I started a thread in MPSIMS a few days ago about Alan Eustace, who recently beat Felix Baumgartner’s record for highest parachute jump. Now I’m wondering what the upper limit might be. I can think of several factors involved- the size of the balloon, the size of the payload, the air density at the upper reaches of the stratosphere.
Baumgartner’s balloon was approx. 30,000,000 cubic feet and took him to approx. 128,000 feet altitude. Eustace’s balloon was approx. 11,000,000 cubic feet and took him to approx. 135,000 feet. So a much smaller balloon, but the payload was much smaller as well (Eustace didn’t use a pressurized capsule, he was suspended directly beneath the balloon in his pressurized suit). The balloons are only partially filled on the ground; the helium expands and the balloon grows larger as it ascends and the air gets thinner.
So I actually have more than one question-
How high can a helium (or hydrogen) balloon go? What is the maximum altitude we could expect someone to reach when attempting to set a new record parachute jump? As it rises, will the helium keep expanding until the balloon bursts? I suppose if you overfill the balloon in the first place it will burst before it gets to the edge of space. And if you underfill it, it will rise until the density of the helium matches the density of the air. How precisely can they calculate the altitude where it balances? As I recall, Baumgartner’s balloon kept rising past their goal and he ended up jumping from a higher altitude than they expected. Could Eustace’s team accurately calculate how much helium they needed to beat Baumgartner’s record by 7,000 feet or is it not that precise? Could they only say (based on the size of their balloon and the payload) “We need this much helium to beat the record by approximately this much altitude”?
[QUOTE=Bumbershoot;17852905
How high can a helium (or hydrogen) balloon go? What is the maximum altitude we could expect someone to reach when attempting to set a new record parachute jump?.[/QUOTE]
So it looks like you could perhaps go a bit higher but it would presumably be rather expensive and complicated, especially given that the man/parachute/lifesupport load will presumably be considerably heavier than a normal scientific payload.
Thanks slaphead, lots of good info at those sites. I can’t spend as much time reading them as I’d like right now; they expect me to do stuff here at work and it interferes with my web-surfing.
According to the paragon/stratex website (the team that worked with Eustace), the largest scientific balloon ever flown had a capacity of 60,000,000 cubic feet. I wonder how high it could go with Eustace suspended underneath in his pressurized suit?
You could get higher by using hydrogen instead of helium, which has a specific gravity about half of helium. Not sure of what risks it would pose, though (yes I know what happened to the hindenberg, but there must be some reasons it’s not used for unmanned weather balloons).
