Revolutionizing transportation with airships is an old idea but a persistent one, and it's usually the military that brings it closer to reality. More than a century after George Griffith described armed conflict fought with "war balloons" in his popular novel The Angel of the Revolution, the U.S. military was considering the merits of transporting materiel with airships. In 2005 Darpa, the Pentagon's experimental branch, initiated Project Walrus and set about finding a contractor to build a "hybrid ultra-large aircraft" that could transport 500 tons of cargo at least 12,000 nautical miles. Pasternak's Aeros got the biggest contract of the project. ("There is only one solution," Pasternak had explained to the Los Angeles Times, "and we have that one solution.") But in 2010, the Pentagon chose not to renew Project Walrus, a fate not uncommon to airship schemes.