Airship
Lifting gas

Lifting gas is generally hydrogen, helium or hot air.

Hydrogen gives the highest lift 1.1 kg/m (0.069 lb/cu ft) and is inexpensive and easily obtained, but is highly flammable and can detonate if mixed with air. Helium is completely non flammable, but gives lower performance- 1.02 kg/m (0.064 lb/cu ft) and is a rare element and much more expensive.

Thermal airships use a heated lifting gas, usually air, in a fashion similar to hot air balloons. The first to do so was flown in 1973 by the British company Cameron Balloons.
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