'Air-filled ballonets control how much this gas is allowed to expand in the envelope'
helium
THE GOODYEAR BLIMP: Air-filled ballonets control how much this gas is allowed to expand in the envelope
Air-filled ballonets control how much this gas is allowed to expand in the envelope
Air-filled ballonets control how much this gas is allowed to expand in the envelope
THE GOODYEAR BLIMP
helium
THE GOODYEAR BLIMP