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Boeing-Skyhook Airship Faces Technical Challenges
waderoush writes "Since the Hindenburg disaster, dreams of giant airships capable of lifting heavy cargo have been restricted mainly to Popular Science covers
(with the notable exception of the Cargolifter AG failure) — until Boeing and a Canadian company called Skyhook announced on July 8 that they're building a 300-foot-long, helium-filled craft that will lift loads of up to 40 tons and carry them 200 miles. But an aeronautical engineer at the University of Washington cautions that there are still some big problems to be worked out with mega-airships, including their stability in turbulent weather."
Unless we run out of helium.
http://www.wired.com/wired/archive/8.08/helium.html
"At our current rate of consumption, Cliffside will likely be empty in 10 to 25 years, and the Earth will be virtually helium-free by the end of the 21st century."
You mis-understand me. "people are trying to build an airship" is news-worthy even if they were built every day. But that's not this article's focus. This article focuses on how some other people (not the airship builders) mention problems with airship design. This article is about raining on someone else's parade.
What makes it particularly stupid is that these people who are predicting the builders' failure are doing so in an industry where virtually nothing has been done for decades. So essentially they are using antiquated data to argue against current endeavours. That's not only mean, it's retarded -- in the correct sense of the word.
Actually, chances of surviving a fire on the ground in an aircraft are quite low. Most of the fatalities in air crashes come from people who burn to death shortly after impact, rather than the impact itself.
I'm also reminded of numerous crashes which happen quite close to the ground which result in massive casualties--Tenerife, in particular, comes to mind. The greatest loss of life in aviation history came about because of a collision on the ground.
One of the things that makes airline accidents so deadly isn't necessarily the altitude, but the speed and the fact that these things are carrying so much damn fuel. I wonder which has more energy, the envelope of the Hindenburg or your average passenger jet fuel tank...
(Incidentally, airships can crash land from quite high altitudes with minimal ill effects. Because they're lighter than air, and contain so much lifting gas, even sizable holes leak quite slowly in comparison to the envelope volume, and the airship drops slowly. Fatal airship crashes have usually involved loss of control, rather than a sudden loss of lift; even the Hindenburg, with the entire envelope aflame, crashed rather gently.)
One of the things that makes airline accidents so deadly isn't necessarily the altitude, but the speed and the fact that these things are carrying so much damn fuel. I wonder which has more energy, the envelope of the Hindenburg or your average passenger jet fuel tank...
Interesting question. I did some quick googling and math. I wasn't particularly careful, so corrections are welcome.
The Hindenburg had a gas volume of 200,000 m^3, at 0.089 kg/m^3 standard density of hydrogen gas, that is a total hydrogen load of 17,800 kg. Hydrogen has a high energy density of 143 MJ/kg.
A fairly heavily loaded 747 will be carrying 136,000 kg of Jet-A at 43 MJ/kg.
So, the 747 has more than twice the energy onboard, although smaller jets would be rougly equal, all depending on the fuel load. I also did not include the diesel onboard the Hindenburg (or its rather flammable aluminum paint).
One significant difference between hydrogen and Jet-A burning is that the hydrogen is going to rise once the gas bags rupture and not hang around on the ground like Jet-A.
Worst...sig...ever!