back to article First rigid airship since the Hindenburg enters trials

The first rigid airship to be built since the 1930s is about to commence trials in California: and the Pelican prototype also features a new technology, never yet flown, which could finally change things for lighter-than-air craft and see the leviathans of the skies make a serious comeback at last. The 230ft-long, 18-ton …

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Facepalm

First eh?

Looks strangely familiar to me...

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

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strangely familiar ..

I thought it looked a bit like Thunderbird 2

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Happy

Re: strangely familiar ..

First thing that struck me too, Lord V. For cargo carrying they just need to fit hydraulic lifting struts and a hollow bit for a pod and bingo!

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Old idea?

I remember reading a kids' book where some precocious children, apparently with access to surprising amounts of funding, used the compressor and tank idea to beat a load of adults in a balloon race. I'm sure that someone with a better memory than me may even remember the title.

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Go

Re: Old idea?

"The Mad Scientists' Club" perchance?

http://www.amazon.co.uk/Mad-Scientists-Club-Bertrand-Brinley/dp/1930900538

A classic.

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Re: Old idea?

Gadzooks Batman, they've reprinted the whole collection!

To the Amazonmobile!

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Re: Old idea?

"The Great Gas Bag Race" story, published as part of the Mad Scientists Club series, by Bertrand R. Brinley. I loved that series....

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Re: Old idea?

That's the one! Just reading that review brought back some memories.

Thanks!

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I recall watching a documentary about the Hindenberg which blamed the disaster on the dodgy skin of the airship rather than the hydrogen. If so, wouldn't it be a bit easier and cheaper to use hydrogen rather than rare and expensive helium?

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The hydrogen is still explosive no matter how you put it. This is supposed to be a military ship after all.

The paint itself would have not caused the ship to be totally destroyed in less than 40sec even if the highly incendiary paint has contributed.

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I think Myth Busters tested it as well, can't remember the outcome..

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Flame

Explosive?

Not really.

Look at footage of the Hindenburg: it burns, sure, but there was no explosion. Hydrogen will only explode if mixed with an oxidiser (air or oxygen, usually) in the right proportion. Without the dodgy paint on the Hindenburg, I reckon than the fire and crash would have been much, much slower and more survivable. A healthy fraction of the passengers and crew survived anyway, albeit somewhat charred in most cases.

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As I recall ( from a while back, admittedly ) the Mythbusters episode showed that the combination of paint and hydrogen made for a more intense burn than either of them alone would have.

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Mythbusters result

The airship models burned way too slow.

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Happy

I was THE one who got that episode running.

Two things.

A recent ??? documentary with an aeronautical engineer, familiar with Zepplin technology, stated that it was the excessively hard turn by the Captain, to help land the Hindenburg quickly by shortening the "coming around" and at the tethering mast, from down wind, that lead to excessive structural loadings, that snapped some of the wire trussing inside the framing, that slashed one or more of the sacks that held the hydrogen.

It was the hydrogen that leaked inside the airship that was assumed to have been ignited by static electricity that started the fire.

The paint, being composed of assorted compounds and layers, included iron oxide and aluminium flake, to which many people have claimed is a thermite mix, that made the fire accelerate along the exterior, while the membranous sewn up goat intestine bags that held the pure hydrogen, burned at an rather great rate of knots, far faster internally, than the skin did.

The exterior, while containing the compounds of thermite, were mixed and applied in a way to discharge static electricity, and reflect solar radiation and while capable of combustion, the compounds in the coating were not capable of burning in a "thermite" type of way.

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Re: Explosive?

@FartingHippo

I do not mean that the airship actually exploded b/c it burned down rapidly. However, (iirc) the exploding mix has quite large tolerance 18-60% of hydrogen by volume. That's it, leakages might be prone to hazard, the ones that won't explode still would be prone to combustion.

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WTF?

'rare and expensive helium'

Last time I checked, helium was the second most abundant element in the universe after hydrogen.

It's not really rare then, is it?

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Re: Explosive?

And the only deaths were actually from people jumping or being burned alive by the fuel, none were killed by the hydrogen directly, or even the skin of the ship.. it fell slowly to the ground...

I wonder if it should be designed to burn up the hydrogen fast, but controlled, and then have an emergency parachute to lower the surviving vehicle to the ground slowly enough for survival....

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Re: 'rare and expensive helium'

It's rare and expensive on Earth.

There's plenty in Jupiter, Saturn and the Sun, all we need is a way to get it...

Chris

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Re: 'rare and expensive helium'

It's rare on earth, because free helium escapes from the atmosphere into space, and the only replenishable earthbound source is radioactive decay (though it does exist in commercially extractable concentrations in natural gas).

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FAIL

Re: 'rare and expensive helium'

On Earth, yes!

It's so light, and unreactive that:

1) If there's any loose stuff, it escapes upwards and is gone

2) It doesn't exist as a compound of anything, so the only source is contained in a finite number of quickly depleting reservoirs.

Once it's gone, that's it until we learn how to bottle it somewhere in space.

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Re: 'rare and expensive helium'

It is rather rare on earth. And is the first to be blown off by the sun.

Hydrogen is lighter, but forms compounds that bind the hydrogen to the earth.

Hydrogen has twice the lifting capability (H2 molecules are nearly twice the volume, and only half the mass).

Personally, I would think a double bag system with carbon monoxide in the outer bag, and hydrogen in the inner bag would be just as safe as using helium. The CO could then bind to any leaking hydrogen (preventing combustion) and still provide 90% of the lift of hydrogen.

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Meh

Burned

The gas in the Hindenburg burned. It did not explode.

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Re: 'rare and expensive helium'

It's rare down here at the bottom of a gravity well full of other gasses and water and monkeys and things. Hydrogen we can at least extract from the water, which is already down here with us. Helium doesn't hook up with other things, so it's not something we can extract from other stuff that's around, and once we let it leak away, it goes up to the top of the atmosphere and stays there until something blows it off.

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Anonymous Coward

Re: 'rare and expensive helium'

"Hydrogen we can at least extract from the water, which is already down here with us"

Certainly hydrogen has some advantages. This whole "really flammable is a bad thing" idea is interesting, because on the same basis you wouldn't come up with designs where you fill an aircraft wing with highly flammable avtur, and then hang a nice hot, fast spinning gas turbine a few feet away.

Most of the Zeppelins lost in WW1 went up in smoke one way or another, the R101 left a big pile of ash, but only when the Hindenburg had the temerity to be caught on newsreel did it become an irresolvable problem. A bit like Concorde, which in a similar manner was acceptably safe until it wasn't, or the dodgy fuel lines on Nimrods.

Given progres in materials science, is it really impossible to produce a reasonably safe means of holding hydrogen in this application?.

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Re: 'rare and expensive helium'

It is on Earth, being mostly combined with natural gas. It requires separation before storage. The US Gov't was buying and storing it but has been selling it off for the last while. There was a story in Scientfc American about the upcoming Helium shortage.

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Boffin

@oldcoder

"Hydrogen has twice the lifting capability"

Nope, by that logic a vacuum chamber would have an infinite lifting capacity.

The lifting capability if the difference between gas density and air density. The molecular weights are:

i) Air: 29 (approx)

ii) Hydrogen: 2

iii) Helium: 4

So the hydrogen has an advantage of 27/29 to 25/29 (or 8% more). Hydrogen is lovely because it's dirt cheap, not super-floaty.

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Re: easier and cheaper to use hydrogen

Probably not an issue with modern tech for a low impact civilian cargo shifter, but not ideal where people will be actively trying to make it not fly, by using tracer & incendiary ammuntion.

I would also be concerned that these are large, slow, and not particularly manuverable targets, so forward support might be a "bit risky", and the concept of "rear areas" has not been seen to exist for some time, hence the flying styles adopted by C-17, Hercs and Chinook pilots.

Low signature loitering radar platform for blue water surface combantants might work?

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FAIL

Re: 'rare and expensive helium'

"Hydrogen has twice the lifting capability [of helium] (H2 molecules are nearly twice the volume, and only half the mass)."

1) The lifting capacity is the difference between the density of air and the density of the lifting gas.

Hydrogen: 1.293-0.0899= 1.2031 kg/m3

Helium: 1.293-0.1785= 1.1145 kg/m3

(at 1 bar, 0° C)

2) The volume of H2 molecules is irrelevant. The number of molecules present in equal volumes of gases at the same temperature and pressure are equal (Avogadro's principle).

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FAIL

Re: 'rare and expensive helium'

...and one small leak in that CO envelope would render your ground crew dead from poisoning! Never mind the issues with refilling it with the stuff.

Helium = too rare and expensive

Hydrogen = too bloody flammable

Airships based on either = not a good idea.

Military applications? Multiple gas cells would be irrelevant against a single brief burst of cannon from a modern aircraft or gunship. Or perhaps one of them there anti-aircraft missiles?

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Re: Explosive?

When I was working around an oil refinery, hydrogen was considered a relatively safe gas -- it's so light that it escapes faster than it mixes with air. Something like ethylene (similar density to air) was considered much more dangerous.

That's not to say that it is as suitable for miliary airships as helium would be -- I seem to remember Biggles shooting down observation blimps.

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Re: 'rare and expensive helium'

Hydrogen molecules are exactly the same volume; 22.4l per kmol, remember.

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Re: can't remember the outcome..

The outcome was that it is plausible the skin was key to the way the Hindenberg went up, but it takes both the skin AND the hydrogen to get the disaster. Essentially the skin acts like a fast fuse while the hydrogen still provides the bulk of the explosive charge.

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Re: 'rare and expensive helium'

Carbon is abundant too, and there are giant Jupiter-sized diamonds.

http://arstechnica.com/science/2011/08/neutron-star-has-turned-its-companion-into-a-planet-of-diamond/

Not really a threat to DeBeers, though.

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Re: 'rare and expensive helium'

> Personally, I would think a double bag system with carbon monoxide in the outer bag, and hydrogen in the inner > bag would be just as safe as using helium. The CO could then bind to any leaking hydrogen (preventing

> combustion) and still provide 90% of the lift of hydrogen.

There certainly could be no problem with this scheme?

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How can this be viable

If an airship was used to transport troops to take on a militarily capable country, surely it just presents a nice large slow moving target for a missle system to put a few holes in?

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Re: How can this be viable

Less of a problem than you might think if lots of gas cells are used - imagine jabbing a knitting needle through a roll of bubble wrap.

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Re: How can this be viable

> If an airship was used to transport troops to take on a militarily capable country, surely it just presents a nice large slow moving target for a missile system to put a few holes in?

Correct.

This is the primary reason they are no longer used.

This is an extract from Storm a biography of Irvin Crick. (The rain maker.)

In the early morning hours of April 4, 1933, Krick's habit of searching out fronts on weather maps involved him in an event which firmly set the course of his future.

With an early morning class at CalTech, Krick took a nap each night during the five hours of little flying activity when the IIO-miles-an-hour Fokker F-IOs flew from Salt Lake City to Las Vegas. As he turned in, he remarked to the radio operator, "I'm glad we're not flying off the coast of New Jersey tonight. There's a cold front coming down from the north-east and a warm front coming up from the south-west. When the two meet there is going to be one awful mix-up. It'll be very violent."

Krick was no sooner asleep than he was shaken awake by the radioman.

"My God, the Akron just went down in the Atlantic off Bamegat Light -right where you said all that rough weather was coming!" he exclaimed. The Akron was an enormous airship -78? feet long, large enough to accommodate five airplanes aboard. It was the pride of the United States Navy. Seventy-three men died in the disaster, the headline event of the day.

At school later in the morning Krick sought out Dr. Theodore von Karman. Known as "master of the wind" for his knowledge of fluid mechanics, this Hungarian-born scientist was chairman of CalTech's Guggenheim Aeronautics Laboratory, which later was to spawn the world-famous Jet Propulsion Laboratory. Von Karman also headed the Goodyear Airship Institute at Akron, Ohio.

"The Akron never had a chance," Krick said. "The wind shear set up by these two opposing air masses blowing in opposite directions was bound to destroy the ship. She should never have been flown into this kind of weather."

Von Karman was impressed by Krick's earnestness. "Get me the velocity of these winds and we'll calculate the stresses on the ship," von Karman told him.

The calculations, by Frank Wattendorf, Karman's assistant, proved Krick to be correct:

The Akron, broken in two like a stick across the knee of a giant, was doomed from the moment the ship left the hangar, although the United States Weather Bureau had reported that the storm posed no danger to flying that day.

***

So that is major problem #2 covered. Modern meteorology can help plan journeys of 5 days and get most aircraft out of harm's way any old three days ahead. I don't know what metal fatigue and electro-static problems still remain.

Problem 3 is the gas and containers

And a loooooong way behind is the ballast problem. There is always going to be a problem with trim, even the most modern submarines have the same thing to contend with. With aircraft yawing and etc., is part of the fun of flying and is compensated for by computers in larger craft.

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Anonymous Coward

Re: How can this be viable

"surely it just presents a nice large slow moving target for a missle system to put a few holes in?"

I can't see a close combat role for this thing, but for a modern AA missile any transport plane or helo is so slow as to be stationary, and in that respect an airship is a bigger target, but speed and manouvrability for anything other than a fast jet don't come into it - you have to avoid being shot at, or deploy countermeasures.

Even old tech hand held missiles like the thirty year old Stinger have speeds of 1,500 mph, compared to the circa 250 mph of a transport aircraft at low alititude, a speed differential of 600 yards a second, if the missile is fired after the aircraft. Cruising speed at higher altitude of a C130J is still only 400 mph, and at those altitudes (unless you're attacking people armed with nothing more advanced than Russian, Chinese or Iranian Stinger- equivalent) you're facing more advanced longer range mssiles moving at speeds of 5,000 mph, a speed differential of more than a mile a second.

Obviously transport aircraft and helos can hide in the terrain and an airship can't, but as we've repeatedly found that doesn't make them invulnerable, and adds risks of its own. A more pressing limitation is the combination of size, acceleration, maouevrability, and load, which is likely to favour helicopters, although it is notable that 32 Chinooks have been lost in Afghanistan, about half of them to enemy fire, and a large proportion of the remainder due to operating to avoid enemy fire (so low flying, unfavourable landing conditions).

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Re: How can this be viable@Mr Fuzzy

" imagine jabbing a knitting needle through a roll of bubble wrap"

Not many AA missiles depend on impact fuses, because you can't be sure of a direct hit - much easier to get within the warhead's destructive radius and detonate (in principle, think of the altitude fuses on anti-aircraft shells in war films (or reality, for that matter).

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Re: How can this be viable@Mr Fuzzy

A payload of shrapnel detonated close to the airship will puncture enough cells to bring it down. I'm sure rockets or missiles can be modified to carry shrapnel. I don't see the point of this aircraft as it's too big, too slow, too vulnerable. Because of the load it can carry the loss of life and equipment if one was brought down would be huge.

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Anonymous Coward

Re: How can this be viable@Gary F

" I'm sure rockets or missiles can be modified to carry shrapnel."

That's how the smaller ones work anyway - many years ago when I saw the stuff on things like this, they used stuff like big bike chains round the warhead, or a cylinder or cone of metal around the charge. On a larger SAM you could use a bigger explosive charge that would damage by blast alone, but even then you've got the residual bits of the missile itself as shrapnel.

However, the size of an airship ins't really material, because it is unlikely they'd carry more than a conventional transport aircraft already does.

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Facepalm

Re: How can this be viable@Mr Fuzzy

Make the outer envelope from kevlar and munitions will bounce off, often with a comedic 'boing!' sound.

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Re: How can this be viable

And how do you resolve the issue of incendiary bullets which are not distracted by countermeasures?

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Re: How can this be viable

It's big and slow moving. You could paint it to look like a cloud, and no-one would see it coming!

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Re: How can this be viable@Gary F

What you are describing is an expanding rod warhead, for example as used on AIM-9H Sidewinders.

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Re: How can this be viable@Mr Fuzzy

As such, instead of hitting the target once, then exploding, the missile would explode and potentially hit the airship in hundreds of places. It may even shred a large section of the craft.

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Re: How can this be viable

"You could paint it to look like a cloud..."

Henceforth to be known as "Winnie-ther-Pooh" camouflage.

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