"Bill Daniels" wrote in message ...
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. Please don't take what follows in any sort of argumentitive
way. I've played out the scenario you describe in making my decision
to buy the BRS. As I reread it, it sounds harsh, but it certainly
isn't meant harshly...just heart-felt. Thanks for taking it in the
spirit it is intended...Dave answered the primary question you had...a
15 knot collision with the earth is gonna hurt for sure. However let's
put you in your Nimbus, busted...at around 980 feet, plummeting
earthward at...oh, let's just say...80 mph. You need to pull your
ripcord at a minimum of, what, 350 feet? That would be
borderline...I'd rather try it at 500 feet. Ok, you have (117 fps
down) 3-4 seconds to open (jettison) your canopy, unfasten your belts
and get out of and away from your glider and pull the ripcord. Pretty
much half the amount of time it took to read that last sentence out
loud. Do you really think you can? Add the g-forces associated with
any significant damage and just making the decision...If you can, you
are a better man than I.

Put me in the same position in my BRS equipped glider...I need to
reach over my right shoulder and pull...much the same move as your
first move to jettison the canopy...but in a different direction, of
course :-). I am now under canopy. I am hanging nose down (I figure
around 45 degrees or so) I've got (around 22 fps down) 20 seconds
(assuming I wind up under canopy at 500 feet) to get my landing gear
down, tighten my straps, brace and take the impact. The glider hits
nose first (with an impact which is a significant fraction of the
total force...let's call it 75% of the force...so about what I would
get by running into a brick wall at 12 mph), and the rest of the force
is dissipated by the glider rotating down to the landing gear...one
would expect that it would take the rest with minimum loading on my
body.

I'm hurting but alive, most likely. You're dead, most likely. God
forbid either one of us explore this scenario...but I prefer my
chances over the non-BRS equipped glider.

Jim