The problem with LSR chute deployment vs sky divers is that in LSR the tow
strap is generally very long and is ejected backwards. The effect of this is
that the cute in LSR is at a virtual stand still when it is snapped open.
Deflated one instant inflating the next. Skydivers generally have thier rigs
inflate when deployed (who wants that feeling of is it gonna work ?) when
you pull the rip cord. There are many ways to softern the jerk loads. Is
this the only analysis possible, heck no! Just use good data and reasonable
physics.
mayf
----- Original Message -----
From: "3liter" <saltfever@comcast.net>
To: "land-speed submit" <land-speed@autox.team.net>
Sent: Sunday, July 11, 2004 11:34 PM
Subject: Chute Force (2)
> 01 Jul 2004 john robinson, Subject: chute loads v/s time
>
> (snip..)regardless of speed, and the loads seen are mitigated by the
> stretchyness of the nylon system, now we were gathering data at 40 bits a
> second/channel and we had enough memory to grab 4 channels for just over
3
> minutes, so we could see the entire jump.
>
>
>
> I am assuming "40 bits a second" means 40Hz (25 milli seconds) and not 40
> bits of resolution (about 1 trillionth of a second). The old 8080 or Z80
> just couldn't log data that fast. If John could capture only a 25 milli
> second slice of data, and the Yank force was a 15 to 35 milli second
event,
> it is most likely they never recorder that data.
>
>
>
> A few years ago I was involved with a high altitude, high speed,
experiment.
> At first glance you would assume there would be little force on the chute
> since the air was so thin (very few molecules up there). However, that is
> not the problem. Even though there are few molecules, the few that are
> there, are traveling at a very high rate of speed. The true-air-speed is
> what influences the chute opening speed. The RATE of opening is what is
> destructive and not the total force after it is fully open.
>
>
>
> I agree stretch will attenuate some of the "shock" force of a fully open
> chute. However, is those last few milli seconds to full deployment that
the
> RATE-OF-OPENING is so high that is destructive. The system can't stretch
> fast enough. -Elon
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