Parachute/Payload fastening

[Fletcher]

So I don't know if this is something you've already planned out, but I
was thinking about the parachute and a way to attach the payload. I'm
thinking that you could drape the parachute over the balloon so that
you don't have to worry about it deploying. The parachute chords can
go around the balloon and meet in the bottom to attach to the payload.
Then once the balloon pops you'd be good to go. Plus I think the
surface of the balloon could help support the payload so the weight is
not all being supported by the knot. Just thought of this a few
minutes ago, so I couldn't' tell you mathematically if draping the
parachute would take some of the weight off of the knot. At the very
least I feel like it takes away a point of failure.

Love the google maps-data interface by the way.

[Fletcher]

And if you need more than one balloon--which I'm guessing you will--
you still should be able to drape the balloon over the bottom/middle
balloon.

[Greg Hughes]

I was also thinking about the more-than-one-balloon thing earlier today.
Seems like there's a limit to how high a balloon can go that is at least in
part determined by altitude, because the balloon eventually bursts once it
expands too much. So I was wondering if using a second balloon that's
inflated with less gas would provide enough lift at the higher altitude, but
since it was less inflated at ground level it would be able to expand more
when at max altitude, staying inflated when the other balloon bursts. I
haven't thought through the physics - does that provide enough lifting power
at altitude possibly?

Might as well see how high it can go. :)

Greg

--
Greg Hughes
http://www.linkedin.com/in/greghughes
gr...@greghughes.net
(503) 766-2258

[Danny Pier]

Really interesting idea, Fletch.

As it stands right now, the parachute has a loop at the top. That
loop is connected to the balloon. Obviously, the bottom is connected
to the payload.

As the balloon rises, there's tension between the payload and the
balloon and with that tension, the parachute is stretched and
unopened. Once the balloon pops, the parachute is now the only thing
carrying the payload and is able to open... (I'll see if i can find a
diagram, or take a picture).

I think the parachute over the balloon idea would definitely work, if
the parachute were big enough, but I don't think the one i got (3 feet
diameter) is. Also, I've been told that there's so little air when it
pops that it's several thousand feet before it can open anyway!
(Sidenote... helicopter rescues on Mt. Everest are near impossible
because there's not enough air there, even at 30,000+ feet, for the
blades to create lift!)

As to two balloons, I've definitely thought that as well! If one is
good... two is better, right!

Unfortunately, it's not all you would imagine. It's all about
pressure. If there are two identical balloons, they will get you to
bursting altitude twice as fast (perhaps), but not twice as high.
They will still explode at the same point. If you have one bigger
than the other, the smaller one bursts as the bigger one continues to
rise, which really only makes the biggest balloon effective, though
maybe it rises slower. Lucky for us there are some BIG ASS
BALLOONS.

http://www.kaymont.com/pages/sounding-balloons.cfm

I've purchased 4 balloons so far. 2 200 gram balloons. 2 500 gram
balloons. 200 grams is more than enough to lift the payload
(impressively). At that point it just becomes a matter of how far do
we push it, to which my answer is as far as we can, within the
budget. Obviously, the bigger, the more expensive. Once the 500 gram
balloons have been flown and we know a little bit more about the
elements... I'm more than willing to see just how far we can go.

Greg, as you mentioned, the less gas in one balloon is also something
I thought about. Not quite sure how that would respond....? Maybe,
if the payload were heavier than the lift of the gas, it could be used
in place of a parachute to glide down? Not sure if it'd go any
higher... or what it would do, really.

Awesome feedback... I may sound like I'm giving lip service when I say
it, but I really can't tell you how cool I think it is to talk these
things out!

-dp

On Aug 12, 10:32 pm, Greg Hughes <g...@greghughes.net> wrote:
> I was also thinking about the more-than-one-balloon thing earlier today.
> Seems like there's a limit to how high a balloon can go that is at least in
> part determined by altitude, because the balloon eventually bursts once it
> expands too much. So I was wondering if using a second balloon that's
> inflated with less gas would provide enough lift at the higher altitude, but
> since it was less inflated at ground level it would be able to expand more
> when at max altitude, staying inflated when the other balloon bursts. I
> haven't thought through the physics - does that provide enough lifting power
> at altitude possibly?
>
> Might as well see how high it can go. :)
>
> Greg
>
> --
> Greg Hugheshttp://www.linkedin.com/in/greghughes

> g...@greghughes.net
> (503) 766-2258