Hi Joe - Assuming this is not a trick question (if a balloon is
neutrally buoyant it won't ascend - so won't ever burst).
Assuming you mean if something else was pulling it up:
The 100g Kaymont (KCI-100) is a re-badged Totex TA-100 and has
a burst diameter of 1.96m (6.4ft) and an average weight of 100g
Ignoring the constraining effects of the latex increasing
pressure at fill:
A 100g balloon will need 100g of lift to make it neutrally
Pure H2 gives a lift of 1.18552 g/L (Air 1.225 g/L
less H2's 0.08988 g/L both STP)
hence requiring 100/1.18552 = 84.3511707L = 0.0843511707 cu
m = 2.978833cu ft of H2 to make it neutrally buoyant.
0.0843511707 cu m of Hydrogen will have a mass of 7.58148g
( 84.3511707L * 0.08988 g/L)
the overall mass will be 100g + 7.58148 = 107.58148g
Assuming a sphere at burst the TA-100 will have a volume of
2.217631 cu m (4/3 Pi r^3)
so for neutral buoyancy the question comes down to at what
altitude does 2.217631 cu m displace 107.58148g of air
or at what altitude does air density become 48.51189g / cu
m (107.58148 / 2.217631)
using the NASA 1960s air density model that gives an altitude
of about 23.85Km (78100ft)
Hope that helps
Steve G8KHW / AJ4XE
0.0843511707 cu m at STP become 2.217631 cu m - a ratio of
using the NASA air density model that gives an altitude of
What this doesn't account for is the pressure increase due to
the elastic tension of the envelope
On 06/09/2020 03:18, Joe WB9SBD
It has been a LONG LONG
time since I have calculated a burst altitude.
Let me see if I am STILL doing it correctly..
I did a calculation on a tiny 100 gram Kamont balloon.
Now i know in theroy this won't work.
But fill it with H2, so it is neutral buoyant.
With those paramaters. what altitude would it pop at?