Puchaz spin - now wearing 'chutes

Bill Daniels wrote:
"Jim Harper" wrote in message
om...

Mike Borgelt wrote in message

. ..

some snippage

The whole ship chute concept is a bit of a worry. There you are in a
large heavy object with absolutely no control. With a personal chute
you do have steering on most rigs nowadays.

With a whole ship chute would it just ruin your day to have save and
then hit the high voltage lines, fall out of a tree, fall over a cliff
etc?

some MORE snippage

Mike Borgelt

Actually, Mike, on that we disagree.

Unless you are using a square canopy for your personal chute, you have
very little choice on where you are gonna land...and hitting the tree,
high voltage lines or over the cliff are gonna suck less if you have
some aluminum or fiberglass around you. Well, that was my decision for
sure.

Oh, and keep in mind that as I disagree with you, I do it with all due
deference to someone as distinguished in our sport as yourself (no
sarcasm, I meant that!)

Jim


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.

Bill Daniels

Hi, Bill.

Too many variables there to calculate for me, but I did visit the BRS
site to gather some data. Their 680 kg. capacity system is 13.5m in
diameter, weighs 16kg, and claims 7.6 m/sec descent rate @ 5000' density
altitude. So in your proposed situation you're going to land with about
a 15kt vertical component and a 15kt horizontal component. Translating
that into G-forces and survivability I'll leave up to someone more
knowledgeable...

OTOH, I'm glad you picked this particular scenario, because I think its
exactly where a BRS system would be invaluable. You're at 300m AGL in
an unlandable ship - you pull the BRS handle and 2-3 seconds later you
are under canopy. In the same situation what are your chances of
popping the canopy, unbuckling, bailing, and deploying your chute in
time? Now what if you're spinning, tumbling, or pointed straight down
without an elevator?

At a sufficient altitude where egress time isn't a big factor, I think
the personal vs. BRS calculation could go either way. The closer you
are to the terrain at the time of the 'incident', the more a BRS system
looks like the only game in town.

All IMHO,

Dave Houlton