airships

Air barges. Make some sense. Even if they had to wait now and then for weather to be conducive it could be a good thing.

It has been tried for mineral survey operations too.

--sp

--
Best regards,  
Spehro Pefhany 
Amazon link for AoE 3rd Edition:            http://tinyurl.com/ntrpwu8

Airships are a great idea, but they should stop using helium - it's a waste of a precious non-renewable resource. (They should not use helium for party balloons either.)

Just use hydrogen. It's far cheaper, and twice as efficient. As long as you don't coat your balloon in highly flammable conductive paint, but take precautions against static and other sources of fire, you'll be fine.

One little accident some 80 years ago, and people are /so/ paranoid about hydrogen airships - it's all blown out of proportion.

And you can burn it as fuel.

But it's not "twice as efficient". Hydrogen gas is less dense than helium, but both of them are a lot less dense than air, so it doesn't make much pra ctical difference.

.

Perhaps. Hydrogen mixtures with air are inflammable and explosive over a wi der range of concentrations than any other gas. Any hydrogen-filled air-shi p is a potential fuel-air bomb, and anybody shooting a missile into one get s a lot extra bang for their buck. Conventional aircraft aren't a whole lot better - conventional jet-fuel is a whole lot denser and easier to spread around - but it's not something to be too relaxed about.

It wasn't a little accident. It killed 35 of the 97 passengers and crew. Mo dern airline disasters have killed a lot more people, but it was pretty imp ressive at the time. The Hindenburg was total loss.

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Bill Sloman, Sydney

You /could/, but you would want to avoid flames and high temperatures. A fuel cell would be better.

True.

So don't mix it with air. It should not be hard to make a lining that does a better job and is safer than the Zeppelin's aluminium paint.

An aerogel filling would be wonderful here - it would provide structure for the airship with minimal weight, isolate heat to avoid the spread of any fire, and greatly hinder mixture of the hydrogen with air if there were any leaks.

Fair enough, aerogel is not cheap at the moment - but I am sure it would become cheap with enough incentive. And money is a renewable resource, unlike helium.

No, hydrogen would not make a good fuel-air bomb. A key point is that if you puncture a hydrogen balloon, the fuel escapes upwards - you get a dramatic fireball but not nearly as much damage to anything else as you might suppose. And it could be hindered in two ways. Either use something like aerogel to make the fire slow and contained, or use explosives (yes, I mean that) to burst the separate cells quickly if there /is/ a fire, so that the hydrogen gets released and burns away above the airship.

Look at the Hindenburg disaster. It was very dramatic, but despite the rapid burning (a significant part of which was the shell and coating, and the wooden frame) and the fall from the mast, two thirds of the passengers survived. And only one person on the ground was killed. Few plane crashes can claim such a good record.

Oh, I don't think safety here is something to ignore - I just think it is something that should not be exaggerated.

If planes, cars, trains or boats were judged to the same standards, we would still be using horses as our main method of transport. (And horses caused a lot more accidents than cars for the distance travelled, but killed fewer people at a time.)

There was a new big helium source found (in Africa?, yup)

George H. (He3 on the other hand...)

That was good news, but not /great/ news:

"The amount of helium is estimated at more than 54 billion cubic feet - which could potentially meet global demand for several years."

Helium is still a precious and limited resource, and completely irreplaceable in many useful applications. Finds like this one (though there have no other finds like it) reduce the urgency of preserving helium reserves, but don't eliminate it.

The nearest source is on the moon, I believe. There is plenty available there, but it's a little inconvenient to mine.

Well nuclear decay keeps making more, but that is rather dispersed.

Historically it came from tritium decay in nuclear war heads, but wiki says we're making it now.

Hmm I was thinking we could get He4 from nuclear waste... but this says not much.

George H.

14 ounces, the dirty dogs). I doubt I'm close enough to share a drink with you. 60 miles from Washington, D.C.

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Rick C

Reminds me of a fire fighting accident that happened some years ago out west. They were flying water over a fire and the updraft snapped the wings off the plane. What a terrible way to go.

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Rick C

I think that one went right past a few people.

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Rick C

Talked? Can't talk when you're strung out. Well, I guess you can but it's not communication. "Free love" wasn't, either, though as you note it got a lot more expensive in the later '70s.

You're about my son's age. He's a real geek. He had a smart phone long before I did. I got it for the hot spot but don't use it for that much anymore (sometimes at work).

IMO, the peak of music was '65 to '75. Before was good, after went downhill fast.

A fuel cell doesn't burn hydrogen? I'm a chemist - for me "burning" is comb ining with oxygen, and I burn the food I eat. Internal combustion engines b urn fuel, but they keep the flames and high-temperatures inside the engine.

Airships move, and can run into things. Making a container that won't break on impact is tricky.

Aerogel may stop convection current, but isn't going to be heavy enough or strong enough to stop hydrogen moving out a ruptured cell - the buoyancy f orces involved are big enough to carry the weight of the airship.

Seems unlikely. Aerogel is made by a subtractive process, and they are diff icult to make cheap. Low frequency loudspeakers could benefit from cheap ae rogel, but long-fibre wool does the same job a lot more cheaply (the extra mass doesn't matter in loudspeakers).

When explosive mixtures detonate, they generate shock waves. Supposing how much damage the shock-wave might do - and where - before the fact isn't wis e.

The Hindenburg was stationary when it caught fire. If a plane catches fire after it has stopped moving, most of the passengers seem to get out.

Hydrogen is an avoidable risk.

We sure as hell wouldn't be using horses for transport, as they do kill a l ot more people per passenger-mile. And somebody calculated that enough hors es to handle Manhattan's traffic would dump six feet of horse manure on the streets every day. We probably wouldn't be using private cars - buses and taxis kill many fewer people per passenger mile, presumably because bus an d taxi drivers get enough practice to be come properly competent.

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Bill Sloman, Sydney

How you gonna preserve it, AFAIK there isn't a jar made that can store it long term.

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This email has not been checked by half-arsed antivirus software

Leave it in the ground if possible. Quotas (as we've had in the recent past) suck.

--sp

--
Best regards,  
Spehro Pefhany 
Amazon link for AoE 3rd Edition:            http://tinyurl.com/ntrpwu8

I don't know. The Hindenburg burnt, rather than blowing up. We might not be so lucky next time. If the bulk of the hydrogen had got mixed with air before it ignited, things could have gotten more catastrophic.

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Bill Sloman, Sydney

Hmmm... This is a tough crowd.

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Rick C

Why would air mix with the hydrogen It seems unlikely that air would leak into a vessel at a higher pressure. I guess we have to worry about air leaking into our gas tanks, too (even thought they're nominally at the same pressure). Slowman's a fool.

ot be so lucky next time. If the bulk of the hydrogen had got mixed with ai r before it ignited, things could have gotten more catastrophic.

Krw has missed the point, as he frequently does. The question is not how hy drogen behaves when it is safely inside the flotation cells of the airship, but what happens when some kind of disaster ruptures those cells and the h ydrogen is free to mix with air.

The Hindenburg seems to have been struck by lighting, and it would be diffi cult to build an airship that could survive a tornado with its gas cells in tact.

If krw had an imagination he could probably come up with other situations w here hydrogen and air might end up mixing in potentially explosive proporti ons.

It's a bit easier to build more robust tanks for jet engine fuel in more co nventional aircraft, but the tanks break when planes crash, and the fuel f requently catches fire.

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Bill Sloman, Sydney

The explosive range for H2 in air is very very wide. However, air is about 15 times denser than hydrogen, so the loss of lift would be apparent pretty quickly if that were happening.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net