The MetLife Blimp was passing through town recently and I had the opportunity to photograph it over three days. Each morning I went go out there before having to check in at the office while the morning light was still right.
The Blimp was moored on one of the large grass areas on the Alliance Airport property which was also in full view from my office window. So, I got to watch its daily activities as the blimp folks would take it out for rides during the day then a small army of deck hands would scamper after the lines hanging from its nose to bring the ship back in for the evening.
I chatted with a couple of the very knowledgeable ground crew guys. The technology is as old as aviation itself. Basically, if you fill a large envelope with gas that is lighter than air then it will cause the ship to rise. Inside the large envelope was another smaller envelope that they pump regular air; the same air that we breathe into. The more regular air that you pump into that smaller envelope, the heavier the ship as a whole becomes and then it sinks.
It was interesting that the power to pump the air into the smaller envelopes when it is in flight comes from the twin Rotax 912 engines that also give it forward and reverse thrust. When the 912's aren't on then they have two leaf blowers pumping air into the scat tubes; an electric blower on one side and a gas powered one on the other. Nothing fancy. These were units that could have come from the Home Depot up the road and were held on with $0.75 hose clamps that probably also came from Home Depot.
The term "ship" really seems fitting. The early morning air seemed very still. But, like the way a ship in the water will gently tug at its mooring lines as the almost imperceptible water currents move that kind of ship, the airship would also pivot and bob gently around its bull-nose mooring point as the wind was waking up.