Editing Airship (section)

===Non-rigid===
{{Main|Blimp}}
Non-rigid airships are often called "blimps". Most, but not all, of the American [[Goodyear blimp|Goodyear airship]]s have been blimps.

A non-rigid airship relies entirely on internal gas pressure to retain its shape during flight. Unlike the rigid design, the non-rigid airship's gas envelope has no compartments. However, it still typically has smaller internal bags containing air ([[ballonet]]s). As altitude is increased, the lifting gas expands and air from the ballonets is expelled through valves to maintain the hull's shape. To return to sea level, the process is reversed: air is forced back into the ballonets by scooping air from the engine exhaust and using auxiliary blowers.