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From: jerrys@mobby.umiacs.umd.edu (Jerry Sobieski)
Newsgroups: rec.skydiving
Subject: Re: High altitude landings
Message-ID: <34556@mimsy.umd.edu>
Date: 16 May 91 14:20:10 GMT
References: <13377@exodus.Eng.Sun.COM> <15939@life.ai.mit.edu>
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Reply-To: jerrys@umiacs.umd.edu (Jerry Sobieski)
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In article <15939@life.ai.mit.edu> bleck@ai.mit.edu (Olaf Bleck) writes:
>In article <13377@exodus.Eng.Sun.COM>, brent@terra.Eng.Sun.COM (Brent Callaghan) writes:
>
>|> The only uncertainty is the landing.  The DZ will
>|> be in the Rockies at 9,500 MSL.  How much harder
>|> will the landing be than at sea level ?
>|> 
>|> What's the increase in rate
>|> of descent and ground speed ?
>
>First order calculation:
>
>Assume steady state fall rate under canopy, so weight equal to
>force on canopy:
>
>W=Pressure*Area=0.5*density*velocity^2(squared)*area of canopy
[much technical stuff deleted]
>Believe it or don't,
>
>-Olaf
>A-12241

(Just what you'd expect from an MIT response:-)

But seriously folks, I think the equation Olaf used is not necessarily going 
to be applicable to airfoils' flight characteristics and/or descent rates.

Empiricly speaking...
I jumped in Casper, WY - 5700' MSL and was quite impressed at the difference
in landing speed.  I weighed ~145 lbs under a StratoCloud (as I recall).  
The landing was not HARD, as much as it was FAST.  I did make it into
the peas which probably was a Good Thing, but the ground speed was
considerable.  

The para-skiers land around 7-8000' I believe (Does anyone out there have
para-ski experience?).  But they have the benefit of cooler air (i.e. denser),
probably higher winds (i.e. lower actual ground speed), and a couple feet
of soft snow (i.e. fewer landing injuries).

I would be prepared to PLF or "slide" in, so a big grassy LZ would be
primo.  Heavy suit/shoes to protect against ground rash, etc.  The more 
wind I think the better as long as it isn't too turbulent from hills, 
treelines, buildings, etc.  Don't expect your normal flare.  I probably
wouldn't try doing accuracy until you have some experience with the 
landing characteristics at that altitude.

I am surprised a 172 could get to 12000' or better (but then I am not
a pilot).  Are you going to do a clear and pull or are you trying to 
get some FF?

Good luck and let us know how it goes.

Jerry


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