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Martha Wells

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Airships

We were talking a bit about airships on Tumblr yesterday, and this is a post I wrote a few years ago:


A Quick and Very Basic Airship Primer

I've seen some bizarre and annoying mistakes made with regard to airships lately, so I wanted to collect some basic links in one handy spot.


What are they?


Dirigibles, Zeppelins, and Blimps

A rigid airship is a powered, steerable, lighter-than-air vehicle which maintains its shape by means of a rigid framework, or "skeleton," surrounding one or more individual cells inflated with lifting gas.

A blimp has no internal skeleton, and a semi-rigid airship has only a partial one.

Rigid airships are generally called zeppelins, but a Zeppelin is actually a rigid airship made by Count von Zeppelin.

Airships are generally not very fast, compared to say, planes. LZ-127 Graf Zeppelin could do about 80 MPH.

Metal-Clad Airships were not popular. Only four ships of this type are known to have been built, and only two actually flew...

Airships used flammable hydrogen as a lifting gas or helium, which is inert but more expensive and the supply was limited, and there was debate on which was better: Aeronautics: Helium vs. Hydrogen Nor is the danger of fire totally eliminated with the use of helium; the gas-tanks and the fuel system generally are still vulnerable. But when a ship is properly designed and carefully handled, the danger of fire is comparatively small, even with hydrogen. Personally, I feel it comes down to whether you'd rather die by burning up or by plummeting to the ground.


Landing: How To

Hot air balloons can land on their own because the balloonist is controlling the temperature of the air inside the balloon with the burner. Hotter air = balloon go up, Cooler air = balloon go down. To land, they let the air cool slowly (hopefully slowly) until the balloon touches down. (Or drags across the ground and then falls over.)

Airships don't do that. See Larry's U.S. Navy Airship Picture Book: Our Landings Were Always Exciting They don't just drop down and park. Landing our giant airship was a major operation where few things were in our favor. Often it took us several tries to make a good approach, roll to a stop, and to get enough groundhandlers on the lines to hold us stationary. The slightest wind could push us enough so that the ground handlers couldn't hold us in place for the mobile mast to approach and lock to the airship bow. That happened many times.

Mooring to a building, like the Empire State Building, is possible but the building has to be carefully designed for it, which the Empire State Building actually wasn't. From the article Airships and the Empire State Building: Fact and Fiction (not online anymore)
Granted, the building's framework was stiffened against the 50-ton pull of a moored dirigible, some of the winch equipment for pulling in arriving ships was installed, and the 86th floor was readied with space for a departure lounge and customs ticket offices. The builder's lawyers even prepared a thick brief, arguing, amongst other things, that owners of neighboring buildings could not sustain a claim of trespass when they found dirigibles overhead. But no one worked out one other problem: wind. The steel-and-glass canyons of Manhattan are an airship captain's nightmare of shifting air currents. Raskob and Smith were inviting the unwieldy craft to come in low and slow, over hazards such as the menacing Chrysler Building spire, and somehow tie up without use of a ground crew. Then, too, if the crew released ballast to maintain pitch control, a torrent of water would cascade onto the streets below. And once secured, a dirigible could be tethered only at the nose, with no ground lines to keep it steady.

Passengers would have to make their way down a swinging gangway, nearly a quarter mile in the air, onto a narrow open walkway near the top of the mast. After squeezing through a tight door, they would have to descend two steep ladders inside the mast before reaching the elevators. "Can you see some 75-year-old dowager doing that?" asks Alexander Smirnoff, the current telecommunications director of the building, as he stands on that walkway.


Crashing: How To

The Hindenburg didn't crash into the ground. The hydrogen gas cells caught on fire, and then it fell.

Blimp Crashlands on Roof of a Building in Manhattan In airship on skyscraper collisions, skyscrapers mostly win.

The Crash of Navy Blimp L-8 If no one is controlling them, airships will eventually hit the ground. Caddies at the Lake Merced Golf & Country Club witnessed the blimp disappear behind two hills, and then rise again after a brief snag on a cliff on Ocean Beach. This snag gouged the cliffside, causing the starboard engine to be packed with dirt, and bending the propeller blades. Also, one of the two depth charges on board the airship broke free from its rack, and fell to the ground at the Olympic Club's golf course.

USS Shenandoah Buffeted severely by air currents, Shenandoah's crew lost control of the airship. Rapidly rising and falling, the airship's structure amidships became overstressed, breaking it in two. As Shenandoah broke up, its external control car and engines fell free, killing Lansdowne and several of the crew. Lieutenant Commander Charles E. Rosendahl and other members of the crew were able to safely descend, flying the bow section as a balloon. All told the crash claimed 14 dead, while 29 managed to reach the ground alive.

And eventually they crash one too many times: USS Macon A violent gust tore off her upper fin, causing damage that soon brought her down into the sea. Though all but two of her crew were rescued, the dirigible sank in deep water, effectively ending the Navy's controversial, and trouble-plagued, program of rigid airship operations.



Oh, and before there were UFOs, there were Unidentified Flying Airships
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thank you! This is fascinating.

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