JumpingMan wrote:

...I
know it exists at some amusement parks. Here's the inspiration to my
friend's idea: www.parabounce.com

The video has me convinced. I want to do it too. Where are you?


It clearly works there with no slack problem. You'll notice there
are
two kinds of harnesses used. One is mostly rigid, allowing for a
more
direct transfer of unward movement, while the other seems to be a
more
straightforward setup...like a parachuter's.

The increase in lift due to heat is a good point...our tethers should
have no problem with the additional pull...right?

Yes, no problem. There woudl be at most only a little additional
lift--very easy to pull back down and as the jumper rises more
rope, and therefor more weight will be lifted. You just need to
keep in mind that if airborn with no tether and net negative lift
there will be no way to come down in a controlled fashion without
releasing a little, and only a little gas. That can be done by
adding a couple of smaller balloons that can be released or
deflated.


Does anyone have a cost estimate for this? They would be starting
from
stratch.


Google can get you prices for balloons, helium, skydiver's harnesses,
and rope. Rope is cheap. Helium is pricey. The rest is soemwhere in
between.

--

FF