Spy Blimp.

This article discusses the utility of unmanned airships. Since an airship can stay aloft for days, Arinc Inc., based in Annapolis, is designing an unmanned version of the American Blimp Corp.'s A-170 airship, which recently performed a 24-hr, demonstration flight over Washington. The company is also looking at the stretched A-180 and other airships with greater lift capacity for carrying payloads of more than 2,200 lb. Now airship builders think that remotely piloted, motorized blimps would make a useful addition to the U.S.'s growing arsenal of unmanned aerial vehicles.