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• s  having a form maintained by a rigid internal structure as well as by internal gas pressure
• s  not fully rigid

• Amundsen was killed two years ago trying to find hapless Umberto Nobile who had been wrecked with his Pole visiting semirigid Italia.
• Airship, semirigid: Form maintained by rigid or jointed keel, together with internal pressure.
• The semirigid dirigible ("blimp") employs a keel or spine of structural metal usually aluminum, to stiffen the under side of the envelope, support cabins, motors, crew.