Ballonet

From Glossary of Meteorology



ballonet

A gastight compartment of variable volume to control ascent and descent and to maintain pressure in a nonrigid airship.

When the ballonet is used within a superpressure balloon, valving of gas increases altitude, and pumping of air into the ballonet causes the balloon to descend. The superpressure is only marginally affected as the balloon changes altitude.