(under subclass 31) Aircraft normally sustained by their buoyancy relative to the air, having also provision for retarding their fall upon failure of their buoyancy, by means of parachutes attached to or formed from some part of their structure.
(1) Note. This subclass includes those aircraft having propulsion means disclosed, but in which the invention is the combination between the gas bag and the parachute, or the conversion from one to the other.
SEE OR SEARCH THIS CLASS, SUBCLASS:
139, for the combination of balloon, parachute and heavier-than-air craft for lowering the latter in an emergency.
