ballonet
nounUK /ˈbalənɛt/
Etymology Borrowed from French ballonnet.
1
Any of several small balloons, inside a dirigible, that can be inflated or deflated to control buoyancy during flight.
- An observation balloon, sausage-shaped and thickened at one end by small subsidiary ballonets, lifted itself, almost as though it were being hoisted by a series of pulls, out of one of the hollows beneath them […].1929, Frederic Manning, The Middle Parts of Fortune, Vintage, published 2014, page 27: