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> Hydrogen is also dangerous, and there does appear to be a double standard here. I don't have beef with hydrogen, but I suspect it's a lot easier to secure fu

> Hydrogen is also dangerous, and there does appear to be a double standard here. I don't have beef with hydrogen, but I suspect it's a lot easier to secure fuel in a liquid state versus a gaseous state. Putting a lot of hydrogen in a relatively small steel container for use in an engine seems quite a lot safer than putting it in a big bubble and then dangling people from it. But I am not an aerospace engineer, could be wrong, etc.

bruce511 4y ago
I too am not an aerospace engineer, but venting hydrogen after touch down seems easy enough. After all if you open the cells the gas just goes away. By contrast a broken fuel tank leads to liquids spilling on the ground, which seems like fun. That all said, liquids don't explode, gasses do. So if you were unlucky and the hydrogen exploded then life would get very exciting very quickly.
- worik 4y ago
  > That all said, liquids don't explode, gasses do There may be a technical definition of explosion that says an exploding tank of fuel is not "exploding". Do you care? A ball of fire is an horrific thing
  - bruce511 4y ago
    It's probably helpful to ignore Hollywood here. We see exploding cars all the time, but in real life cars don't explode. They can burn of course, and a fireball is a fireball, but an explosion creates shock waves, and all kinds of ancillary damage. Recall the Beirut explosion recently - the fire was relatively contained, but the damage from the explosion is vast. So yeah, talking about gasoline here - the liquid doesn't explode, it burns. However the gas (as in gas, not liquid) can explode, rupturing the tank and spraying burning liquid everywhere. The worst case is a tank mostly empty - the fumes explode, spraying the rest of the liquid. The best case is a full tank. Liquids can absorb a lot of heat, without expanding or creating pressure. Once they boil though (which requires that the liquid doesn't already "fill the tank", pressure builds leading ultimately to the rapid disassembly of the container. Incidentally this is why throwing an _empty_ aerasol can on a fire is very dangerous, possibly more dangerous than a completely full one (depending on the contents). But to your point, and explosion and a fire are very different animals, with very different outcomes.
culebron21 4y ago
I don't know the statistics, but a damaged and leaking LPG cylinder seems more dangerous than leaking kerosene or gasoline, because the gas boils off and leaks itself. Here's what happened 10 years ago: https://www.youtube.com/watch?v=FG1LGKieTxY https://www.youtube.com/watch?v=FG1LGKieTxY I understand that it's just reckless driving. And had this been a gasoline tank, it may have burned as well, but at least no cylinders would have flown around. Though, its still seems safer than pressurized methane. 300 bar make cylinders explode, probably from material fatigue. It doesn't burn, because decompression makes it super cold, but still, the car is ripped apart. https://www.google.com/search?q=%D0%B2%D0%B7%D1%80%D1%8B%D0%B2+%D0%B1%D0%B0%D0%BB%D0%BB%D0%BE%D0%BD%D0%B0+%D0%BC%D0%B5%D1%82%D0%B0%D0%BD%D0%B0&tbm=isch https://www.google.com/search?q=%D0%B2%D0%B7%D1%80%D1%8B%D0%...

bruce511 4y ago

I too am not an aerospace engineer, but venting hydrogen after touch down seems easy enough. After all if you open the cells the gas just goes away. By contrast a broken fuel tank leads to liquids spilling on the ground, which seems like fun. That all said, liquids don't explode, gasses do. So if you were unlucky and the hydrogen exploded then life would get very exciting very quickly.

worik 4y ago
> That all said, liquids don't explode, gasses do There may be a technical definition of explosion that says an exploding tank of fuel is not "exploding". Do you care? A ball of fire is an horrific thing
- bruce511 4y ago
  It's probably helpful to ignore Hollywood here. We see exploding cars all the time, but in real life cars don't explode. They can burn of course, and a fireball is a fireball, but an explosion creates shock waves, and all kinds of ancillary damage. Recall the Beirut explosion recently - the fire was relatively contained, but the damage from the explosion is vast. So yeah, talking about gasoline here - the liquid doesn't explode, it burns. However the gas (as in gas, not liquid) can explode, rupturing the tank and spraying burning liquid everywhere. The worst case is a tank mostly empty - the fumes explode, spraying the rest of the liquid. The best case is a full tank. Liquids can absorb a lot of heat, without expanding or creating pressure. Once they boil though (which requires that the liquid doesn't already "fill the tank", pressure builds leading ultimately to the rapid disassembly of the container. Incidentally this is why throwing an _empty_ aerasol can on a fire is very dangerous, possibly more dangerous than a completely full one (depending on the contents). But to your point, and explosion and a fire are very different animals, with very different outcomes.

culebron21 4y ago

I don't know the statistics, but a damaged and leaking LPG cylinder seems more dangerous than leaking kerosene or gasoline, because the gas boils off and leaks itself. Here's what happened 10 years ago: https://www.youtube.com/watch?v=FG1LGKieTxY https://www.youtube.com/watch?v=FG1LGKieTxY I understand that it's just reckless driving. And had this been a gasoline tank, it may have burned as well, but at least no cylinders would have flown around. Though, its still seems safer than pressurized methane. 300 bar make cylinders explode, probably from material fatigue. It doesn't burn, because decompression makes it super cold, but still, the car is ripped apart. https://www.google.com/search?q=%D0%B2%D0%B7%D1%80%D1%8B%D0%B2+%D0%B1%D0%B0%D0%BB%D0%BB%D0%BE%D0%BD%D0%B0+%D0%BC%D0%B5%D1%82%D0%B0%D0%BD%D0%B0&tbm=isch https://www.google.com/search?q=%D0%B2%D0%B7%D1%80%D1%8B%D0%...