The Cargo Airship That Wasn’t

Helium has been, and always will be, too scarce and expensive to vent to regulate lift in airship operations. Designers have explored many concepts to overcome the limitation of helium’s fixed ascensive force in the effort to make a practical cargo airship. One long held hope has been to mate the helium bag to some sort of lifting rotors. One example, the cyclocrane prototype, mounted propeller engines on controllable surfaces, allowing vectored thrust. Another, the Piasecki Helistat, got Government funding to mate four existing Korean-war era helicopters to a framework made of irrigation tubing attached to a spare ZPG-2 bag. Before the deadly crash of that lashup, Goodyear Aerospace joined in with their own design. Reaching the model stage as seen in this promotional video, the idea was made more cost-effective by the elimination of the complex and expensive helicopter rotor heads. One can see forward or reverse thrust would have been provided by smaller tractor props on the structure, while the larger rotors via throttle control could lift and carry the weight of the payload. This promised to overcome the limitation of not being able to vent lifting gas, since the air by the envelope displaced lifted the basic weight of the vehicle. The deadly crash of the Piasecki Helistat effectively ended this design philosophy, ironically before the concept of placing large spinning rotors adjacent to the rather fragile gas containment could be tested in operational conditions.