High Altitude Balloon Ideas (2.0) Options

[djellison]

So - now I live in the USA, I've been researching what's possible over here regarding balloon flights.

Firstly - the laws for ham-radio are much more relaxed, so instead of having to use bespoke 10mW transmitters for tracking... you can use an off the shelf 10W APRS tracking device ( http://www.byonics.com/microtrak/mtaio.php ) . You don't need to contact the FAA if it's below a certain mass. There's a lot more country to land it in, rather than the north sea.

So - I'd very much like to start thinking about what unique project we, as a bunch of spacey people, could use a high altitude balloon flight for.

Here's some of the things that have been done recently in the field of amateur high altitude balloon flights :
If you want to be blown away - a cinematography group used the HD-Hero action cameras to record some genuinely breathtaking footage - http://www.youtube.com/user/kevinmacko -
They also used a ShadowBox - a sort of data-logger-of-awesome - http://shadowboxlive.com/
You can now get fairly cheap back-up tracking using the SPOT locators http://www.findmespot.com/en/
There's now an almost off the shelf APRS tracking system including data - http://www.rpc-electronics.com/rtrak-hab.php
These guys have pulled off a number of flights including panoramas being shot as they went - http://sites.google.com/site/ucsdnearspaceballoon/

SO - what, if anything, might we do that's new, unique, interesting, given the options that have opened up in the last couple of years?

[AndyG]

1/ I like the idea of returning home, or, indeed, to any safe/designated landing areas that your payload might find itself near.

There are issues here - any "proper" glider would find itself in a ~1% air density environment at the point of release. Something scaled to work down here will simply plummet from up there. Cheaper and simpler would be to stick with a parachute, but one with some element of a glide ratio. 3:1 is easily attained, 5:1 more difficult (best paraglider canopies are around 11:1) but either of the former should be plenty from an altitude of 30km or so.

One big benefit in a controlled/gliding recovery is that the payload could be made much more stable after release - making it a better camera platform - and it would be possible to program in 360s at stages/altitudes during the descent to give full panoramas if required.

2/ Everybody uses weather balloons, good for 30km. But we know we could balloon to 50km. I think, as a goal, that's more an altitude suitable to UMSF's ambitions!

3/ As to alternative payloads - the artistic-eco-guerilla in me rather fancies a couple of thousand sycamore seeds, released at height.

4/ The somewhat saner, rationalist side of me thinks that demonstrations of the ambient temperature and pressure are essential - but would it be possible to demonstrate the lower gravity at balloon altitude?

Andy

[djellison]

There are issues here - any "proper" glider would find itself in a ~1% air density environment at the point of release. Something scaled to work down here will simply plummet from up there. Cheaper and simpler would be to stick with a parachute, but one with some element of a glide ratio. 3:1 is easily attained, 5:1 more difficult (best paraglider canopies are around 11:1) but either of the former should be plenty from an altitude of 30km or so.

But, the same rule applies as for your glider concerns. at 10 mb it's going to be at a screaming velocity to generate that glide ratio. I've actually seem them try to do that - the parafoil return. It's damn hard because you have almost no means of 'hanging' the parafoil in a way that allows it to reliably inflate after balloon sep. It's a very very hard thing to pull off. You HAVE to do a cut-down, not a burst, because otherwise the burst balloon ruins any chance your parafoil had.

2/ Everybody uses weather balloons, good for 30km. But we know we could balloon to 50km. I think, as a goal, that's more an altitude suitable to UMSF's ambitions!

Zero Pressure Balloons are very big, very hard to find, very expensive, and take a lot of very very expensive helium. PLUS - you HAVE to have a cut-down or you're never returning to the deck. It's an idea worth looking at though

3/ As to alternative payloads - the artistic-eco-guerilla in me rather fancies a couple of thousand sycamore seeds, released at height.

Environmentally, politically, legally even, ..... no. Moreover, the sort of place this is likely to occur, they would never germinate.

4/ The somewhat saner, rationalist side of me thinks that demonstrations of the ambient temperature and pressure are essential - but would it be possible to demonstrate the lower gravity at balloon altitude?

Yup - internal temp, external temp, pressure, maybe humidity, UV flux, IR flux, etc etc.

Gravity scales as over the square of the radius. 6,378km^2 compared to 6,410km^2. W're talking 2.4583 against 2.4338 (both x10^-9) - It's a change of barely 1%. I doubt there's a means of measuring gravity that accurately within the mass and volume constraints....and given the 'entertaining' ride things get up the hill and down the hill, that 1% gets lost in the multiple-G bouncing around in every direction.