While the term originally referred solely to operating the aircraft, it has since been expanded to include technology, business, and other aspects related to aircraft.[2] The term "aviation" is sometimes used interchangeably with aeronautics, although "aeronautics" includes lighter-than-air craft such as airships, and includes ballistic vehicles while "aviation" technically does not.
https://en.wikipedia.org/wiki/Aeronautics

A lifting gas or lighter than air gas is a gas that has a lower density than normal atmospheric gases and rises above them as a result. It is required for aerostats to create buoyancy, particularly in lighter-than-air aircraft, which include free balloons, moored balloons, and airships.
https://en.wikipedia.org/wiki/Lifting_gas

https://www.google.com/search?q="lighter-than-air craft base...




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Note added at 1 day 33 mins (2022-09-23 05:49:17 GMT)
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Aircraft such as balloons, nonrigid airships (blimps), and dirigibles are designed to contain within their structure a sufficient volume that, when filled with a gas lighter than air (heated air, hydrogen, or helium), displaces the surrounding ambient air and floats, just as a cork does on the water. Balloons are not steerable and drift with the wind. Nonrigid airships, which have enjoyed a rebirth of use and interest, do not have a rigid structure but have a defined aerodynamic shape, which contains cells filled with the lifting agent. They have a source of propulsion and can be controlled in all three axes of flight. Dirigibles are no longer in use, but they were lighter-than-air craft with a rigid internal structure, which was usually very large, and they were capable of relatively high speeds.
https://www.britannica.com/technology/airplane/Types-of-airc...

ВОЗДУХОПЛА́ВАНИЕ, пе­ре­дви­же­ние и пре­бы­ва­ние в воз­душ­ной сре­де ле­та­тель­ных ап­па­ра­тов лег­че воз­ду­ха, среди которых раз­ли­ча­ют сво­бод­ные и при­вяз­ные аэ­ро­ста­ты, стра­то­ста­ты, ра­дио­зон­ды, ди­ри­жаб­ли, гиб­рид­ные ЛА.
https://bigenc.ru/technology_and_technique/text/1924089

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Note added at 1 day 3 hrs (2022-09-23 08:24:19 GMT)
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https://cyberleninka.ru/article/n/sovremennye-mirovye-tenden...

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Note added at 1 day 6 hrs (2022-09-23 11:33:06 GMT)
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https://books.google.by/books?id=Kxy5AAAAIAAJ&pg=PA208&dq=li...