Imagine you’ve got a dirigible the size of the Hindenberg, constructed with modern materials, and with helium, rather than hydrogen, as the lifting gas.
How much could it lift?
Air at STP masses 0.077345 pounds per cubic foot.
Hindenburg carried a gas volume of 7,062,000 cubic feet.
Filled with vacuum that’d lift 546231.6 pounds (273 tons).
7,062,000 cubic feet of is 199,973,571 liters.
At STP, that’s 8,927 moles of gas.
8,927 moles of H[sub]2[/sub] masses 17,854 grams-> 39.3 pounds.
8,927 moles of He masses masses 35,708 grams -> 78.7 pounds.
546231.6 - 39.3 = 546,192.3 pounds = Hydrogen filled Hindenburg lift capacity.
546231.6 - 78.7 = 546152.9 pounds = Helium filled Hindenburg lift capacity.
The above assumes zero mass lift bags, and structure for the Zeppelin. Regardless, modern matterials can probably trim off more than the 39 pound lift deficit incurred by using helium rather than hydrogen.
Incidentally, it’d cost about $264,000 to fill the Hindenberg’s bladders with helium at the 1986 price.
He has not gotten cheaper since then.
That should be 8927 kilomoles, I think. (22.4L/mol at STP.)
Assuming the helium is enclosed within a bag made of modern materials is it there forever or does it always eventually leak out?
Dagnabit, that’s right.
So it tqkes 39,300 pounds of hydrogen, or 78,700 pounds of helium.
That gives the hydrogen filled Hindberg a lift advantage of 39,400 pounds over the helium filled craft; about 20 tons.
Lord knows what that does to the cost of filling the thing. There must be a special, cheap, dirigible grade, or no one could afford to use it.
astro, helium does still leak, as described in this article on the cost of the stuff:
The Hindenburg was mostly made of aluminum, which I think counts as a modern material. That’s what modern airliners are made of. Though I’m sure modern alloys are somewhat stronger, and the gas bag material can be made from modern plastics.
The Graf Zeppelin II (LZ130) was similar in size to the Hindenburg and used helium. It carried 40 passengers, and almost as many crew members IIRC. Not sure how that translates to payload.
The framework was made of Duralumin, which is an aluminum alloy (IIRC with titanium for increased structural rigidity).
The actual inflatable ballonets within the exterior fabric and framework were made of Goldbeater’s skin in the Zeppelins (and American rigids). I’m sure we have better fabrics for gas retention today, but remember that the helium atom is so small it can slip through almost anything thin enough to be distensible.
The Hindenburg was built with compartments within the rigid frame, as opposed to the gondola slung below it, which was/is the only “payload” space on blimps and also on many of the early rigids. It did carry some cargo, but was built to compete with ocean liners, and carried passengers in some luxury.
It would seem to me that a variety of configurations would be possible, from a heavy-lift ship using hydrogen for lift, maximizing the use of interior space, and slinging the cargo beneath, to using a fair amount of the interior for passenger/light cargo space.
It’s worth noting that the Hindenburg disaster occurred because (1) the coating of the exterior envelope was a flammable compound, and (2) there’s some evidence pointing to sabotage (remember that the Zeppelin corporation was strongly anti-Nazi and operating by German law with Nazi insignia, etc.). Hydrogen is nowhere as dangerous a lifting gas as the R-101 and Hindenburg disasters would lead people to think, when handled with some sense (e.g., don’t have anything that could emit sparks near where hydrogen may vent to mix with the air).
The framework was made of Duralumin, which is an aluminum alloy (IIRC with titanium for increased structural rigidity).
The actual inflatable ballonets within the exterior fabric and framework were made of Goldbeater’s skin in the Zeppelins (and American rigids). I’m sure we have better fabrics for gas retention today, but remember that the helium atom is so small it can slip through almost anything thin enough to be distensible.
The Hindenburg was built with compartments within the rigid frame, as opposed to the gondola slung below it, which was/is the only “payload” space on blimps and also on many of the early rigids. It did carry some cargo, but was built to compete with ocean liners, and carried passengers in some luxury.
It would seem to me that a variety of configurations would be possible, from a heavy-lift ship using hydrogen for lift, maximizing the use of interior space, and slinging the cargo beneath, to using a fair amount of the interior for passenger/light cargo space.
It’s worth noting that the Hindenburg disaster occurred because (1) the coating of the exterior envelope was a flammable compound, and (2) there’s some evidence pointing to sabotage (remember that the Zeppelin corporation was strongly anti-Nazi and operating by German law with Nazi insignia, etc.). Hydrogen is nowhere as dangerous a lifting gas as the R-101 and Hindenburg disasters would lead people to think, when handled with some sense (e.g., don’t have anything that could emit sparks near where hydrogen may vent to mix with the air).
Slightly OT…
There was a recent DARPA project to develop an airship capable of 500-1000 tons of cargo to places that can’t be reached by boat or ordinary cargo planes. It’s supposed to be a hybrid airship design, using a combination of lift, buoyancy, and thrust to stay in the air. See here, here. I’m unclear on whether any prototypes were actually built. It seems that the companies involved in developing such an airship are now making some attempt to continue development for civilian applications.
Not really OT at all. I’m wondering if modern airships wouldn’t have a role in the construction business, particularly skyscrapers and bridges. Heavy lift capacity, high controlability, what’s not to like?
Duralumin is an alloy of Aluminium with Copper, Magnesium and Manganese.
It wouldn’t surprise me if there are a bunch of engineers who doodle designs for this sort of thing in their spare time. If you were willing to use Hydrogen and had the full panoply of modern materials, CAD, and simulation techniques, it would be possible to construct something that was a huge leap over historical airships. However, it’s always been difficult to find something that airships can do really well that can’t be done as well or almost as well using other techniques.
e.g. in construction cranes are a very well-established and proven method, and helicopters are used where necessary. Airships *might * be able to do it better, but who’s going to gamble millions to go from good enough to better, and persuade all the officials to agree to let them try it? Everyone looks at an airship, wonders ‘hmmm - what happens if there’s a really strong gust of wind while it’s winching 70 tons of something solid into place?’ and orders a crane instead.
The drawbacks would tend to be high initial, operating and storage costs, and (as slaphead indicates) vulnerability to high winds.
How much Helium leak per hour from the average airship?
… and RPGs?
Geez, they already say Dungeons and Dragons leads to Satanism, now you’re saying they can cause airship accidents too? 
I’d honestly be curious about what sort of damage an unguided anti-tank rocket would do to a helium airship. If we’re assuming the airship is used in a military application, I’m also curious about what sort of defenses you could rig on it and still have it be practical for whatever you want to use it for (freight carrying? Airborne surveilance/command and control? Just a big farking gunship that can block out the sun for psycological effect?). Maybe some window-mounted miniguns, a hatch that you could open on the floor to fire a gun through (or to just drop garbage and such from) would be simple enough to rig.
Actually, I think you’d likely be able to have more of an effect by using IR-guided man-portable anti-aircraft missiles to take out the engines providing the airship with control. If nothing else, the airship would be unable to keep a good gust of wind from gently pushing them off the battlefield for you.
That said, I recently learned that there is a series of tethered airships (in this case, called “Aerostats” because they don’t move) rigged up with radar and such for spotting drug-runners and spetznatz paratroopers and such from flying into the US from the southern borders. Seems that 12 of these things, properly placed, has full overlapping radar coverage of the Mexican border and the Gulf Coast, which I think is just kinda neat. One of the aerostats is very stealthily parked above Fort Huachuca. It doesn’t look that big until they park it on the ground, and you notice the cute little trees next to it…
That’s a problem with many projects anyway.
And can cranes lift something as heavy as a dirigible can as high as it can? Lift capacity seems to be 248 tonnes (less airframe). Could a dirigible lift a motorway bridge into place, for instance? This would allow the bridge to be constructed elsewhere and transported directly to the site.
Having just watched the Discovery channel at lunch today, I thought I was on top of the latest airship technology. CargoLifter AG promised to bring the airship back to preemenience. I guess they were wrong.