This suggests that the calcs I did comparing Helium to Hydrogen were wrong, I hope you get the idea.
The Relative Lifting Ability of Hydrogen and Helium
Although helium weighs twice as much hydrogen, because each gas is so much lighter than air helium provides about 93% of hydrogen’s lift at full purity. In practical operation it is impossible to achieve or maintain 100% purity of either gas, reducing helium’s lifting ability to about 88% of the lift of hydrogen.
The actual lifting ability of each gas varies with temperature, pressure, and humidity, and to take account of varying atmospheric conditions and gas impurities airship designers often conservatively estimated helium’s lift at 60 lbs per 1,000 cubic feet and hydrogen’s lift at 68 lbs per 1,000 cubic feet.
Relative lifting ability of 100% Hydrogen vs. Helium
60° F, Barometric Pressure 29.92″ Hg
Weight of Lifting Gas
(per 1,000 cu. ft.) Weight of Air
(per 1,000 cu. ft.) Net Lift
(per 1,000 cu. ft.)
Hydrogen 5.31 lbs 76.36 lbs 71.05 lbs
Helium 10.54 lbs 76.36 lbs 65.82 lbs
The Effect of Helium on Airship Range and Payload
In actual use, because of physical realities and operational considerations, the use of helium can reduce an airship’s payload lift by almost half.
