German-American "Sperm" Dirigible Set for Maiden Flight

The unmanned airship maintains stable buoyancy by separating helium in its head from fuel cells in its tail

Forget those cigar-shaped dirigibles of yore. German-American collaboration has produced a tadpole-like airship that could debut within days, and make even a jaded Sky Captain take a second look.

The STS-111 "Stratellite" drone airship has a segmented design that uses a trick from the golden age of dirigibles to overcome buoyancy control issues. Helium meant for buoyancy only fills the head compartment of the airship, while the sagging tail section holds a "Fuelgas" mixture that has the same density as air. That allows the buoyancy of the ship to remain stable even as fuel burns off.

The Register reports that the Graf Zeppelin airship of the 1930s previously used this technique by filling a quarter of its hull with neutrally buoyant "Blaugas" fuel. A smaller prototype in the video gives a good idea of how the full-scale, 111-foot-long airship will fly.

Sanswire and TAO Technologies GmbH envision the STS-111 as a medium-altitude ship that could lurk around 60,000 feet to serve as a communications relay point.

PopSci has examined many other airship designs that have recently come into vogue as commuter transports or even flying luxury hotels. But admittedly, none of those boasted quite so ... unique a shape.