Examples from the Web for ballonet
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.
There are two noteworthy innovations in connection with the ballonet.
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.