High altitude balloon payload, from Sable-3 discussion Options

[djellison]

http://www.unmannedspaceflight.com/index.p...20&start=20

We began talkin about a UMSF balloon - and who know what might happen if enough people think about something hard enough, thoroughly enough and long enough.

How's about this as a starting point.
http://vpizza.org/~jmeehan/balloon/ with http://www.chem.hawaii.edu/uham/part101.html as an important regulatory start point (I'm going to look up the UK regs for this as well)

http://www.srcf.ucam.org/~cuspaceflight/nova1launch.html is also very impressive - all done in the UK

This http://www.makezine.com/blog/archive/2007/...video_podc.html is particularly impressive - I like the multiple-cameras slant.

Anyway - thought I'd get a thread going - this is an idea I like too much to let it gather dust in a corner - the one thing that I think would be nice to achieve is self-portraiture of some sort - think Beagle 2's WAM etc....perhaps in a corner of the FOV of one of/the imaging system. What sort of limit's should we set ourselves? 1kg 10x10x20cm? (sort of 2U Cubesat-on-a-diet budget)

Doug

[AndyG]

Thirty Thousand Metres Via A Plastic Bag

The above is a Flash tool for helping develop high altitude balloons. Briefly: the Met balloons are made of some rubbery compound which stretches under reduced pressure until the point at which they burst. With a given quantity of lifting gas in them, the approximate altitude for the burst can be calculated beforehand. Much more Romantic, and Golden-Age-Of-Ballooningy, are the light plastic/Mylar balloons that are part-filled with lifting gas, and gain sphericality at altitude. These are truly bouyant - with the right parameters, they'll find a level of no-lift, no-sink - which makes them ideal for higher altitudes and longer durations. Naturally UMSF engineers could employ a timer to cut loose the Earth-Return Package from such a balloon and achieve higher altitudes than otherwise.

On to the tool...

There's four yellow sliders, one for altitude, three for the balloon. Set the desired balloon parameters first. Radius is the desired balloon radius, Density is envelope density (970kg/m3 seems to be ok for most commercial polyethylenes) and Thickness governs the quality of the envelope, measured in gauges, as shown below:

Gauge Sort-of-Thing
70 Light Duty Rubbish bags - (those bags which literally are rubbish when they burst after putting hardly anything in)
150 Heavy Duty Rubbish bags
200 Refuse Sacks
800 Heavy Construction Film

Setting the three balloon sliders produces a number of results for the balloon. Most important are the volume and envelope mass.

Now move the altitude slider - as the height increases, the figures for Hydrogen and Helium's excess lift drops. Once the excess lift, for a chosen gas, falls below the payload mass, that's the maximum altitude achievable. At this point, the Hydrogen and Helium required figures make sense - these are the mass and volume of the chosen lifting gas required at sea level.

Example: Radius - 5m, Density - 970kg/m3, Thickness - 70 gauge. Max Helium altitude with 2kg payload = 30500m, 31100m with Hydrogen (so not worth the bother for the added risk?)

Max altitude for same balloon with a 100kg Doug payload (generously including thermal gear and some oxygen) ~14000m.

Enjoy!

Andy