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Hydrogen-Powered Aircraft == Anti-Terrorist Device?
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?
yeah, hydrogen-filled aircraft have proven so safe in the past...
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.
-John Van Voorhis
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
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?
Learn from the mistakes of others. You won't live long enough to make them all yourself.
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?
Good quote, too many chars. Seriously, the slashdot 120 char limit sucks!
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.
I like fire ants. They are very spicy!
The Hindenburg's problem wasn't that it was full of hydrogen; it's the fabric the outer covering was made of that did it in.
Please read up on these things before spouting retardedness.
- A.P.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
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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?
Albeit at a lower temp than avgas. Remember the Hindenburg? Goes "boom" pretty well, too.
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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.
roche
Bah Humbug!
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.
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.
This sig isn't original enough, it's time to come up with something witty...
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?
---If you can't trust a nerd, who can you trust?
Whoa, someone's trying to crash a blimp into the Sears tower!
... Sheesh. This is getting boring.
*BOOOOIIIINNNGGGGGG*
Well, there he goes again...
*BBBBOOOOIIIINNGGGG*
And again
Change the channel.
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
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.
Mr. Ska
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 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).
Dr. Frank J. Nagy Fermilab Computing Division Authentication and Directory Services Group
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.
A solution to the problem with music today
How about the way the Hindenburg's superstructure collapsed in the heat of the fire?
UNIX/Linux Consulting
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.
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.
I don't know if this idea would have any effect on an airliner filled with fuel from combusting on impact.
So instead of having terrorists flying around in giant fuel-air bombs, they can now be flying around in hydrogen bombs!
Here.
the morons are out in droves today...
that would go over like a lead zeppelin
sulli
RTFJ.
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.
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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.
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))
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.
You trolls just don't stop, do you? Even if the story's not vaguely open source related you try...
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...
Recursive: Adj. See Recursive.
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 . . .
'I ain't a liar, baby, and I ain't proud I just want what I'm not allowed.' -- Violent Femmes, 36-24-36
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.
"You saved 1968." - Ms. Valerie Pringle to the crew of Apollo 8
I wrote about this 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] 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&
All but God can prove this sentence true.
1) I think researchers have determined that the shell of the Hindeburg was to blame for the disaster, not the H2.
... 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.
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
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.
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.
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.
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!
Wireless Bristol
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.
Gentoo Sucks
for pete's sake just STOP THE AIRPLANES FROM CRASHING INTO A SKYSCRAPERS. end of story!
Violate propriety
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, that makes perfect sense. After all, hydrogen is a perfectly safe thing to put in a flying machine...
Teach your kids: "C++ made baby Jesus cry."
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.
Don't use a tragedy from the 30s make us fear the fuel of this century.
--mycr0ft
Me physicist. Me make rockets.
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.
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
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 a bit of a cliché...
SO YOU'RE GOING TO DIE: The Comic for Dealing with Death
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, 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. t m
Other alternative fuels are at http://www.lerc.nasa.gov/WWW/TU/launch/foctopsb.h
OT - but annoying.
/index.htm rather than /main.htm, so if you keep clicking the "Home" link it fills the screen with your navigation frame.
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
It's fun to play with, in a "wow someone actually got paid for this?" kind of way.
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.
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.
the imagery is a little too scary .....
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
The aim of science is not to open the door to infinite wisdom, but to set a limit to infinite error.
-Bertolt Brecht
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.
Here is the ultimate weapon on anti-terrorism.
-Shade
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?
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Like hydrogen isn't flammable? Gimme a break.
Only the State obtains its revenue by coercion. - Murray Rothbard
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.
i used to work in a place that used a lot of hydrogen the 2 ways to store it were liquified and compressed. compressed took a lot of space and did not hold mutch. liquified is a very strange setup, it constantly builds up pressure and excess hydrogen must be vented. i don't think this setup would be a good idea on a plane, and gallons of liqufied hygrogen pouring out iin the event of a crash could be bad, it's extremly cold and evaporates to an explosive gas.
You all seem to be forgetting why the WTC collapsed. They hit high enough up to weeken the load bearing outer skeleton of the building. I would venture to say that any explosion or impact could collapse them.
The steel gets weeker as you go up. Name you weapon and you could probably do it.
You would have to realize though the steel gets weeker as you go up. Failure in even the top couple floors could cause that professional looking achordian effect.
The main thing that will most likely prevent planes from being used as cheap bombs is the fact the four planes were already used as cheap bombs.
I don't see the recent security clampdown going away anytime soon.
Just my opinion.
This sig is xenon coated, and will glow red when in the presence of aliens
The primary reason for the Hindenburg going up in flames was because the skin was extremely flamable, more so than the hydrogen inside! Remember if hydrogen wasn't combustable we couldn't use it as a fuel! (Barring fuel cells) How many have died from gasoline started/fueled fires? Just because one high profile accident happened doesn't mean it's use as fuel should be dismissed out of hand.
I'm not up on the energy costs of various hydrogen compounds, but if you're carrying it as water, which I presume is to be the exhaust gas, you're postulating a perpetual-motion machine. (I.e., getting net positive energy from the process H2O -> H2 + O followed by H2 + O -> H2O. Separating hydrogen from some other substance may cost less than from water, but it still sounds bogus.
Further, how much energy do you get from hydrogen combustion, and based on that, what weight H2 is needed to supply the equivalent of one plane's-worth of aviation fuel? What volume would that amount take, under what conditions?
Any chem. types out there with answers? All I've got are questions. :-/
I refuse to believe corporations are people until Texas executes one. -- desert rain on http://www.dailykos.com/user/
This topic comes up a lot especially in alternative fuels discussions. This is the info that I have. It may not be 100% accurate, though.
Issue 1: Hydrogen is a gas, which means that you need to compress it in order to get enough fuel onboard. Fuel equipment now has to deal with the increased pressure. This adds expense and weight to whatever it is you are building. Weight is bad for airplanes. Liquid petroleum fuels are very dense and do not need pressurized containers. Thus a full load can be carried without the need for bulky equipment.
Issue 2: The economy is designed to handle liquid fuels. Gasses are handled, but in much smaller quantities. Changing the infrastructure to deal with handling gasses is probably the most prohibitive part of using gaseous hydrogen as a fuel. And don't bother with liquid hydrogen. The handling issues associated with that are worse than compressed gas (insulation, boil-off vents, etc).
On the plus side, hydrogen is well suited to gas turbines and jet engines. Clean and efficient. It's just a bitch to store and handle.
When someone makes room-temperature liquid hydrogen, that'll be the day we all switch.
Remember, You are unique...just like everyone else.
we should all have pedal powered airplanes... a full capacity 767 with everybody cycling the distance. Might have to get rid of those cosy bed-seat things though :)
ok, so maybe not, lets get giant birds like the flintstones then. Or a big catapult and a big baseball mit... and we could run Linux on them... (at this point author carted off for 'special' treatment)
The additive you refer to was placed into a jet that was deliberately crashed. The wing was severed in the process in a very spectacular manner, resulting in a tremendous fireball. At once the test was deemed a failure before any of the data was analyzed. Since it was 'expensive', the fireball produced all the justification the airlines needed to kill the project.
Unfortunately, when the data was analyzed, it was shown that the metal skin of the aircraft survived. Seats made of that cushy foam junk survived the fire. In fact, most of the damage to the plane (mind you it was missing a wing...) was soot, not intense heat. The test was a spectacular POSITIVE result, not a blatant failure... how many fires currently result in nothing left of an airplane?
Of course, show anyone the video with a 'fireproof' substance in a tremendous fireball moments after impact and they'll say it's a failure, regardless of the fact that the metal skin of the aircraft, usually the first thing to 'melt', survived. Illogical? Yes. Political? Probably. Good Science? No.
into portable hydrogen bombs.... or better yet. Lets make them run on nuclear power instead, that plutonium won't burn.
The solution being touted for fuel-cell automobiles is fairly simple: compressed storage.
Now, I have no idea how much compressed storage would be needed to hold an optimal amount of gaseous hydrogen for an airplane. In addition, compressed hydrogen would make for one HECK of a bomb. Yeah, there wouldn't be a fire;instead, the 60000 lbs of hydrogen would explode with tremendous force, blowing the buildings instantly to smithereens.....
"Chill, Orrin!"---Trent Lott
The memory of the spectacular destruction of the Hindenburg airship affects people's perception of hydrogen and their acceptance of the gas as an energy source. The lighter-than-air craft burst into flame--in full view of a crowd of reporters and newsreel cameras--while landing in Lakehurst, New Jersey, U.S.A., on 6 May 1937. Hydrogen has long taken the blame for the disaster, which effectively ended travel by zeppelin.
But retired NASA [National Aeronautics and Space Administration] engineer and long-time hydrogen advocate Addison Bain, who has been conducting extensive research on the incident, concludes that hydrogen played no part in starting the Hindenburg fire. To learn what really happened 60 years ago, Bain used NASA's latest investigative techniques to analyze original wreckage from the Hindenburg; conducted interviews with the few remaining survivors and those who have detailed knowledge of the Hindenburg's construction; examined original film footage and other documentary evidence; and visited the airship's former mooring sites in Lakehurst and Akron, Ohio, U.S.A. The dramatic findings of his research were reported at the National Hydrogen Association's 8th Annual U.S. Hydrogen Meeting and are the subject of the cover story of the May 1997 issue of the Smithsonian Institution's Air and Space magazine, published in observance of the incident's 60th anniversary. (Bain also plans to publish a complete manuscript with all data as well as two books for the general public and young adults.)
Observations of the incident show evidence inconsistent with a hydrogen fire: (1) the Hindenburg did not explode, but burned very rapidly in omnidirectional patterns, (2) the 240-ton airship remained aloft and upright many seconds after the fire began, (3) falling pieces of fabric were aflame and not self-extinguishing, and (4) the very bright color of the flames was characteristic of a forest fire, not a hydrogen fire (hydrogen makes no visible flame). Also, no one smelled garlic, the scent of which had been added to the hydrogen to help detect a leak.
This colorized photograph of the Hindenburg airship as it burned gives several proofs to the theory that it was the extreme flammability of the fabric cover, not the hydrogen inside, which caused the disaster.
Bain's study uncovered two contributing factors: the prevailing atmospheric conditions and the unorthodox method of landing at Lakehurst. First, thunderstorms had come through the Lakehurst area that day; lightning could still be seen at the time of the Hindenburg's landing. Secondly, the airship made a "high" landing: the zeppelin was moored at a high altitude and winched down to the ground via landing lines dropped from the airship. This, in effect, created a ready-made ground-to-cloud electrical path in the highly charged atmosphere. This combination of factors could prompt severe corona activity on any airship. In fact, an eyewitness reported seeing a blue glow of electrical activity atop the ill-fated Hindenburg before the fire started, which is indicative of the extremely high temperatures typical of a corona discharge.
Bain's suspicions of the zeppelin's fabric covering were raised when he learned that a cellulose nitrate dope with powdered aluminum might have been used on the Hindenburg. Bain was able to obtain two 60-year-old fabric samples representative of those used on the airship. At the NASA Materials Science Laboratories at Kennedy Space Center, testing included chemical and physical analysis using the scanning electron microscope, X-ray energy dispersive spectroscopy, optical microscopy, infrared spectroscopy, and tests of flammability, electrostatics, conductivity, surface and volume resistivity, thermogravimetric analysis, and corona discharge exposure.
At the NASA lab, one of the fabric samples subjected to a flame propagation test burnt up in seconds, still volatile after six decades. The remaining sample was subjected to high-voltage electrical fields, replicating the atmospheric conditions surrounding the Hindenburg that fateful night. The electric arc burned a hole in the fabric; however, when the sample was mounted so it remained parallel to the arc (as the airship was), the fabric ignited and disappeared in seconds.
The Hindenburg fabric was found to be made of a cotton substrate with an aluminized cellulose acetate butyrate dopant. The observations of the fire listed above, in fact, are consistent with a huge aluminum fire. (The brightness of the space shuttle's rocket boosters are an example of aluminum-based combustion.) So, it was the extreme flammability of the Hindenburg's fabric envelope which caused the disaster and not the lifting gas inside.
Files examined at the Zeppelin Archive in Friedrichshafen, Germany, yielded final confirmation of Bain's theory. Several handwritten letters, when finally translated from German, corroborate what Bain uncovered. Wrote electrical engineer Otto Beyersdorff on 28 June 1937, "The actual cause of the fire was the extreme easy flammability of the covering material brought about by discharges of an electrostatic nature."
If you watch the Hindenburg footage you'll notice that it burned but did not explode. Most of the people who died in Hindeburg died from jumping from the aircraft not from being burned.
A major university in Florida(sorry the specific one eludes me) did tests on hydrogen fuel tanks. In one of the tests they shot a bullet at the tank and initially thought nothing happened. Review of high speed video recordings revealed there was a quick release of hydrogen and nothing else, no explosion. Remember hydrogen is lighter than air(duh) and dissapates quickly.
The biggest problem would the actual fuel tanks. For hydrogen tanks to work you need something akin to a thermos, an outer tank and an inner tank with a vaccum in between. On hydrogen prottype cars the fuel tanks are I believe 25% bigger maybe even more.
Hydrogen power would be great. Your only emission is water vapor, all you need to make it is water and electricity. Better yet algae produces hydrogen naturally. I've read that some scientist speculate that if you had a few large algae farms you could produce enough power for the entire US.
Hindenburg exploded because its envelope was coated in the same chemicals that Morton-Thiakol uses in the Space Shuttle's solid rocket boosters.
It doesn't matter if I've eaten Taco bell or not, wearing boxers soaked in rocket fuel is a bad idea.
First of all, hydrogen isn't all that explosive. The Hindenberg situation was different from this situation in two ways: it was coated in rocket fuel (not known to be explosive at the time), which airplanes would not be, and it used the hydrogen for lift (lighter than air gas), rather than just for fuel.
Having a hydrogen-powered airplane would have been far preferable to a hydrocarbon-powered one, because the hydrogen, being a gas, would have gone out of the buildings. Sure, it would probably have gotten to places that the liquid fuel didn't, but much less of it would have burned, because it would have diffused to essentially normal conditions pretty quickly (there's hydrogen gas in air, remember). Sure, it would have left the building pretty effectively on fire, but such buildings are rated to be able to withstand a fire fueled by the stuff normally found in them for long enough to put the fire out and evacuate the building.
On the other hand, just switching the fuel is beyond our current technology. Jet engines are rather carefully-designed devices, and you can't just switch the fuel in them without changing a lot. And we don't yet have the fuel tanks and support systems for hydrogen; it needs to be kept under high pressure in order to fit in the airplane, and that means something strong, and designed for high fuel and low fuel situations, which will be heavy. Gas just needs a container that doesn't leak, since it's a liquid anyway.
Furthermore, the support systems for hydrogen-powered stuff aren't nearly as well in place; no big generation plants, no suitable fuel trucks, and so forth.
In 1945 at the end of World War II, an Army Air Corps B-25 twin-engine bomber plane crashed into the 79th floor of the Empire State building, due to fog.
Since then, large buildings, including the WTC, were designed to take a major hit from air craft, it will do a lot of damage, but the resulting fire which was hot enough to melt steel was the big problem.
Reminds me of the adage "If frogs had wings, their asses wouldn't smack the ground when they land". There is a 0.00000000000000000% chance that future terrorist attacks will share any implementation details with the WTC attacks. This is just yet another example of someone trying to capitalize on the general populace's temporarily inability to think rationally. He may as well take out a full page newspaper ad, complete with a statement condemning "the cowardly attacks" by those "hiding in the shadows" augmented by a picture of his product's packing, or offer up a national I.D. card so that American Citizens can be more heavily identified.
I think the problem--and the solution--lies in our foreign policy. Will the Pashtuns, about to recieve aid from the West, be the next ones to bite us in the ass?
"What is the sound of one belly slapping?"
Electrically powered aircraft would solve the problems associated with toxic and flamable liquid fuels, as well as increasing the 'current' range of commercial flights. They would be limited only by the length of the extention cord. It's so obvious, that it can't even be patented. You're all free to use this idea to make your fortune.
- - - If the sun is a star, why can't I see it at night?
I had to think about this for a minute, but look at the following. If the weight to energy ratio of jet fuel is better than hydrogen, they'd need to carry more hydrogen. More fuel adds more weight, and thus you need more fuel to carry the extra weight.
I mean, it just seems so stupid. What's the point? It's easy to act like a moron. Morons do it effortlessly. What does it prove to act stupid - that you can act dumb, too? This doesn't strike me as a grand accomplishment. Perhaps it's a malicious joy in infuriating others. Again, this doesn't seem particularly impressive - you can irritate people by accident. It's another no-brainer. What's the point?
Let me ask you something. Can you come up with something to say that would make readers feel as good as what you wrote made them angry? Now, that would be impressive. Improving things is always harder than destroying them, whether moods or communication or software or buildings.
I know lots of people who know how to insult, and only one or two who knows how to give a really good backrub. Lots of people can break things, but only a few know how to repair them, much less make improvements. Do you believe that you can't post something that would be considered "Insightful", and so out of jealousy you want to ruin things for others?
So, again, I ask: What's the point? What do you get out of it?
PHEM - party like it's 1997-2003!
Of course hydrogen is flammable, but that's not the whole story of what happened to the Hindenburg. The simple story is that the discharge from the tower to envelope (or envelope to tower) started the envelope burning. The fire on the ship ignited the hydrogen in the gasbags, and the disaster resulted. A fire-resistant envelope would have prevented the fire from penetrating to the hydrogen, or would at least have held it off for quite a while, giving firefighters time to try to stop it. Also, hydrogen is no more flammable (and is less explosive) than jet fuel, and so in a modern vehicle (aluminum skin doesn't burn very well) it's not really an issue.
Virg
Just to wind up with lenigan@astro.uiuc.edu.
I don't know how feasible powering a plane with hydrogen is - I sort of follow hydrogen energy news and don't recall ever coming across any prototype jets or prop planes. I don't know that hydrogen could power a jet sufficiently. Storage methods (tanks etc.) are heavy, possibly too heavy for economical flight. I question whether this is a realistic scenario or just wild speculation.
The big problems with hydrogen are cost, lack of a production infrastructure, lack of a distribution infrastructure, difficulty of storage, and the unlikllihood of a widespread manufacture of any kind of hydrogen vehicle lacking resolution of all these other issues. Making a plane fly on hydrogen would certainly not be a simple "retrofit". This would be a transition from a liquid to a gasseous fuel with totally different combustion characteristics.
Hydrogen is clean to burn either chemically (fuel cell) or through combustion and simple (if not easy or necessarily efficient) to generate, and therefore may become a valid way to transform renewable forms of energy into a storable fuel, and to make energy from conventional fuels more efficeintly and cleanly. But I doubt very much it will be the fuel of choice in planes any time soon
It Is the Nature of Information to Transgress Artificial Boundaries
While hydrogen would not have burned like the jet fuel, I'm not sure it's practical in airliners because of the huge distances they travel. Hydrogen as a fuel doesn't provide a lot of bang for it's volume.
What really gets me is the possibility that abestos could have delayed the colapse for up to 4 hours longer. They stopped spraying asbestos in the buildings above the 64th floor becase NYC banned it. They were wetspraying, which was a technique used to eliminate asbestos from getting in the air. While we'll never know how long if any those building would have stayed up, the belief at the time was that asbestos would provide 4 hours longer before the girders melted, hopefully giving time to evacuate the building.
Asbestos, much like hydrogen has been demonized, somewhat unfairly. While there is no argument that it is not dangerous, there can be safe ways to utilize dangerous materials. Unfortunately people jump on these bandwagons too quickly to make informed decisions.
I remember when they removed asbestos from my elementary school, the teacher told us that dust from the ceiling tiles was asbestos, probably exactly what she thought. In actuality, it was normal dust, and the asbestos was covered by fiberglass and foil insulation, and was harmless, until they started scraping it all off that is...
He's right about one thing, it was the heat that breaked the towers. But it wasn't just that. The towers are stabding up with the aid of a core of concrete and steel which is covered with a layer of asbestos. The asbestos should in normal cases protect the metal from getting to hot (which makes it softer). According to calculations this "core" should withstand a fire. But when the planes smashed in to one tower, the core was damaged. And because of that the steel in the core went hotter than it should have gotten from a normal fire.
I think that the towers would have been brought down by planes using hydrogen fuel because the core was damaged and couldn't protect the buildings akilles heel.
Hydrogen fuel makes a "colder" fire than burning airplane fuel. That is because it has a lower energy per mass ratio. But hydrogen fuel can't be applied (I think) because you will need much more of this kind of fuel than ordinary fuel. An ordinary boeing contains about 56000 litres of fuel, to substitute that with hydrogen you will have to multiply that number with about 10 or so. Also Im not sure that planes could use hydrogen fuel because it gives lesser energy. Maybe it just can substitute gasolin as a fuel.
But one thing is for certain, any type of aircraft is, or can be, used as a terrorist device!!!
2 reptiles beneath your current threshold.
Just wait. As soon as the next terrorists get upset, we'll find out that walking isnt safe.
I am waiting for the day when I terrorist hi-jacks a pedestrian and walks him into the Washington Monument, or Sears Tower, or perhaps the Sydney Opera House.
The only safe way to travel is Amtrak. Well. You're safe from terrorists. Because if an Amtrak train crashes, everyone just assumes it was just another Amtrak train crashing. They do it all the time.
I mean... you can hijack a train and crash it (somehow), but there is a good chance it would have crashed anyways, so...
I recall seeing something on cable TV in the not-so-distant past regarding aircraft crashes and improvements made, or about to be made, to aviation fuel to reduce the fire hazard to passengers. How would hydrogen based aircraft compare in this regard? I think it is better to optimize for the more likely scenario of a normal crash into the ground than aberrations such as attacks on buildings.
I believe coal-powered aircraft would be a better compromise. Although possible, a coal-fire would be much less likely.
A Dr. Fun cartoon with ants and a blimp. :)
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
perhaps it would have prevented WTC from collapsing, but they still could of flown into it.
The Kruger Dunning explains most post on
Okay...
Even if all you had to do was retrofit all the engines, and fuel tanks on all available airplanes. (I don't think this is the case) This would be a monumental task. There are thousands and thousands of airplanes. These planes are robust and available... and no matter how you power them, they'll be dangerous.
Why not focus on the source of the problem: ie, passengers taking control of aircraft. Lock the doors to the cockpit (obviously). And secondarily, lock the passengers to their seats. Nobody goes to use the bathroom without a flight attendant unlocking the seat-belt. There... no more planes flying into buildings... or being hijacked, etc.
(haha, couldn't resist)
The planes would be lighter on takeoff (relative to their un-fueled weight). Should allow for shorter runways, right?
:)
Mr. Sharumpe
-- The above comments are just my opinion. If you are going to flame me, save your time. I am fireproof.
There are no naturally occurring terrestrial sources of H2, so we have to manufacture it. The 2nd law of Thermodynamics says that any time we use energy to create energy, we're losing some energy. So the question is -- where does the energy to create the hydrogen come from?
Oil? We're back to the same pollution problems we had before, plus we'd use MORE oil than just burning it as a jet fuel.
Nuclear? That's probably the best solution, but we'd have to build new plants to create the energy, and then deal with the waste.
Wind or Solar? They are clean, but aren't economically viable yet. Who wants to pay $10,000 for a coast-coast flight?
Hydrogen doesn't really make economic sense yet, since most of the sources we could use to make it are either too expensive or are easier to use directly, without converting to hydrogen in the middle.
Then there are the storage problems. Hydrogen is a very low energy fuel, so the planes would have to carry a MUCH larger volume of it in order to achieve the same energy content. For airplanes, greater volume = greater energy costs.
How many people could a conventional 747 carry, if it was fueled by hydrogen - 4? 5?
Help find a cure for Gidget.
Way I heard it, the envelope was covered with a very flammable material for some engineering reason.
A hydrogen-powered aircraft would almost definately have to use liquid hydrogen as a fuel, as it's very unlikely that you could fit enough compressed gaseous H2 into an aircraft's fuel tanks. Liquid H2 is a bitch to handle and expensive to produce.
Also, remember that aircraft engines have to have a VERY high power/weight ratio. If your engines + fuel are too heavy, you don't have any payload capacity. It would be very difficult to build an air-breathing hydrogen motor that was suitable for aviation. It seems likely that any H2 powered craft would also need an oxidizer in order to generate enough power to carry a meaningful payload. This means carrying LOX (Liquid Oxygen) or some other oxidizing agent -- rocket fuel, in other words. Oxidizers are corrosive, explosive, and very nasty to handle; not somthing you want on a passenger aircraft. A planeload of H2 + O2 would probably make a far better weapon than one full of gasoline.
It's a nice idea on the surface, but I don't see hydrogen being a replacement for gasoline in aircraft anytime soon. The power requirements are just too high to get away without an oxidizer, the fuel would be expensive, and refuelling would be a logistical nightmare. It's an entirely different engineering problem than powering a ground vehicle -- for which a hydrogen-powered fuel cell IS a viable power source.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
after all the R&D that went into such a project came back, tickets would be significantly cheaper because hydrogen is the easiest /cheapest material to come by in the entire universe. now for the reality - CDs were supposed to cheaper after the initial R&D costs were made back... woops
in most parts of the globe, it's still wednesday, but many of those people are asleep. Some people are in thursday already, but it's definitely not friday where the show is produced (U.S.)....?
- passion
when hydrogen burns, it gets 60,000 degrees (f) hotter than it was. (go look it up, i did) that's hotter than jet fuel. one good thing about burning hydrogen - it makes water, and you're gonna need all the water you can get to put the fire out.
I think that the people that are working on this hydrogen powered aircraft are using the WTC tragedy as an unfortunate publicity tool for what will probably turn out to be a dead end.
If hydrogen were actually a viable alternative to jet fuel, there would be more research into it and we'd hear more about it. Unfortunately, because everyone's awareness is hightened about the WTC collapse after the crash, people begin to think that there needs to be a solution to this "problem."
Think of it this way though. Is there really a "problem" with planes crashing into large buildings and causing them to collapse? While the WTC was an unfortunate accident, it was isolated and is not a common enough occurance to warrant completely changing the fuel that aircraft run on.
My deepest sympathies go out to those affected by the horrific tragedy of September 11, but I don't think that hydrogen is the solution.
Linux is so bad it's free and most people don't use it. But you have the source code, so it's your fault.
Yup, and taking away everything including people's tweezers means that only someone insane enough to not understand their odds of success would attempt to perform a copy-cat crime.
While the terrorists who crashed into the Pentagon and WTC were ruthless, they seemed to understand their chances of success very well. The next terrorist act (assuming there will be another one) will most likely be as difficult to see coming as this one was. And, in retrospect, it will probably seem just as easy to prevent, if only we'd been looking in the right place.
That's not to say their ideas are without value, but they definitely have an agenda.
I do not recall the exact data so do not shoot at me.
1 Mole H2O : 10 gram, (H : 1 g.mol-1 , O : 8 g.mol -1). Meaning 100 Moles in 1 liter of water, so between 50.000 to 60.000 Kjoules in one liter.
I do not know the data for Kerosin or other hydrocarbons elements. Perhaps someone know the data for theoretical 100% combustion of kerosin ?
Plus remember that H2 *need* to be produced from water.
As for H2 being more "safe" I do not think. Once released during an accident from the cell, it would expand explosivelly, then mix with oxygen , and burn brutally sucking all O2 from the surrounding.
The main advantage to hydrogen is that it would disperse if there was a leak.
The main disadvantage is that its density is horribly low, even when liquified.
Why not use propane instead? It too will disperse (though it'll drift down instead of up), and it can be stored at a density approaching that of gasoline.
If you want something that won't pool, ethane will work, though that's harder to liquify by pressure alone. It's about as dense as air, and so will just tend to spread out if released.
Methane would drift upwards, but you'd need a cryogenic tank to hold liquid methane. Much higher energy density per unit _volume_ than liquid hydrogen, though.
So far I count 37 occurances of the word "Hindenburg" in this discussion (39 now!).
try { do() || do_not(); } catch (JediException err) { yoda(err); }
Unfortunately, I think people forget that hydrogen-fuelled jet airliners would likely use liquid hydrogen as its fuel.
Unlike hydrogen gas (which burns relatively safely), liquid hydrogen when it ignites will do it with a force that makes a dynamite explosion seem like a minor event. If the planes that crashed into the World Trade Center were fuelled by liquid hydrogen, the initial fuel explosion would have so much kinetic force that the building would have collapsed right there and then.
If I remember from the Challenger explosion, when the solid rocket booster leak ignited the fuel in the external fuel tank the force of the explosion was equivalent to a 1 kT tactical nuclear warhead. That's why liquid hydrogen must be handled with extreme care.
They used a metal paint coating to lower the temperature inside the big gas blob. At that time, they had no idea how flammable the paint actually was.
War is one of the most horrible things a human can be exposed to. And one of the worlds largest industries.
Hydrogen isn't a naturally occurring fuel. We're dependant on oil today because it IS a naturally occurring fuel, and therefore cheaper to use than other, man-made fuels. If we were to use hydrogen as a fuel, we'd have to burn MORE oil to produce the hydrogen than if we just used the oil directly.
How does that help matters?
Help find a cure for Gidget.
Ok, after reading this article and many of the replies, I have come up with some observations.
First, the planes would be using liquid hydrogen, not gaseous, so all the comments about needing to compress the gas, or contain the gas, or the gas not having as much energy as jet fuel need to read the damn article!
Secondly, there are about a zillion different opinions based on guesses and I didn't see a single person who was qualified (at least no one say why they were qualified) to say what would happen when the plane hit a building. It's all just a bunch of speculation.
Third, we know what caused the Hindenburg to explode. About half the messages are saying that it wasn't the hydrogen, it was the coating. It should also be noted that the Hindenburg was not filled with liquid H2 so the comparison again is not really valid.
What I'd like to see is someone who works with H2 in a liquid form to post their thoughts on what would happen based on their own observations and experiments with liquid H2. The closest I saw was one individual who talked about seeing the drops of H2 liquid just kind of floating downwards instead of just falling like water.
The other point is that I saw many posts saying how H2 contains a lot of energy, and others saying it contains very little. Logic would say that one of those is wrong. Once again, I would like to see someone who knows what they are talking about post something and include either a reference or a credential, or something to compare H2 and jet fuel in regards to energy density.
I guess this is slashdot, I'd just like to see more people that do know what they are talking about post and less people that think they know what they are talking about claiming that they do... But again, this is slashdot, so I cannot expect much different.
<-- end rant...
We've had gasoline powered aircraft for years. I think those big jets have experimented with other exotic fuels as well.
What? Gasoline and hydrogen are different? Well... Not according to Taco!
Smirk, giggle, guffaw!
I'm also interested in reasons why this system might be practical or not practical in automobiles, if anyone feels like going a bit off topic
I don't care if it's 90,000 hectares. That lake was not my doing.
Very Stupid. Here's an anti-terrorist device:
A rubber band powered plane.
The Slashdot Editors need to smoke some marijuana.
Do you share your marijuana?
So OK, maybe hydrogen isn't such a perfect idea. However, if you just put a few cows on board...
Reports of my deaf have been greatly exaggerated.
Guess what? Asbestos is much more dangerous than terrorism. It just kills you slower, and allows some corporation to profit from your demise.
Oh no! It's the evil and horrifying asbestos! That awful substance which as been absolutely and unmistakably proven to be dangerous to humans in any form and at any dose by the increased lung cancer statistics in factory workers who were continually exposed to the dust of one form without protective equipment and smoked a lot of cigarettes!
The general ban on asbestos isn't the result of scientific evaluation, but a media frenzy and panic in the uninformed public. Asbestos is certainly less dangerous than, say, gasoline, and very useful. It's just a matter of safe handling.
---
You'd be surprised at the broadband connection available to things crawling around in your hair.
As has been repeated innumerable times already, the Hindenburg fire was the result of combustion of the dope used on the skin, not combustion of the hydrogen tanks.
A well-crafted lie appears unquestionable - Dama Mahaleo
IANAA (I am not an architect), but all my architect & engineer friends, as well as most reports on tv, have agreed that the reason that the towers fell was not the impact itself, but rather the expansion of the metal structure of the building. When the metal expands, it pushes up against the floors above it, and when the floors refuse to move up, the structure buckles under the weight. That's why the buildings took arround an hour to finally fall. They were designed to withstand earthquakes and gale-force winds, both of which would have more kinetic energy than an airplane (granted the force of an airplane striking a building is more focused than high winds, but the total strain on the frame of the building is going to be a lot less).
Asbestos in solid form (like insulation) is perfectly, 100%, safe. Until it starts to crumble and asbestos dust starts to fly around. The preferred treatment for a house with old asbestos insulation is to encapsulate it - not remove it. Removal will get more of it flying around the building than sealing it in place.
From my understanding, producing enough hydrogen from electrolosis to power a significant percentage of the existing vehicles is not feasible. It costs more to create oxygen, than producing gasoline from petrolium. As bad as "Chain reaction" was, it did get one thing right. Finding an efficient way to create hydrogen from water that doesn't require external energy is a holy grail of hydrogen fuel research. It take more electricity to produce hydrogen than burning the fuel. The same problem exists for fusion reactors. For several decades now, scientists have tried to harness fusion energy, but they can't reach the point of chain reaction without causing a huge explosion. Any company that tries to make hydrogen through electrolosis will never make a cent or become profitable. That along with the other issue mentioned makes hydrogen fuel impraticle. When safety, health, and ecology become more important than making a buck, hydrogen fuel may have a chance.
I'm not sure why you think that you need to burn oil to get hydrogen, or why you think that hydrogen isn't naturally occuring. Hydrogen is the most abundant element in the universe. And you can get all the hydrogen you need from the ocean.
Lockheed's legendary Skunk Works, headed by Jack Kelly directed one of his thermodynamics engineers to work on a feasibility study of a hydrogen-powered aircraft that could make the 100K feet altitude and mach 3+. Ben Rich (the father of the f-117 Stealth Fighter) along with another engineer worked on the idea of using hydrogen.. They worked on designing saftey systems as well as aircraft tankerage that could handle high (500 degrees+) temperatures. They dealt with hydrogen leaks as well as testing on how hydrogen would explode if it's tanks would rupture. One such test let pure LH (liquid hydrogen) out and they then set off a spark.. The LH burned off in a flare and there was no explosion. But they mixed Hydrogen gas with Oxygen gas and tried agian. The resulting bang and shockwave ricoched off nearby buildings and about knocked two men off a scaffolding two blocks down the street! The bottom line on the project was this: Was it feasable for the military to handle out in the field? No. Is there going to be problems with logistics in getting the hydrogen out to third world countries to fuel the aricraft? Yes. How big would the aircraft be if it had a 2,000 mile range and be able to handle all the mission paramters? about as long as a football field, with 80% of the aircraft being tankerage! BTW, the project was called 'Suntan' and the info is public info for those that want to peer at the first hydrogen powered aircraft engine built by Pratt and Whitney.
First rule of holes; When in one, stop digging.
Boy, here's an idea: let's develop an extremely expensive technology that lets us use liquid hydrogen for airplane fuel when we already have thousands of airplanes flying the friendly skies with the regular jet fuel system, all so terrorists can't hijack planes...
Or... have the flight attendants trained dually as security officers, all toting stun guns and combat knives. Seems a lot cheaper to me, and more fun too.
~ now you know
The Challenger violently exploded because of the liquid oxygen. Fuel is important, but oxidizer is usually the limiting factor.
Dave Barry (iirc) even covered this in a column on the world's ultimate barbeque grill. Charcoal brikets, hardly an explosive, a tank of liquid oxygen, a lit cigarette in the charcoal as an ignition source, and a long rope. One tug, *boom*, and the charcoal burned fast enough to vaporize most of the cheap grill. In the Challenger explosion, you had that oxidizer dumped into the middle of gaseous hydrogen so there was an even quicker burning than you have with charcoal and its relatively low surface area/fuel ratio.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
The simple answer is way the Hell too much. The airline industry (and the leasing industries associated with it) operate on very tight profit margins. Just look at how disasterous the last month has been for the airlines. They are NOT going to be paying to design, much less paying to install, an entirely new type of engine. The bill would be trememdous!
My father runs a small aircraft leasing business, and basically the industry, which already had a glut of aircraft, is looking at total and utter devestation. This is an industry where every time the government imposes new noise level limits for aircraft, firms go out of business by the dozens. His firm is small enough to find a way through it, and well diversified besides, but the firms that own most of the aircraft that the airlines fly, firms like GE Capital, are going to take huge hits. There simply will not be any money available for refits, and barely enough to meet government mandated maintainence checks, much less a project of this magnitude.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
Since planes are powered by buring stuff, given the weight of the plane is less with H2 fuel. Then you would need to carry less energy on a hydrogen fueled plane the a conventional one. It would have less distructive potential, just DON'T run wires through the fuel tank, and test the crygenic hydrogen stirrer moters first (not another Apollo 13).
(Most likely, they'd use plain hydrogen, which has no neutrons, and merely reacts with any element on the further side of the periodic table. Which means you REALLY don't want to collide with a tanker containing fluorine.)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
True, you don't need to burn oil to get hydrogen, but you do need an energy source. While H2 may be the most abundant element in the universe, it isn't just sitting around waiting for us to pick it up (at least, not on Earth). To get H2 from the oceans, we'd have to use more energy to liberate the hydrogen than we'd be able to get out of the hydrogen thus libreated (2nd law of Thermodynamics).
Where does that energy come from? Well, today, the bulk of our energy comes from oil, so that's why I said we'd need to burn more oil to make hydrogen than we would if we simply used the oil directly.
Help find a cure for Gidget.
2 technologies could take care of so many problems, yet we are not investing in them. If we invested more research into nuclear fusion for our nation's power grid and started funding to move every car, truck, and boat/naval vessel to hydrogen power, not only would the enviromental impact be more than significant, but we could pull out of the middle east %100 and not get involved with these savages that kill in the name of religion.
The impact of the planes did not destroy the towers. They were build to take a *massive* shakedown like that and still stand. They fell because the steel they were made out of started getting mushy when their temperature approached the melting point of steel. In other words, take out the fuel fire and just have the kinetic energy of the impact and the towers would have stood. (but the damage would have been bad enough that it would still have taken a long time to fix them.)
Don't label something "offtopic" unless you know the topic well enough to tell what's on topic.
was it me, or was that website about using hydrogen as a fuel.
now im no chemist, but couldnt one store a bunch of water and apply an electric charge to it to split the H and the O. there you have your oxydizer and your fuel. once ignited, wouldnt it turn back into H2O?
"Alot of people don't know what they are doing...and most are pretty good at it." -George Carlin
Well folk, You msut have H2 and an oxydizer with you. Why do you think challenger had oxygen tanks ? H2 turbine do not work by releasing violently H2 but by H2 combustion...
So much for safety, at least with fossile fuel you do not carry both oxydizer and Hydrocarbon together on the same plane...
OTOH it would make a very nice Kamikaze bomb.
Re-read your point #5. You start by saying the fire was not a signifigant part of the collapse, but then your further explanation says just the opposite. Was this just a writing mistake or am I missing something?
Don't label something "offtopic" unless you know the topic well enough to tell what's on topic.
My understanding is that a large number of people in the WTC were instantly cremated by the 15+ tons of burning jet fuel . Yes, the hydrogen plane would've reduced this risk.
Is a hydrogen plane really feasible? Not really. People can design, build and fly prototypes but they really are uneconomical and inefficient. Hydrogen's specific energy (Joules/kg) and energy density (Joules/liter) are much lower than jet fuel. At best, commercial flights would require liquid hydrogen as a fuel which still doesn't have an energ density close to jet fuel.
This, to me, is one of the most compelling reasons to use electric cars, since gas based fuels are really best used for flying. Anyway, this guy seems to be promoting his objective (of getting research and design money for hydrogen powered flight) by using the recent disaster.
Oh well.
The fuel handling problems would need to be addressed, but I think the bigger problem is where does the hydrogen come from? There's no naturally occurring H2 supply on Earth, so we'd have to manufacture it (probably from water). The energy it takes to manufacture hydrogen is much greater than the energy that would be released by burning it. It really makes a lot more sense to just directly use the energy that would have gone into hydrogen production.
Help find a cure for Gidget.
How many more times do you think there will be a coordinated group of hijackings of airplanes which are then flown into buildings?
I'm thinking that it was a one-time shot and the terrorists will come up with a new idea for the next attack. They're pretty creative when it comes to mass destruction.
I mean, if a terrorist does hijack a hydrogen powered plane and flies it into the White House, being hydrogen powered probably wont help too much.
-J5K
The libertarian solution to the failures of capitalism is to apply more capitalism til the failures are fixed.
(When Oxygen and Hydrogen reacts, to form water, you get energy. You must put in EXACTLY that amount of energy to seperate them again. Any less is no good, and any more than that, you're losing out, since you won't get the difference back, later.)
The best "fuels" are those which are already in a form that can be used. The reason being is that you're otherwise playing the Great Energy Shuffle, just moving energy round, and loosing some on every conversion. (See Thermodynamics, Laws Of, II).
Really, the entire concept of a "terrorist-proof" aircraft is as futile as a child-proof bottle, an indestructable toy or a secure web server. You are much better off to confine and limit the problem. Sure, the hydrogen solution does this, to some extent, but in ways that could produce still worse problems. (Hydrogen hits the chlorine vapour in the air conditioning, and merely dissolves the locals, rather than incinerates them.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
I see it as really impractical. Converting the commercial planes to be hydrogen-powered would cost more than any company could afford, especially now. I think putting more money into the security measures taken before a person gets onto a plane is a better solution.
How would a plane equipped suchly ever land?
Have the autopilot disengage again on contact with the tower? Allow pilots to override based on security codes simultaneously entered from multiple points in the plane? (That would at least make hijackings require larger, more detectible groups). Or tower and autopilot autonegotiate landing pattern and route? We have the technology for this, too.
Of course, then you have the problem of someone spoofing the tower's address and hacking your autopilot...OK, still a few issues here. But we already HAVE the proximity warning for ground and mountain collisions: right now it just issues an audible warning to pull up, and quiets down when the collision is no longer imminent. That could be easily modified to pull up FOR YOU only when needed.
You can apply many thousand joules of kinetic energy to a palmtree and it will just swing. The WTC towers were designed to withstand the windpressure of a hurricane.
Because in the case of H2 turbine you have to carry your own oxydizer with you. You have to make it react with *something* to get your energy.
So now you want to retrofit plane with a load of oxygen (or any other oxydant) and hydrogen... Or should i say PAYload ?
Plus it cost energy to produce this hydrogen. It would cost much more money than than refinning fossile fuel.
Finally to the guy saying that retroffiting airplane would cost 2000$.... I rather think you forgot some four-five zero as the technology is not the same at all, particulary it involves cryotechnologies. It is not simply a mater of exanging of fuel.
And finally as many pointed out, there is the volume question.
First post.
Planes aren't cheap bombs, they are just convenient ones...
What's the point of a standard if you cant have more than one.
Sure I'm paranoid, but am I paranoid enough?
Fuels like gasoline, liquid propane, etc:
http://www.ior.com.au/ecflist.html
Hydrogen compared to gasoline:
http://www.ovonic.com/hydrogen/facts.html
Looks like hydrogen is the big winner here folks.
ed
I know a little sig that's just ten words long
You msut have H2 and an oxydizer with you. Why do you think challenger had oxygen tanks ?
Because it was built to operate in outer-space, where there is no readily available oxydizer (the atmosphere).
Seastead this.
MacGyver worked for the Phoenix Foundation, not the Phoenix Project.
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.
The Hindenburg didn't explode, it just burned fast... not fast enough to qualify as an "explosion", either.
To get fossil fuels from the earth, we'd have to use more energy to liberate the fossil fuels than we'd be able to get out of the fossil fuels thus libreated (2nd law of Thermodynamics).
Smaller buildings = less danger.
Better usage of geographical spaces = no big cities = less danger.
More fuel efficient cars = less dependency on imported oil = we can let go of the middle east (let them solve their own problems for a change) and the rich terrorist-financers will starve to death, since their oil will be worth half a penny.
Fast trains (TGV-like, some 250MPH) = less airplanes in the sky = more control = less danger.
How far away are we from just filling the plane with water and a high powered electrical device to derive the H2 out of the water as needed, leaving only the O as a by-product.
This would actually put out any fire after impact.
Or better yet, have the airplane draw moisture out of the sky as needed.
Maybe this is a hundred years away but I can see it now: "Ladies and gentleman, we are running low on fuel, we'll have to fly thru some clouds here to fill up."
> Hydrogen as safe alternative fuel... Um... Hindenburg, anyone?
Two points: the Hindenburg burned because of the envelope, not the hydrogen (see the many posts explaining this), and the Hindenburg used diesel fuel for power, and hydrogen for lift.
> 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.
Not likely a problem. Most of the experts consulted believe that the sustained fire is what caused the collapse of the buildings. As the videos show, the force of the initial explosions was mostly external anyway (remember that huge fireball?) so even if the force of the hydrogen was significantly more powerful (which it wouldn't have been, for reasons below), the extra force would simply have thrown debris farther, not done much more damage. It's very likely that if the planes used to hit the WTC towers had been hydrogen powered, they'd still be standing. In addition to not having burning jet fuel all over the building (which actually trapped people in the floors directly below the impact, by running down the stairwells), the force of the explosion would tend directly out along the impact vector, then upward. The rapid expansion of the hydrogen as it escapes the tanks tends to inhibit explosive force (increase in volume means decrease in temperature and pressure), so the extra force gained by the fact that hydrogen burns very efficiently is offset.
> Then there's the issue of storage... wouldn't high-pressure
> crtyogenic fuel tanks be prohibitively heavy for an aircraft?
Yes, they are, and that's why hydrogen fuel cells aren't more popular. Once that problem can be solved (materials scientists have been working on this for a long time, mostly for space vessels) hydrogen has a chance against fossil fuels, but not until then.
Virg
Hydrogen is not safe to use as a fuel(when they use them in the outer edges of warheads to give them an extra kick, you know it is explosive.) It is way too dangerous. Now if they put compressed hydrogen toward the front of the WTC and then crashed it into the building, we would see a major boom.
Just because a bunch of people believe or do something stupid, doesn't make it any less stupid.
Not so. We're not CREATING fossil fuels, we're just picking them up out of the ground. The 2nd law of Thermo doesn't apply to drilling for oil in the same manner it applies to creating hydrogen.
Help find a cure for Gidget.
How exactly are you going to fix 110 story skyscrapers when the 80-100th floors are straight out missing?
Yes, H2 would produce a large explosion on impact. Probably bigger because the fuel is under pressure and is much more flammable. Let's recall why they called it a "hydrogen" bomb...
-Wallace
"I am Jack's complete lack of suprise." -Fight Club
Please explain how the use of hydrogen as a fuel would "decrease the dependancy on foriegn oil"?
It's made from natural gas or coal, silly.
Hey I need some points: let me mention that the Hindenburg explosion was caused by the paint on the skin of the blimp, NOT the hydrogen.
Now mod me up, like the 50 other people who mentioned this and made it to +3, Insightful.
guh.
we're not creating hydrogen either. that would require quite a bit of energy ... somewhere around mc^2, so in that case i would agree. however, we would be "picking" hydrogen out of the ocean. fairly synonymous with oil refinineries.
The WTC towers were constructed with, essentially, redundant substructures. The exterior supporting beams, placed only 1 meter apart rather than the normal 6, could support the entire weight of the building without the internal supporting structure (which, of course, could support the full weight itself). While tower number 2 may have collapsed from the hit it received (it fell rather quicly after being hit), the prevailing theory is that at least tower 1 required the intense heat of the fire to weaken the remaining support before falling. Even if the hydrogen tanks ruptured and the Hydrogen ignited, you'd only have one hell of a flash fire, leaving only normal combustables in the building and on the plane burning after a few seconds. This could have allowed at least one of the buildings to have remained standing, and very possibly allowed those trapped above the impact point to make their way down.
Just how easily aircraft can be retrofitted with Hydrogen engines or electric/fuel-cell based power I've no idea.
how about making sure that cockpit is secured with a bulletproof door/wall, and not a curtain.
if one can't get the control of an airplane, chances are there is no reason to hijack it.
when hydrogen oxidizes (burns), the only product is water (h2+o2 -> h2o). this is definately much safer for the environment, not contributing to the break down of the ozone layer and what not.
Even at 5000psi, it's still a relatively low energy density compared to refined petroleum products.
Mr. Ska
Hydrogen's specific energy is much higher than jet fuel. Its volumetric energy density is lower.
> Isn't sugar a hydrocarbon?
No, sugar is a carbohydrate, not a hydrocarbon. The difference is the "-ate", which is chemist's talk for "oxygen", which means it only works for fuel if you "-ate" it. However, after eating enough sugar, I could power a jetliner with my fidgeting....
Virg
we would be "picking" hydrogen out of the ocean. fairly synonymous with oil refinineries.
Except for one key difference. Burning H2 yields H2O; this reaction is exothermic, hence we can use it as an energy source. But that means that getting H2 from H2O takes energy. Indeed the first law of thermo tells us it takes at least as much energy as is released by burning H2 (else H2O->H2->H2O could be used as the basis for a perpetual motion machine).
The second law would suggest (I haven't figured out how to formalize this as a proof) that you in fact will end up having spent more fuel energy than the system (fuel + burning H2) outputs. Even if not, you're basically using the H2 as an (allegedly safer and/or more convenient) battery to store the energy from the fuel.
The analogy to oil refining breaks down because burning oil doesn't result in unrefined oil, so there is not an analogous cycle of chemical reactions.
I may be wrong in that there may be 1 or 2, but all airlines have been losing money for the longest time. There ARE no profitable routes. The government is continually giving the airlines money.
or from water silly
/.
Excuse me? Speaking as an ex-employee of Thiokol Chemical Corp. (was briefly Morton-Thiokol, but only until the salt boys finished stealing Thiokol's diversified holdings, bankroll, and reputation) I'm wondering exactly which chemicals you're talking about.
I've watched the Hindenburg film and it sure looks like burning hydrogen gas to me. And burning magnesium, wood, and aluminum, too - granted. But what are these "same chemicals" you are referring to?
I don't think Thiokol's produced an explosive fuel compound since the sixties.
--Charlie
One of the ongoing ways to make plane crashed more survivable is research into jellied fuel. The big problem with jet fuel is that it atomizes very easily, and that creates nasty fire clouds surrounding the plane.
I don't think it would have helped in this case, though.
It doesn't mean much now, it's built for the future.
has gotten us all to believe that petroleum is safer then Hydrogen. Enough studies have been done to date that show hydrogen is much safer. The best quote was that if the fuel we used was initially hydrogen based, the arguement of what is safer would be flipped, but would be defended even more vehemently. Hydrogen is safer, it doesn't sit around and burn, you get a quick burn and it is gone, plus you need to have the right conditions for that to happen. With jet fuel, it doesn't seem possible to rupture a fuel cell without a fire.
Hindenburg.
Jet fuel is a far cry from diesel. Relative to jet fuel, diesel may as well be crude oil.
I dunno...I know some chicks who dig some pretty weird stuff - but probably not that weird.
I'm the stranger...posting to
... locking the passengers to their seats ...
... stop someone from *taking* command of the aircraft
... looking outside ... remember how we swallowed the key?"
I don't know about you, but if I want to travel in a prison transport of ANY kind (airplane, bus, etc.) I'll commit a crime first, to make sure I have the *whole* experience.
I agree we need to change our focus
... but while we're busy trying to lock the trouble out -- let's make sure we don't lock ourselves in.
"On the inside
-- 'Cage of Freedom'
Metropolis (Georgio Moroder soundtrack)
This mind intentionally left blank.
A few days after the attacks, I read an interview on either the jeruslaem post or haaretz daily's websites with an architect who had been one of the lead designers for the WTC towers. He compared the construction of skyscrapers in the US (steel frame) and Israel (reinforced concrete).
Architects know steel is more vulnerable to damage by fire than concrete. So the WTC structure was encased in concrete to provide additional time to evacuate the building. IIRC, he stated that they did not expect the building to survive a fire such as the one following the crashes, but to survive long enough to evacuate following impact of a smaller aircraft (B-707, I believe). Designing a building to be "safe" against all threats is impractical - you have to make a tradeoff at some point.
As to why Israelis use concrete and not steel, it's a matter of cost. Reinforced concrete is far cheaper in Israel than structural steel. In the US, lower costs for steel and resulting faster construction times overall make steel a better choice.
It was a lofty (sorry) project funded by NASA and McDonnell-Douglas to make a hypervelocity spaceplane. The project was cancelled because MDC couldnt figure out a way to reliably contain the huge amounts of hydrogen slush they were trying to carry.
See, on a car, you can afford to have a huge steel tank full of hydrogen. On an aircraft however, thrust/weight considerations preclude using any more steel than is absolutely necessary. Keeping all that fuel in a big steel bottle was out of the question, the weight would have kept NASP on the ground permanently.
Enter composites.
The decision was made to try to keep the H2 slush (yes, that's slush as in "slushee", meaning a mix of liquid and solid H2) contained in a composite honeycomb tank, for weight and expense reasons. And the tanks kept cracking. Enough that the whole project was scrapped because of the gas tank.
The performance envelope of a hydrogen tank is severely brutal. You need to contain many thousands of atmospheres of pressure, and you need to also deal with a operating temperature of a few degrees above absolute zero.
But wait, it gets better!
Now, you also have to realize that the Shuttle hs been doing this for years. How? With spherical tanks. the reason that the shuttle's main tank looks like a blimp is because the tanks are all spherical. With NASP and any other H2 burning aircraft, you will need to design the tank around the aircraft, not vice versa. This means having a tank shape and structure that is considerably weaker than a sphere, which will always be strongest for a given weight limit. You will now have seams, corners, and edges to try to make as strong as the flat sections, all the while, the hydrogen is busily trying to pop your tank into the aforementioned sphere.
Unfortunately, composites research hasn't come too terribly far from the days of 1992 when NASP finally got the project axe. The same problems remain, only far greater than they were for NASP: NASP was designed to use up most of it's hydrogen very rapidly on the way up into space, generating all it's speed in a few minutes, with just a little remaining for moving around when it re-entered the atmosphere.
When you're talking about making a jetliner burn H2, you, by the use of the word "jetliner", define its flight envelope as being subsonic, stratospheric, with a flat flight profile, not the ballistic one of NASP. That means you will need constant burn rates, and enough fuel to last 14 hours for the long haul flights (LA to Tokyo or Sydney).
With current technology, that might be an insurmountable hurdle right now. Perhaps in a decade or so, if the right people make the right discoveries in materials science it will be possible, but don't hold your breath.
Chris, who worked for the company formerly known as McDonnell-Douglas.
This space for rent.
All that talk about Hindenburg ... Remember the Challenger blowing up? So much for a liquid hydrogen.
It is always amazing to see the number of arm chair experts that crawl out of the woodwork whenever Slashdot makes a technical or scientific post. The level of ignorance being passed off as as knowledge is simply astounding. Here are a couple of actual, relevant 'facts'.
1. Prototype Jets burning H2 have been in existance since the 1950s. A relevant link is
here http://www.bellona.no/data/dump/0/04/41/5.html.
2. The energy stored in a H2 tank is greater
than that of a jet fuel tank of equivilent weight. The size is somewhat larger.
3. As far as I know, the explosion of the space shuttle was cause by the solid boosters.
You still are =)
Don't forget that the SR-71 was developed from a lot of work that went into designing a hydrogen fueled aircraft. When the design became too heavy and range estimates fell like a rock it was abandoned in favor of hydrocarbons.
God damn - The amount of sheer stupidity, scientific, speculative and societal, exhibited in these comments would gag a maggot.
The Challenger didn't run on pure liquid hydrogen, but on a special compound called Hydrazine ( H2NNH2), which is VERY explosive (and corrosive too if I remember correctly) and extremely reactive. It will never make a safe commercial fuel for airliners, if for no other reason than manufacturing and safe storage costs.
To make things more interesting, it's also highly toxic (hydrogen - h2 - is not).
Osha comments on it as:
1.1.2. Toxic effects (This Section is for information only and should not be taken as the basis of OSHA Policy.)
Hydrazine is a severe skin and mucous membrane irritant in humans; in animals, it is also a convulsant and a carcinogen. In humans, the vapor is immediately irritating to the nose and throat and causes dizziness and nausea; itching, burning, and swelling of the eyes develop over a period of several hours. Severe exposures of the eyes to the vapors causes temporary blindness lasting for about 24 hours. Recurrent exposure to hydrazine hydrate has been reported to cause contact dermatitis of the hands without systemic intoxication.
In humans, hydrazine is absorbed through the skin, by inhalation, and orally; systemic effects include weight loss, weakness, vomiting, excited behavior, and convulsions; the chief histologic findings are fatty degeneration of the liver and nephritis. (Ref. 5.6.)
Of course hydrogen still reacts well in the presence of oxygen, but unlike hydrazine, requires a spark or other catalyst to start cumbustion.
- The Ravnos
FreeSpiritMind.com
Kyndar: Exotic Imports, Jewelry, Candles, and Incense http://www.kyndar.com
Don't forget that the SR-71 was developed from a lot of work that went into designing a hydrogen fueled aircraft.
Yes, one of the more entertaining parts of Skunk Works, IMHO, is the section where Ben Rich talks about his research and experimentation with liquid hydrogen.
~Philly
Hydrogen could propel an aircraft of that size, but only if it were stored in liquid form (highly compressed or extremely cold, and compression is much less expensive than cryo tanks). The space shuttle is powered by hydrogen powered engines, and the reaction is the simplest chemical reaction:
2H2 + O2 => 2H20
If the tanks were to leak, and sealing at these pressures is difficult, the leaking hydrogen would immediately vaporize (i.e. dry) and would be very volatile. Any rupture to the atmosphere coupled with any source of heat significant to cause combustion would cause a reaction exactly like the space shuttle Challenger we all saw in the 80's.
There safety of hydrogen as a fuel source depends on how it is stored in the aircraft.
One method of storing this is just to store it as a compressed gas. This is not a very efficient way to store it, and it will have considerable negative impact on the range and or cargo capacity of the aircraft. In other words, air travel would get a lot more expensive and more rare. Not likely to happen. This method would also be dangerous because a rupture of a compressed hydrogen storage tank would release a lot of energy just from the bursting of the pressurized tank. The hydrogen would then be mixed with the surrounding air in a potentially VERY explosive combination, much like an FAE bomb. It is unlikely that a large portion of the hydrogen cloud would have the right fuel/air mixture to explode, but even a small percentage would be a big explosion. In an open area a large portion of the hydrogen might escape without burning, but in an enclosed area like the WTC, a large portion of it would probably still have burned. No benefit to using this method, and a lot of negatives.
The Hydrogen could be stored in a metal hydride. Basically the hydrogen is "soaked up" into metal like water soaking up into a sponge. Amazingly you can get quite high hydrogen storage densities with this method, even higher than storing it as a compressed gas. It will be much less of a fire hazard than conventional jet fuel. The hydrogen will not come out of the metal-hydride "sponge" all at once; so even if there is a fire it will be a small but long fire instead of a big, quick one. This method will be even safer because of the fact that the planes will never leave the ground. Metal-hydride may give good storage densities for automobiles, but the fuel tanks would be way too heavy to use on an aircraft.
The third method is cryogenic storage, as either liquid or slush hydrogen. This method gets the best storage densities as hydrogen storage goes; but it is still a lot less dense than normal jet fuel. That means you still need much bigger fuel tanks to get the same range. This might not be more expensive (and might even be cheaper) because of possible engine improvements. But you have the problem of handling a cryogenic fuel, which adds to costs (and the possibility of a ground crew injury). Then you have the problem of where to put the fuel. There isn't enough room in the wings to put all the fuel there, like is done with normal jet fuel. One possibility is to put it in the fuselage, but that is VERY dangerous because you now have the double threat in a crash of killing the passengers with cryogenic hydrogen before they have a chance to be killed in the resulting fire. Putting the extra tanks out on the wings makes sense from a structures point of view because you have shorter load paths, and would get the cryogenic fuel somewhat further away from the passengers; but it still would not eliminate the fuel as a risk. Yes a puddle of liquid hydrogen WILL burn. As the liquid boils it mixes with the air, creating a flammable mixture. As the mixture over the puddle burns the heat increases the rate of boiling of the puddle. This is actually not too different from what happens when a puddle of non-cryogenic fuel burns. Will it be less of a fire hazard? Maybe. A hydrogen fire will not emit as much thermal radiation, which seems safer; but for the same reason it is invisible and therefore harder to fight (a problem that might be solved with trace impurities). In an open area a hydrogen fire will dissipate more quickly and cover less area, but that doesn't apply to the WTC case because it wasn't in an open area and hydrogen might have actually been worse because of the possibility of explosion instead of just fire. I also wonder what that high a volume of cryogenic hydrogen would have done to the steel structure upon impact; the huge temperature swings from ambient temperature to cryogenic to a hydrogen flame might have caused the collapse to happen sooner. In a normal crash that happens in an open area hydrogen is theoretically safer, but modern jet fuel is not as explosive as most people believe, thanks to evolutionary refinements in its composition and I have not seen any full up aircraft tests (such as have been performed with modern jet fuel) that assesses the added hazard of storing large volumes of cryogenic fuel in a passenger aircraft.
On the plus side, hydrogen powered aircraft could have smaller (possibly cheaper and more quiet) engines. They would not pollute as much (though they still generate NOx). Despite the extra tankage, the aircraft might even be lighter and cheaper. It is possible, therefore, that a fleet of hydrogen-powered airliners might be cheaper to buy and operate than a fleet of normal ones. Or at least it would be if you didn't have to factor in the capital cost of rebuilding the entire fuel production, fuel transport, and refueling infrastructure. But of course you do. If something (a huge terrorist campaign or a sudden shortage of oil) were to wipe out our current fuel infrastructure and we had to rebuild it from scratch, then we might want to look at hydrogen again. Until then it will take a revolution in fuel storage density, hydrogen production and transport technology, or some new super hydrogen-only super engine to justify junking a fuel infrastructure we have already paid for.
This is not a new idea. Hydrogen has been considered as an alternate fuel in airliners since at least the 1970s. There are good reasons why it has not been adopted.
Bottom line, for now liquid or slush hydrogen is the only practical storage method for large aircraft. Even then, the storage densities of Hydrogen suck. Fire hazards are safer, but it almost certainly would not have prevented the WTC collapse (it might even have hastened it). The added hazards of cryogenic fuel (especially if stored in the fuselage) may more than make up for the reduced fire hazard. Like so many other technologies, it offers the tantalizing potential for reduced costs; if only we didn't have an already-paid-for infrastructure that supports the current technology of choice... but we do. If you are building a scramjet then it is probably worth the effort to put up with the extra tankage and the cryogenics and the custom fuel infrastructure. If you are building a passenger jet, then you are just asking for more cost with only incremental benefits that have yet to be demonstrated in full up testing. If the gov't wants to help this along, they could have an X-plane program to demonstrate full up development of a hydrogen cargo plane or bomber (the engineering would be similar enough to a civilian airliner for lessons to carry over), then slam one of the planes into the ground in a simulated crash when the program is over to get data on the actual safety of large hydrogen powered aircraft. Until then, the technology will (rightly) lie dormant until something makes it more economically attractive (i.e. a more efficient use of resources).
References: Hawkins, W.M. and Brewer, G.D., "Alternate Fuels Make Better Airplanes: Let's Demonstrate Now," _Astronautics_and_Aeronautics_, Sept. 1979
Raymer, D.P., _Aircraft_Design:_A_Conceptual_Approach_, AIAA, 1992
Wouldn't hydrogen fuel cells, in cars or planes or where ever technically possible, reduce the US dependence on Middle Eastern oil? Not to be too much of a cynic or an isolationist, but wouldn't that alone help to lessen some terrorist problems, if we could decrease our presence in the region?
I don't know off the top of my head. If you've seen the Hindenburg film, then you haven't seen hydrogen burning. Hydrogen burns almost invisibly, with a dark blue flame, not billowing red and orange flame.
Basically the gist of it was that the envelope was doped in a sealant that uses the same chemincal composition as solid rocket fuel. An electrical discharge (static charge is the commonly accepted source) ignited the envelope. It burned for quite a while before the hydrogen exploded.
It was ages ago that I did a report on a number of different kinds of fuel, and the information could have been out of date by that point, for all I know. Somebody mod Mista Blue Informative. :>
Only if it involves those clever anagrams (really!) that you used for the first one. What a riot!
I have met guys who work on development of Cryogenic rocket engines for space applications. One of the componets used in these is Hydrogen. From whatever I have heard, handling Hydrogen in any form is a VERY tricky thing, since leakages can easily cause major explosions...
You don't use fuel cells in jets. You pump the H2 directly in, its just a fuel that burns and creates thrust. It even works better than JP-4 (jet fuel) because it gassifies at STP. No sprayers or injectors required.
********* sig: If you don't like the law, get filthy stinking rich, and buy a better one.
According to this page (view with scripting turned off) they changed the spelling so Americans would know how to pronounce it. Not sure if that's the real story, but it's better than any other I can think of.
sulli
RTFJ.
Given that George Dubbya's revenue comes from oil I wouldn't hold my breath waiting for it to receive support from high up.
of course this is hindsight
but how about just making it SOP to dump all but enough fuel to land as soon as the bad guys demand control of the plane.
tanker planes used to practice doing this at otis afb regularly.
of course the 30 years of dumped fuel is now percolating thru much of cape cod, but they *do* know how to do it
(their point was emergency landings with as little fuel on board as possible)
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
This is the second time I've seen him posting this.. he's just reusing the same troll over and over again! At least it's more ecologically sound, I guess.
Falling or being burned by diesel from the engines.
The planes still may have been impressive bombs, but maybe the attacks would have been economically more difficult for the terrorists to pull off. I dont think its much of a stretch to say that their funding came from, if not one or more middle eastern states, at least individuals who owe their entire fortunes to the sale of oil. If airplanes could run on hydrogen fuel cells or other non-oil-based alternatives, one can assume we would have that technology in cars and other devices. (I base this assumption on the fact that planes are designed to be as light as possible. Current cells are quite heavy and it requires so many of them, that is why they are not used in cars much until recently. If my assumption is wrong, please correct me.)
If we, as a culture, become less dependant upon oil, the individuals/countries sponsoring these groups will have less income. Decreasing demand would not only decrease the volume of their sales, but the price per volume would decrease as well as suppliers competed to stay in business.
Of course, I realize that if we take away this source of income, these groups will probably find a way to get it elsewhere. However, most of these governments have made so much money in oil, they have forsaken development of other industries. When it dries up, they will be in trouble, at least for a while. I think these groups would experience the same effects.
The ivory tower has never had to reach so h
They've already done the AIRPLANE CRASHING thing... I'll bet you a 200 mhz cyrix 686 that they aren't going to do that again. I'm sure they've got tons upon tons of other means. That was the first thing I thought when I watched the WTC crashes. 'What else is going to come, surely that can't be all...'
If I were the gov't I wouldn't be so much worried about the planes and jets anymore, but perhaps buses, trains, etc. You can't do the same tricks to death.. sooner or later people catch on and I know they know this. Get over the whole plane thing now. Its not very likely at all to happen again in the near future.
You're nothing; like me.
It's true that fire suppressing foam can be nasty stuff, but it's not usually outright poisonous. One problem is that foam works by smothering out the fire, and if a person got caught in the foam blast, they'd have the same problem, as humans and fires both need a constant supply of oxygen. However, the main reasons water is used are:
1.) Water is cheap compared to foam.
2.) Water is sufficient to put out most building fires (grease at Mickey D's and jet fuel excluded).
3.) Water is cheap compared to foam.
4.) Water is not very likely to kill someone caught in the suppression zone like halon can.
5.) Water is cheap compared to foam.
Virg
...safely would be very hard considering the people in the plane. Wouldn't latest events be nearly as horrific if those planes hit some abandoned building in the middle of nowhere? I mean, sure h2 aircraft idea is cool but what is the fuss about it being anti-terror device?
Gentlemen, you can't fight in here, this is the War Room!
Where does that energy come from? Well, today, the bulk of our energy comes from oil, so that's why I said we'd need to burn more oil to make hydrogen than we would if we simply used the oil directly.
I don't think the bulk of our grid energy comes from oil; I think oil is mainly used in vehicles (due to its high power density) and some home heating systems. You would be using grid energy to produce the hydrogen, so that's more likely to use coal, natural gas, nuclear, wind, solar, etc., most of which can be found locally.
Ooh, a sarcasm detector. Oh, that's a real useful invention.
Public concern has been so missdirected. Airplane fuel, crypto, nuclear power plants, give me a freaking break! It's like all the anti-technology trolls are having a field day with the national press. There is no way to think of all of the devious things people can do, and no way to block them all without crippling eveyone's ability to do anything.
Wanna kill lots of people? Let's see, how can we do that? How about blowing up a train load of chlorine tanks in a major urban area? How about a distributed fire bomb attack? A few timers and gassoline containers placed here and there over a few months can light up something that no one could stop. How about hijacking a truck load of fuel and another full of fertilizer? Drive it into a tunnel, into a parking garage, a crowded football stadium and boom. Why not break a gas main in the food court of a very large mall? Then there are the traditional targets, dambs and what not. Hey, that was easy, all the gaurds were at the airport waiting for yesterday's strike.
What are you going to do about it? Stop making plastics? Outlaw possesion of more than ten gallons of fuel? Make farmers go back to manure? Fuel everything with liquid hydrogen? Why not safe and dependable rubberband power? Right.
I'm not having a good day. Does it show?
Friends don't help friends install M$ junk.
High speed nuclear powered aerial gondolas.
--Blair
"No? Dang."
A quick Google search found a NASA article concerning hydrogen powered aircraft vs. JP powered aircraft, I know the article is old but...
0 4/ ch6-7.htm
To sum it up: The JP fueled aircraft was 1/2 as long, but had 40% greater mass; 60% of the mass of the JP fueled aircraft was fuel, opposed hydrogen consuming 1/3 the mass of the hydrogen powered aircraft. The JP powered aircraft had 3/5 the range of the hydrogen powered aircraft.
http://www.hq.nasa.gov/office/pao/History/SP-44
> One place this did happen was (IIRC) in the 1930s. During heavy fog, a twin engine biplane rammed the Empire State Building.
The plane that hit the Empire state building in dense fog was a B-29 bomber (four engines, single stage wings), and it was in 1945.
Virg
Well, trains have the same benefits - while the people aboard can be killed, it's hard to ram a train into anything other than it's own station or another train.
Modern high-speed trains can travel about half the speed of a jetliner and have lower front-end and back-end costs. That is, it's far easier to put a train where you want it (downtown Manhattan isn't a problem) relative to an airport, and it takes less time to board and disembark. Right now, you're looking at an extra hour to board and disembark, and probably another 30 minutes extra travel time to your destination for most major cities for air travel relative to train.
Assuming that doesn't change, any travel of less than about 1000 miles is break-even between high-speed train and airplane. While introduction of high-speed trains to the transportation infrastructure won't prevent what happened on 9/11, we could reduce the number of flights by 1/2 to 2/3. That gives the nation 2x-3x as many resources to devote to protecting the long-haul flights, would substantially improve the air congestion that we current are facing, and could provide a redundant means of moving goods around the county: 10 hours NY to LA is fast enough even for some FedEx rates.
While high-speed rail is more expensive than developing new airliners, long-term it's probably far more cost effective when considering needed development of new airports, etc. High-speed trains could be developed along the right-of-ways used by the interstate system, taking them closer to urban areas, to airports, etc.
Reinforced concrete gets more and more impractical for buildings over about 40 storeys though.
On a pount to pound comparison, hydrogen as about three times better than any of the pure hydrocarbons (62,000 BTU/lb vs. around 21000-22000 for methane, on down through the diesels, etc. (18,500 or so per lb) and then the alchohols, carbon monoxide, and sulfur.
What hydrogen is not is a good fuel by volume: in order to carry a sufficient volume of the stuff, it has to be in the form of liquid hydrogen (also known as LH2), with the accompanying problems of keeping it at cryogenic temps, etc.
Other problems besides the question of where to get the hydrogen from and transport, etc. also contribute to why it probably won't be used on airlines any time soon: Cryogenic tanks would tend to be very heavy, and weight is the enemy of fuel efficiency on aircraft. Secondarily, hydrogen burns very very hot and unburned hydrogen is very corrosive to many kinds of metals. So you have secondary issues about how to handle the fuel as it transitions from it's extremely cold liquid state through the gaseous phase into combustion, and then keeping the engine temps sub-critical.
But if all the other problems were solved, the LH2 fueled 747 could fly the same number of passengers about three times the distance on the same weight of fuel.
...Open Source isn't the only answer -- but it's almost always a better value than the alternatives...
guns are more along those lines, or genocide.
this is just something that goes against one of their agendas, but there are plenty of ways around it... like bringing on a bomb, then they have a guided missile for free (cost of bomb I guess).
There are some odd things afoot now, in the Villa Straylight.
Just because something has as much or more stored energy than something else does not neccesarily mean that it is as volatile.
:-)
Fuel cells can work in a number of diffrent ways. And you can store hydrogen in a number of diffrent ways. If the hydrogen were stored in water for example, it most certainly would not deontate from a simple impact. Of course hydrogen stored as water could not be converted into energy because it's in a lower energy state than free hydrogen and water.
But the same goes for Uranium. You'd think that would make a big boom, but if we had nuclear powered airplanes, and one hit a building, it wouldn't explode like a bomb. If containment was breakched of course, there'd be a whole other problem, and there's no way americans would stand for nuclear powered jets right now.
So there are perfectly safe ways to store energy in an easily retrievable form which won't go boom when the fuel hits something.
Coal for example. Let's build coal powered airplanes!
It's not common knowledge but when the use of asbestos was stopped abruptly above 64th floor the afghan asbestos mining got into cashflow problems that they never recovered from. For this(and some other) reasons they did not take it too well.
Later on these people were very helpful to provide Bin Laden with the inside info they had on WTC and a nice fireproof system of connected hideouts in the deserted mines.
Ironic, isn't it.
An explosion of hydrogen on a rocket would not be the same as hydrogen on a plane.
Hydrogen would disperse very quickly.. very very quickly, because it is a gas at room temperature and a fire (which is hot) makes things expand, the the hydrogen would expand consuming any available oxygen, and at the same time become very cold.. if I'm correct.. hey!, this might actually put out fires.. no oxygen and no heat! Now as for rockets.. I believe they carry large ammounts of oxygen.. so they can burn a lot very quickly..planes don't need to burn all thier fuel in a short time.. so don't need oxygen tanks for fuel..
Now, the WTC, I think clearly withstood with force of the impact.. If it wasn't for the sustained burning they probably would have held together
okay, this is my two cents
Hydrogen has 1/6 the amount of energy stored in it as gasoline does (vs. about 2/3 for ethanol and 1/2 for methanol). I expect it's even worse for jet fuel. That means that the same fuel capacity has 1/6 the range, which will give most long range jetliners a range too short to be of any use whatsoever.
And despite this clueless clown's assertions to the contrary, hydrogen tanks will cheerfully explose, not matter what, under the right conditions. Especially since it has to be kept under intense enough pressure to be liquid to be of any use at all as a fuel.
Well since they're allready laying off a ton of people they might aswell lay off the pilots and invent a advance automatic pilot system that can handle any kind of situation. With built in terrorist shockers! No pilot to kill/move out of the way and the terrorist can't do anything.
Or! make all the pilots sit in a big room and modify the planes in Radio Controlled ones! That way I can get a job flying planes.
/me dusts off his Flight Simulator for windows 95
Any resemblance with actual facts is purely coincidental :)
A friend of mine, who's now an attorney, used to be a LOX Jockey for the Navy. The fighter pilots breathe pure oxygen at night and above 10,000 feet during the day, and it's supplied from a tank of liquid oxygen that's plugged in to the side of the plane. A relatively small unit, capable of being hefted and installed by a single person, contains a 24-hour or more supply of O2 for the pilot.
So there is some precedent for the use of cryogenic liquids in airplanes - it's not off-the-wall technology.
And besides, you wouldn't have to pipe the liquid to the engines - you'd just have regulators attached to the tanks that deliver gaseous hydrogen to the gas turbines.
-Michael Pelletier.
Sure JP7, the fuel used to fly the SR-71 would be expensive but that stuff just does not burn... They did tests by dropping a lighted match into a can of it and it put the match out. Also engines would be fairly easy to retrofit. Just a matter of setting up refineries that can handle that much volume and convincing people the added cost is worth it. But it might not be that much if produced in volume. I dont really know the tecnichal info on the whole thing.
Just a thought... why don't the planes lock the doors to the cabin during flight.
That way no-one can actually take over the flying of the plane.
If none of the crew, including the pilot, can physically open the door then a hijacker would have a difficult time making the pilot fly into a building.
Simple - much more than changing every airport in the world.
-- You ain't seen me, right?
Lets face it, oil is the root of the terrorist attacks on the US. America wouldn't give a shit about the Middle East if we weren't dependent on the oil from there. The oil corporations basically dictate the types of governments that run the countries over there. That is why there is so much anti-American sentiment in the middle east.
I wondered about this, also.
From the linked site, it appears that you'd have install different engines and different fuel tanks, probably a whole new plane. I don't think the tech is ready.
Also, we don't have sources for hydrogen capable of delivering the quantities it would take. I understand hydrogen is more difficult to ship than natural gas.
That said, however, hydrogen is not as dangerous as other fuels because it rises. I've read that the people who burned to death in the Hindenburg wreck were covered with diesel fuel. The real hazards were that and the aluminum paint used on the hull.
If you really wanted an airplane that did not have any explosive or flammable fuel on board, there are two options.
One, of course, is physical energy instead of chemical energy. I am, of course, refering to a big rubber band. I had a small model airplane that worked on the same principle when I was young. Of course this is not practical, since range would be incredibly short.
The second solution would be to use nuclear energy. A small atomic pile could provide power for the engines. A heat exchanger could take heat from the reactor and input it into the engine in place of the normal fuel combustor. Considerable research was done on this concept during the 1950s and 1960s and the theory is sound. I am sure that some people are going to immediately complain that this design replaces the danger of fire with the danger of a release of radioactive material in the event of a crash. I am happy to report that as part of the Nuclear Aircraft research previously mentioned a reactor design was developed that could survive a high-speed, worst-case-scenario crash without releasing any radioactivity. The technology was demonstrated by slamming a prototype into a hardened concrete target at the aircraft's top speed. Given the current advances in materials and nuclear technology since the Nuclear Aircraft program, surely even greater safety could be achieved with present designs.
I do not expect either of these solutions to be implimented, but then I don't expect to see Hydrogen airliners either (or at least until oil gets a LOT more expensive).
I remember the standard school test for hydrogen was when ignited there was a popping sound. Why? cos its pretty damn explosive.
The next time I fly a plane and I hear a popping sound I hope its my ears and not the fuel!
-- Cheer, Cheer, The Red and the White.
A little knowledge is a dangerous thing.
There are a lot of people on Slashdot that know a little bit about the science and technology outside their area of expertise.
What amazes me is the belief by so many people that the experts and specialists who work in these fields must be idiots who cannot see the obvious solutions that seem to occur to the "brilliant" outsiders that reside here at Slashdot.
A little hint people. If it is a completely obvious solution, then at least one of the "experts" has probably also thought of and analyzed it. If a completely obvious solution has not been implimented then it is probably because there is some subtle problem with it that is beyond your ability to forsee.
Regardless of other consequences, using hydrogen fuel would also help cut down on polution around airports. Since Hydrogen burns to form water, airports would at worst be a bit steamy, instead of borderline toxic.
BlackGriffen
If anyone is familiar with the theory well enough maybe he/she can explain what would happen if some plutonium fell into a tokomak plasma generator? Basically the question is what happens to a heavy radioactive particle if it is hit with billions of overheated neutrons and some He4 alpha particles? Would there be an electrical discharge?
You can't handle the truth.
What about nuclear power? It will not explode at all in a crash. We already have nuclear powered submarines, aircraft carriers, and space probes. Why not a nuclear powered jetliner?
It's true, if the plane were filled with Hydrogen instead of jet fuel there wouldn't have been that big orange fire... There'd have been a big BLUE fire, and a nice explosion to boot.
For the people who want to say that Hydrogen is perfectly safe, I have two words for you: The Challenger. Space shuttles run on Hydrogen after all, so I guess there's no danger of explosion or fire....
This guy is an opportunistic fuckwit, and nothing more.
Ok, so there may be some merit to the idea. At normal temperatures, hydrogen would quickly vaporize. Being lighter than air, it would be less likely to puddle, and the expanding gas would likely displace most of the air in a building, therefore snuffing out any fire inside. With any luck the fire would burn mostly outside, where there's a ready supply of oxygen.
On the other hand the amount of fuel needed to power what would be a very heavy aircraft (with the extra weight and drag of pressurized tanks to carry around) might just come gushing out and pour deep into the building first, just like the jet fuel did. And the energy released during the explosive decompression of the tanks could very well do a lot of damage. What's worse is that while the structure might be saved, many more people would die a horrible death of suffocation and extremes of temperature!
Using a nuclear reactor to power a plane would eliminate most of the threat of fire. But we immediately see the problem with that. Rather than speculating what kind of fancy new barn door might be closed after all of the livestock has escaped, we should channel our energies into finding the horse thief!
Also, H by itself doesn't contain any usable energy that we can liberate (except through nuclear reactions). The energy that you can liberate by burning H2 is actually less than the energy it takes to separate existing H out of whatever molecular bond it's already in, to make it into H2. So, in essence, by electrolysis, or whatever method we choose to use, we are "creating" H2, in the same way that if we combined gaseous H2 and gaseous O2 to get H2O - we would be essentially "creating" water out of its constituent components.
Refining oil is not the same at all - we already have the really long carbon chain, which contains a fair amount of usable energy. To liberate that energy, we burn the oil as a fuel - in whatever form we need it - fuel oil, gasoline, kerosene, etc. All forms already contain energy, we're just releasing it through an exothermic reaction. The energy that we put into refining doesn't actually add any energy to the oil, we're just changing it's form somewhat to make it easier to use. All of the energy we get out of it is already there.
Think of it this way: burning oil is like dropping a brick from the top of a building. The potential energy already exists, we're just releasing it. "Creating" and then burning H2 to release energy is like picking up a brick, climbing the stairs to the top of the building, and then dropping it off. There's no useful potential energy in the brick until we climb the stairs to the top of the building to increase the energy. However, in "useful" terms, it's usually better to use the energy it would take us to climb the stairs and drop the brick by directly throwing the brick. Same results, less energy used.
See the difference?
Help find a cure for Gidget.
Simple -- use nuclear power to crack the water. This does actually mean we need to build some efficent recyclers for spent fuel (we don't have any commercial ones AFAIK). That would seriously reduce the output of nuclear waste from these plants, but even if we don't the nuke plant doesn't have to fly over my house at 300+ knots.
Ok, those of you who don't beleive in nuclear power can consider your favorite power source, but the point is that H2 combustion permits you to move the power from a fixed site, to the airplane (just like we move fossil fuels from where they are), and in general it's a lot more feasible than using those other sources in the plane. Anybody care to comment on the efficiency of h2 as a power transmission medium?
I see the difference. What you don't seem to be able to see (or perhaps are simply neglecting to mention), is that hydrogen is a particulary good place to store that potential energy. Why ? Because it can be used in reactions that produce no by-products (i.e. H20 -> add electrical energy -> H2 + 0 -> derive electrical energy -> H20) using fuel cells for instance. This means that it is completely environmentally neutral, and yes it is also far safer than gasoline, as it is explosive over a much narrow range of conditions, and dissipates rapidly.
If I had a project which involved flying objects filled with flammable substances, I wouldn't call it 'Project Phoenix'. Project 'flying extinguisher', perhaps.
Hyrogen is much more volatile than gasoline... don't know about jet fuel
It's not even his troll, he copied it off some other guy a week ago, and is just re-using it constantly.
l@m3r
who cares how easily aircraft can be redesigned with safer fuel -- the government, under threat of arrest, confiscation, and imprisonment, is taking your tax dollars and giving them to the airline companies. as the multibillion-dollar Star Wars project has confirmed, the government has no qualms about spending the money it takes from you without your permission.
Hollywood, Television, has become the dream machine. We need to take that back; each of us is a Dream Machine
In Toronto the ground crew towing an Airbus lurched forward too quickly causing the nosegear to bounce slightly. At the apogee of the bounce the computer interpretted the lack of pressure on the landing gear as the plane being in flight, then throttled up the engines to avoid stalling. The plane plowed into a hanger wall and Airbus prompted shipped a patch for its software.
The intense heat may have caused the towers to collapse which cause thousands of deaths, but the intense heat would also have sterilised any attempt at biological warfare which could have affected millions. This sprang to mind following the hype and the sales of gas masks etc when CNN was waffling about the threat of biological warfare regarding these attacks. Of course there are better methods (eg putting in water supply) but just a thought.
Phillip.
Property for sale in Nice, France
Besides close packing, this limits the rate of release. To some extent, the rate can be tailored (to, say, 120% of maximum consumption in nromal operation). In the case of the WTC, the slow release would have resulted in a slow burn rather than an ultra-hot explosion (the big orange flash just after the second plane got eaten by a building). If the fuel tanks were thoroughly enough ruptured, the H2 concentration might even be too low to support continuous combustion.
As well as all of this, H2 doesn't make as good an explosive as jet fuel (it burns slower). The H2 in jet fuel is packed closer together, kind of like in the special catalytic tanks, than in the wild state.
However, all of this would require a complete redesign of passenger aircraft and their engines for the considerably different storage, transfer and burning properties of H2. You could not realistically retrofit existing aircraft, with the possible exception of short-haul jets. There would be other prices to pay for the reduced efficiency of pure H2, such as bigger storage facilities and more frequent supply runs.
Hindenburg died firstly due to badly chosen material for the skin and bladders, and secondly because of poor design (inadequate facilities for static discharge, for example).
Got time? Spend some of it coding or testing
Many airplane crashes and other accidents just cause small leaks and fires when fuel tanks are damaged, and most or all of the occupants survive. A fairly small leak in a liquid hydrogen tank would cause all of the fuel to soon vaporize and escape--if it is ignited, the aircraft would be destroyed and those inside would likely be killed.
Someone I used to work with was at ground zero of a small hydrogen explosion in a university lab in Gothemburg, Sweden. He was in the middle of a roomfull of escaped hydrogen gas when it caught fire. He lost his eyebrows, but the fire did not burn long enough for his hair or clothes to stay alight. Apparently the force of the explosion was enough to dislodge bricks from the wall some distance away, so it was better for him to be inside the explosion and getting hit with the force from a small amount going up, than at the outer edge, where you get hit with everything between you and the centre.
No! Really? (-:
Splitting the H from the O requires energy (which is why you get energy back when you burn it again). If you could reclaim the H2O after burning, you wouldn't need to carry much fuel at all.
So where do you get stupendous amounts of energy from? The most efficient source would be a pair of small nukes (for balance and redundancy). If you could pull a political rabbit out of a hat and get permits for flying sundry reactors around 24x7 you would be much better off simply using the nukes to heat air directly, or at least to heat a denser fuel than H2.
Another proposal I've seen which is much better is to use a big flat satellite to convert sunlight to microwaves and focus the result onto the 'plane. No chemical pollution at all (clean reaction mass like water or just heat air), no storage problems, little or no explosion if you crash. And cheaper to run, too. If another WTC was in the offing, it would help to turn the aircraft off; unless the hijackers knew how to switch over from microwave power to the backup system, you'd cut your casualties from circa 6000 to circa 300.
BOC, that's all science-fiction stuff (even though we could have built it in the '60s) which takes longer than a term of office to do, and so nobody wants to fund it.
Got time? Spend some of it coding or testing
It seems now because of what happens any plane veering slightly off course would be noticed.
Why not build some burners into the plane to burn off the fuel as fast as possible but only leave enough to reach a local airport. Alternatively maybe dump the planes fuel (possible with a chemical added to stop the fuel dumped being flammable).
This should be able to be triggered remotely by authorities so whenever there is a suspect plane they can dump or burn the fuel off so a crash isn't as disastrous.
I don't belive it will be the entire solution but part of a wider solution.
That is a metal hydride cell, these ae fine for cars where a little added weight doesn't harm your performance as much as an airplane. On a airplane you want as little fuel containment structure for as much fuel volume as possible. Metal hydrides don't store nearly enough hydrogen for its weight to make it effective in anything you have to put in the air. The most effective way to store hydrogen is in a cryogenic tank and even those are bulky.
I'm a loner Dottie, a Rebel.
doesn't matter WHAT fuel you use, if it is capable of producing more energy than lighting it took, it can become an explosive. that sounds like a primary requirement to powering a plane/dirigible/rocket/human cannon to me. if you are going to move tens of thousands of tons of metal, fuel, knickknacks, and paying passengers overhead and hope to do so reliably, there is always going to be a risk that somebody can use the contrivance as a weapon. TWA-800 showed that jet fuel makes a dandy FAE bomb, and that fuel is little different than the number-2 fuel oil that TV ads in North Dakota used to say is so safe to have in your home, you can put matches out in a beaker of nice, clear fuel. I seem to remember the account exec telling me it took 3 takes to get that ad on film. it's all in how you present the fuel, the air, and the spark to each other... and any fuel can be vaporized and ignited explosively.
if this is supposed to be a new economy, how come they still want my old fashioned money?
The energy density of hydrogen compared to gas or kerosene is low. A gallon of jet fuel will take you a lot farther than a gallon of liquid hydrogen. It would certainly be clean burning but you would have to have high-pressure cryogenic tanks to hold the liquid hydrogen, which adds weight, and you'd have to carry a _lot_ of it to go the same distance as a standard kerosene/jp4 jet.
Your plane ticket prices would really shoot through the roof. Only the rich need consider flying.
In Bushworld, they struggle to keep church and state separate in Iraq as they increasingly merge the two in America.
Assuming we can create a containter that is strong enough to withstand the air pressure outside, wouldn't a blimp with a vaccuum inside instead of helium/hydrogen work even better? After all, isn't it true we use the first two elements because they are so light? Make it even lighter by removing all the gas and the air pressure around it will push it up, right?
Remember "Bring 'em on"? *sigh
A *fantastic* source of information on H2-powered aircraft and rockets is at http://www.hq.nasa.gov/office/pao/History/SP-4404/ contents.htm.
So you have to move the burning match from far enough away not to ignite the fumes to under the surface of the liquid gasoline fast enough to keep from igniting the fumes before the match is smothered, and you only have to do it not quite fast enough just once to probably render yourself and any onlookers unable to perform that or any other experiment ever again.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
The Hindenberg had a fair number of survivors, and those who died did so because of impact or because of the fuel used to drive the engines. Hydrogen, as the starter of this thread pointed out, is volatile, so when it caught on fire it burned off nearly invisibly and instantly. The engine fuel, however, burned longer. The majority of the fire was due to the fact that the shell was coated/impregnated with iron oxide and aluminum powder, a.k.a. THERMITE. Nasty stuff, that.
Alternate fuel sources do not release as much energy as gasoline. The current fuel source was chosen for a reason: it is a very energetic fuel, if somewhat polluting. The problem is not in the choice of fuel but in the inefficiency of the internal combustion engine. Gasoline releases more energy per molecule of fuel burned than most other fuels, but if it is only ~20% efficient then you need 5 molecules to match the theoretical energy output. This means that the IC engine makes gasoline 5 times as polluting and 1/5th as energetic as it appears on paper.
On the other hand, hydrogen or other fuel cells are mostly electrochemically driven, so the efficiency is much higher (can get to ~80-90%). Hydrogen has the advantage of being the cleanest fuel (end product is just water, not CO2), but power output and efficiency are problems for automobiles, let alone something as big as a plane. Once in the air hydrogen would probably work, but getting the plane off the ground would require tremendous volumes of H2 or tremendously powerful slingshots. Fuel cells are currently being used in buses in Chicago and Vancouver, but buses don't try to defeat gravity.
Liquid hydrogen propulsion was considered and rejected for the SR-71. And there was talk of it for the National Aerospace Plane from the Reagan era. But it's not an easy thing to do.
I think Israel has enough bombs going off with sufficient regularity for them to not consider anything that tall as anything other than an all too tempting target.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
The U.S. military has converted to less-volatile fuels, from JP-4 to JP-8. But the airlines already used JET-A, which is essentially the same as JP-8. There's JP-5, which is less volatile and is used by the Navy for carrier aircraft, but it's considered too expensive for the USAF and the airlines. We probably won't see a change there.
by this logic we should be opening attachments in outlook again.
Terrorist 1: "I've got an idea, let's kidnap the president and hold him hostage"
Terrorist 2: "That's a great idea! Oh wait, no...they've got hydrogen-powered aircraft these days"
...are we sure that, given a new-standard of hydrongen-powered planes, there won't be any more gasoline/cherosene powered planes around? one of them, packed with some sort of explosive, could be enough.. are we going to make cherosene powered planes illegal? or to backdoor them? :)
-- There are two kind of sysadmins: Paranoids and Losers. (adapted from D. Bach)
OK, so the energy to volume ratio is lower, so you have to compress it. That way when you get a leak, it becomes a real danger much faster...
And since it is highly pressurized, that will be more likely...
On the whole, I think Hydrogen would be a gad idea...
Also, for the historical record, the Hindinburg was not unprecidented. There had been other, even more serious zepplin accidents. And Zepplin Metalworks now is getting ready to produce a new line of Zepplins, called the Zepplin NT. I hope this is not an omen of things to come...
LedgerSMB: Open source Accounting/ERP
Hydrogen is very light so even in liquid form you need a large tank to hold it. The solution is to compress it so that it occupies a smaller space. If you can, squeeze it so much that the atoms start fusing. The advantage of this process is that you get lots of energy out and don't have to burn the hydrogen at all.
Whatever your opinion on the energy-capacity of Hydrogen... It still stands to reason you need the same amount of energy to fly a 747 load of people from X to Y. It's not as if using hydrogen means you don't need to expend the same number of joules.
So -- It doesn't matter if you use jet fuel, hydrogen or a rubber band -- the same amount of energy capacity needs to be airbourne.
That energy also has to be readily available (as it is for jet fuel or hydrogen)... So if an accident is going to happen, that energy is going to go somewhere (blast, fire, heat, whatever).
I will grant you that if someday, we were to have an abundance of electrical energy that we didn't know what to do with immediately, then hydrogen would appear to be a likely storage container for that energy.
Help find a cure for Gidget.
The above AC is right. It is the LH2 +LO2 that makes the big boom. Without enough oxidizer, the LH2 can't all ignite at once.
Not trying to be a troll, here, but it seems unlikely that an automatically-engaged auto-pilot system which cannot be overridden by a human would ever gain approval. If it could be overridden, then it would be ineffective, I suppose.
Perhaps a compromise? What about a pilot-triggered, irreversible auto-pilot? Terrorists board a plane, take the crew hostage, and begin making demands of the captain (or attempt to enter the cockpit and take control). Pilot presses "giant, red button" enters secret key sequence, confirms and--Presto! The plane will now begin beaconing an emergency signal as the auto-pilot takes control and lands the plane at the nearest airport of suitable size. Rig it so that it cannot be reversed until the plane has landed and powered down.
Seems to work for the night manager at 7-11: take away the ability to "open the safe" as it were. They might take a few lives in the cabin, but they would be unable to use the plane as a missile.
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The production of hydrogen also makes it pretty inefficient. You're only going to get the same number of ergs out of the hydrogen as you put in to extract it. So the energy you spent getting the fuel for a plane you could have put into an magnetodynamic slingshot to shoot it into the air. Airplanes are also inconvenient shapes for storage of hydrogen which really wants to be stored in spherical chambers since you're going you have to keep it in a liquid for and thus under pressure. It works for the STS because the main fuel tank stores hygroen in a spherical tank inside the skin of it. To put hydrogen tanks inside of jet liners you'd need to put them in the cabin. Tanks aren't going in the wings like you can do with kerosene base jet fuels.
I'm a loner Dottie, a Rebel.
The Ansul (and other comparable) systems used in restaurants are, for obvious reasons, of relatively low toxicity. Still, when a system is discharged, the kitchen must be thouroughly cleaned, then inspected by the health department (or an approved agency) before the restaurant may be reopened (at least in Indiana).
The foam is also designed to smother grease fires without starting electrical fires and (IMHO) would be largely ineffective in dealing with the kinds of temperatures we saw in the WTC incident. If you consider that recharging a system can cost in the neighborhood of $3,000 for a SMALL restaurant (not sure about installation costs, let alone retro-fitting the install), then add in the added cost of a system using the foam they have on airport runways to smother jet fuel fires, then multiply by the size difference between Red Lobster and all the high-rise towers in every major US city...well, see points 1, 3, and 5 above.
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Fusion is not yet a goer, and it is still not certain that it will ever be a goer. Beamed microwave from powersats is a most definite goer, could be built with 50 year old technology and still turn a profit. Fusion (CanDu and the like) is much cleaner than coal, oil or petrol and could be on-line by next year but for politics.
Hydrogen takes energy to make. That energy doesn't pop out of thin air. You need energy to get hydrogen.
Which savages? Mao? Trotsky? Lenin? Stalin? Hitler? Got the point?
As for meddling in the Middle East to protect energy sources, why not buy LNG from Australia instead? We've got plenty of it, it's called ``the North West Shelf.'' And there are other places in Oz and elsewhere. Or use WW2 technology for making diesel from coal, of which the USA has (pun intended) heaps? The official excuses for continuing to muck around in the Middle East are starting to sound pretty thin now.
Got time? Spend some of it coding or testing
You'd harpoon it from a suitable mooring tower, then reel it in like a jellyfish on a ten-pound line. Of course, actually stopping it would be a bit of an issue... (-:
Got time? Spend some of it coding or testing
You'd harpoon it from a suitable mooring tower, then reel it in like a jellyfish on a ten-pound line. Of course, actually stopping it would be a bit of an issue... (-:
Got time? Spend some of it coding or testing
Unfortunately, when hydrogen burns in the presence of Nitrogen (as in our atmoshere) it creates harmful NOx gases which are tha major source of ozone depletion etc. So while hydrogen theoretically burns cleanly it doesn't in practice. Plus hydrogen doesn't produce as much energy because it burns very hot but also very quickly. As for hydrogen being more dangerous, the initial explosion would be more violent but it would probably not have bruned nearly as long - in this aspect i think it would be better
NeuTurbo
In the late 60's, North and South Vietnam settled an agreement about how to live one with each other. Everything was ok, until the USA started the infamous "Phoenix operation", which was a *terrorist* (yes, that's not a misuse of the word) attack against the North Vietnam leaders, conceived to make their people think that the attack was actually made by South Vietnam. Everything to "protect" the world against the "communist plague". And so the war started, with the USA losing shamefully 60.000 soldiers, burning lots of vietnamese with napalm, and the whole story you all know. Now it's interesting to hear that something named "Phoenix" is being told as a "terrorist" weapon. Funny, isn't it?
(considering the high level of misinformation the USA people have about their international affairs, and the fact that slashdot moderators share this problem, it's unlikely this message will have a high score)
The plane itself is not yet feasible, but for cost reasons, not scientific. It can be built, but it'd be too costly to operate at this point. As to the solar engines, I'm assuming you're discussing solar collectors, although I must have missed any mention of it in the discussion. They do clog up the landscape, insofar as anything visible does, and they can take up a lot of area, but if it's properly built, it's very un-shiny from the sky. Since the point of a reflecting solar collector is concentration of the light, all of the mirrors catch light from the sun and direct it toward the collector in the center, like a radar dish. From above, you'd just see a hundred different views of the collector.
Virg
> Why not take a Relevant Disaster like the Challenger Explosion
> for an example of how a hydrogen fuel jetliner would explode?
Actually, the Challenger disaster is not a good example of this, since the hydrogen burn isn't what destroyed Challenger. When the Solid Rocket Booster burned through its standoff and broke loose, it pivoted nose into the ship. This increased the yaw force significantly, which essentially turned the ship and the main tank sideways into its flight vector. As soon as the ship was turned sideways into its airstream at more than 6,000 mph, the wind shear tore it to pieces. The main tank suffered the same fate, and the ruptures left a big wad of H2 and a big wad of O2 which then made a big cloud, but the shuttle had already been blown to bits by shear force before that explosion ever happened.
> Any fuel that can fly a jetliner is going to be dangerous, and burn at high temperatures.
This is true, but there's one thing that hydrogen does that AirG (or AvGas or any other petroleum product, for that matter) doesn't: dissipate. It would burn hot, but it doesn't burn long, which was the original issue that started the discussion.
Virg
That alone makes the acts of the September 11 terrorists impossible to repeat IMHO.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Second: IANAC (I am not a chemist) but wouldn't the hydrogen still have to store the equivalent amount of energy as the AvGas? Yes, hydrogen burns faster so you wouldn't get the long lasting fires that the WTC got but wouldn't that mean that it would give up the energy quicker, ie HUGE explosion? Hell, it might have brought them down quicker. I'd hate to see what the equivalent of 37,000 litres of AvGas would do if it all burnt quickly! Then again, hydrogen needs lots of O2 to burn so it might only seriously burn once it left the building. And professional fuel chemists among us?
I suggest that instead of replacing jet fuel with hydrogen to make airplane crashes safer, we concentrate on doing away with the fuel altogether. The aircraft could be made to fly using only the atmosphere it travels in as the fuel source. Of course, this would be a monumental technical challenge. In order to reduce its diffuclty to a manageble level, our initial airliner design could focus on just eliminating the fuel used during cruise, and could still carry a small amount of fuel for climb-to-altitude and descent-to-landing. This will mean that there is still a slight fuel danger on the aircraft, but it would be much reduced over current designs.
With the problem reduced to merely eliminating the fuel used during cruise, the problem becomes easier. The proposed airliner could be designed to cruise in the Ozone Layer. Once in the Ozone Layer, the use of conventional engines could be stopped and the aircraft could cruise on engines powered by the catalyitic decay of ozone. Ozone is only a meta-stable arrangement, and its decay into normal oxygen releases energy. The proposed airliner's engines could contain a catalytic bed that would greatly accellerate the decomposition of ozone. The heat released in this process could be used to replace the heat normally gained by burning fuel. An added benifit of such an ozone burning airliner would be that it could have effectively unlimited range, as long is it remained in the Ozone Layer.
I think the only thing to do now when an aircraft is hijacked in mid-air is to shoot it down before it gets near a city. Sorry, all you passengers, but it's too much of a risk. And yes, I'm prepared to take that risk myself. I'm thinking of coming to NY next month. Any recommendations?
I wonder if there would be less animosity toward America if hydrogen rather than fossil fuels were the main source of energy for high-speed long-distance travel.
As long as you go off-topic get SOME of your facts
right!
The Hiddenberg was, as were all Zepplins, of Rigid
construction!
Rigids have self-supporting structure, with separate
internal gasbags!
The Goodyear Blimp is, as is common with Blimps, a
pressure-supported shaped flying gasbag!
Between these two types, there is the Semi-Rigid;
which has usually a rigid keel structure preventing
it from being classed as a blimp!
----Even in the Thirties, the extra safety-factor
of using Helium was recognized. The US had an
embargo on the export of this gas to Germany largely
because it disaproved of Nazi politics.
----Helium supported Airships also came to grief!
The British R-101, and the American Akron and
Macon, to name just three.
----The early US Rigids came direct from Germany,
as the spoils of war after WW1. In US operation
they were converted to Helium lift.
Regards,
JK
(David Bowman, EVA near HUGE Monolithic Win-PC in orbit around Jupiter) "My God - its full of Malware!"
The ME163 Komet flown towards the end of WWII by the Luftwaffe used hydrazine as a propellent. Read the history of these pilots to see some interesting experiences with the stuff. The dangerousness of hydrazine was hammered home into the pilots and flight crews. One demonstration was simply pouring some on the ground and watching things spontaniously burn on contact. Nearly pure hydrogen peroxide was also used with it and it was almost as dangerous. If one spilled on the other they basically exploded! C-Stoff: 57% methyl alcohol, 30% hydrazine hydrate, 13% water T-Stoff: 80% hydrogen peroxide, 20% stabilizers Burn ratio was about 3 units t-stoff to 1 unit c-stoff. As you can see flying such a plane was close to piloting a flying bomb.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
Pure hydrogen does indeed burn nearly invisibly.
So does pure methane, but if you ignite a juicy fart you'll find it lights up a dark room with all kinds of colors, depending of what you've been eating. (NOTE: reproducible experiments are the basis of the scientific method.)
The Hindenburg was not entirely composed of pure hydrogen, therefore it should not be expected to have burned as pure hydrogen does. This does not mean hydrogen was not burning.
The dopant used on the Hindenburg had very little in common with solid rocket fuel; it had more chemistry in common with the roll of tape on my desk, in fact.
--Charlie