ballonet

n. 气室(调节气球升降)

bal.lo.net

n.（名词）
One of several small, auxiliary gasbags placed inside a balloon or a nonrigid airship that can be inflated or deflated during flight to control and maintain shape and buoyancy.
辅助气囊：置于气球或软式飞艇内的一个小的、辅助性的气囊，可通过在飞行中的充气和放气来控制和保持形状和浮力

来源：
French ballonnet [diminutive of] ballon [balloon] * see balloon
法语 ballonnet [] ballon的小后缀 [气球] *参见 balloon