Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Hydrogen-Powered Aircraft == Anti-Terrorist Device?

Cliff posted about 13 years ago | from the safer-usually-means-better dept.

News 701

maladroit asks: "Today on NPR's Talk of the Nation/Science Friday , Harry Braun of the Phoenix Project said that a hydrogen-powered airplane would not have produced the fire and intense heat that brought down the World Trade Center towers. Is this true ? What are the other advantages and disadvantages of hydrogen fuel ? Details on the Phoenix Project's website are a bit sketchy, but I'm sure the Slashdot crowd has some answers (and Richard Dean Anderson jokes)." Sounds like a good theory, it doesn't account for the hostage aspect, but it would prevent the use of aircraft as cheap bombs. Would there be any drawbacks? How much would such a refit cost for your average commercial aircraft?

Sorry! There are no comments related to the filter you selected.

My Experience With Linux!!! (-1)

egg troll (515396) | about 13 years ago | (#2384229)

I work as a consultant for several fortune 500 companies, and I think I can shed a little light on the climate of the open source community at the moment. I believe that part of the reason that open source based startups are failing left and right is not an issue of marketing as it's commonly believed but more of an issue of the underlying technology.

I know that that's a strong statement to make, but I have evidence to back it up! At one of the major corps(5000+ employees) that I consult for, we wanted to integrate Linux into our server pool. The allure of not having to pay any restrictive licensing fees was too great to ignore. I reccomended the installation of several boxes running the new 2.4.9 kernel, and my hopes were high that it would perform up to snuff with the Windows 2k boxes which were(and still are!) doing an AMAZING job at their respective tasks of serving HTTP requests, DNS, and fileserving.

I consider myself to be very technically inclined having programmed in VB for the last 8 years doing kernel level programming. I don't believe in C programming because contrary to popular belief, VB can go just as low level as C and the newest VB compiler generates code that's every bit as fast. I took it upon myself to configure the system from scratch and even used an optimised version of gcc 3.1 to increase the execution speed of the binaries. I integrated the 3 machines I had configured into the server pool, and I'd have to say the results were less than impressive... We all know that linux isn't even close to being ready for the desktop, but I had heard that it was supposed to perform decently as a "server" based operating system. The 3 machines all went into swap immediately, and it was obvious that they weren't going to be able to handle the load in this "enterprise" environment. After running for less than 24 hours, 2 of them had experienced kernel panics caused by Bind and Apache crashing! Granted, Apache is a volunteer based project written by weekend hackers in their spare time while Microsft's IIS has an actual professional full fledged development team devoted to it. Not to mention the fact that the Linux kernel itself lacks any support for any type of journaled filesystem, memory protection, SMP support, etc, but I thought that since Linux is based on such "old" technology that it would run with some level of stability. After several days of this type of behaviour, we decided to reinstall windows 2k on the boxes to make sure it wasn't a hardware problem that was causing things to go wrong. The machines instantly shaped up and were seamlessly reintegrated into the server pool with just one Win2K machine doing more work than all 3 of the Linux boxes.

Needless to say, I won't be reccomending Linux/FSF to anymore of my clients. I'm dissappointed that they won't be able to leverege the free cost of Linux to their advantage, but in this case I suppose the old adage stands true that, "you get what you pay for." I would have also liked to have access to the source code of the applications that we're running on our mission critical systems; however, from the looks of it, the Microsoft "shared source" program seems to offer all of the same freedoms as the GPL.

As things stand now, I can understand using Linux in academia to compile simple "Hello World" style programs and learn C programming, but I'm afraid that for anything more than a hobby OS, Windows 98/NT/2K are your only choices.

thank you.

Re:My Experience With Linux!!! (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384304)

I'm amazed at the effort you put into that. There aren't any true statements in there, but I'm really impressed. Good work, Egg Troll.

Re:My Experience With Linux!!! (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384418)

mr egg troll are you bob abooey in disguise?

Hindenburg (1, Funny)

agrounds (227704) | about 13 years ago | (#2384233)

yeah, hydrogen-filled aircraft have proven so safe in the past...

Re:Hindenburg (0)

Anonymous Coward | about 13 years ago | (#2384251)

As I remember, they have credited the fire of the Hindenburg not to the fuel as much as to the flammable material used to build the baloon.

actually, you're right. (5, Informative)

Wakko Warner (324) | about 13 years ago | (#2384267)

The Hindenburg's problem wasn't that it was full of hydrogen; it's the fabric the outer covering was made of [ttcorp.com] that did it in.

Please read up on these things before spouting retardedness.

- A.P.

Wrong! (-1)

egg troll (515396) | about 13 years ago | (#2384273)

The Hidenburg's problem was that it was powered by a weak and ineffective Open Source OS. Had it been run by Windows, or even the MacOS it would not have crashed. But thats what you get for trusting something to a project written by hobbyists in their spare time.

Re:Wrong! (0)

Anonymous Coward | about 13 years ago | (#2384326)

You trolls just don't stop, do you? Even if the story's not vaguely open source related you try...

Re:Wrong! (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384350)

Why stop?

oh right (0)

ArchieBunker (132337) | about 13 years ago | (#2384433)

Like hydrogen isn't flammable? Gimme a break.

Re:Hindenburg (1)

alnapp (321260) | about 13 years ago | (#2384289)

;-)

But, seriously, Hydrogen fuelled as opposed to filled, would, I suspect be safer than the Hindenburg & normal avialtion fuel.
However, if it would have caused less damage at the WTC is debateable as I belive the explosion only had to weaken the metal substructure for the buildings to fall, and a large aircraft is still a large aircraft, whateer its fuelled by.

Re:Hindenburg (3, Insightful)

Jburkholder (28127) | about 13 years ago | (#2384357)

> belive the explosion only had to weaken the metal substructure for the buildings to fall

Nope. The intense heat of the burning jet fuel weakening the structural steel is what supposedly caused the buildings to ultimately collapse.

The structure was designed to withstand temperatures of a 'normal' fire for something like two hours. The intense heat of the burning jet fuel caused the steel girders to weaken and collapse in much less time.

But think about it. If the impact of the planes were enough to bring down the towers, shouldn't they have toppled over right away?

Re:Hindenburg (0, Redundant)

chporter (173609) | about 13 years ago | (#2384407)

The reason the WTC collapsed was not because the crash weakened the structure. The planes were full of jet fuel for the trips across the country. (This is said to be part of the terrorist plan.) The high-temperature of the burning jet fuel compromised the structural integrity of the steel, which is why the building collapsed. If the jets were relatively empty, like they would be on a trip from Boston to NY the fires would not have lasted as long and the building would probably still be standing. The WTC towers were designed to withstand impacts from large aircraft (707? 727?) and the steel was designed to withstand heat for prolonged periods of time.

The hydrogen fuel would not burn as hot and also would evaporate very quickly.

Re:Hindenburg (0)

Anonymous Coward | about 13 years ago | (#2384408)

Huh? Most reports say that it was the fire, not the impact or explosion, that caused the collapse.

Re:Hindenburg (1)

n3bulous (72591) | about 13 years ago | (#2384445)

What news source have you been watching? I think every major (US) station reported that the buildings collapsed because of the intense heat generated by the jet fuel fire. Since the structural integrity of steel starts to disappear around 7k F (though I heard 3 or 4 different temps tossed around), the towers collapsed under the weight of the above floors.

Because each floor could only support maybe 2 floors of weight (w/o additional support, i.e. floor A supports B, B supports C, but if B doesn't support C, then A has to directly support B and C), the building collapsed. This is how they intentionally collapse buildings so they fall straight down.

If you take out the base, they fall over as if you were cutting down a tree. The base is so reinforced that you need a really big problem down there to knock it over, which is why the WTC bombing failed.

Source: ABCNews and some architect/structural engineer giving a statement about an hour after the WTC collapsed.

Re:Hindenburg (3, Informative)

pjt48108 (321212) | about 13 years ago | (#2384318)

Actually, the Hindenburg burned due to a special treatment applied to the canvas, which made it highly flammable. Add to that the diesel fuel for the engines, and your real culprit is > dead dinosaurs, aka fossil fuel. According to reports I have read, hydrogen will, essentially, evaporate and disperse immediately, since it is the lightest element in the whole big Universe.

FFJKPP (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384238)

Foist Fire Jon Katz Petition [petitiononline.com] Poist!


Stupid Lamness Filter.

Oh, the humanity! (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384253)

Somehow I don't think the poster means Zeppelin NT...

Remember the Hindenburg? (0, Redundant)

jvv62 (236967) | about 13 years ago | (#2384254)

I think you still have problems with a big explosion. What you probably won't get is a long burning hot fire. The explosive tendency of hydrogen gas is one of the reasons that you haven't seen those super clean burning fuel cells in standard passenger cars yet.

Hindenburg (1)

bIOHZRd (196012) | about 13 years ago | (#2384258)

Or however its spelled... this would be IMO at least twice as powerful a burst.. since they would probably use compressed H2, meaning more H2 in there, meaning more fuel for an explosion. just my .02

Re:Hindenburg (2)

MagikSlinger (259969) | about 13 years ago | (#2384430)

You are right, but not because of the Hindenberg. As others have pointed out, the Hindenberg was destroyed by something else. You also seem to have this strange notion that commercial jet fuel (kerosene basically) is safe. In a crash, I'd rather be in a hydrogen powered plane than a jet fueled one: I'd probably survive. Hydrogen burns up, jet fuel splatters and sprays and burns on the ground. In a crash, the hydrogen would vaporize into a gas (absorbing a fair bit of heat in the process thus cooling the airframe and reducing explosion risk) and float up. If it ignites, it's going to be doing it above your head.

But to your principle point, at least twice as powerful, you are right but not because jet fuel is safer. The hydrogen-oxygen combination is the second most powerful rocket fuel known to science. Per kg, hydrogen burns way more energetically and more effeciently than jet fuel. The only problem is getting enough hydrogen in the plane: you'd have to use cryogenic hydrogen. Then the fuel tanks would have to become giant thermos bottles which ups the weight of the plane and you pretty much loose the advantages of hydrogen.

Hydrogen is safer than gasoline and all those other liquid fuels. It burns more efficiently with a greater conversion into mechanical energy. The only problem we face is how to store it without adding an extra hundred pounds or more to our fuel tanks.

Hydrogen Fuel? (0, Troll)

Gryffin (86893) | about 13 years ago | (#2384260)

Hydrogen as safe alternative fuel... Um... Hindenburg, anyone? =:{o

No, it wouldn't burn for a sustained time, like jet fuel did, but it would burn even more violently, hence causing more initial injuries.

In fact, a more violent explosion mith have collapsed the towers right away, and those 10,000 or so folk wouldn't have had the chance to escape like they did.

Then there's the issue of storage... wouldn't high-pressure crtyogenic fuel tanks be prohibitively heavy for an aircraft?

Re:Hydrogen Fuel? (1)

hnsn (243874) | about 13 years ago | (#2384328)

And you would get planes exploding every day from all kinds of small mishaps.

Re:Hydrogen Fuel? (2)

BinxBolling (121740) | about 13 years ago | (#2384399)

Hydrogen as safe alternative fuel... Um... Hindenburg, anyone? =:{o

The Hindenburg disaster was not caused by the use of hydrogen [ucla.edu] , but rather by the material used on the skin of the zeppelin.

New anti-terroristic way of travel! (1)

FortKnox (169099) | about 13 years ago | (#2384262)

Its called "Walking". There is no possible way you can take down buildings with this new form of travel.

It bugs me that people think up of "anti-terrorist" this-or-that. First think of what it'll cost to change the world over to your "new idea", then think how realistic it is.

BTW - what's up with the new "technology" picture. New motherboard?

Re:New anti-terroristic way of travel! (0)

Anonymous Coward | about 13 years ago | (#2384391)

ooohhh! What a good idea! Say, I have to go to LA from Boston next week. Better start walking now eh?

Re:New anti-terroristic way of travel! (3, Interesting)

jiheison (468171) | about 13 years ago | (#2384415)

Its called "Walking". There is no possible way you can take down buildings with this new form of travel.

What if you are carrying luggage packed with C4? Or one of these "suitcase nukes" that I keep hearing about?

If these attacks had taken place at street level, even more people would have died.

Bagel ready! Smoked Nova Salmon Pieces (-1, Offtopic)

Anonymous Coward | about 13 years ago | (#2384263)

Trader Joe's Nova Salmon Pieces are made with farm-raised Atlantic salmon. We worked with one of the premier smoked salmon processors to supply this treat. The salmon has been air-dried, smoked and cured in the finest European tradition. It's packed under kosher supervision and contains no artificial colors or flavors and no preservatives.

It's not only the fuel (4, Insightful)

Red Aardvark House (523181) | about 13 years ago | (#2384266)

The fuel made the explosion worse, but anything the size of an airplane hitting a building at 350+ MPH will do some serious damage.

Electrical fires can still result from such an impact.

Jet Fuel (1)

Mateorabi (108522) | about 13 years ago | (#2384344)

But it was the fuel. Jet fuel burns hotter than most combustable materials. So hot infact that it caused the mettal supports to eventualy melt/soften and buckle. Hydrogen would give a quick but relatively colder boom and disipate. Some floors would be lost, but structural integrity would remain.

Of course imagine if Hindenberg had been piloted into a crowded stadium, etc. People are not built of steel.

Re:Jet Fuel (3, Informative)

ScumBiker (64143) | about 13 years ago | (#2384428)

Bullshit. Jet fuel is simply slightly better refined kerosene, basically diesel. High flash point, relatively cool burning. It's about like charcoal lighter fluid, doesn't go poof!

Why do I know? I'm a general aviation pilot. As such, I'm pretty close to jets frequently, and I've asked the fueler monkeys.

On to the topic. I'm not sure why hydrogen isn't used for jets, other than the fact that it's a bitch to store and transport. I'd think it'd be an ideal fuel for just about everything, since in it's pure form the only burn by-product is water.

BTW, the Hindenberg got smoked mainly because of the aluminum-oxide paint on it's exterior surfaces. Think solid fuel rocket.

Re:It's not only the fuel (2, Interesting)

Anonymous Coward | about 13 years ago | (#2384355)

It's not the size, it's the mass that counts. Airplanes are not very massive for their size. Truth be told, both WTC 1 and WTC 2 survived the impact. It was the fire that weakened the steel. Had there been no fire, there would have only been a couple hundred killed.

Note: part of the reason the fire at WTC was so devistating was that the do-gooder environmentalist whackos stopped the use of asbestos from being used to fireproof the steel columns which supported the structure. The building's chief design engineer is on record as saying that any large fire above the 70th floor would cause failure of the structure due to pancaking caused by lack of adequate fireproofing on the support columns. He said this before the building was ever occupied.

SURVEY!!! (0)

TRoLLaXoR (181585) | about 13 years ago | (#2384270)

OK

WHat do you people wanna see? Here's your options... I hae a few things written, which would you like to see?

1) a story about Emad's orgiastic party with Malda
2) a story about Cyan, a selfish, mentally unstable art-person who keeps a (public) private web journal
3) an update on why Kansas City is gay

Please reply to this with the number of your choice.

1-2-3 (-1)

TrollMan 5000 (454685) | about 13 years ago | (#2384282)

How 'bout all three?

Um...the what was that Zepplin? (0, Troll)

Thomas M Hughes (463951) | about 13 years ago | (#2384271)

Am I the only one who remembers why they stopped building hydrogen blimps? You know that problem with them being _highly explosive_?

Sure, you'd avoid the problem of burning jet fuel after the crash, but wouldn't having a compressed and concentrated supply of hydrogen on board equate to a bigger boom from the start?

Hydrogen burns (1)

wiredog (43288) | about 13 years ago | (#2384276)

Albeit at a lower temp than avgas. Remember the Hindenburg? Goes "boom" pretty well, too.

Re:Hydrogen burns (4, Redundant)

Seanasy (21730) | about 13 years ago | (#2384406)

It wasn't hydrogen burning.
From the DOE H2 [doe.gov] website:


Did hydrogen cause the Hindenberg to blow up?

No. A recent study [ttcorp.com] of the accident implicates the paint used on the skin of the airship, which contained the same component as rocket fuel.

Re:Hydrogen burns (2, Informative)

drinkypoo (153816) | about 13 years ago | (#2384438)

The paint on the skin of the aircraft was most likely ignited by a static discharge (According to eyewitness accounts) but the hydrogen contributed to the burning. If they hadn't painted the ship with some volatile paint, however, it would likely never have caught fire in the first place.

Cost Effective (1)

roche (135922) | about 13 years ago | (#2384280)

The airlines are already loosing millions, and now they would have to spend billions to replace or modify the planes to use hydrogen as a fuel. That would surely drive the airlines out of buisness.

Less Boom, Yes, but Safer? (1, Insightful)

ptgThug (515679) | about 13 years ago | (#2384285)

The hydrogen fuel cells would have less boom because the hydrogen wouldn't be liberated until needed. The Hindenburg carried hydrogen. These fuel cells will carry water or hydrocarbons. They will split the hydrogen out as it is needed.

But... I would imagine a full size jet liner weighing how many tons dry, would still be enough of an impact at over 400 mph to bring down the WTC.

Re:Less Boom, Yes, but Safer? (3, Informative)

night_flyer (453866) | about 13 years ago | (#2384330)

The "Impact did not bring down the WTC, the super heating of the steel infrastucture did

each "cube" of the building was designed to withstand a certain amount of pressure, when the ones that were superheated colapsed, it increased the pressure on the lower cubes that they could not handle it, thus they collapsed, thats why the building fell straight down and not fall over when the plane hit

Re:Less Boom, Yes, but Safer? (1)

ptgThug (515679) | about 13 years ago | (#2384367)

The building, like most big buildings, is designed to not fall over sideways. The moment of inertia for that would be impressive to overcome.

If the fire really caused the building to collapse, then this building couldn't withstand a fire without the collision, and that needs to be addressed.

Re:Less Boom, Yes, but Safer? (1)

night_flyer (453866) | about 13 years ago | (#2384389)

just what kind of fire do you think would be equivilent to a jet fuel fire form an almost fully fueled 757 on a cross country flight?

Re:Less Boom, Yes, but Safer? (0)

Anonymous Coward | about 13 years ago | (#2384358)

Considering the final product of a hydrogen fuel cell is water, you'd be suffering a net energy loss if you carried the hydrogen as water, liberated it from the oxygen to produce H2, then recombined it with oxygen to produce water again.

Re:Less Boom, Yes, but Safer? (1)

palutke (58340) | about 13 years ago | (#2384365)

Water is too heavy. You might as well suggest lead-acid batteries.

Hydrocarbons? Maybe, but I'm skeptical.

Re:Less Boom, Yes, but Safer? (1)

afay (301708) | about 13 years ago | (#2384382)

Actually, yes the WTC towers could and did withstand the impact of two full size jet liners. I read a while ago (sorry no link) that they were designed to withstand a direct impact from a 747. In that respect, they were designed and built well. What the designers didn't take into account was the temperature and which jet fuel burns and what that would do to the steel support beams. From what I understand, hydrogen burns but at a lower temperature, so new planes that ran off hydrogen probably wouldn't have caused the collapse of the towers.

Re:Less Boom, Yes, but Safer? (1)

Pravada (217899) | about 13 years ago | (#2384440)

One of my teachers worked for the structural engineer who built the WTC. They were constructed to withstand the impact of a 707 (the largest airplane at the time of their design, about the size of a 737). The 747 is quite a bit bigger than the 767s that actually hit it, *and* has bigger fuel tanks.

Re:Less Boom, Yes, but Safer? (1)

Coniine (524342) | about 13 years ago | (#2384409)

I think you're missing something : the likelihood of powering passenger aircraft with H2 Fuel cells is about, approximately, roughly...nil. Hydrogen as a fuel? Sure for a turbine engine. Fuel storage? Highly compressed gas? Maybe. Cryogenic Liquid? More likely. As metallic hydrides? Not Sure, sounds heavy. I think that a cryogenic liquid H2 fuel would have lowered the temperatures reached inside the structures, maybe avoiding the collapses. Is it "safe" or even desirable? Probably not.

Re:Less Boom, Yes, but Safer? (1)

ptgThug (515679) | about 13 years ago | (#2384416)

Okay, as someone has said in another threadlet, a designer of the buildings disliked the lack of fireproofing and said that any fire above the 70th floor would collapse the building. *shrug*

Water may be too heavy. That explains why the automanufacturers are not releasing there water based fuel cells. I thought it was so the petro companies could still sell gasoline. :)

But point is, the fuel cells will not be like the Hindenburg. They will not carry LOH like the shuttle either.

Re:Less Boom, Yes, but Safer? (2)

gorilla (36491) | about 13 years ago | (#2384434)

These fuel cells will carry water or hydrocarbons. They will split the hydrogen out as it is needed.

No they won't. It would take exactly the same amount of energy to split out the hydrogen as you would get back in recombining it in a fuel cell. When you consider the unavoidable efficency losses, that means you're behind.

Re:Less Boom, Yes, but Safer? (1)

diadem (464192) | about 13 years ago | (#2384439)

The WTC was built to withstand the impact, and it did. It was the intense heat from the fires that brought it down, NOT the impact.

However, I do agree with your point - I am more of "find the cure" than "supress the symptoms" kind of guy. I would rather time and money be invested in direct security measures, such as guards on flights and giving pilots tazers.

Well... (1)

steveo777 (183629) | about 13 years ago | (#2384288)

I'm no expert, but I have messed around with burning hydrogen before, and even though it doesn't burn as hot as jet fuel (propane, right?), it does have other problems. Considering that it would be in liquid form in the cells, when/if one broke open, the hydrogen would expand so fast that all the oxygen in the imediate area would be gone. Not to mention a MUCH more forcefull explosion.
It just seems to me that the initial explosion would put out a greater shockwave and deal more destruction.
This knowledge comes from my childhood experiance of taking slightly compressed hydrogen/oxygen and using it to propell potateos. It always went farther than anything else I used (propane, gas fumes, ether, etc.). Just my one and two-thirds cents.

It does have good points. (5, Informative)

cryptochrome (303529) | about 13 years ago | (#2384294)

Well at the very least, hydrogen is a renewable intermediate energy source, unlike the oil used to formulate AvGas these days. And presumably it would be less polluting as well. Both excellent reasons for gradually making the switch, but I don't really see how it would make a plane less of a bomb. The synopsis claims it's safer in an auto crash (presumably because it disperses rapidly), but would that necessarily apply to an airplane? Sure, it wouldn't have burned in the WTC as long, and possibly not as hot, but H2 being a gas wouldn't it have been more explosive?

Why stop there? Bring back blimps. (5, Funny)

torpor (458) | about 13 years ago | (#2384295)

Whoa, someone's trying to crash a blimp into the Sears tower!

*BOOOOIIIINNNGGGGGG*

Well, there he goes again...

*BBBBOOOOIIIINNGGGG*

And again ... Sheesh. This is getting boring.

Change the channel.

Umm ... hydrogen ... blimp ... Hindenburg ... (1, Insightful)

taniwha (70410) | about 13 years ago | (#2384411)

the imagery is a little too scary .....

low energy density (5, Interesting)

mr.ska (208224) | about 13 years ago | (#2384297)

Yes, hydrogen-powered aircraft won't be a terrorist threat. As soon as they're off the ground, they'll need to land for refuelling.

It's the same reason why automotive engineers are having such a big problem getting hydrogen-powered cars economically feasible (apart from the storage problem). Compared to gasoline, hydrogen has an abominally low energy density. What does that mean? To get the same amount of energy on-board, you'd need to carry many times the amount of gas in hydrogen. That means either HUGE fuel tanks, or severely curtailed range. Not being an aerospatial engineer, I can't comment about the former, but the latter just won't fly (pardon the pun) with commercial carriers. "Yes, we can get you from New York to Los Angeles. You have seven brief layovers for refuelling..."

Interesting idea, but not practical. If you're still worried about planes flying into buildings (it's been used once, if they're smart they'll now switch tactics) maybe installing fire-suppressing foam (like the systems they have in McDonalds' in the kitchen) on tall buildings to smother any high-temperature fires that break out.

A simpler method may be simply to install nose radar in *all* sizable airplanes, and automatically engage the autopilot when flying within 1000m of an object (building, mountain, etc.) to avoid it. We have the technology, folks.

Re:low energy density (0)

Anonymous Coward | about 13 years ago | (#2384360)

there was an early airbus that attempted to use such "fly by wire" technology. In a demonstration of the plane, the airbus pilot buzzed the crowd of people gathered to look at the new plane. The plane then decided that it was supposed to land and crashed into the runway. Removing the pilot's control of a plane in any case is a pretty dumb idea; furthermore, it has been done to death in the past.

Re:low energy density (1, Informative)

Anonymous Coward | about 13 years ago | (#2384447)

Just to clarify, hydrogen has a high energy density by weight (doesn't have all those pesky oxygen and carbon atoms found in other hydrocarbon fuels), but has a low energy density by volume.

Hydrogen is a high-energy-density fuel.. (4, Insightful)

astroboy (1125) | about 13 years ago | (#2384298)

And like all fuels, is highly reactive. It's main safety advantage over hydrocarbons is that, since hydrogen really wants to be a gas at STP, it won't `pool' like oil would if you were to spill it. This means, given a spill, a lot of it would just waft away rather than their being a contained region of fuel to catch fire.

This is good news, to be sure, but a plane crash is clearly not the same as an oil spill. How the burning would proceed would depend completely on how the fuel was contained in the plane, and what happened to the containment. Clearly, it has the potential to burn just as hot as hydrocarbons -- it has to contain the same amount of energy as the jet fuel, 'cuz the plane still has to fly.

Since, as far as I know, no one is even remotely close to building plane-engine-type hydrogen-powered engines (fuel cells are about as close as its gotten) discussion about relative safety is all going to be wild speculation.

Hydrogen: Pros and Cons (5, Informative)

franknagy (56133) | about 13 years ago | (#2384299)

Hydrogen burns very hot but (1) it requires mixing with considerable air to produce an explosion and (2) being very light it tends
to burn "up", i.e. to rise. The plane would be
fueled with liquid hydrogen at 20 degrees K
(only Helium liquifies at a lower temperature) and would evaporate quickly into a gas. Unlike the current JPx fuels, the hydrogen disipates rapidly and would stick to stuff and burn. The hydrogen would burn and disipate rapidly and
leave behind only those pre-existing materials which have been ignited.

One problem is that even liquid hydrogen is very light (very low density) and so requires very large tankage. The Shuttle's external fuel tank is mostly a hydrogen tank (something like 80% of the volume?) with a surprisingly small liquid
oxygen tank at the top. I have seen a liquid hydrogen bubble chamber being filled and marveled at the droplets of liquid hydrogen entering the chamber and just floating down (drifting really, not falling like water droplets do).

Re:Hydrogen: Pros and Cons (1)

JeffRC (103922) | about 13 years ago | (#2384422)

Actually the volume is more like 70%, but thats consistent with the lower density and the fact that it takes twice as much hydrogen as oxygen by volume to make the engine run (H2O being the final product). Mass wise its a different story. There is eight times more oxygen than hydrogen by mass, which is why hybrid air breathing rocket engines such as scramjets are interesting for space launch. Also the energy density of a hydrogen tank depends on how much structure (and mass) your willing to commit to in order to increase the tank pressure.

just floating down (3, Insightful)

wiredog (43288) | about 13 years ago | (#2384427)

Huh? Wouldn't H and H20 fall at the same rate? Or is the chamber not evacuated? Or do I need more coffee before posting?

Hydrogen airplanes (1)

i_am_nitrogen (524475) | about 13 years ago | (#2384305)

While hydrogen would burn with less heat and not as long, an explosion in a collision would seem to be much bigger, causing more immediate damage to the target. I don't think that the WTC towers were levelled by a big roaring fire, but by the damage done to the building immediately upon impact -- the top 20 or so floors eventually caused the damaged floors to collapse, and the force of that falling debris caused the rest of the buildings to disintegrate, perhaps by design.

Re:Hydrogen airplanes (1)

drodver (410899) | about 13 years ago | (#2384397)

Wrong! If the planes had been empty of fuel the buildings wouldn't have come down. The designer and other structural engineers have said this many times. They came down because the jet fuel fueled fire weakened the steel beams until they couldn't hold the weight of the floors above. Also, why would the rest of the building be designed to disintegrate? That would serve no purpose.

Hello Challenger? (1)

Neil Watson (60859) | about 13 years ago | (#2384308)

Are we forgetting the huge explosion that consumed the heat shielded Challenger?

How about the way the Hindenburg's superstructure collapsed in the heat of the fire?

Energy distribution would be different (1)

JeffRC (103922) | about 13 years ago | (#2384309)

While the fire was the key to weakening the central core of the towers and hence the collapse, I'm not sure hydrogen would make it safer. The energy required from a hydrogen fueled aircraft for transcontinental flight would be the same as standard jet fuel. On impact the entire hydrogen fuel supply would detonate as opposed to only a fraction as in jet fuel. While there would not be a long sustained fire to weaken the structure, the initial energy release might be strong enough to cause immediate collapse versus what actually happened. In which case, over 30,000 people could have died instead of 5,200.

Similar ideas have already been rejected. (1)

atheos (192468) | about 13 years ago | (#2384310)

I remember watching a television program a few years ago suggesting a safer tank for Airliners, that prevent the fuel from burning on impact.

I don't remember the specifics, but I believe that there was either an exterior tank that had a foam substance inside the inner wall, or some kind of a fuel additive to prevent combustion on exposure. I think I remember the airliners rejecting the proposal due to it being too expensive or something. Here's a CNN article on the same lines.

[cnn.com]

I don't know if this idea would have any effect on an airliner filled with fuel from combusting on impact.

Re:Similar ideas have already been rejected. (1)

atheos (192468) | about 13 years ago | (#2384337)

my html sucks.
here is the link again.
www.cnn.com/US/9712/12/twa.hearings [cnn.com]

What, are you crazy??? (0)

Anonymous Coward | about 13 years ago | (#2384311)

So instead of having terrorists flying around in giant fuel-air bombs, they can now be flying around in hydrogen bombs!

Shut up about the Hindenburg and read this! (0)

Anonymous Coward | about 13 years ago | (#2384312)

Here. [ttcorp.com]

the morons are out in droves today...

In the words of Jimmy Page... (1, Offtopic)

sulli (195030) | about 13 years ago | (#2384314)

that would go over like a lead zeppelin

Re:In the words of Jimmy Page... (1)

Reality Master 101 (179095) | about 13 years ago | (#2384375)

Rock and roll trivia: That was actually said by The Who's Keith Moon, and Led Zeppelin decided they liked the name.

Liquid Hydrogen no safer than Jet Fuel (1, Insightful)

niteshad (118441) | about 13 years ago | (#2384315)

After reading on the Phoenix Project website that they plan to use liquid hydrogen (as opposed to hydrogen fuel cells) their claim of increased safety lacks merit. We have only to look at the Challenger catastrophe to realize that liquid hydrogen is an extremely volatile and flammable element. Substituting one highly flammable fuel for another does not increase safety.


No idea what they're talking about (5, Interesting)

jridley (9305) | about 13 years ago | (#2384322)

Point one: don't bring up the Hindenburg unless you know what you're talking about. The Hindenburg disaster was NOT initiated by a hydrogen explosion, it was improper maintenance and a highly flammable skin. In reality hydrogen *is* safer than liquid fuels. Think about it, if you were trapped in a wrecked car, would you rather have hydrogen leaking 10 feet from your head, or gasoline? Keep in mind that pure hydrogen in a tank can not explode, there's no oxygen. I'll take hydrogen any day.

Point two: Hydrogen is NOWHERE NEAR dense enough to use as an airliner fuel. You'd need all the room in the entire ship including the cabin taken up with hydrogen tanks, and then some, in order to fly cross country.

Hydrogen is infeasible (0)

Anonymous Coward | about 13 years ago | (#2384323)

Having seen studies on hydrogen for use as an automotive fuel, there are several big problems:

1) procurement - hydrogen is usually obtained through either electrolysis or from refined fossil fuel. Electrolysis is too costly - it requires as much energy to create the hydrogen as it provides when burned.

2) energy density - hydrogen goes into liquid phase at 4 degrees kelvin. therefore, it cannot provide the energy per unit volume that a liquid fuel can without an obscenely strong pressure vessel.
If it was better, it would have been used already.

--Lael
(at lael (dot mit edu))

"Not fighting the last battle" (1, Insightful)

Anonymous Coward | about 13 years ago | (#2384324)

It's doubtfull the same kind of attack will occur again. Now that its happened we will probably prevent it (as it is somthing preventable).

We should stop worrying about planes so much, and start focusing on other possibilites.

However much you might not like terrorists, you ought realize not all of them are stupid, and they won't strike twice in the same way.

Well, ONE problem (5, Informative)

NMerriam (15122) | about 13 years ago | (#2384332)

This might prevent some of what happened on the 11th, but you still have the kinetic energy of a 200-ton plane with 60,000 lbs of thrust hitting the target at 500 mph.

It wasn't the jet fuel that rammed the plane all the way THROUGH tower two on live TV. It might not have burned hot enough to cause the tower collapses, but having hydrogen fuel wouldn't have made the planes bounce off the towers, either...

It's not the fuel stupid. (-1)

www.sorehands.com (142825) | about 13 years ago | (#2384334)

Sure the jet fuel cause some people more problems, but the issue is a big jet hitting a big building very hard!


Look at an meteor hittting the earth. The impact and results of the impact that causes the damage, no fuel.


Maybe you want lots of fuel in the jet, then the pilot can self-destruct the plane before impact. This is not going to be the next terrorist attack vector. They will try another means to cause destruction and terror.

This wouldn't really help . . . (1)

palutke (58340) | about 13 years ago | (#2384341)

A 400,000-pound aircraft traveling at 500+ MPH will do a lot of damage, whatever it's fueled by.

Also, it would require roughly the same amount of potential energy in your gas tank to get from coast-to-coast, whether your burning jet fuel, hydrogen, coal, or anything else, so the amount of potential energy the plane has when hitting the building isn't going to change much.

I agree with the previous posters that compressed hydrogen would probably explode much more violently, but have a much shorter duration. Pick your poison . . .

K.E. = .5 * m * v * v (again) (5, Insightful)

TrumpetPower! (190615) | about 13 years ago | (#2384345)

...but it would prevent the use of aircraft as cheap bombs.

I wrote about this [slashdot.org] the day after the attack:

Something I just thought of a little while ago, to help me gain some perspective on what happened:

A Boeing 767-400ER [boeing.com] [boeing.com] has a maximum takeoff mass of a shade more than 200,000 kg. It has a typical cruise speed of 840 km/h.

Using our favorite formula for kinetic energy, that comes to about 5.6 billion Joules, or between one and two tons of TNT.

Or, in other words, just the force of that much mass at that speed is about the same as a WWII blockbuster bomb. Add in some twenty thousand gallons of jet fuel...and I still can't wrap my mind around that much destructive force.

And I thought cars on the freeway were deadly!

May such magnificient machines never again be used for such awful, awful purpose.

b&

Just a Semi-educated Guess (1)

Coniine (524342) | about 13 years ago | (#2384346)

1) I think researchers have determined that the shell of the Hindeburg was to blame for the disaster, not the H2.

2) If a hydrogen powered jet is practical I think it would have been less destructive than the deisel fueled ones that hit the WTC.

My reasoning is fairly straightforward :

A gaseous fuel would probably disperse much more rapidly and over a wider area than the deisel fuel did. We probably would have seen a much larger flame zone outside the builing as a result. Hydrogen flames would probably be less visible - more pale blue than orange and yellow.

I think the destructive force would have been less because less fuel would have remained in the building to burn and heat the structure. If I recall several experts have said that prolonged high temperatures weakened the steel in the buildings.

So ... the fire and explosions would have been extreme but probably not as long-lasting. It still would have been a disaster just not a catastrophe.

Very true... (5, Insightful)

supabeast! (84658) | about 13 years ago | (#2384347)

A hydrogen powered plane's fuel tanks would have blown up all at once. The reason the WTC attacked worked is that airplane fuel is sticky and burns slowly when there are massive amounts of it, so it got all over the inside of the building and generated insane amounts of heat over time, starting other fires, etc. Hydrogen would have just blown up, with a small explosion and a lot of fire at impact, but little other damage.

Hydrogen is unlikely to be seen as a viable fuel, however, because for so many years it was believed that the Hindenburg was destroyed because of the hydrogen that held it aloft. Even now that the truth is known (The Hidenburg went down because the skin was painted with powdered aluminum, AKA rocket fuel, and when the mooring line grounded arcing electricity caught the aluminum on fire.), it is rarely spoken of because so many sources still quote hydrogen as the source of the explosion.

Challenger (5, Informative)

Artagel (114272) | about 13 years ago | (#2384348)

The space shuttle Challenger had a fair bit of hydrogen. It blew up just fine.

Now, as to continued flame, that's a different matter. It is unlikely that the hydrogen would act as an effective fuel to continue the fire for much after the initial impact.

The fundamental energetics of hydrogen combustion suck compared to fossil fuel combustion.

Hydrogen comes into its own more in the context of things like fuel cells. I don't think that the high demands of take-off powering would be well met by fuel cells. Cars can take longer to accelerate on a highway for instance with less loss of functionality. Either the airplane gets off the ground by the end of the runway, or it doesn't. The ability to abort a landing and lift off again is an important safety consideration.

The reason the site is short on details is that anyone who can make hydrogen work better than fossil fuels will make billions in the first year. It's a fantasy for anything but fringe applications. (Compare the Motorola fuel cell story today. Even that is methane-based, not hydrogen.)

Looks like our journalist at NPR had to fill a slot by deadline and went with what he could get to fill it.

He's got the "WHAT", he needs more "HOW". (1)

Snar Bloot (324250) | about 13 years ago | (#2384351)

I guess maybe if you bought the book or the video the author would go into more details as to how he would effect this massive change (I'm not just talking about the airplane fuel here). However, from reading the website mostly what I got out of it was he is pointing out all that is wrong with our sources of power today, and telling us where we should be, but he doesn't tell us how to get there.

Read the quote below, and then think...for something as important as the oblivion of humankind (his words), you'd think the book with the answers would be less than $28.

One thing is clear: humanity now stands at the threshold of the end of life as we know it, and given the exponential nature of the events now unfolding, the oblivion and/or utopia scenario will occur sooner than most people expect.

Hindenberg wasn't all hydrogen.. (0)

andylaurence (233927) | about 13 years ago | (#2384361)

I see all these comments about hindenberg, but I remember reading on /. earlier this week that hydrogen was not the cause. Aparrently, the skin was coated in rocket fuel (unknown to the makers). Besides, hydrogen does not burn with a big yellow flame, but hindenberg did.

I can't see hydrogen making much of a difference though. You still need the same amount of energy from the fuel, which will create just as much damage. I can't see any way that a building could survive an aircraft attack anyway.

The problem with the WTC was that the walls were the main structure. This meant that when the windows were all blown out, and the bulk of the wall was smashed it was only a matter of time. Mind you, even if the structure was inside, a plane travelling at 300+mph is going to have an effect anyway!

Bad idea.. (4, Interesting)

cmowire (254489) | about 13 years ago | (#2384366)

First, you would have a hard time refitting an existing aircraft to be hydrogen fueled. I'd rate it as impossible. You need fuel lines that can handle cryogenic temperatures. You need to replace the whole fuel-tank assembly. You need to replace the entire engine. Along with that, a lot of other systems and fluids will need to be changed.

The fuel tank sizes need to be changed. Hydrogen has a LOT of energy, but it's not especially dense.

You'd also have to change the current petrol-based fuel distribution system. Might I mention that, despite the Hindenberg disaster being more related to the design of the craft rather than the use of hydrogen, hydrogen is much less safe to deal with than petrol-based fuels.
Plus, there are exactly zero hydrogen fueled aircraft in existence. This is for a reason. During the cold war, some pretty intelligent folks tried to make it work, and failed.
It IS somewhat likely that hydrogen would avoid the exact circumstances that brought about the world trade center crash. But there are problems.

For one, the aircraft will have a nasty tendancy to explode. One of the reasons why the Chalenger disaster was so bad was because the entire hydrogen tank, filled with liquid hydrogen, evaporated very fscking fast, blowing the top and bottom off the tank and atomizing it. Then it burned very quickly.

Hydrogen is very light. So in the case of massive fuel leakage, most of the hydrogen would float upwards and leave the area relitively quickly. If you can keep it from forming a fuel-air-explosive.

I consider that more of a way for scientists to get more funding for hydrogen experiments than anything else. Sure it might be nicer if you crash into a building, but there's so many other things that can go horibly wrong. The only hydrogen powered craft in existence are rockets, which do not have anything CLOSE to an airliner level of reliability. There are not any production-grade hydrogen-powered jet engines.

the obvious answer (1)

chron (96048) | about 13 years ago | (#2384370)

I guess the whole idea of preventing airplanes from going into buildings in the first place is just too hard to handle so we gotta start thinking of how to build airplanes and buildings to handle such events.

for pete's sake just STOP THE AIRPLANES FROM CRASHING INTO A SKYSCRAPERS. end of story!

Hydrogen fuel (2)

Silver A (13776) | about 13 years ago | (#2384371)

Hydrogen has some drawbacks as a fuel, in general, though is also has some advantages. (I don't really understand them that well, but I do know they exist.) In terms of crashes, a hydrogen-fueled plane that crashed would explode all at once - once the fuel tank was ruptured, all the fuel would either burn quickly or blow away, rather than continue to provide fuel for the fire as avgas does.

A hydrogen fueled 747 crashing into the WTC would likely have caused a bigger explosion on impact, but the resulting fire wuoldn't have stayed so hot for so long - if the building didn't collapse right away, it may not have collapsed at all.

Well, of course... (0)

Kitanin (7884) | about 13 years ago | (#2384376)

Harry Braun of the Phoenix Project said that a hydrogen-powered airplane would not have produced the fire and intense heat that brought down the World Trade Center towers.

Well, that makes perfect sense. After all, hydrogen is a perfectly safe [nlhs.com] thing to put in a flying machine...

H2 Lighter than air (1)

mycr0ft (207814) | about 13 years ago | (#2384380)

Hydrogen, being a lighter than air fuel quickly disperses from the scene of the accident.

Why did the Hindenburg burn? Newer theory: It was made of highly flammable cloth and hit by lightning. See one description here [exn.ca] .
Don't use a tragedy from the 30s make us fear the fuel of this century.
--mycr0ft

Still a bad idea from possible tank eruptions (2)

Masem (1171) | about 13 years ago | (#2384383)

The problem with hydrogen is not so much the flammability (though that is an issue for automotive fuel cells), but the pressurization of the gas in order to have enough to fuel flight.

In a topic a while back, the idea that if you took a compressed cylinder of H2 to a field, and shot at it with a bullet, it would be unlikely that you'd cause the cylinder to explode; however, because of the rate at which that gas will escape, the cylinder will suddenly have a huge amount of kinetic energy in a random direction. If you ever saw the crap flick 'Chain Reaction', at one point Keanu axes off the top of a cylinder, using the reverse force to push a multi-ton slab of concrete away from his escape route. While that does approximate real life, typically a damaged cylinder can break through brick walls and do tremendous amounts of physical damage before it's exhausted. And this is the stuff that's common in most academic settings.

Imagine the amount of H2 gas you'd need to power a 747 from NY to LA. Sure, you can compress it to maintain the same volume, but the higher the amount of compression, the thicker you'd need to make the fuel storage, which means more mass to fly, which means more fuel in order to accelerate that mass. If you go too thin, then a small amount of wear can lead to gas vent; I very much doubt that a pilot would be able to steer a plane effectively if it was venting a large amount of expanding gas.

Project Phoenix??? (3, Funny)

kisrael (134664) | about 13 years ago | (#2384395)

Project Phoenix??? You would think they could choose a more reasuring name for hydrogen powered aircraft, given people's perceptions!

Of course, by now it's also [projectphoenix.com] a [hud.ac.uk] bit [wisc.edu] of [sbu.ac.uk] a [sloanweb.net] cliché [seti.org] ...

Highly Explosive as Gas, but gelled might work (1)

Krieger (7750) | about 13 years ago | (#2384396)

Because using highly explosive fuel is a much better idea. If stored properly (gelled) it is possible that hydorgen could be used safely, however the quantities that are needed would most likely be needed preclude that. Besides... Anyone remember the Hindenburg? Or rather I should say that compressed hydrogen would be bad....

Besides they don't necessarily need to switch to hydrogen, see the following http://trc.dfrc.nasa.gov/gallery/photo/CID/HTML/in dex.html [nasa.gov] , where they talk about using fire suppresants in the fuel to stop the fires after crashes...

See NASA for alternative fuels, for gelled hydrogen http://www.grc.nasa.gov/WWW/TU/launch/GELLED.htm [nasa.gov] .
Other alternative fuels are at http://www.lerc.nasa.gov/WWW/TU/launch/foctopsb.ht m [nasa.gov]

Mr Hydrogen, fix your HTML (1)

jdludlow (316515) | about 13 years ago | (#2384400)

OT - but annoying.

If by some miracle, the person in charge of that site is reading this, your HTML is hosed.

You close the freameset tag 5 times and noframes tag twice. Most of these are outside of your html tag.

The fun part is that you have all of your "Home" links pointing to /index.htm rather than /main.htm, so if you keep clicking the "Home" link it fills the screen with your navigation frame.

It's fun to play with, in a "wow someone actually got paid for this?" kind of way.

Dispelling a few misconceptions (5, Informative)

Steffan (126616) | about 13 years ago | (#2384401)

I've read a few things here which only help to spread the myths about hydrogen. Here are some of the common misconceptions and why they are untrue.

1. Hydrogen is extremely explosive - Hydrogen is not *extremely* explosive. It can be explosive, but it needs a certain amount of oxygen in order to explode.

2. The Hindenburg explosion was caused by the hydrogen. - It is widely believe that the explosion was caused by the flammable fabric covering of the ill-fated airship.

3. Myth#1 is why we don't have Hydrogen-powered cars - Actually, the biggest problem is that hydrogen is, for lack of a better term, sparse. (Opposite of dense). It's difficult to package a sufficient amount of it in a reasonable volume. There is ongoing work to change this by combining it / embedding it in other materials or packages, i.e. Carbon nanotubes.

4. Hydrogen is hazardous flammable substance - Because of its being the lightest (least dense) gas, a hydrogen fire will bascially burn in an upward direction. In addition, the gas will dissipate quite rapidly - imagine what would happen if you 'spilled' some Helium - it would just float straight up, even if it was on fire. Hydrogen does the same.

5. The fire was not a significant part of the tower collapse - While the kinetic energy of a fully loaded 757 / 767 cannot be ignored, if that was *all* there was, the towers would be standing today, and probably repairable as well. The collapse was caused by the extremely hot (1500+ degree) fires burning long enough to weaken the steel structure. The beams were rated for 1 hour of fire resistance. They held for at least that long, and then gave way, causing the 6 million lb. floor to fall and begin the domino effect.

EXPLOSION BUT NO FIRE (0)

Anonymous Coward | about 13 years ago | (#2384402)

A hydrogen powered aircraft would produce a large explosion, but the flames would be gone as soon as the explosion ended. There would be no fire that burned for days or hours or even minutes. Much safer and rescue crews could get to work immediately.

Ph.D., Physics.

Hydrogen safety (0)

msmikkol (155023) | about 13 years ago | (#2384414)

Hydrogen has high energy density vs. weight, but low energy density vs. volume. In addition, hydrogen is very light and does not accumulate easily. Being very light means that leaked hydrogen dilutes very quickly after an accident.

There is a very good article on automobile fuel safety at http://www.eren.doe.gov/hydrogen/. Check it out.

--
msm

Less fire more bang (1)

pizero (461424) | about 13 years ago | (#2384421)

The most powerful conventional bombs are called Fuel Air Explosives (FAE's). They work by allowing compressed volatile gas to expand and then igniting it. While the hydrogen wouldn't be left in pools to continue burning, it would cause a much larger explosion. If I recall correctly, FAE bombs have an explosive yield that is measured in kilo-tons of TNT.

Secret Weapon (1)

Shadowin (312793) | about 13 years ago | (#2384423)

Here [landoverbaptist.org] is the ultimate weapon on anti-terrorism.

-Shade

Retrofit cost not worth it (2)

Ars-Fartsica (166957) | about 13 years ago | (#2384446)

Retrofitting the thousands of commercial jets in use with new engines simply isn't practical.

As it stands, the terrorists have already blown their wad with reference to planes - they likely wouldn't use them in a subsequent attack - there are still plenty of transportation systems (land, sea) that are still wide open and completely insecure.

Load More Comments
Slashdot Login

Need an Account?

Forgot your password?