In reply to Reach>Talent:
> (In reply to colina)
> Helium will give you about 1kg of lift per m3 of gas...
> Average person weighs about 70kg, so needs 70m3 of helium to offset that. Unfortunately you've got to carry the gas in cylinders. A 9m3 cylinder weighs about 85kg so you get 0.5kg of net lift per cylinder. 140 cylinders would be required to make you bouyant and you'd need at least another couple to make any noticable lift...
So the first fine tuning where the balloon and cylinders stay on the ground and the balloon is tied to the climber avoid the cylinder weight issue. To get 80kg of lift only 9 cylinders are needed.
Second fine tuning. Rather than try and cancel all the climbers weight and have them float down the system just aims to reduce the fall force enough so they can land safely. The air resistance as the climber drags the large balloon down will also have a parachute effect. So maybe it only needs 30 or 40kg of lift instead of 80, which would be 4 or 5 cylinders.
Still not quite there though....