"The Army wanted a vehicle that could be delivered within 18 months, so Northrop Grumman looked for a low-risk design and an experienced partner, says Metzger. The companies that preceded HAV developed the Skyship 500 and 600 commercial airships and the Sentinel 1000, a half-scale demonstrator for a U.S. Navy airborne early-warning airship that never materialized."
Says it all really. Abridged version should say "tried it didn't work and 3 companies later we're back again to ask for more wonga"!
Complete poppycock on MQ-9 needing 12 aircraft to provide 24/7 coverage for 3-4 weeks. They've been doing 24/7 with 2 aircraft and a spare for over 9 months - now that is persistance and its still going!!! You'll need the same amount of people to man an unmanned baloon for a 24/7 single orbit shift pattern as you would for MQ-9.
POPPYCOCK!
LJ