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Hydrogen and helium are the most commonly used lift gases. Although helium is twice as heavy as (diatomic) hydrogen, they are both significantly lighter than air. Thus helium is almost twice as dense as hydrogen. The lifting power in air of hydrogen and helium can be calculated using the theory of buoyancy.
Based on specific lift (lifting force per unit volume of gas), the greatest static lift is provided by hydrogen (11.15 N/m 3 or 71 lb f /1000 cu ft) with helium (10.37 N/m 3 or 66 lb f /1000 cu ft) a close second. [172] In addition to static lift, an airship can obtain a certain amount of dynamic lift from its engines.
Aerostatic lift or buoyancy, in which an internal fluid is lighter than the surrounding fluid, does not require movement and is used by balloons, blimps, dirigibles, boats, and submarines. Planing lift, in which only the lower portion of the body is immersed in a liquid flow, is used by motorboats, surfboards, windsurfers, sailboats, and water ...
Bernoulli's principle can be used to calculate the lift force on an airfoil, if the behaviour of the fluid flow in the vicinity of the foil is known. For example, if the air flowing past the top surface of an aircraft wing is moving faster than the air flowing past the bottom surface, then Bernoulli's principle implies that the pressure on the ...
Example: A helium balloon in a moving car. When increasing speed or driving in a curve, the air moves in the opposite direction to the car's acceleration. However, due to buoyancy, the balloon is pushed "out of the way" by the air and will drift in the same direction as the car's acceleration.
High-altitude balloons or stratostats are usually uncrewed balloons typically filled with helium or hydrogen and released into the stratosphere, generally attaining between 18 and 37 km (11 and 23 mi; 59,000 and 121,000 ft) above sea level. In 2013, a balloon named BS 13-08 reached a record altitude of 53.7 km (33.4 mi; 176,000 ft). [1]
Helikites are used by telecoms companies to lift 4G and 5G base stations for areas without cellphone coverage. Helikites range in size from 1 metre (gas volume 0.13 m 3) with a pure helium lift of 30g, up to 14 metres (gas volume 250m 3) able to lift 117 kg. Small Helikites can fly up to altitudes of 1,000 ft, and medium-sized Helikites up to ...
A vacuum airship, also known as a vacuum balloon, is a hypothetical airship that is evacuated rather than filled with a lighter-than-air gas such as hydrogen or helium. First proposed by Italian Jesuit priest Francesco Lana de Terzi in 1670, [ 1 ] the vacuum balloon would be the ultimate expression of lifting power per volume displaced.