How Is the Ascension Rate of a Helium Balloon Calculated?

[Imustthink]

How do I find the accelerating ascension rate of my helium balloon?
Ignore factors such as the increase of volume as it ascends, temperature, wind etc.
I just want the basic ascension rate of ideal non changing conditions.

rho_f Outside air density - I think typical air density is this - 1.2 kg/m^3

v Volume - 179.59438 m^3

m Mass - 90.7184 kg

g Earth's gravity - 9.80665 m/s^2

Through some research I have been given this formula but am not sure if its the correct one or how to compute it.

a = g*(rho_f * V - m)/(rho_f*V + m)

And also this link

http://en.wikipedia.org/wiki/Buoyancy#Beyond_Archimedes_Principle

 

[LightHero]

It is not possible to calculate the exact ascension rate of a helium balloon under ideal, non-changing conditions without taking into account factors such as temperature, wind, etc. The ascension rate of a helium balloon is affected by these variables and thus cannot be accurately calculated.