Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: DoctorBeaver on 10/08/2007 18:20:57

Title: Helium v hydrogen v hot air in balloons
Post by: DoctorBeaver on 10/08/2007 18:20:57

If you had 3 balloons of equal dimensions & equal unfilled weight  - 1 hot air and the other 2 filled with helium & hydrogen respectively -  how would they compare with regard maximum ceiling?

I don't envisage the helium or hydrogen balloons carrying tanks of gas; just fill 'em up & let 'em go with enough ballast to equal the weight of the hot air burner.

Title: Helium v hydrogen v hot air in balloons
Post by: syhprum on 10/08/2007 21:00:56

Balloons are not normally rigid structures and are free to expand as they lift off, the greatest altitudes are achieved by flexible Helium filled balloons although greater heights could probably be obtained with the use of the slightly lighter gas Hydrogen but there are two big problems with its use, firstly it is inflammable and secondly its tiny molecules are very difficult to contain.
Hot air balloons have the great advantage that the gas is very cheap but they need to burn fuel to keep it hot although hot air and Helium structures can be combined to obtain some of the advantages of both.
There is a class of Helium balloon that has a rigid envelope that that is not free to expand that will float at an assigned air pressure level and is capable of orbiting the Earth several times.   

Title: Helium v hydrogen v hot air in balloons
Post by: DoctorBeaver on 10/08/2007 23:50:10

Thank you, syhprum. I thought that would be the case.

Title: Helium v hydrogen v hot air in balloons
Post by: ukmicky on 10/08/2007 23:56:07

You going flying doc ,you thinking of doing a branson in a gas filled balloon. :)

Title: Helium v hydrogen v hot air in balloons
Post by: DoctorBeaver on 11/08/2007 00:02:36

Quote from: ukmicky on 10/08/2007 23:56:07

You going flying doc ,you thinking of doing a branson in a gas filled balloon. :)

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Fnono%2F6.gif&hash=7ba7ca9c01a4fb4cb30a5751006006b5) My paws are staying on terra firma.