US PATENT SUBCLASS 244 / 97
.~.~ Buoyancy varying
Current as of: June, 1999
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DEFINITION
Classification: 244/97
(under subclass 96) Devices and arrangements for controlling lighter-than-air craft by changing the buoyancy of all or part of the craft with respect to the surrounding air.
(1) Note. Devices for compressing or expanding one or more gas cells to alter their buoyancy, are found in this subclass.