The Second Age of Airships 363
The Telegraph has a story about a new generation of airships. It says "It's a new vehicle. It's a hybrid because we're combining helium lift, aerodynamic lift, a hovercraft landing system, and vectored thrust... If you can get beyond the word airship — because that has a lot of history — people think about them differently."
Great, instead of peak oil ... (Score:5, Informative)
we'll have peak helium.
http://news.slashdot.org/story/10/07/05/2159215/Price-Shocks-May-Be-Coming-For-Helium-Supply?from=rss [slashdot.org]
Re:Great, instead of peak oil ... (Score:5, Informative)
Technically we hit peak helium a long, long time ago. Most of what's used today is out of storage collected decades ago.
Re:Great, instead of peak oil ... (Score:5, Funny)
I thought helium was refined essence of Chipmunk - surely a renewable source?
Re: (Score:2, Insightful)
It's common to trot out the example of the Hindenberg as to what can go wrong, but by comparison with the mess a 747 makes when it hits anything at 570mph, it's fair to say airships are pretty safe. In the Hindenberg disaster, 63% of the passengers survived. Whereas, if your plane crashes you can usually be pretty sure
Re:Great, instead of peak oil ... (Score:4, Interesting)
Re:Great, instead of peak oil ... (Score:5, Informative)
Having usable amounts of helium trapped in one place so you can collect it efficiently is quite rare though. There's a reason that > 90% of helium was taken out of the great plains, it's one of the few places where it occurs in large enough quantities to be feasible. There are, of course, other places (Algeria apparently is the new number 2 producer according to Wiki), and as the price increases it will become more economical to capture and refine from natural gas wells that ignore it today. That's one of the reasons there was a big push to stop government control of the price of Helium, it's important that we start collecting more of what's available before we vent a potentially precious resource into the atmosphere because its too expensive to capture.
Re:Great, instead of peak oil ... (Score:5, Informative)
Re:Great, instead of peak oil ... (Score:4, Funny)
That's probably for the best. Who'd want to have everyone's voices gradually get more and more silly?
Re:Great, instead of peak oil ... (Score:5, Informative)
"What helium is present today has been mostly created by the natural radioactive decay of heavy radioactive elements (thorium and uranium), as the alpha particles that are emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations up to seven percent by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation."
Looks like another good reason to build LFTR reactors that can also take
the current radioactive waste and dispose it for good.
http://www.youtube.com/watch?v=WWUeBSoEnRk [youtube.com]
Good transition til we can upscale other clean energy sources.
Re:Great, instead of peak oil ... (Score:5, Informative)
It is not like alpha emitters are a particularly rare thing...
No. The problem is that the alpha emitters have half-lives in the billions of years. While there's plenty of helium being produced inside our planet, the problem is one of venting. No one is willing to stand over active volcanoes to collect it for some reason. The helium that comes up through permeable rocks in the crust can't be collected because it's so diffuse. So we're stuck with those helium pockets that can be collected - those that happen to be trapped (along with natural gas) under rocks that aren't permeable. Those pockets took - billions of years to create, and dozens of years to empty.
Re: (Score:2)
No peak, just lack of demand. Iran is venting tons of the stuff into the atmosphere, what with all the natural gas they're burning at the wellheads.
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From TFA:
"Currently, the lighter-than-air market uses only two per cent of all the helium bought in the world. Most of that is used to blow up party balloons. "
Based on that I would expect the demand for party balloons would drop very quickly as the price of helium rises. That would allow plenty of helium to shift to airships.
Re:Great, instead of peak oil ... (Score:4, Informative)
"Most of that is used to blow up party balloons."
http://www.nap.edu/openbook.php?record_id=9860&page=27 [nap.edu]
party balloons could come under "pressurizing and purging" or "other" but the vast majority is used in cryogenics, welding or controlled atmospheres.
Re:Great, instead of peak oil ... (Score:4, Informative)
The way I understand it, we privatized the US supply of helium back in 1996. We targeted selling 850 million scm by 2015, reserving 17 million scm for the federal government's reserve. The price has been set artificially low in order to get that 850 million scm sold off in time.
In other words, we're not approaching peak helium, we're stupidly, deliberately, actively rushing toward it.
http://www.agiweb.org/gap/legis106/helium.html [agiweb.org]
http://www.blm.gov/nm/st/en/prog/energy/helium/federal_helium_program.html [blm.gov]
http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=9860 [nationalacademies.org]
https://twitter.com/timoreilly/statuses/17831735662 [twitter.com]
Re:Hydrogen or hot-air (Score:4, Insightful)
The claims of thermite paint being the cause of the explosion has been debunked. Mythbusters featured one of the better known debunking.
Re: (Score:3, Informative)
Re:Hydrogen or hot-air (Score:5, Funny)
The video i watched was in black and white...i was under the impression colors hadn't been invented yet!
is there a Turner Colorized version somewhere?
Re:Hydrogen or hot-air (Score:5, Informative)
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Forever. (Score:5, Funny)
I will forever associate the word "airship" with Final Fantasy VI. Damn you, early-mid 1980's birth!
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It does feel like we're getting closer to the FF6/FF9 style of airship....
Personally I would prefer a more FF7/FF8 or FF12 style of airship....
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why not FFIV? you start the game on the Red Wings as Cecil!
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I won't ride in an airship that wasn't designed by Cid.
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fact, not being a gamer at all, I'm somewhat confused as to how there can be more than one Final Fantasy, but that's not the point
From this Wikipedia article [wikipedia.org]:
"As Sakaguchi planned to retire after completing the project, he named it Final Fantasy."
Re:Forever. (Score:5, Interesting)
Re: (Score:3, Informative)
Helium (Score:2, Troll)
Is this really how we should be using the Helium we have left on Earth?
Re:Helium (Score:5, Insightful)
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I think I missed the memo explaining how helium was now a scarce resource.
Helium is UNSAFE! (Score:2, Funny)
Nope! We should ban this right now!!!
a lot of "history" (Score:2)
If you can get beyond the word airship — because that has a lot of history
Ya, "history", all the bad kind [wikipedia.org]
Re: (Score:3, Funny)
Your sig is very appropriate today!
And not just a German problem. (Score:2)
Don't forget the Shenandoah, R38, Roma, Akron and Macon. The Los Angeles was the only rigid US airship that didn't go crashing into the earth or sea and that is only because we the good sense to ground it before it had to chance to take out another crew. I can think of no other mode of transportation with such a failure rate and in the end it has only done Goodyear and Goodrich any good.
I hate to rain on this guy's parade, it is an awful neat one, but what advantage does it serve? In war it is the definitio
Holy steampunk Batman!! (Score:2)
Cool!! Airships! Does this mean we all get brass goggles and leather aprons and other Steampunk essentials?
We need way more retro-future stuff like this! That's freakin' awesome.
Next, zombies in London. :-P
Re:Holy steampunk Batman!! (Score:4, Funny)
Next, zombies in London.
Those aren't zombies, they are members of the House of Lords.
Re:Holy steampunk Batman!! (Score:5, Funny)
Obligatory Annual Article (Score:2)
Every science magazine since the 1950s has felt obliged to talk about the "blimp renaissance" once a year, along with a "promising prototype".
I'm still waiting for the news of a prankster somewhere that flies a large RC blimp with a picture of Osama on it.
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Sure, but these guys got a $500,000,000 contract from the US government to actually make some of these things.
Grab Your Goggles and Polish Up Your Brass (Score:2)
It's going to be a Glorious Ride!
Or maybe not [buzzfeed.com]
Hybrid Air Vehicle (Score:2)
He picks a name that abbreviates to HAV. Hmmm Haich - Aiii - Veee... HIV!
Seriously...
D'oh! (Score:3, Funny)
Monorail!
Not the first try to revive airships (Score:5, Informative)
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Yeah, or put another way, we've been hearing about it for 20 years now and we've never seen anything actually in the air... take this story with the same grain of salt.
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I don't think they're even as high as the tenth... There's been a pretty steady stream of attempts since the 1960's.
Of course, the lack of airships tooling about the skies should tell you much.
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Popular Mechanics had a decent article on this last year:
http://www.popularmechanics.com/technology/aviation/airships/4242974 [popularmechanics.com]
I hope the Cardington team gets funding and critical mass, because airships are quite usable for various tasks, and moving one around is a lot cheaper than moving a plane merely because that the lift is provided already. Airships have a lot of practical uses:
1: Transportation of goods across the Atlantic or Pacific. It won't be as fast as a jet, but if done right, will be a lot fas
Trains will be faster (Score:2)
Maybe if they could focus (Score:3, Insightful)
Sure, there is a place on this planet (or just above it) for airships. However, trans-atlantic passenger service isn't one of them.
‘You go to Richmond Park International. At 11 o’clock on Thursday you get on board the SkyCat200. There are hundreds of staterooms on it and you dinner dance your way across the Atlantic. At two o’clock on Friday afternoon you’re getting off at the East River in New York. You’ve travelled 3,000 miles overnight and there’s no jet lag.
Or, you could get on an airplane, be in New York in a fraction of the time, and spend the rest of the day recovering from jet lag.
Realistically, SkyCats would be most useful in the transport of heavy loads – the largest SkyCat can carry up to 200 tons – to harsh environments
That's more like it. If you attack problems like heavy lifting, surveillance, even tasks like fighting forest fires, you don't have to sell it by saying "it's a hybrid"
At that time they tested a full-sized airship against a range of artillery including a Russian mounted machine gun filled with .22 calibre armour-piercing incendiaries and a SAM-7 surface to air missile. What they learnt was this: the airship is almost invincible to attack. Helium is an inert gas, so it doesn’t explode.
Did the test include shooting at the crew? I'm sure they'll find that sitting nearly motionless over a well-armed enemy does not make airship pilots invincible.
"stop shooting at us you idiot" (Score:2)
Did the test include shooting at the crew? I'm sure they'll find that sitting nearly motionless over a well-armed enemy does not make airship pilots invincible.
WTF?! [lmgtfy.com]
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Did the test include shooting at the crew? I'm sure they'll find that sitting nearly motionless over a well-armed enemy does not make airship pilots invincible.
This was a test for military use. The military's plans for use in Afghanistan is for an unmanned, reconnaissance vehicle. No crew required.
Call them "ecological airplanes" and quote fuel (Score:2)
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Ummm .. except that an "airplane" is specifically talking about something using a fixed wing [wikipedia.org] for lift.
This is a lighter-than-air vessel that can be steered -- by definition, an airship [wikipedia.org].
An airship and an airplane are fundamentally different in terms of how they fly.
Airships simply will not be practical, sorry (Score:4, Insightful)
Now imagine the costs if the thing must always take off at constant load. It would be like old sailing ships that had to fill up with gravel ballast to make safe return trips (because if they returned empty the wind could simply push them over.) Currently an Airbus 380 can transport about 150t of freight one way, and if it makes the return journey empty, OK it is a wasted trip but it requires less fuel for takeoff, which is significant on short hauls.
If you try to solve the problem by having pumps to transfer gas from the envelope to storage tanks, to control the buoyancy, you have to factor in the cost of ferrying around the pumps and the tanks. It is not impossible, but it would be complicated and expensive and require extensive safety testing before it could be certified. Much of the simplicity relative to an airplane would be lost - and you still end up with something that requires as much or more room as a 380 - a helicopter replacement this is not.
Re:Airships simply will not be practical, sorry (Score:4, Informative)
How did this get rated insightful? I guess neither the mods nor you bothered to read the article.
These are hybrid vehicles. They aren't airships or balloons. It's not about lifting payload with gas alone; it's a lift hybrid system. The gas can offset anywhere from the weight of the vehicle to some percentage of the cargo. Thrusters and a lifting-body airfoil shape then provide the rest of the lift. From the research that has been done so far, this is feasible, practical, and economical. At this stage it is also economical to pump helium around to control the gas lift. Some designs use just fans to pump helium from large lifting bags into storage bags. Since the helium is at such a low pressure, it doesn't take much to move it and to change the buoyancy of the entire system.
Really, it's not as hard or as bad as you make out. It appears to be absolutely practical in the long run. And these guys have years of experience in this field now, which you do not, as near as I can see. In fact you just made up the stuff in your comment. Sounds good and logical, but what you said has no basis in the current facts of the field, and is certainly not relevant to the types of airships this company is designing. In the article one of the guys bemoans the fact that armchair airship "experts" such as yourself have a real negative impact on public perception of these hybrid air vehicles and negatively impact their ability to research this stuff.
Re:Airships simply will not be practical, sorry (Score:4, Insightful)
2. The article is about a hybrid air vehicle. These use a combining of helium lift, aerodynamic lift, a hovercraft landing system and vectored thrust, so it's not entirely reliant on maintaining bouyancy.
Sorry to cast an umbrella under your rain but... (Score:5, Informative)
(1) one only needs the "modern" technology of the "compressor" to re-compress the gas into dense storage cylinders. They _used_ to vent the gas because the compressors and storage were more expensive and heavy than the cheap replacement gas. Modern technology can solve this really easy. You can fit 80 cubic feet of air (so probably like 100 cubic feet of helium) into a scuba tank, and it would be quite heavy thereafter. Intelligently done, a large number of flexible ballon-like bladders and one or two semi-rigid (pressurized) bladders would be easily sufficient to change the overall displacement of an airship by up to 50 percent without even getting into "high" pressures (e.g. more than three atmospheres or so in the pressurized fixed-size bladders). It's not rocket science, its basic pressure mechanics and displacement.
(2) many of the craft being discussed are only "mostly buoyant", with vectored thrust and lifting bodies etc, so that the static weight of the craft is neutrally boyant, then only the thrust to lift or fly the cargo is spent. E.g. the goal is to make the weight of the _vehicle_ free. Think of the helicopter. Right now we have to maintain thrust to lift the copter and the people, which uses far more fuel than just lifting the people.
(2a) once you are lifting only the cargo weight, crashes are lots safter as something with the weight of the cargo but the drag profile of the whole vehicle will have a much lower in-atmosphere terminal velocity, unless of course someone decided to shape it like a giant dart pointing straight down. 8-)
So, Good Sir Nay-Sayer, yes, if nobody actually thinks about the problem, then ballast becomes a hassle. But then again, if nobody thinks about breaks, a speeding car is quite a problem as well.
Secondary facts re: seagoing vessles et al. (Score:4, Interesting)
The parent of my parent post brings up putting rocks in sailing vessels as argumentative support, he is wrong for at least two reasons.
(1) Many modern non-sailing vessels still use ballast. The problem isn't old-timey nor is it "solved", nor is it _really_ the same issue as buoyancy with respect to airships. In a seagoing vessel the problem is that a non-trivial amount of the vessel must remain "above" the water over which the vessel must remain buoyant. As such, to remain upright, as cargo is loaded above the waterline, one must add weight below the water line to keep the ship upright. In an airship the entire ship is "submerged" in the air, so the issues are much simpler. That is, an airship and a submarine are in the same domain, but an airship and a sailing ship are not.
[ASIDE: One of the things the boat commander of a submarine must watch for is rolling over during initial dive. In surface operation, the sub is a surface ship, and its center of gravity is below its center of buoyancy just like any other ship. In underwater operation the center of gravity must be above the center of buoyancy or it won't sink below the surface. That moment when the two must cross is tricky, as they must "cross", not "pass each other". That is, if say the port side takes on ballast faster, the center of gravity would pass to the port of the center of buoyancy and the ship would roll. The normal way to make this happen most safely is to be under-way at the time of submersion or surfacing so that the wing-like bow planes and rudder etc. can be used to counter any small tendency to roll. The single most dangerous submarine maneuver is the static (non-moving) submerge. It is virtually never done as messing it up is expensive in both lives and equipment. Surfacing is safer than submerging as "blowing" the ballast tanks can right the ship very quickly if it starts to roll, and can be done before reaching the surface. That leads to that really dramatic "breaching" thing where a significant fraction of the sub leaves the water entirely before crashing back to the surface. Dramatic, "safe", but again, hard on the men and gear. (I hear it's fun though... 8-)]
(2) Ballast was much more spoken of, and "tricker" in the age of sail as the power source (the wind) wanted to push the ship over anyway. Additionally, _letting_ or even encouraging the wind to push the ship over a little (e.g. heeling) could lead to increased speeds and efficiencies.
(3) Ballast in seagoing vessels is more important and variable because you want enough to stay upright, but each little bit more than that sinks the ship a little more, causing more of it to interface with the viscous watter instead of the less-viscous air.
(4) Water can not be meaningfully compressed. Things "denser than" water also cannot be meaningfully compressed. (e.g. compressed enough to substantially effect displacement.) Air and lifting gas is eminently compressible. Consequently airships, in issues of both displacement and buoyancy, are completely dissimilar to anything seagoing (except a scuba diver in a wetsuit 8-) so none of the natures and limits you (grandparent poster) mention really apply as such.
24 hours to get to Europe? (Score:2)
Hello Airplanes? It's blimps... congratulations you win.
-If you have not watched Archer, you have missed out.
they forgot one. (Score:2)
would be cooler if it could also be a flarecraft in ground effect.
HAV vs. HAVnot (Score:3, Funny)
"If you can get beyond the word airship" (Score:2)
Why would I want to? It's a wonderful word.
> because that has a lot of history
Yes. A fine one.
Uh hello, planes? It’s blimps. (Score:2)
– Archer
Seriously - no Archer fans here? My god this so the Skytanic!
Danger zone anyone? Anyone?
-CF
Lockheed is way ahead with airships (Score:5, Informative)
Lockheed's P-791 airship [youtube.com] has been flying around Palmdale for several years now. This is a product of Lockheed's Skunk Works. It is slightly heavier than air, and those four "feet" are lift fans. This has advantages and disadvantages. It takes fuel to stay up, for one. On the other hand, takeoff and landing are easier; the craft can land on a runway and taxi as a hovercraft. No mooring mast required.
The P-791 looks far more controllable than any previous airship. Rudders and elevators are ineffective at low speed. The P-791 has four propellers, each fully and independently steerable in two axes, plus speed, and maybe blade pitch. Plus the four lift fans. So it is controllable in all six degrees of freedom, even at zero speed. With classic airships, having twenty controls to manage by hand would be hopeless. With flight control computers, it's possible, once the airship has been characterized. That's really what flight tests of the P-791 are for - figuring out the control strategies. In the video,it's clear that the propellers are all being steered independently, which indicates computers and sensors are busily working to stabilize the beast. This is probably an easier job for the Skunk Works controls team than any of the stealth fighters they've done, all of which are unstable in all three axes.
The Zeppelin NT [airshipventures.com] has a similar, but less flexible system, with three steerable fans plus a lateral tail rotor, all controlled by a fly-by-wire system. I suspect that the Skunk Works put more degrees of freedom into their prototype than are really needed, so that they could experiment with different control strategies and find the best way to control their unusual craft.
The Zeppelin NT has a compressor system, so they can reduce lift by compressing some helium into a high pressure tank and letting some of the ballonets deflate a little. This is preferable to dumping ballast or helium.
helium shortage (Score:2)
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If there is a shortage why are we wasting it in party balloons?
Vaccuum ships? (Score:3, Interesting)
If Helium rises because it is less dense, would it be possible to force a balloon open, using some sort of supports, and end up with essentially a balloon filled with nothing, and thus able to rise? Or is this beyond current material science?
Re: (Score:3, Interesting)
If Helium rises because it is less dense, would it be possible to force a balloon open, using some sort of supports, and end up with essentially a balloon filled with nothing, and thus able to rise? Or is this beyond current material science?
I tried to calculate this a couple years ago, and using metal with an excellent strength/weight ratio -- Aermet 310 -- and a spherical model with stiffening ribs, I couldn't find any viable solution: no matter how large the diameter of the sphere, the weight of the metal required to contain the vacuum against the external air pressure was greater than the vessel buoyancy, and I went up into kilometer-radius ranges.
I didn't try it with composites because that's a lot harder to make valid design assumptions,
Re: (Score:3, Interesting)
A vacuum balloon is going to be very difficult if not impossible.
A vacuum aerogel, however, might be in the realm of possibility. Aerogels have been made with evacuated bubbles inside, making the whole lighter than air. [youtube.com] The record so far is apparently 1 mg/cm^3 [wikipedia.org], which is just lighter than air at 1.2 mg/cm^3. That's not great, but it's a young technology that will get better.
Alas, a vacuum aerogel airship would need to be very large -- too large to make on Earth. We would need orbital manufacturing facil
Speed and mass are issues. (Score:3, Insightful)
Airships are slow; there is no way around it. They have huge cross sections and drag is a big factor. If your airspeed is 30knots going into a 30knot headwind your ground speed is 0knots. Even a moderate wind of 10knots will decrease your speed by 33%. Crosswinds are a similar issue. An airship can spend much of its forward speed compensating for winds.
Mass is also an issue. Large airships are docked to towers to keep them on one place for loading and unloading. This docking process is very precise. It is somewhat like porcupines kissing; too fast and the tower gets knocked over and/or the airship damaged, too slow and you never get there. Winds complicate the matter. Many accidents have happened due to strong gusts or wind dieing at inopportune times.
Then there is landing area. Each airship needs a circle at least the radius equal to the length of the airship as it needs to be able to swivel into the wind. You could put the airship inside a hanger but that maneuver it tricky (can not be done in windy conditions) and the hangers are huge/expensive.
Depending on the winds, the airship may note get out of the hanger, get loaded, get launched, reach the destination, get tethered and or get unloaded. This makes flights very unreliable in even moderate weather.
I just love how the article says that airships will save lives in Nunavut. I am sure that sending 200 tons of stuff that the locals can not afford to buy will really help the situation. Throwing stuff at people is not the solution to social issues.
Re: (Score:3, Informative)
It won't fix everything, but it will save a few lives, which is what the article said to me.
Lack of housing, poor health care, and lack of education are also all directly linked to the cost of transport. Government only has so much money and it currently costs multiple times the value of the goods to transport them to the needed locations.
Also don't point me to an article done by a fellow that visited briefly at best and doesn't actually know any of the logistics involved in doing anything at all up here. I
Airships will never be practical... (Score:4, Insightful)
The main determinants of fuel consumption are: 1) speed; and 2) the surface area of the front of the vehicle (since that determines how much air must be pushed out of the way). Since airships are very large, they will never be fuel efficient unless they travel very slowly. If they travel very slowly, then we must ask: why not use a train or a ship? Trains and ships will always have vastly greater carrying capacity, because they don't require helium to lift their cargo which has modest lift for a given volume.
In short: if speed is not important, then trains and ships will always be far cheaper and carry far more; and if speed is important, then airplanes will always be faster and more fuel-efficient at high speeds.
Airships are neglected because they suffer from fundamental limitations and therefore have few uses.
Granted, airships may find niche uses. Airships do have several advantages: first, they can hover for long periods; and second, they require little infrastructure (like long landing strips, ports, or train tracks). Since they can hover for long periods, they have found a use as floating advertisements, and they may find a use as floating observation vehicles for the military. Since they don't require infrastructure, they may find a use in transporting cargo to areas which lack airports, train tracks, or ports. But they will never take over the bulk of transport between major areas, because of fundamental limitations of the technology.
Every few years, someone starts a company to revive the airship. The venture always fails, because o
f fundamental limitations of airships that will always prevent widespread adoption. Perhaps some com
pany will eventually succeed, but they will succeed in a niche market, not widely.
Jeez, airships again? (Score:3, Funny)
Re:Arrogant prick (Score:4, Informative)
Airships make more sense for transporting cargo than people. They let you bypass the bottleneck of a port and let you take the cargo directly to its destination.
Re: (Score:3, Insightful)
Airports for airships (Score:2)
Until we get lots of airships all contending for airspace directly at the destination
Then how about a compromise: You can keep building dedicated facilities where these airships land, but unlike with ships, you don't have to locate them all on the coast. I've got a name for them: "airports". Because airships can use shorter runways, an airport on a given amount of land can probably service much more traffic than an airport built for conventional jet airliners.
Re:Arrogant prick (Score:5, Insightful)
Re:Arrogant prick (Score:4, Insightful)
What, exactly, makes it a dumb idea?
I've been on 5hr flights -- they're no fun. I can only imagine some of the really long flights must be friggin' brutal. Give it hotel amenities, a bar, a dance floor -- whatever -- and send people on a more leisurely trip without jamming them in like cattle and shoving them through airports. I can see it being a popular mode of travel.
Heck, just the romantic notion of it is kind of cool. I'd *love* to go on an airship voyage. It would be just plain old cool.
For leisure travel, it would be absolutely awesome way to see the world. I can see people paying to travel on one, if nothing else, for the novelty of it.
Re: (Score:2)
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Maybe it's dumb for transporting people, but it may prove to be perfect for holding cameras over Afghanistan for 21 days at a time. Time will tell, but it's an interesting idea and something different. Let's see how it plays out. Lots of people take cruises, it's not too far fetched to see people paying to float around, say, the Grand Canyon area for a few days.
Re:Hydrogen (Score:5, Insightful)
Half as dense as helium (so twice the lifting power),
Uh, no? It's being lifted by air pressure caused by air density of about 1.2 g/L; helium has a density of 0.1786g/L, so a vacuum would at most supply 14% more lift. Hydrogen at .08988g/L supplies 7.5% more lift-- hardly twice the lifting power.
Re:Hydrogen (Score:4, Funny)
vacuum would at most supply 14% more lift
OK, so let's fill our airships with vacuum. More lift and absolutely no danger of it going up in flames! Well, there's the problem of how to get the pressure with vacuum. But that's easy to solve: Just put enough dark energy in. If it can inflate the complete universe, it surely can also inflate a little balloon.
Half as dense != twice lift (Score:5, Informative)
The other problems with hydrogen are (a) that it leaks out of just about everything even faster than helium does and (b) your safety statement is utterly unproven - because nobody has recently built full size airships and compared the safety record to current winged aircraft, which are quite extraordinarily safe. Historically, airships in the 1930s might have been safer than airplanes - but since then airplanes have had over 70 years of technical advancement which have paid off massively.
Re: (Score:3, Informative)
Using the lift tables here
http://www.chem.hawaii.edu/uham/lift.html
Gas Dia. Ft. Vol. l Lift gr. Lift Lbs.
Helium 24 204976.41 210369 463.79
Hydrogen 24 204976.4 228550.5 503.87
503.87/463.79 = ~1.09
so using Hydrogen over Helium is a net gain of ~9% lift.. don't get be wrong but 9% is a lot of extra
Re:Use hydrogen. (Score:5, Informative)
Oh, jeez, the "rocket fuel" BS again. Might want to read this:
http://www.airships.net/hindenburg/disaster/myths#flammable-cover [airships.net]
rj
Re:Use hydrogen. (Score:4, Insightful)
Hydrogen is the correct answer, but people don't want to hear it because of the images of the Hindenburg crash.
This is ridiculous. The Hindenburg crash isn't 9/11: it was nigh 80 years ago and I'm not even distantly related to anyone who died on it. I have no emotional connection to the disaster whatsodamnedever. I reject hydrogen in airships because it's dangerous as hell. There are just too many potential sources of ignition (sparks from machinery, static discharge) for it ever to be safe enough for flight, if we hold it to the same standards of safety that commercial jets are.
Gasoline burns hotter than hydrogen, but thanks to the Hindenburg crash video, we don't have hydrogen cars either.
Gasoline burns, hydrogen explodes. There's a difference. And the issues with hydrogen cars are a multi-paragraph post that I don't feel like writing right now, but (lousy energy density, present impossibility of storage, no infrastructure) are the main reasons, not lingering Hindenburg memories. Who on earth modded GP Insightful?
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Not to mention the detail where the hydrogen: whether burning, exploding, or miraculously transforming into wine, is holding the damned airship up. Even if it were possible to safely redirect the force of the heat and explosive energy of the hydrogen going up, the airship would crash from lack of lift. The temperature it burns at or the force of its explosiveness is almost immaterial to whether it's a good idea to try to keep a machine in the air using highly flammable gas.
Re:Use hydrogen. (Score:5, Funny)
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Not to mention the detail where jet fuel, whether burning, exploding, or miraculously transforming into wine, is stored in the airplane's wings which are holding the damned airplane up. If the jet fuel catches fire, the plane's going down. Period.
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Re:Use hydrogen. (Score:4, Informative)
Gasoline burns, hydrogen explodes
No, both burn and either will explode if ignited in an encloded space, just like gunpowder. Take a firecracker and empty the powder out and light it it will simply burn.
Hell, I made the "scientific discovery" that hydrogen burns and not explodes in the seventh grade. [slashdot.org][journal] Where did you get the idea that hydrogen explodes? Mythbusters tanked that one, too.
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Gasoline burns hotter than hydrogen, but thanks to the Hindenburg crash video, we don't have hydrogen cars either.
Actually, no. Storing hydrogen at the 10ksi needed to make it volumetrically competitive with modern battery technology makes it very dangerous.
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I'm planning on floating in circles over the lake at a few hundred feet.
That would make for some awesome fishing.
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The most common RPG, the RPG-7, firing the most common round would automatically detonate at around 2700 ft.
The Stinger would barely make 15,000 ft.
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A few relevant points:
- 20,000 feet is nearly 4 miles. You'd have to have a half-assed tracking system on a half-decent missile system to hit a target 4 miles straight up. An actual rocket-propelled grenade ain't gonna cut it. I'm not saying the tech isn't available, and I'm sure there are shoulder-mounted SAMs that can handle it, and I don't doubt that some insurgent groups might get access to them, but it's not what you can pick up at a Soviet Military Surplus store.
- If you hit anythin