ballonet

[ bal-uh-ney ]

/ ˌbæl əˈneɪ /

an air or gasbag compartment in a balloon or airship, used to control buoyancy and maintain shape.

Origin of ballonet

From French, dating back to 1900–05; see origin at balloon, -et

The magneto was run by a belt from one of the ballonet blowers.

The War in the Air; Vol. 1 |Walter Raleigh.
Ballonet, filled by a separate motor giving 7.5 inches of water pressure.

Jane's All the World's Aircraft |Various
There are two noteworthy innovations in connection with the ballonet.

Jane's All the World's Aircraft |Various
It appears to be rearing up on end, as if the extremity saddled with the ballonet were weighted.

Aeroplanes and Dirigibles of War |Frederick A. Talbot

The air pump, which should have pumped the ballonet full of air to keep the balloon rigid failed to work.

Aircraft and Submarines |Willis J. Abbot.

ballonet

/ (ˌbæləˈnɛt) /

an air or gas compartment in a balloon or nonrigid airship, used to control buoyancy and shape

C20: from French ballonnet a little balloon