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Date: Tue,  7 Nov 89 04:25:03 -0500 (EST)
Subject: SPACE Digest V10 #218

SPACE Digest                                     Volume 10 : Issue 218

Today's Topics:
			 Jupiter Balloon data
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Date: 7 Nov 89 08:29:24 GMT
From: agate!typhoon.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU  (George William Herbert)
Subject: Jupiter Balloon data


	This is the promised Jupiter Balloon data.
	Please treat this all as an unpublished manuscript for a scientific
proposal or paper.  Frank and I are finishing calculations and intend to 
publish and would be upset if someone stole it all :)

	The proposed balloon is simple in concept.  Using a nuclear heat
source, probably a small reactor, as a pure heat source, we propose to
manufacture a hot-hydrogen balloon for long term scientific probing into
the jovian atmosphere.
	Our assumed balloon used a thin double wall envelope of somewhat 
(about 50%) thinner walls than current materials.  With a insulative gap
of hydrogen to minimize heat loss.  
	The SP-100 reactor was taken as standard for the project.  Stripping
it of all but it's core and heat transfer equipment lowers its weight to
a little less than a ton.  It gives a pure heat output of about 2 megawatts
(extrapolated from published data).  Given that the maximum heat useage is where
the loss equals the output, we derived a formula for surface area versus 
interior temperature, and the corresponding bouyancy for a given radius.
	Our test case (off quick calculations) was a fourty meter radius 
balloon.  It gave a estimated 15 tons lift, allowing for errors and some
fudge factor (all conservative).  With a reactor weight of one ton, and a 
envelope at around three tons (perhaps more like five to six being conservative)
and necessary structure, we got a useful load of four to eight tons.
	This is not the optomization point for the design, either.   Making
the balloon larger and lowering internal temp.  raises the bouyancy a lot.
A seventy meter radius balloon would have closer to thirty tons lift.

	It should be obvious that the limit is not the liftable weight but
the weight we can toss to Jupiter.  Including an ablative shell, the above
balloons are truly massive.  Getting them to jupiter is more of a hassle than
making them work, IMHO.

	-george william herbert
[this article and the abstract preceding it are copyright frank crary and george 
william herbert.  we ask that you not publish it or use it as the basis for a 
published article.  feel free to show the idea around, though.  you heard it here
first!]

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End of SPACE Digest V10 #218
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