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Hybrid Airship

 
 
Reply Wed 5 Jan, 2011 09:06 am

http://www.bbc.co.uk/news/technology-12110386

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Type: Discussion • Score: 2 • Views: 1,833 • Replies: 11
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Ragman
 
  1  
Reply Wed 5 Jan, 2011 09:35 am
@gungasnake,
That airship looks pretty good. Wonder how they do in strong cross-breeezes or when there's strong wind-shear conditions?
gungasnake
 
  1  
Reply Wed 5 Jan, 2011 10:56 am
@Ragman,
The Hindenberg had flown something like a quarter million miles before it's end and the funny thing is that there was no danger involved in the way the German zeppelins used hydrogen, an atmospheric spark caught the alum-oxide paint on fire. There's positively no need for helium and helium doesn't even lift as well as hydrogen.
Ragman
 
  1  
Reply Wed 5 Jan, 2011 11:52 am
@gungasnake,
Anytime you're dealing with a flight, you have a possibility (even a probability) of sparks.

Perhaps they made the choice partly due to a public perception of the safety issue as that scene from 1938 in NJ of the burning Hindendburg is indellibly etched into the public's collective consciousness. (Witness the lack of interest or R/D $$$ in hydrogen-powered cars). The actual reason for the incendiary explosion of the Hindenburg is still hotly (no pun intended) contested. I think the reason you list in your explanation is the current scientific theory. However, the mfrs chose helium for lifting the craft for a reason. I'll bet it's about cost and safety concerns, if not marketability to the public.

Here's a quote about comparisons:

"Hydrogen Arguments. While helium is exceedingly light as compared with air, it is somewhat heavier than hydrogen. The total lift of a helium-filled dirigible is accordingly some 10% less than that of the hydrogen-filled airship. The difference does not appear important at first sight, but the total lift of the gas carries the structure, the motors and the crew. It is only the last 20% or so that is available for carrying fuel, and hence a difference of 10% in the gross lift may spell a difference of 50% in the fuel-carrying capacity. On long-distance flights this difference is vital.

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.

Another strong argument of hydrogen partisans is the fact that owing to the minute quantities of helium found in the natural gas at its source, an extremely expensive system of fractional distillation is necessary and the cost will always remain excessive.

General View. For a number of years the Navy has held that our helium monopoly meant supremacy in the air as far as dirigibles were concerned. But recently the attitude of the Bureau of Aeronautics has changed and its officers in various public utterances have advocated a return to hydrogen.

A strong technical case could be worked up for either side."

Read more: http://www.time.com/time/magazine/article/0,9171,786149-2,00.html#ixzz1ABWIGsDx"

FWIW, I'd be interested in a ride in that helium-powered craft, whereas I wouldn't even consider a ride in a hydrogen-powered vehicle of any sort.
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rosborne979
 
  1  
Reply Wed 5 Jan, 2011 11:57 am
@gungasnake,
Looks interesting. What's its payload capacity?
Ragman
 
  1  
Reply Wed 5 Jan, 2011 12:21 pm
@rosborne979,
No idea. Perhaps Google can supply or the article or video relates that info.

Helium Usage for Airships, Nalloons and Rocketry
“Because it is lighter than air, airships and balloons are inflated with helium for lift. While hydrogen gas is approximately 7% more buoyant, helium has the advantage of being non-flammable (in addition to being fire retardant).[28] In rocketry, helium is used as an ullage medium to displace fuel and oxidizers in storage tanks and to condense hydrogen and oxygen to make rocket fuel. It is also used to purge fuel and oxidizer from ground support equipment prior to launch and to pre-cool liquid hydrogen in space vehicles. For example, the Saturn V booster used in the Apollo program needed about 370,000 m3 (13 million cubic feet) of helium to launch.”
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gungasnake
 
  1  
Reply Wed 5 Jan, 2011 04:23 pm
@rosborne979,
I believe I saw a figure of 100 tons, not sure. Nonetheless particularly with hydrogen you'd be talking about a very cheap way of moving substantial loads around the world with no need for airports or other infrastructure.

Helium is rare, expensive, and is involved in creation/evolution arguments since by rights it shouldn't be there at all if the planet actually were 4B years old while hydrogen is totally cheap and simple and made with electric currents and water.

Assuming they get the hydrogen thing right, this one has the potential for major benefits.
Ragman
 
  1  
Reply Wed 5 Jan, 2011 04:29 pm
@gungasnake,
gungasnake wrote:

I believe I saw a figure of 100 tons, not sure.


Actually, in the BBC video, the common-tater clearly states (around 0:35 sec mark) that the production model of the planned 1000 ft ship will be able to lift 1000 tons.
rosborne979
 
  1  
Reply Wed 5 Jan, 2011 07:19 pm
@Ragman,
Ragman wrote:
Actually, in the BBC video, the common-tater clearly states (around 0:35 sec mark) that the production model of the planned 1000 ft ship will be able to lift 1000 tons.

That's one ton per ft of ship. I haven't done the math, but that doesn't seem right. The ship would have to have one hell of a girth to make that work wouldn't it?
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rosborne979
 
  1  
Reply Wed 5 Jan, 2011 07:22 pm
@gungasnake,
I can see ships of this type being decent mechanisms for transport of freight, if the carrying capacity is what they say it is. But I can't see many passengers using them for travel, unless the airship itself was part of the experience (like a cruise ship). But then they would have to make these airships very luxurious. They would be competitors to the cruise lines I would guess. I wonder how their operating costs compare to cruise ships carrying similar passenger loads.
Ragman
 
  1  
Reply Wed 5 Jan, 2011 08:17 pm
@rosborne979,
My guess is no one knows yet as there is only this prototype. However if you consider the relatively reduced costs due to (almost no) ground crew, almost no pollution and perhaps less wear-and-tear compared to a cruise ship, it lo0ks pretty good.
gungasnake
 
  1  
Reply Wed 5 Jan, 2011 11:10 pm
@Ragman,
If they can get over the hangup about hydrogen then you're talking about a gigantically cheap and efficient way to move goods and possibly also people across big distances and also to get things to places which don't have big airports or complex infrastructure. You're talking about running two or four tractor engines as opposed to jet aircraft engines, and you've got those new IC engines coming online as well.
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