4 ms·
Yes, but while hydrogen (H) has half the mass of helium (He), H is only 8% better than He in providing lift in the air, if I computed correctly (as that is gene
by FabHK 5y ago
Yes, but while hydrogen (H) has half the mass of helium (He), H is only 8% better than He in providing lift in the air, if I computed correctly (as that is generated from displacing much heavier air), so it's not a huge deal:
He: 0.1786 kg/m^3
H: 0.08988 kg/m^3
Air: 1.225 kg/m^3
Air vs He: 1.0464 kg/m^3
Air vs H: 1.13512 kg/m^3
To put it differently, for helium, the lift is about 86% of the weight of the displaced air, while for hydrogen it's 93%.
Both very good, and both are much better than hot air!
(which gives a lift of only about 25% of the weight of the displaced air, at typical temperatures of about 120 deg C)
- zabzonk 5y agoAccording to the wikipedia page I linked to: > In a practical dirigible design, the difference is significant, making a 50% difference in the fuel-carrying capacity of the dirigible and hence increasing its range significantly But I wouldn't know :)
- FabHK 5y agoOh, very interesting. The linked TIME article from 1924 (!) gives a bit more detail: > While helium is exceedingly light as compared with air, it is somewhat heavier than hydrogen. The total lift of a helium-filled dirigible is accordingly some 10% less than that of the hydrogen-filled airship. The difference does not appear important at first sight, but the total lift of the gas carries the structure, the motors and the crew. It is only the last 20% or so that is available for carrying fuel, and hence a difference of 10% in the gross lift may spell a difference of 50% in the fuel-carrying capacity. On long-distance flights this difference is vital. > Nor is the danger of fire totally eliminated with the use of helium; the gas-tanks and the fuel system generally are still vulnerable. But when a ship is properly designed and carefully handled, the danger of fire is comparatively small, even with hydrogen. https://web.archive.org/web/20110209024932/http://www.time.com/time/magazine/article/0,9171,786149-2,00.html https://web.archive.org/web/20110209024932/http://www.time.c...
- WalterBright 5y agoNote that a contributing problem to the Hindenburg disaster was the exterior canvas paint was chemically about the same as rocket fuel.
- andreareina 5y agoThat's what I remembered, so I was surprised it wasn't mentioned in TFA.
- app4soft 5y ago> Both very good, and both are much better than hot air! No. Hydrogen is highly explosive/flammable — that is why Helium is preferred.