Bryan,
My Stroud chutes all use "sleeves" or "bags" and deploy smoothly every
time. I have, however, opened a couple of them without the "bag" and the
opening shock is much greater. And don't forget opening speed in your
opinions/data......makes a hell of a difference when going faster than the
chute is designed for. I have three chutes now. Drogue stabilizer (ribbon),
main (400 MPH max ribbon) and emergency (below 250 MPH solid tri canopy).
Skip
At 01:28 PM 12/15/03 -0800, Bryan Savage wrote:
>Terry
>
>The opening force (hit) depends, mainly, on two factors.
>1) Chute design
>2) Deployment method.
>
>Design
>My book, The Parachute Manual by Dan Poynter, specifies the following:
>Simple round canopy, like a WW2 chute, 1.8
>Cross 1.2
>Ribbon 1.0 - 1.3
>The table this came from lists 28 different canopy types.
>
>Deployment.
>The lowest deployment force occurs when, after the all components of the
>system are in position, the canopy is allowed to open over a period of
>time (3-20 sec)..
>There are several methods used to try and accomplish this. Only two do
>an excellent job and they aren't practice for us. They are the sleeve and
>a reefing system. The sleeve is a bag made out of chute cloth that is
>a little longer than the chute canopy when it's laying on the rigging table.
>The pilot chute attaches to the top of the sleeve. The sleeve has a flap
>at the bottom and holes for rubber bands that hold the shroud lines.
>The pilot chute pulls the sleeve out full length, then the lines are pulled
>from the rubber bands . When the lines come out of the last rubber band
>the pilot chute begins to remove the sleeve which allows the main canopy
>to begin opening.
>A bagged chute works the same way except when the bag opens, after
>line deployment, the entire canopy is released. It can't open because all
>of the suspension lines (shroud lines) are held together by a reefing
>device. As the canopy tries to open, the reefing device is pushed down
>(forward) allowing the canopy to open..
>Both of these methods are 99.999% reliable when the chute is packed
>by a trained rigger in a parachute loft.
>
>I went through all of that to emphasize one thing. Make sure all of the
>lines (tow & chute) are pulled out straight behind the car before the
>canopy is allowed to start opening
>
>END of part I (The facts)
>Part II (My opinions) in my next Email.
>
>Bryan
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