What’s the difference between an airship, a dirigible, a Zeppelin and a blimp? It isn’t a bad joke, there is an actual difference, as described here.
A blimp’s shape is maintained by the pressure of the gases within its “balloon”, whereas a dirigible’s shape is maintained by a rigid framework, which holds the buoyant gases inside. Zeppelins are an airship product manufactured by a German company called ZLT Zeppelin Luftschifftechnik. They are best known for the use in World War One, but still manufactured today. An airship is an umbrella term for any “a power-driven aircraft that is kept buoyant by a body of gas that is lighter than air”.
Why do you need this information? Because airships are coming back into fashion. Admittedly every now and then this story is recycled by the press, and there’s normally a lot of hot air involved. But this time the story is more grounded in the reality of cold hard cash and defence deals.
Northrop Grumman is developing the Long Endurance Multi-intelligence Vehicle (LEMV) hybrid airship project in a $517 million deal with UK firm Hybrid Air Vehicles. Airships make sense to the military now as they did in World War One. They can stay up in the air a long time; can maintain position at high altitudes; are energy efficient with a large range; use established and reliable technology and can carry heavy payloads. Hybrid Air Vehicles offers a heavy lift airship and a surveillance airship. The Northrup Grumman vehicle is in testing now with the aim of putting it into service next year.
While Northrup’s looks the furthest forward, there are similar projects are being developed, such as Lockheed Martin’s HALE-D and TCOM’s Blue Devil and look to be progressing well. Other projects such as Boeing’s Skyhook, which is being developed with a Canadian firm and UK firm Skycat’s funky plane / airship hybrid haven’t been reported on for a while.
The trend though is for defence and cargo applications, passenger use is still very restricted.