Date: 12 Jun 89 19:39:20 GMT
From: jtk@mordor.s1.gov  (Jordan Kare)
Subject: Re: space news from May 1 AW&ST

In article <332@aeras.UUCP> tneale@aeras.UUCP (Tom Neale) writes:
>In article <1989Jun4.055452.12921@utzoo.uucp> henry@utzoo.uucp
> (Henry Spencer) writes (and correctly I might add):
>
>>If I haven't got the terms mixed up, no, they are not the same thing.
>>...A parafoil is a gliding parachute, with two surfaces kept
>>apart by ram pressure and a rectangular shape.  Parafoils have largely
>>replaced circular parachutes for high-performance sport parachuting.
>>They are parachutes first and wings second.
>
>You've got the terms just right, Henry.  I think the technical term
>is "ram air inflated, semi rigid airfoil. It was invented and patented
>by Domina Jalbert in the 1960s.  Pioneer has been working on
>this recovery system for many years.  It is a very, very large ram
>air parachute (several thousand sqaure feet I think; sport parachutes
>for 1 person are 150-300 sqaure feet). 
>
>The really tricky part is the deployment (reefing) system that allows the 
>thing to open slowly so as not to damage the payload or the parachute.
>An abrupt opening at high speed will cause the fabric to fail and the
>parachute to self destruct, or at least subject the payload to such a
>high deceleration force (>>15 G) as to damage it.
>
>Because of the extreme altitudes they can afford to open it very slowly,
>like one or two cells (ram air compartments) at a time.  I don't know
>how this is accomplished but I'll try to find out from some parachute
>designing friends of mine.
>-- 
>Tom Neale	

 I'll just toss in a note here... the parafoil sport parachute
was indeed impractical because of the very high opening shock 
until about twenty years ago, when Steve Snyder (a world-class jumper
himself) invented and patented a sufficiently reliable slow-deployment
mechanism, and started marketing parafoil chutes, first as
Steve Snyder Enterprises, then as Paraflight, Inc.  The 
deployment mechanism uses (as I recall) a steel cable run through eyelets
attached to the chute; as the cable slides free the chute opens.

Steve Snyder has moved out of parachute manufacturing and now makes
and sells the "Paraplane" -- a parafoil wing attached to an
ultralight-styles chassis and engine that makes a very nice
personal airplane.  Not only does the wing fold up so you can
stuff the whole thing in the trunk of your car, but if the
engine ever fails, your parachute is already deployed!

As a side bit of irony, Steve, who has made uncounted parachute
jumps (after all, the rule for people who develop new parachute
gear is "you built it, you test it!") and done various other
high risk things like fly his own jet airplane, suffered his 
only serious injury a few years back... smashed his hip when
he fell off the roof of his house while installing a solar
water heater.  And they say solar energy is safe... :-)

Why do I know this? Steve happens to be a cousin of mine....

Jordin (What kind of a nut would jump out of a perfectly good airplane?) Kare

	jtk@mordor.UUCP	jtk@mordor.s1.gov