[Space] Why the payload was bouncing around some much.

Christie Dudley longobord at gmail.com
Mon Feb 8 14:20:16 PST 2010


Someone was talking about adding elasticity to the line.  it made me think
that no, we need some sort of tension damping effect.  Which led to
recollection of my applied differential equations class which was taught by
an aerospace engineer who kept talking about springs and damp-pots in
modeling aircraft.  Could we could create something that would become
overdamped and never, ever underdamped considering we don't have any good
idea of what the conditions will be?

Do submarines have stability problems in turbulent water?

Christie
_______
"The road of excess leads to the palace of wisdom." -- W. Blake.

The outer bounds is only the beginning.
http://www.flickr.com/photos/genriel/sets/72157623376093724/


On Mon, Feb 8, 2010 at 2:09 PM, Michael O <m at dgmo.org> wrote:

> I think it's less the drag on the payload, and more than the balloon is
> dumping turbulent air onto it. So streamlining it won't stop it being bashed
> around by frothing vorticies of air.
>
> The much longer tether is pretty much the only useful think I could think
> of too.
>
> On Mon, Feb 8, 2010 at 1:37 PM, Christie Dudley <longobord at gmail.com>wrote:
>
>> What if we made the payload more bullet or torpedo shaped?  If it's being
>> bounced because of drag from the top, it makes sense to reduce that.  I was
>> wondering why they put pointy ends on the EOSS payloads they pictured.  That
>> would explain it.
>>
>> Christie
>> _______
>> "The road of excess leads to the palace of wisdom." -- W. Blake.
>>
>> The outer bounds is only the beginning.
>> http://www.flickr.com/photos/genriel/sets/72157623376093724/
>>
>>
>>
>> On Mon, Feb 8, 2010 at 1:25 PM, Jonathan Moore <moore at eds.org> wrote:
>>
>>> Well we should use a much longer tether next time. That would help
>>> with the effects you describe but also with other effects too.
>>>
>>> Also did any one else notice how clearly we were in two different
>>> winds during the flight. If you look at the kml file you can see that
>>> at lower altitudes we went mostly south but at upper mostly west. For
>>> people wanting to steer the balloon it seems that changing altitude
>>> might be a easy way to do it.
>>>
>>> On Mon, Feb 8, 2010 at 1:20 PM, Michael O <m at dgmo.org> wrote:
>>> >
>>> > Some discussion at lunch reminded me to mention my pet theory for why
>>> the
>>> > payload was bouncing around to much.
>>> > I'd originally assume it was wind shear layers, but the video shows it
>>> was
>>> > moving around fairly violently for pretty much all the ascent.
>>> >
>>> > So my new theory is that having a 7ft+ balloon rising at a pretty
>>> decent
>>> > pace leaving a bunch of turbulent air beneath it which the payload is
>>> being
>>> > dragged through.
>>> >
>>> > This makes adding fins or suchlike to the payload a non-starter I
>>> think.
>>> > It'll just make it even more affected by the turbulence.
>>> > So now I'm back to having no idea how to usefully stablize the payload.
>>> >
>>> > _______________________________________________
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>>> >
>>> >
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>>
>>
>
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