Ballonets are used to maintain the shape of non-rigid airships, and as buoyancy compensation.

Could ballonets also be used for buoyancy compensation in a rigid airship?

I'm wondering if a ballonet system could be used for limited height-control in a story I'm writing.


1 Answer 1


Yes, inflating ballonets in an airship's rigid envelope would necessarily compress the "gasbags" therein containing lifting gas, thereby increasing that gas's density and reducing the airship's buoyancy.

However, the extra pressure that this would impose on the gasbag skin would demand a stronger and thus heavier skin. The extra weight of both the skin and the ballonets themselves might not justify their use. So your guess of limited height control is justified: squish the gasbags only a few per cent, with ballonets so light and flimsy that they often break (which is no cause for alarm).

  • $\begingroup$ Could a balonet be placed in each, or some of, the individual cells? These would have to be heavier, to withstand pressure, of course. $\endgroup$ Feb 16 at 1:21
  • $\begingroup$ Ah -- reinforcing several gas-bags will quickly increase weight as much as reinforcing the outer envelope; having multiple balonets and inflating systems will add more weight, and we're in the same position as before... I think. $\endgroup$ Feb 16 at 1:54

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