There seems to be a tendency for groups that get together near Disneyland to start talking about imaginative ideas, namely airships. DARPA's Walrus - clubbed like a baby seal by Congress in 2006 - was first unveiled at a DARPATech conference at Anaheim, and a senior USAF airlift planner, speaking this week at the Airlift/Tanker Association conference, mentioned that the USAF is still looking at the airship idea.
Lockheed Martin Skunk Works boss Frank Cappuccio remarked shortly after the demise of Walrus that the concept itself was not unsound - the problem was that the idea of a monster with a 500-ton payload "didn't pass the giggle test". Since then, the Skunks have continued to hawk their P-791 prototype as a potential platform for sensor and other demonstrations while promoting airships for surveillance as well as transport.
Meanwhile, California start-up Aeroscraft, which was the other successful Walrus bidder, has been using DARPA and other funds to demonstrate the variable buoyancy which is the key to its own design.
A practical heavy-lifter using both buoyant and dynamic lift - which was the key difference between Walrus and the giant airships of the 1930s - has enormous appeal. It appears possible to grow it to a payload where an airplane is not only expensive but barely practical (landing gear weight, for instance, tends to get out of control). The structure is simple and lightly loaded and high-tech engines are not needed, so it could be inexpensive to build.
Moreover, it lands and takes off vertically - an ideal quality in a military transport, and one that makes it less vulnerable from a strategic viewpoint than you might think. An airship can land anywhere, disgorge a whole lot of stuff and be gone before the adversary can react.
Since the new ships can make themselves heavier than air on demand - and Lockheed Martin's P-791 had air-cushion feet that could be put into reverse to suck the ship down to the ground - they are far easier to handle than the classic airship, and don't need to take on ballast as they discharge cargo.
A crazy idea, maybe. But is it that much crazier than a 200-foot-span tilt-rotor?