A few times a year, all the gadget blogs get excited about some new lighter-than-air vehicle. Sometimes it's a little one for the determined hobbyist, a big one for specialised cargo, or a huge one that's never even going to exist.
And then there are the modern Goodyear-Blimp tiddlers that're shamelessly described as "Zeppelins", despite only being a third - often less than a quarter - of the length of the proper ones.
I mean, look at the "Zeppelin NT". It's 75 metres long, and can only carry 14 people, or a payload of less than two tonnes. Zeppelin bombers in World War One were already more than twice as long, and carrying 16 tonnes!
This, for example, is the LZ1, the very first of the Zeppelins. It was already 128 metres in length.
I, therefore, officially demand that we bring back the hydrogen-filled zeppelin!
They'd be very safe, especially with modern technology; giant bags full of hydrogen need be no more dangerous than giant fuel tanks full of kerosene, which I remind you are usually mere feet away from the jet engines that're burning the fuel. Modern control systems could intelligently manage multiply-compartmented cellular gas-bags, to automatically keep the zeppelin in the correct attitude, manage altitude, and keep the thing flying even if someone flies his Learjet straight into the side of the airship.
If people just can't get past their irrational terror of hydrogen, then you could of course just fill your zeppelin with helium, like the old American ships. But hydrogen gives more lift and can be easily manufactured from water; the world's helium supply all comes from natural gas. Lots of scientists and engineers are beavering away at finding efficient hydrogen-storage technology, too, because we'll need such technology for fuel-cell cars to become practical. I wouldn't be at all surprised if some of the same tech came in handy for managing lifting hydrogen in airships. And, heck, some of the hydrogen could also be used as fuel!
The one great advantage of a dirigible airliner is that legroom is not an issue. You don't get vast lifting power - even the gigantic, 245-metre-long Hindenburg only had a payload capacity around the same as that of a 70.6-metre-long 747-400 freighter - but you can have as much space as you like. You just don't get to fill that space with heavy stuff. Modern lightweight composite materials would be very helpful, here; we could probably make a 75-kilo grand piano if we wanted to, these days.
(One of the indications that the huge design-concept "Strato Cruiser lifestyle zeppelin" I linked to above is not a workable device is its hilarious inclusion of a topside swimming pool. That would weigh at least a hundred tonnes, and maybe a lot more; a standard Olympic pool contains at least 2,500 tonnes of water. It'd get a lot lighter when the airship turned and the water all sloshed out, of course.)
This, for instance, was just the dining room on the Hindenburg. It also had a lounge, a writing room, a smoking room (which contained the single lighter permitted aboard the vessel...), bathrooms, a crew mess hall, and small, but private, cabins for the 50-to-72 passengers.
"Oh, but what if someone tried to hijack the zeppelin, or blow it up?", I hear, from the people who don't mind having their shoes examined before they're allowed onto a plane.
Well, if the hijackers are only armed with box cutters, passengers could just run away from them through the modern zeppelin's acres of lounges, bars and tennis courts. And if terrorists had, let's say, a two-part shaped-charge-plus-thermite guaranteed-747-killer of a bomb, you could stand back and let 'em set it off, straight out into a gas-bag. The venting gas might catch fire, but the straight hydrogen inside the gas cell cannot support combustion by itself, and automated systems could dump the cell's contents out the side of the airship, or pump it into other cells. The damage would be a reduction of total lift by a few per cent, at worst. The frame of the airship could be a tensegrity structure of light composite beams and pressurised gas cells, so there'd be no single component an attacker could break to bring the whole ship down.
Even if the terrorists were running around with satchels full of bombs setting them off wherever they could, they'd still only be able to damage the gas cells adjacent to the passenger areas. You wouldn't even need to have gas cells in such locations, if you didn't mind making the airship somewhat larger.
Let's see - what other objections might there be?
Oh, yes: "What if a storm catches you? You'd be blown around like a toy balloon! Storms were a big problem for the old hydrogen airships, you know!"
Well, yes, they were. But that was because the old passenger dirigibles - and the early military ones - had a cruising altitude that seldom exceeded 2000 feet, and was often much lower. Like other aircraft of the time, they didn't have pressurised passenger compartments, so they simply couldn't fly too high without everyone needing oxygen masks and eight layers of sealskin.
Back in WWI some bomber airships were made as "height climbers", flimsier in structure to make them able to attain great altitude; doing so was rather dangerous, and horrible for the crew, especially when the engines started freezing up. Even when flying at modest altitude, the old dirigible engines often needed in-flight maintenance, which was a very exciting task. None of these problems would apply to a modern zeppelin, with a pressurised cabin and reliable engines, or even fuel-cell-powered electric motors.
With modern technology to manage the gas bags, modern engines, vectored thrust for much better maneuverability and pressurised gondolas, modern dirigibles would only need to worry about weather during takeoff and landing - and they could probably delay landing a lot longer than a 747 can. The rest of the time, they'd deal with storms in the same way that regular airliners do - by flying over them.
This does creates obvious limits to the routes airships could fly, though, since they couldn't make much headway against fast high-altitude air currents. We could easily make dirigibles twice as fast as the Zeppelins were, but that still only gets you to 260km/h. If you're happy to go in the same direction as a jet stream, though, it'll boost your speed by an easy 50-to-100 knots.
I think the main actual reason why nobody's brought back the zeppelin is that they wouldn't be cost-competitive with heavier-than-air craft, in the same way that ocean liners couldn't compete with planes. Airships might be able to compete for some exotic cargo applications, perhaps, as per the above-linked SkyHook JHL-40, a hybrid zeppelin/rotorcraft, but they certainly couldn't deliver passengers from A to B anything like as cheaply as an airliner.
In a fantasy world where everybody wasn't utterly determined to turn every field of human experience into a money-making operation, however (hey, how's that all working out for you, world?), and assuming that we actually could make 38,000-foot-capable pressurised zeppelins if we wanted to ("...we can put a man on the moon, but we can't..."), then airships certainly would be competitive, if one's aim was to travel in a pleasant way.
Ocean liners of the sky, able to cover 5000 kilometres a day and take off and land virtually anywhere, which cause people to actively compete to buy a house near the airport, just to be able to watch them. Sounds like an improvement to me.
14 July 2009 at 11:22 am
Shades of The Deltoid Pumpkin Seed. Lighter-than-air craft might be a cost-effective way to ship cargo, especially food from growers to starvers.
14 July 2009 at 2:59 pm
If you are going to get with the times, you may as well make it Nuclear - nearly 50 years ago, they were considering it.......
http://www.time.com/time/magazine/article/0,9171,901851,00.html
14 July 2009 at 3:24 pm
Maybe if you set up your Zepplin Airways/Shipping as a non-profit organisation, hopefully eligible for tax breaks, it'd keep costs down enough for those who were enthusiastic about it to enable it to be a going concern.
Would be pretty awesome.
14 July 2009 at 3:44 pm
Sorry Dan, you don't get to fly over the weather. Consider the density lapse rate with altitude: at 2000ft altitude you have a density (normalized to sea level) of 0.94; at 5000ft 0.86. At a pretty modest 10000ft (which won't get you above all the weather; ask airliner passengers from the 1930s), your density ratio is 0.738, and you're pretty well boned.
High altitude flight is unfortunately not an airship's strong suit.
Had I a beer less inside me I'd figure out Hindenberg's max altitude with zero load. Maybe tomorrow. I'd bet AU$10 it's less than 2.5km.
14 July 2009 at 4:17 pm
If there is the remote possibility that you might enjoy your air travel then the terrorists have won. Remember, if they are denied their pyrrhic victory by your airborne misery that makes those countless hours of suffering all worthwhile.
14 July 2009 at 4:26 pm
Would it be possible to have an elastic bag which expands as you increase in altitude, thus preserving your density ratio? Or am I getting it completely wrong?
14 July 2009 at 4:38 pm
6:
It sounds entirely reasonable since it's what the weather balloons do, but I'm not sure that the end result would be a Zeppelin / dirigible. :-)
The opposite (so to speak) seems like it would be possible without major changes though – you could perhaps take on the surrounding air for ballast at lower altitudes. (and then you could start out with a giant high-altitude craft instead; which would of course be even more economically unsound)
14 July 2009 at 5:29 pm
Getting a dirigible to high altitudes on displacement lift alone is probably impractical, but there's no reason you couldn't turn the whole ship into a giant flying wing. It's not a new idea, though. Have enough lift just floating to get you up 1000-2000 feet, then you've got a massive wing that only has to lift whatever the difference in lift between sea level and 35,000 feet is.
14 July 2009 at 5:39 pm
Assuming Thuli's suggestion to overcome Erik's point is theoretically reasonable, instead of an elastic, expanding bag you could use the efficient hydrogen storage technology mentioned in the article to compress some of the hydrogen as you climb. Then you would release some of the stored hydrogen again as you descend. What that would mean for efficiency, I have no idea.
14 July 2009 at 5:55 pm
The "height climbers" routinely operated above 20,000 feet (where they were safe from fighter attack), even while still carrying their (modest) bomb load. They didn't actually work very well, but they were built with technology that's almost a hundred years old now.
I think the major problem the height-climber designers faced was not making an airship that could get to 20,000 feet, but making one that could go that high and then safely land. The height climbers had an appalling safety record, but now that we don't have to line gas bags with cow-gut any more, we could probably make a couple of improvements.
14 July 2009 at 6:26 pm
Unfortunately the really scary storms extend far above airliners service ceiling. Air France 447 flew into some of this, although it's uncertain to what degree this was connected to the crash.
Of course, modern Zeppelins would be better equipped to do what airliners actually do... fly around the nasty stuff. Weather satellites and on board radar are definitely a step above the 30s!
In it's favor, kerosene has a far narrower range of flammable mixtures, and is a lot less prone to leaking.
That said, I'm all for it. I've spent enough time in economy class that I'd love a mode of travel that was limited by mass but not volume!
A related question I was puzzling over earlier. How does the efficiency compare ? On first thought, you'd expect an jet to be far worse, but an airship has that huge frontal area to deal with. It might actually be worse, unless you can make your envelope out of thin film solar cells ;)
14 July 2009 at 7:07 pm
Paging Doctor Hiram Hackenbacker, Doctor Hackenbacker to the techological optimism ward.
14 July 2009 at 7:13 pm
Huh, well it turns out that he wasn't called Hackenbacker in that episode, and he never used "Doctor". So much for my memory.
Here's terror.
14 July 2009 at 7:20 pm
It's interesting that you've brought this up cos I've discussed it with friends before and am a strong advocate for bringing them back. And you're right that hydrogen doesn't have to be dangerous in the slightest. I'm surprised by why as to why you say they would be so cost-ineffective vs heavier than air planes. surely the fact that they would use, far, far less fuel would mean they would get cheaper and cheap to run over their lifetimes, after the inital investment. I would suggest that perhaps hot air technology could be used to compensate for density variations, and easily changing altitude. also a good way to reduce the cost of propulsion would be, to suppliment the jet engines, by using solar to heat the air. you could draw the cool air in at the front (if there was room or if you used compressors and tanks, you could draw much colder air from cold veins thus increasing the effeciency there) and then pass that air through an outer bag over the whole of the very, very big balloon, (is balloon the right word?) painted black, and it would heat up considerably with that much surface area.
Also I don't think storms would cause that much of a problem, because what you're forgetting is that you can land the thing almost anywhere and anchor it. they could easily be design to float so you can land on the ocean if you needed to. Unlike a jumbo jet you don't have to find a 2 mile landing strip wide enough to take a 767. You can obviously land very quickly by venting hydrogen.
If there was a serious problem (read, fire), could you detach from the balloon and land with parachutes? But then also, if you did design it like a large wing, (makes it easier to take advantage of thermal pockets right?) then surely it wouldn't be impossible to design a machine that in the event of ditching the balloon could operate as a regular heavier than air, areoplane. you wouldn't probably have all the fancy airplane gubbins, you'd get on a 747 but a couple of rolls royce engines that you regularly use for lighter than air propulsion (probably only running at about 10%), and something that can glide on air veins. incorporating landing gear wouldn't be too hard, tho would add some weight, you could thrust the engines up to full power, to stay airborn, and carrying just enough fuel to make an emergency landing wouldn't be too hard. (could the engines be adapted to burn hydrogen, because you'd have reserve tanks of that anyway?)
so I think there are quite a few engineering solutions if some smart people actually sat down and just built the thing.
but for me the biggest appeal, is 2 fold. one, that you would have to drive hours to the airport. there could be an airfield for these things in every town. and also, for some journeys speed doesn't matter so much. Flying say from here in the UK to let's say Denmark, or even just france. Why pay to sit in a horrible crampt airplane, when instead, the journey might take 9 hours, but it's basically a luxury cruise, with a dining room, there could be live enetertainment. a bar, large conference rooms with full video conferencing. and offices for hire, so businessmen, could do a full days work, rather than trying to struggle with their laptop on the drinks tray on a plane. duty free shops. the slower speed and lower altitude ought to make cellular communication usable, or failing that satellite internet wouldn't be hard to include. as you mentioned, individual rooms with beds. if they used a nasa style water filtering system, then they could even include showers. If they could do all that and make it cost not much more than the plane ticket would be, I'd be the first to sign up. And even if it was more expensive than the plane, it might not be once you don't have to drive or get a taxi / train to the airport, pay for long stay parking, and then get a taxi / train / hire car from the airport at the other end for the hundreds of miles you destination is from the big international airport.
Just had a final thought, obviously the biggest problem has got to be flying a massive non aerodynamic shape into the wind, which would take a lot of effort from the engines thus fuel. but could you not instead perhaps build a design with 3 of 4 smaller baloons, shaped like sails? which could be rotated to use the wind for propulsion. or alternativly. assuming you can pump the hydrongen in and out of the cells at will, you could open certain cells right from one end of the balloon to the other, to create vents for the air to pass through, so as to decrease the surface area that the wind is blasting against. with computer control you could design and instantly create just about air paths through the baloon, so that if the wind is hitting you at 20 knots from the east, and you're travelling north, you can take in the air on the east face of the balloon and expel it from the southwest side.
please feel free now to use like science to explain how wrong i am.
14 July 2009 at 7:23 pm
It's not about getting about quickly as a commuter planes, it's about getting there in style, right?
14 July 2009 at 7:46 pm
From what I've read, the biggest issue with dirigible transport is handling the transition when you load and unload cargo.
ie, if you have a 20 ton cargo pallet, and the zep is in equilibrium after landing, you then have to deal with the 20 tons worth of lift that is suddenly applied after the cargo is removed.
Passenger transport is quite viable, if slow, but cargo transport is more of an issue
14 July 2009 at 9:03 pm
For cargo I'd have thought you just pump in water ballast from the ground as you unload. You could even carry the pumps onboard, powered by the engines. Just land near any lake, sea or sewerage plant, throw out your kevlar hose, and bob's your uncle.
Or you could use vectored thrust - make the zep buoyant enough to lift half the cargo weight, use propellers or turbofans to lift the rest, fly to your destination, put the cargo on the ground, put the engines in reverse to push the zep down and then release the line. It's not as unsafe as it sounds as you can still dump gas as an emergency measure if an engine fails. Plus vectored thrust controlled by computer will make life a lot easier flying through a storm or if you have a really big gas leak.
There is a definite market for special lifts of things too big to move by road. For example, all else equal the bigger the steam turbine the more efficient it is, but the limit to size is the ability to install the main shaft.
That market is not especially price-sensitive (when you're spending billions on a power plant spending a few million to rent a zep is worth it to get a more efficient plant). But someone has got to be game enough to spend the billions developing the thing to find out if that's right.
14 July 2009 at 10:46 pm
The reason why so many cargo-dirigible plans keep being made must be that even gigantic helicopters can only lift 20-odd tonnes, and getting 100 tons of lift out of an airship has been possible since before WWII.
Helicopters aren't even particularly fast (I think the fastest production helicopter remains the Chinook!), and a loaded cargo heli usually has pretty miserable range. So you'd really think that someone would have made at least one giant cargo-Zeppelin by now.
Perhaps part of the problem lies in what you do with your cargo-Zep in between jobs. Just taking your unique aircraft to air shows and wowing the crowd seems to work for the Antonov 225 :-).
14 July 2009 at 10:56 pm
Although I like the concept, in the US improving the passenger rail system is more likely and meets maybe 95% of the airship's benefits. And when I say "more likely", I mean "not all that likely at all". On the whole I'd rather travel faster with slightly less elbow room on a train than much more slowly with cavernous spaciousness all around.
14 July 2009 at 11:17 pm
"It's not a balloon! You stupid little thick-headed Saxon git! It's not a balloon! Balloons is for kiddy-winkies. If you want to play with balloons, get outside."
14 July 2009 at 11:26 pm
The idea of using zeppelins to transport heavy cargoes to remote/inaccessible locations is a very interesting one. A couple years ago, I had a work assignment that took me to the middle of nowhere in sub-saharan Africa. Most of the supplies and equipment were trucked in. A typical transit time for the few hundred miles was somewhere around two weeks, thanks to the condition of the "roads". When they originally built the plant, they had to fly in much of the larger equipment using Antonovs. (one of the An-225's actually crash landed and had to be disassembled and flown back out by another An-225).
Don't forget that with an airplane, you'd have to unload that cargo, then truck it to the right site, then use a crane to lift it into place. The zeppelin could simply float over to the construction site and place the equipment exactly where it needs to go.
15 July 2009 at 12:29 am
Yeah, and it's much the same deal with trains; you probably can't talk anyone into laying tracks to the exact place where you want your cargo delivered, but an airship has not a whole lot less landing-site flexibility than a big helicopter. Airships are even better than flying boats!
(Oh, and I think it was probably some other Antonov that took the bits of some other, other Antonov away from your work-site, seeing as there's only ever been one completed An-225 in the world. :-).
15 July 2009 at 12:54 am
It seems to me that fuel efficiency may be a serious concern. Even leaving aside vectored thrust, air resistance is going to be a problem: while drag increases with the square of the velocity (in this regime), it also increases with the cross-sectional area, and while a fast dirigible might fly at a quarter the speed of a 747, it almost certainly has more than sixteen times the cross-sectional area. Worse, that's an estimate of the drag force; what we care about is not the fuel consumption per second, but the fuel consumption per kilometer. This increases (roughly) linearly with speed and linearly with cross-sectional area, so given the huge cross-sectional area of a zeppelin, it's going to have to go very slowly to have fuel efficiency comparable to a 747.
15 July 2009 at 1:45 am
We have blimps flying over central Florida quite frequently (advertising for the theme parks, etc.) Even with these little guys, their biggest difficulty has always been trying to control them during descent. Their engines simply can't cope with sudden changes in wind direction. The wind loading on a huge Zeppelin might make it simply uncontrollable at low altitudes. But then this is Florida, with some of the nastiest weather on Earth (despite what the Chambers of Commerce claim).
15 July 2009 at 5:25 am
I think the little blimps probably also have quite weedy engines, judging by their pathetic cruising speeds. (Here in Australia, Sydneysiders used to get an object lesson in this, thanks to the endless drone of an Alan Bond blimp trundling across the sky. Before awkward questions were asked and Mr Bond fell back upon the first refuge of unimaginative scoundrels, of course.)
Proper cigar-shaped dirigibles have a much better ratio of cross-sectional area to lifting power than do Goodyear-type blimps, and so could today tote around very serious propulsive power, including fancy multi-angle propellers that could really bite the air at any speed down to zero. I think they still wouldn't be easy to keep on station at ground level when the wind's a bit changeable, but I also wouldn't be at all surprised if the more-than-an-order-of-magnitude changes in various engineering variables since the heyday of the zeppelin meant that there's some big improvement that nobody's quite thought of yet, which would make giant airships every bit as practical as giant aeroplanes made of metal, or giant ships made of iron, suddenly became, against all sane counsel, in the past.
15 July 2009 at 6:01 am
@mayhem:
the keyword is "suddenly". You don't lift the cargo out of an airship with an oversized forklift, you let the airship lower its cargo, maybe in a pod (somewhat Thunderbird 2 style). Once that nudges the ground (the combination then still has about neutral air buoyancy) you run the helium-compressing-buoyancy-reducing thingamawhatchit until the strain gauges on the cargo-hoisting gubbins show zero. Only then you unhook the cargo, inflate the cells just a whisker or jettison some ballast, and float away gently.
15 July 2009 at 6:30 am
I'm a big fan of hydrogen power, one thing to remember though is that hydrogen has a flammable range of between 1% & 88%.
This means that pretty much any mix of hydrogen and air will burn / explode.
Gasoline for comparison has a flamability range of 1% to 7% (which is why your car won't start when you've "flooded" it - you've gone over the flammability range & have to wait till some of the vapour condenses on the walls of the cylinder thereby reducing the mix ratio).
Oh and hydrogen, especially high pressure hydrogen does lovely things to metals as it diffuses into them (eg storage containers, pipes, struts & cables). The gas comes back out of solution inside the solid objects forming voids & expanding cracks, I can't help wondering whether similar effects would be noticed in composite materials - probably at lower temperatures & pressures too since they're primarily comprised of plastic & carbon.
15 July 2009 at 9:00 am
A little BOTE on efficiency: According to this source Hindenburg had
While efficiency (not to mention reliability and power/weight!) has improved since the 30s, this should give us an order of magnitude estimate of power requirements. Hindenburg cruised at 77-84 MPH (same source). Higher altitudes at the same speed would be more efficient, but chances are you'd keep the IAS the same (or higher) and so cruise power should be roughly similar. For an air ship drag will also have to go up with altitude, because we need more lifting volume.
Hindenburg had could carry 70 passengers and 40 crew. Using modern materials and less luxurious accommodations, I'll assume our airship can double that, carrying 120 persons. Because of the longer flight times, a larger portion of these will have to be crew compared to an equivalent jet, although probably not to the extreme seen in the Hindenburg.
Taking Patrick Smiths New York to London round trip example. Suppose we can cruise at 160 MPH, over a round trip of 6400 miles, for 40 hours of flying time. Plugging in 3400 hp and a good diesel specific fuel consumption of 0.3 lb/hp*h we end up with 40800lb of fuel. This is about 1/4 the amount used by Patricks 767. The 767 carries about 2x as many passengers so this works out to 1/2 the fuel per passenger. Hmmm, not so bad, if the assumptions stand and I haven't flubbed the math somewhere.
The 160 MPH with the same power requirement as Hindenburg is probably optimistic. Hindenburg could fly at over 6000 feet, but a ship capable over ~40000 feet (required to get a 160MPH true airspeed at an ~85 indicated) would have to be substantially larger, or carry less payload. Even fudging in a cleaner shape, more efficient props, lighter structure and so on, I have doubts.
The assumption that it would travel the same distance as the 767 is also dubious. The slower airship would be forced to be more cautious with weather and suffer a greater penalty for adverse winds. OTOH, the assumption of only carrying double the number of people is probably pessimistic... even with emirates grade accommodations.
This old flightglobal article gives some interesting details on airship airline service.
@Matt-S actually, you can't just land an airship just anywhere in the event of a storm. You need a freakin huge airship hanger. An airship close to the ground is more likely to sustain damage than one riding it out in the air. Sure the passengers will be happy to be alive, but you'll still go out of business if your fleet gets trashed on a regular basis.
15 July 2009 at 11:35 am
@Mohonri - If it was an epic Antonov that crashed, it would have been an AN-124 as there are quite a few of those. There was only one AN-225 completed and it is still in service. Still a fantastically large airplane.
It sounds like quite an interesting project you worked on too.
15 July 2009 at 1:20 pm
I think you're all way too dismisive of the dangers of Hydrogen. Sure, it wont explode like a bomb but if this ship catches fire it will burn to a crisp and all passengers will end up in the ocean. Helium offers almost the same level of lift with none of the danger. Whats the problem?
The big issue of airships is their problem of crashing into the ground. Many accidents occured when landing. My solution is to never land the things. Bring everything up to them with service aircraft equiped with shyhooks, including fuel and the passengers. Always keep them at a high enough altitude so that sudden presure changes dont cause saftey issues.
Another questionmark I have is the 5000kms a day claim. It's more like 3000, but even then, you're burning fuel at a faster rate than needed.
15 July 2009 at 1:37 pm
Whoa, I fail at multiplication. 70+40*2 should be 220! If I haven't screwed anything else up, that leaves my Hindenburg 2.0 carrying about the same number as a 767 (a bit on the low end, but this is BOTE), and gets us back to ~1/4 the fuel burn.
15 July 2009 at 1:59 pm
@reyalp,
You should also multiply 40800lb of fuel by 4 as there are 4 engines. I get about 80 tons. This isnt a realistic fuel load as the lifting capacity of the gas is only 200 tons or so. 180 tons on Helium. A ten megawatt (13000 or so hp) engine will weigh a lot by itself as well, at least 30 tons and probably a lot more. This doesn't leave a lot for the structure and canvas let alone any passengers.
The numbers don't work. You can't go 160MPH.
15 July 2009 at 2:57 pm
@loseweightslow.
No, the fuel consumption is based on 3400 HP, which accounts for all 4 engines: 850hp each at cruise.
4*850*40 = 136000 hp hours
* 0.3 (lb/hp*hour) = 40800 lb.
I did fudge a bit taking the max speed (before extrapolating to ridiculous altitude) while using cruise power. At the max power of 5280 hp we'd need ~64000 lb of fuel.
With current diesel technology, you can get this kind of power from a few tons without much problem. Of course given the premise of flying at airliner altitudes, you might have to use gas turbines instead, which are lighter but have a worse SFC.
I mentioned that 160 MPH for the same drag was very quite optimistic.
Note that according to the flightglobal article I linked earlier, the real Hindenburg could carry up to 143,000lbs (~64 metric tons) of fuel, yeilding a quoted range over 8400 miles. Using the quoted cruise power I get an SFC of 0.37 lb/hp*hr from this, which is in the right ballpark. Modern large diesels do quite a bit better.
15 July 2009 at 3:49 pm
Sorry, I thought you just did the figures on twice the speed so four times the power required.
I realise now, you are just assuming a high flying altitude. Less air up there means less air resistance so you go faster. Basically, you need 1/2 the air density. (actually, I'm not sure if it's 1/4 the density, I dont know rule which applies) The problem will be how to get air ship up that high to start with. For example, the Hindenburg would only have a 100 ton lifting capability in it's 200,000 cubic meter envelope at that height, so the ships Helium bags will be half full on the ground. This, once again it leaves nothing for the super structure and passengers. Not to mention the passenger cabin now needs to be strong and heavy enough to support presurisation.
Ive be thinking more about Dans "two-part shaped-charge-plus-thermite" bomb and I cant think of a way that this doesnt send hundreds of burning hot fragments in every direction for hundreds of meters, piercing every enevlope on the way and starting a fire at every point that a fragment exits. The Hindenburg burnt in 34 seconds and it had to cover the whole 200 meters in that time. If a fire starts in the middle, you have 17 seconds before the whole ship is gone. It doesnt matter how fast you pump out gas it wont make any difference.
15 July 2009 at 5:39 pm
With a dirigible you can also run a nice big, relatively slow prop making thrust much more efficiently than a jet engine. A rolls Royce trent has a specific fuel consumption of about .56, so burns .56 pounds of fuel per hour per pound of thrust. An average gasoline engine gets roughly the same fuel burned(.5-.6) per HORSEPOWER per hour. But that 1 horsepower is generally good for around 3-4 pounds of thrust at low speeds depending on prop, airspeed, etc. So roughly 3-4 times thrust per pound of fuel.
15 July 2009 at 5:51 pm
"seeing as there's only ever been one completed An-225 in the world."
Which I've seen, purely by chance.
I was riding past the Muenster-Oldenburg airport one day a few years back when I saw a plane take off. Look better: mmmkay, that's a massive crate. Look even better: hey, it's six-engined, you don't see that very often.
Back home I checked up on six-engined jet aircraft, and it couldn't have been anything but the 225. I hadn't really noticed the double tail, though.
15 July 2009 at 7:22 pm
An airship needn't use diesel engines though. It could use electric motors, and something the size of the Hindenburg could fit around 10000 sqr-metres of solar panels on its upper surface, possibly double that if it were wing-shaped.
If you generate an average of 50W per sqr-metre (not sure how realistic that is) then that's 5MW of power you can send to the engines. That's probably not enough to power a decent cruising speed but the the rest can be generated by fuel cells.
That would certainly reduce the fuel weight, but I'm not sure how much 10000 sqr-metres of solar panels would weigh...
15 July 2009 at 7:37 pm
loseweightslow: The fire on the Hindenberg didn't spread because of the gas, it spread because the envelope was (necessarily, given the materials available) flammable. Presumably a modern airship wouldn't make that mistake. Certainly, even the Hindenberg didn't go up like a "two-part shaped charge and thermite" bomb. It didn't explode at all!
15 July 2009 at 7:44 pm
The problem with helium, of course, is that it's a limited and expensive fossil fuel (it gets into the natural gas supply from radioactive decay, we can't actually mine it or anything) with a price which is highly sensitive to fluctuations in supply. You should've seen the party balloon market a couple of years ago, the whole thing was practically in crisis. By comparison, hydrogen is a no-brainer.
As a bonus, a solar-powered hydrogen vehicle could convert its ballast into a supply of oxygen and lifting gas at will, and conversely, use its lifting gas and outside oxygen to generate electricity and ballast.
15 July 2009 at 8:24 pm
The US used helium in its airships, but that caused some problems. Most importantly, when you're using helium you have to conserve it. Just venting it to the atmosphere whenever you want to go down very quickly becomes very expensive. With hydrogen it doesn't matter, because hydrogen is cheap and easy to make.
The USS Los Angeles is a good example; see this photo. Because it was filled with helium, venting the gas cells to bring it back down (or stop it going up) wasn't an option. The German Zeppelins continued to use hydrogen, and just threw it away when necessary.
Regarding the stability at low altitudes: I think a big Zeppelin would do better than a blimp here. Simply because of its size and mass, it's less likely that the whole thing will move into a region of cooler or warmer air at the same time, and any movement that does occur will be slower. You see this sort of thing with helicopters. A little RC helicopter is almost un-flyable without some sort of electronic stabilisation (normally gyroscopes). A full-size helicopter takes far longer to do anything and is therefore controllable without that.
loseweightslow: the German Zeppelins frequently got shot at during WW1. You can see a list of them here. Very few of them were actually destroyed by fire while airborne. A few burnt in their hangars, but most were destroyed either by their crew (after a forced landing) or crashes. The Graf Zeppelin didn't get shot, but it did get hit by lightning a few times, and that also caused no problems. Burning in the air like the Hindenburg did is very rare. As has been said above, the paint on the Hindenburg had something to do with it (highly flammable), and that was fixed quickly (the LZ-130 solved the problem). I suspect that a deliberate explosion inside a hydrogen-filled Zeppelin would punch a lot of holes in it, but it probably wouldn't cause many (if any) fires.
15 July 2009 at 11:04 pm
"The fire on the Hindenberg didn't spread because of the gas, it spread because the envelope was (necessarily, given the materials available) flammable."
Um, no. It spread because of the gas. It almost doesn't matter what you dope the cotton with, it wont burn at over 5 meters per second. The doping may have caused the material to catch fire but once the fire was started Hydrogen was the whole show. One kook gets a documentary and everyone thinks Hydrogen has nothing to do with it. It's a myth.
As far as Zeplins not burning when shot, the first link when I google for "wwi zeplins" says "Only later in the war did the tide turn against the zeppelins. New planes with more powerful engines were built that could catch the midnight marauders. These new planes also carried a new weapon that would exploit the zeppelins Achilles' heel: incendiary ammunition. Bullets laced with phosphorus would burn with a hot flame that could easily set the massive volume of hydrogen aflame. When a zeppelin burned, eye witnesses said that it would light the night sky."
The wikipedia entry itself makes mention that the invention of incendiary ammunition made commerce raids unviable.
Hydrogen burns, easily. It's not safe, particularly from a motivated attacker.
16 July 2009 at 12:09 am
And yet, a motivated attacker on a Zeppelin would probably do less damage than one in a 747.
When bombs go off in planes they cause structural failure; the plane just can't keep afloat if it's breaking to bits.
In an airship, damage can be limited. Pressure/heat sensors on the gas cells could vent them to air if a fire was detected, and since (I presume) the material they'd be made of would be fire-resistant, what hydrogen did burn shouldn't set fire to the whole thing, and most importantly shouldn't set off the hydrogen in the nearby cells.
And then you have to consider that motivated attackers can and do bring planes down (and buildings along with them...), but we keep flying them anyway, because they're too damn handy to give up, even if it costs us lives. I can see no reason why it wouldn't be the same with zeppelins, in the hypothetical world where everything wasn't run solely for the Almighty Dollar and they could exist.
(Mind you, all my knowledge about Zeppelins originates from the Wikipedia, so there might be a few holes...)
16 July 2009 at 1:55 am
loseweightslow: I'm not saying that the fire spread by using the canvas as some kind of wick, I'm saying that the fire spread simply because the canvas could burn in a hydrogen fire, and therefore provided absolutely no containment. The airship frame might as well have been floating in a big bubble of burning gas once the fire was underway. The individual enclosures became meaningless.
In the modern era, you would hope to construct each enclosure from a fireproof material. The first benefit is that a trivial fire on board can no longer turn into a catastrophic one by spreading into the enclosures. The second benefit is that even if an enclosure was ruptured, the fire could not spread beyond it. You'd want the fire control system to automatically eject the burning enclosure (perhaps by tethering it to an intact enclosure and then cutting both loose) before there was enough heat inside it to cause a loss in the structural integrity of the craft as a whole.
Whether you could make the enclosure light enough, fireproof enough, and strong enough, is the big question.
16 July 2009 at 2:10 am
"Hydrogen burns, easily."
So does kerosene, yet it's stored next to the engines, inside the wings of most commercial aircraft. If it goes up, the wing goes, and you crash. If the engine goes up, the kerosene goes up, and the wing goes, and you crash. You mention incendiary ammunition as a way for bringing down a Zepplin - that would be ideal for bringing down a Jumbo. Yet, somehow, commercial aviation as we know it continues!
The existence of a hypothetical "motivated attacker" with access to an arbitrary selection of destructive technology is not a big part of any rational risk assessment.
16 July 2009 at 2:13 am
I really do not get peoples rather irrational fear of hydrogen. Hydrogen is very flammable, yes. But it is also not very explosive and has relatively little energy to release. Compare hydrogen to just about any other flammable gas or liquid and you'll quickly realize just how benign it actually is. I'd much rather sit, in my car, with a tank of hydrogen behind me than with that nasty gasoline stuff - that shit is dangerous! The pressurized nature of such a hydrogen tank poses more risk than the flammability of it's contents!
As for the burning of the Hindenberg - nobody has claimed that the hydrogen didn't have a lot to do with it but it most certainly was not just the hydrogen that caused that accident. The fact is that the outer skin was doped with the equivalent of thermite paint - the initial fire began, reached a temperature sufficient to ignite the doping and then it was all over - you have a lightweight thermite reaction being sustained and accelerated by the hydrogen. As for the claim that cotton won't burn at >5m/s no matter what it's doped with... well, then explain exactly why we see, in the footage of the accident, the skin of the airship largely disintegrating at the same rate the fire itself propagates through the airship. If the skin couldn't burn as fast as the hydrogen then this should not have occurred.
A modern design for an airship would have quite a few safety advantages over previous ones. Advantages like continuous thermal and pressure monitoring of all of the gas cells, continuous gas concentration monitoring (stay out of the flammability range and you can't burn it), fire retardant and self sealing cell materials, non-thermite doped skin materials.....
Also, there are fire control methods which could be used to control fires in cells - rapid venting, inert gas insertion (think a Halon system), water misting (which inhibits hydrogen burn quite nicely), and no doubt dozens of other things clever engineers would come up with given the need that were not available in the 20's and 30's.
Nothing is ever safe from a motivated attacker... but living in fear really, really sucks and is completely pointless. Bad things happen. Bad people exist. You cannot prevent a well motivated individual from doing something horrific - if they want to bring down a plane, or derail a train, or blow up a building they'll find a way to make it happen. Not doing something because somebody might destroy it is idiotic - if we operated this way we would have ceased flying after the first time a plane was hijacked or bombed.
16 July 2009 at 3:04 am
I wish I could remember where I last was involved in a lengthy discussion about this. I'm pretty sure it was to do with the DARPA proposal for a 500tn heavy lift airship, ostensibly for the movement of tanks and materiel to places where formal landing sites are few and far between and where you probably need to unload fairly quickly.
I remember being shot down rather well by some highly knowledgable types on the subject of heavy cargoes. From what I can recall the main points were to do with scalability of pumps and storage requirements for the gas that you pump out to reduce lift - as the volumes scale up to be able to move truly large cargoes, the increasing amount of time to pump the gas around and the amount of dead weight the storage cells involve start to severely affect performance. I think there was also something in there to do with dumping heat from compressing all the gas but memory is hazy.
I do like Stoneshop's idea of hovering for a while and lowering the cargo on a pod, it also nicely deals with the issue of having a honking great big flat bit of ground to park your airship in. I suspect it may make things even more weather dependant than they currently are though.
Nevertheless, I don't see airships 'taking off' (hur hur) in a big way until they can reliably handle moving a quantity of ordinary cargo containers and loading/unloading them reasonably rapidly - otherwise trucks and or ships do a pretty good job that is difficult to compete with.
Separate point, isn't there some other significant issue with hydrogen being a bugger to store and move without really well engineered pipe linkages cause being so light it seeps out all the invisible cracks or something?
16 July 2009 at 3:10 am
Hmm, thinking about this some more, I could see cargo airships being incredibly useful for the pacific & caribbean island nations as well as Africa - it'd be a damn sight easier to deliver goods to & from the islands via air than from sea and the weather is generally fairly predictable.
Not sure how easy you can fly around hurricanes, but they usually come at the same time of year so I guess you can avoid them, same as the cruise ships do.
The main reason I'm hooked on cargo shipments is that the kind of thing that lends itself to delivery this way tends to not be time dependant - building materials, food supplies and so on, which means that the slow speeds of airships become an asset if the problems of actually carrying enough goods can be overcome.
16 July 2009 at 9:27 am
@ Alex
The question of selection of gas cell material is a tough one. Remember that you only have 180 grams per square meter to work with. It needs to be air (hydrogen) tight, non flammable, fire retardant, and not deform or tear at all under the heat of a modest fire. If you can name such a material, I can be swayed.
Also, I apologise for misunderstanding your meaning of the contribution of the canvas. Contrary to Starks claim, many people do indded believe that the Hindenburg would still have gone up exactly the same way with the same number of deaths if it was filled with Helium.
The problem with incendiary bullets is that while it's near impossible to hit a 747, going 400kph, in the wing during take off from a standing point outside the airport. It's considerably easier to hit a 200 meter long 40 meter wide target going 50kph from the same vantage point. If the airship is simply filled with Helium, we don't have this discussion.
@Stark,
Mythbusters built a model of an airship, a few meters long, then coated the skin with 15 pounds! of thermite and set it alight. It would have taken 5 minutes for that thing to burn up if they didn't introduce the Hydrogen. The skin material might have assisted in the starting of the fire but once lit this was nothing but a Hydrogen fire. Of course, the fire is just as likely to have started static electricity igniting vented gas. I think Hydrogen proponents desperately cling to the doping theory because if they didn't, no one would (or should) take them seriously. I've seen the doping theory disproved several times, once using actual skin material from the Hindenburg.
As for Halon systems and water sprinklers. How much do you think that would weigh? Remember, you have to protect a volume of 200,000 cubic meters. It's not enough to just hand wave and say science will take care of it.
16 July 2009 at 11:01 am
@ loseweightslow: ...that's the whole POINT of handwavium!
16 July 2009 at 2:53 pm
Something that is often forgotten is that the Hinderburg accident wasn't especially deadly compared to modern jet crashes. Of 97 people on board, only 35 died, most of those after the event due to burns or falling from heights; most of them would probably have lived with modern medical technology.
Modern aircraft crashes - well it's usually just a matter of picking up the charred remains - with tweezers.
Yep, hydrogen burns. As a matter of fact, so does jet fuel; and in almost every single aircraft accident that doesn't result in instant death due to massive trauma, the fatalities are all due to very nasty intense fires.
So how exactly is this different to hydrogen?
Lots of ways: hydrogen fires are notably less intense than hydrocarbon fires; the major issue is loss of lift. A notable number of fatalities in the Hindenburg accident were caused by good old gravity when they tried to jump from the airship. Most survivors walked out of it once it was on the ground. OK, yes, they ran for their lives, but you can't run for your life from a jet airliner crash unless you are very lucky!
The threat of snipers with incendary bullets seems a little far-fetched, really, as I think loseweightslow is a little misinformed as to the takeoff speeds of modern airliners - usually between 200-290 km/h, and that is at the point of takeoff. In the takeoff run the aircraft is a lot slower than that, of course. The stories of WWI biplanes shooting down Zeps is true, but read up on how close to the target they had to get to be successful, it wasn't exactly fish-in-a-barrel, and there was a good chance you wouldn't survive the attack!
A modern airliner is very vulnerable to such sniper fire, yet jetliners don't drop from the sky due to sniper fire all the time. Why? Sniping an aircraft is a major operation - you won't be on the airport grounds, presumably, so you will have to hit your target from something like a mile away at least. At this distance you will be hard-pressed to hit anything unless you have a military rifle and military training. You just don't hear of it. An airship field is by nature a massive space, thus reasonably easy to secure. Certainly a job no harder than any other airport.
As for sniping from a distance, you would be surprised how quickly the cops will approach you with if you are carrying anything that looks even remotely dangerous near an airport, especially if you are in a park - I doubt you could do it with a large rifle in daytime, and nighttime just makes your job harder. If you did go to the effort - why? High likelihood of getting caught or stopped ('ello sir, where are you going with that 50cal sniper rifle today?) - there are far easier ways of causing more severe mayhem with less risk. (I won't say what, though, but we're lucky structural engineers don't seem to have terrorist tendencies!)
@Toolman83 the fuel/air mixtures for gasoline vs. hydrogen are correct for engines, and yes, you can flood your engine with too much gasoline so it won't go - but try that outside an engine, or in a semi-exposed engine like a jet engine - flooding a jet engine with fuel doesn't stop it, it gives you nice big gouts of flame out the back, or backfires that can spit turbines out the front - not good. Once structural integrity is gone I'd rather be on something buoyed by hydrogen then fueled by hydrocarbons - statistical evidence gives you a far better chance of survival.
16 July 2009 at 2:59 pm
In case I didn't make it clear (and I didn't), I think airships are a bloody brilliant idea, and I want more of them.
16 July 2009 at 3:24 pm
Ooh, - thought experiment for you ('s all):
What has more bouyancy than Hydrogen? - Nothing!
Yep, a vacuum! A few years back I worked out what you would need to build a vacuum-ship. It would look freaky - a bit like a diatom, and you need tensile & compressive elements and sheets that start to require physical properties somewhat like scrith, but reach the required level of material science and it is possible.
It might implode, but it definitely wouldn't burn.
16 July 2009 at 5:41 pm
BCF (no, not the camping store..) pretty much makes Hydrogen inert in very small concentrations, when well mixed.. maybe some large mylar paddles in the gas envelopes or a fountain pump in the bottom?
16 July 2009 at 5:49 pm
A vacuum lift dirigible would be much more frightening than one filled with hydrogen. Just cruising along then all of a sudden there's a massive sound like someone crushing a coke can and "oh the humanity!"
16 July 2009 at 11:08 pm
No, the strength of the materials you'd need to build it would mean it would probably bounce off most 'clouds-with-rocks-in' it may bump into.
At least I worked out the maths of it; the clowns who did that giant 'Strato-cruiser' one mentioned would have got a nice big FAIL from me if I was their design tutor. Sure you can design for not-quite-possible materials, but once you start breaking laws of physics directly, you fail. The engine on the back isn't going to work - it will just tip straight up into the air, without other engines to help keep trim. As for the spa and swmming pool, well Dan dealt with that. The bungy jumping platform is useful though - you could push the on-board DJ off it sans bungee.
"My design has a dedicated DJ..." stop right there, FAIL. Actually add more FAIL for looking like something by Zaha Hadid. Anywaaayyy....
I've been a big fan of airships for a while now, and having read a few books about them, there are a few lesser-known failures and near-failures of airships that are truly frightening. Like submarines, airships can 'go vertical' if you get them out of trim, so yes, everything slides to the stern (or bow), the thing goes out of control, and may break in half. The film 'Kiki's Delivery Service' has a quite realistic scene of an airship doing exactly this. Unfortunately, problem-solving witches are not common in our reality, curse the luck! The two big US airships, USS Akron and USS Macon was were lost due to structural breakup caused by 'operator error' rather than being inherently dangerous. (They were both helium filled, but whatever lifting gas you use if go beyond the design limitations, you'll crash)
Read up on the list of Zeppelins shot down in WW1 - sure they weren't a tide-turning weapon, but they weren't all cannon fodder either. Some absorbed a lot of punishment before coming to grief; others took something like 3 canisters of incendaries to actually catch fire. Sure, I would not personally have wanted to crew a war Zeppelin; but for drinking G&Ts while drifting quietly over the Okavango Delta watching a pride of lions stalk some buffalo? Yep, I'll have some of that!
17 July 2009 at 3:13 am
For passenger airships, there is also the psycological factor.
How many passengers will be willing to fly a hydrogen Zeppelin after that ohh so horrible Hindenburg desaster?
After having heard for nearly a century that those things are extremely dangerous?
I know, that isn´t quite true but that is not what the general public "knows"
17 July 2009 at 4:02 am
How about floating gently to your location, that would be fucking badass!
I for one, welcome our new airship overlords.
17 July 2009 at 5:30 am
I found this interesting. Assuming anyone here hasn't already read it.
http://news-info.wustl.edu/tips/page/normal/10754.html
17 July 2009 at 7:51 am
Just tossing out a wacky idea here that I'm sure I haven't properly thought through, but what about an airship constructed with a frame that's a cigar-shaped Hoberman Sphere-like structure? Constructed of some nice hydrogen-proof lightweight composite. It could expand and contract to alter the density ratio, helping with both high-altitude and cargo-loading. I can imagine the movable truss either inside or outside the gas cells, with various ways of interacting with the cells. You'd need a really nifty material for the gas cells, or just have them be expandable bags withing a larger bag... hmmm....
17 July 2009 at 2:47 pm
Could you use a bunch of shrink wrapped, vacuumized bubbles of aerogel?
Aerogel is supposed to be fairly strong, although it shatters once its strength is exceeded. Being shrinkwrapped may give it extra strength though. Can you stick it in a vacuum and sucessfully get rid of the air inside?
17 July 2009 at 5:41 pm
Thuli is on to something!
Make aerogel with helium?
Lighter than air, or at least neutral bouyancy (make it at low pressure?) and extremely resistant to attack, wrap a light frame around it to hold it together...
Anyone find any mention of attempts to use aerogel that way?
17 July 2009 at 6:02 pm
Yes, you can make evacuated aerogels, and it's even possible to make them (ever so slightly) lighter than air! but you lose quite a lot of the strength, and it's also pretty expensive. That said, they could probably be pretty useful in some airship-related applications. Maybe not for the structural parts, but how about an aerogel sandwich material for the walls of the gondola? (As a very lightweight insulation.)
Well, yes. Helium prices have gone up, mainly due to increased use of superconductors. On the other hand, there's quite a lot of it being pumped out into the atmosphere in Russia, where they don't (yet) try to separate it out of the natural gas.
At the same time, advances in superconductors mean that it ought to be possible to use liquid nitrogen instead of hydrogen which should free up a significant portion of the worlds supply of He.
Still, He will almost certainly remain significantly more expensive than hydrogen, and given that it only offers abut 10% more lift I'm sure that it would make more sense to develop some kind of efficient fire retardants.
18 July 2009 at 2:55 am
I think you meant to say that helium offers 10% less lift than hydrogen. No other gas is lighter than hydrogen.
Also, I too have seen many of the various experiments with doping and hydrogen fires... and in all of them you got a faster burn with both elements together than with either alone.
The Hindenburg was doomed from the start of the fire - doping or no doping but the speed at which it was completely consumed was product of both elements together. Anybody who doesn't think that the intervening 72 years between the Hindenburg disaster and today would make a huge difference in the engineering and safety has paid absolutely no attention to materials science for the last 72 years.
Can a dirigible be made absolutely safe and fire proof? No. Not even if it's using Helium - it still carries fuel after all and incendiary rounds into a fuel tank will do bad things just as they would in a hydrogen cell. Of course, the odds of this kind of attack occurring outside of an active war are, historically speaking, zero. Comparing the takeoff of an airship to a 747 is ridiculous by the way - the aircraft has a long run out to speed, and a relatively slow and shallow climb once out of the airport bounds where it is well within the engagement envelope for any number of weapons. An airship on the other had can simply rise vertically - never having to hit the edges of the usually quite large and reasonably secured airport it would operate from - putting it out of effective range for most portable weapons short of shoulder fire surface to air missiles. It can also, with modern technologies, climb quite quickly - azopod style engines would allow for vertical thrust potentially giving the air airship a prodigious climb rate at sea level.
Unfortunately nobody is likely to build large scale airships again anytime soon. Aircraft meet our needs, they are well understood, and the infrastructure is in place. It's the same reason we won't have any significant alternative fuel cars for many years to come. Simply put, it is inertia. Without some earth shattering improvement that everyone instantly sees the value of (and the opportunity for massive profit) neither traditional fossil fueled cars nor the air transport industry are likely to change in any significant way any time soon.
Sad isn't it?
18 July 2009 at 5:21 am
If oil prices rise to the point that cheap air travel is no longer possible then airships could make a comeback, although I imagine we'll be deep into a permanent recession once that happens.
The same applies to alternative fuels. No they won't take off as long as there's plentiful cheap oil, but there won't be cheap oil forever.
Of course it could be 10 years or 100 years before it runs out, but chances are that people who are young now will live to see it.
19 July 2009 at 2:17 pm
Well if this mob have anything to do with it, Dan could get his wish.
The SkyKitten is pretty cool, and exists.
The SkyCat, (if they build it to even half capacity) should be amazing
http://www.worldskycat.com/index.html
"...carrying payloads ranging from 20 to 1,000 tons, the SkyCat hybrid air vehicles..."
Marketing BS? Maybe, but I hope not....
19 July 2009 at 2:24 pm
... on review of the pdf from the website, looks like it might be a dead project... damn.
2 August 2009 at 1:55 am
I'm afraid it would have to be hobbyist stuff.
You could maybe make a commercial service "fly" for small-scale local sightseeing (assuming you could somehow get people past "but the only one we've ever heard of is the Hindenburg, which burned in horrible infamy"), along the lines of "let's look down on the New York skyline from above for an hour", but for distance travel, it's a non-starter.
The reason commercial jet aircraft have become so popular for travel is because they're fast. It isn't necessarily entirely rational in all cases, but people are always in a hurry, and that's what sells plane tickets. I don't think very many people would spend that kind of money to fly, at least, not on a regular basis, if it weren't significantly faster than other modes of travel (most notably driving).