Daniels wrote:
Eric Greenwell wrote
My understanding is the "whole glider" German rescue systems will lower
the glider nose down at about 40 degrees or so. If it is more level, it
is likely to oscillate wildly so much the descent and impact can't be
controlled. So, the landing gear is irrelevant, but the cockpit
structure is extremely important. The nose must absorb the "landing".

A Nimbus 2 might be a poor candidate for installing a system that won't
be tested, except when you really need it. Your safety might be better
served by selling the Nimbus and buying newer glider with a more crash
tolerant cockpit. At least in the US, crashing while landing (meaning
the last 100' of altitude) still claims more pilots than unsuccessful
bailouts.

To summarize the thread so far:

The BRS requires a reinforced cockpit to absorb the non-trivial landing
impact forces. Most accidents involve premature termination of tow or
landing errors where a BRS 'chute wouldn't help anyway. Or perhaps,
mid-air collisions at an altitude where a personal 'chute is the equal for a
BRS for survivability.

A BRS is likely to require non-trivial pilot training and discipline in its
operation and maintenance. Injuries should be expected with the used of
either personal or BRS 'chutes.

On the other hand, taking the 'chute off the back of the pilot and putting
it on the glider adds significantly to ergonomics and comfort. The BRS can
be deployed at low altitudes where a pilot with a personal 'chute is
unlikely to make a successful egress. This altitude band favoring a BRS
probably expands where the pilot is old or infirm.

Maybe it's something to think about on a new glider but retrofitting an
older glider is problematical. A BRS is perhaps a useful option but not a
panacea. I remain skeptical but open to ideas.

I think that's a good summary. For me, it's not possible because I have
a motor glider. That also excludes about half the German production.

I don't think the on-ground safety aspects are difficult - remember,
these units have been used successfully (BRS lists 159 saves so far) in
ultralight aircraft for many years and they have systems for the Cessna
150, 172, 180, and Cirrus, so it's not like the basic system is new.

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA