That may work in the US, but it will be much harder in Europe, because of the very high price of land around cities.
20 miles from Paris, a cultivated field sells for about 150 Euros/sqm, about half a million dollars per acre, just because some day something might get built on it.
20 years ago, the cost of 1 mile of highway about 5 miles south from Paris was about 500 million dollars mostly because of the price of the real estate you had to build it through. The price today would probably be at least twice that, probably more like 3-4 times.
It's because of those costs that flights to London City airport are twice as expensive as the same flights to Heathrow.
That's why the trend in Europe is to build high-speed trains instead. There already are train stations inside cities.
Re:35 min. NY to LA passenger flights? Keep dreami
on
The Future of Flight
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· Score: 1
There was also the fact that the planes were getting old and maintenance costs were escalating.
A Mach-2 plane requires a lot more attention than a subsonic one, and it's much more expensive to prolong its life.
There are conductorless subways already, and nobody seems to mind much.
There will be pilotless aircraft sooner or later.
There is a powerful incentive to design pilotless fighters:
Current AA missiles can maneuver at 30g and a piloted aircraft is limited to about 10g lest its pilot passes out. There will come a time when piloted aircraft will be sitting ducks for missiles.
Once the technology has been developped for the military, it will only be a matter of time for it to migrate to commercial planes, just as was the case for fly-by-wire a couple decades ago.
A dual-decker TGV carries 510 passengers over 450km (280 miles) in 110mn.
With a top speed of 300kph, we can assume it's using its max 8,800Kw for about 60mn and, say, on average 60% of that the rest of the time for a total 8.8 + 5/6 x.6 x 8.8 = 13.2 Mwh for the trip.
At 12 Mwh per ton of fuel, that's 1.1t. Diesel fuel weighs about 8 pounds per gallon so that's about 300 gallons.
Assuming our TGV is 80% full (that seems about typical from my experience), it's getting 280 x 510 x 0.8 / 300 = 380.8 miles per gallon per passenger.
Firstly, there is by definition no "cheap" way to make hydrocarbons out of CO2 and water. It's like making hydrogen out of water: what you must do is reverse the combustion process and somehow "put back" into the system the energy you got out of it when you burned the stuff, plus some overhead because no system is 100% efficient.
For the system to make sense the energy source must of course not come from fossil fuels. It has nothing to do with ecology, it's just that if you use fossil fuel to make ersatz fossil fuel, you'll just end up with less fuel than you started with.
Much as I am a staunch supporter of nuclear power, I must admit that this reverse manufacturing of hydrogen and hydrocarbons is one of the few areas where wind farms and solar electricity actually make sense.
The main problem wind sun and wind as electricity sources is they're unreliable. By unreliable I mean that the production of a given plant depends on random factors and plugging a wind farm on an electricity distribution network causes load balancing headaches because electricity is almost impossible to store and production must at all times be equivalent to demand.
If on the other hand you use your wind farm to extract hydrogen from water, for instance, output variations become much less troublesome.
On a different note, even Greenpeace should favor nuclear over coal plants:
Coal contains trace amounts of uranium and thorium. When you burn millions of tons of coal, however, those few ppm's of radioactive elements translate into very sizeable amounts: it's been estimated that coal plants in the US released 800t of Uranium and 1970t of thorium. So besides CO2, coal also produces large "nuclear" wastes - which are just as radioactive as nuclear plant byproducts but do not seem to receive much attention.
Re:Don't worry, long flights will be around a whil
on
The Future of Flight
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· Score: 1
Oh, I see...
It's not specific to the US, btw.
And even if the practice is theoretically allowed it remains possible for a country to keep protecting domestic airlines by keeping a tight hand on airport slots.
But that's mostly politics in my eyes.
Re:Don't worry, long flights will be around a whil
on
The Future of Flight
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· Score: 1
So it was a purely technical reason that made it possible for a concorde to land and take off from JFK if the other airport was Heathrow or Charles De Gaulle, but impossible if that other airport was LAX???
years of uptime is what gets recorded for servers by netcraft.
X does crash, yes, but the kernel?
I've had exactly one instance that could be a kernel lockup: X hung and after a full hour I still couldn't get a console so I got fed up with waiting and rebooted. So there definetely was a problem. That's one lockup per roughly 5000 hrs of uptime and pretty taxing use.
On the other hand, I have a hard time believing people who say they managed to run Word for weeks without rebooting on Win98. My experience is more on the lines of a day with just one reboot was worth remembering.
The problem was the implication that once you'd learned how to solve your problem you couldn't divulge the information to third parties, in other words help others.
Not only is this against the spirit of free software, it can arguably be a violation of the GPL:
Suppose you fork the project, but couldn't have written your mods without reading the documentation. Is this a violation of the NDA?
Or more bluntly, if for all practical matters the license terms forbid you to post a makefile if you've read the documentation before writing it, is this really free software?
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I've read that the energy expenditure to get to LEO was roughly the same as for flying 10,000 miles. Didn't check it, though.
That may work in the US, but it will be much harder in Europe, because of the very high price of land around cities.
20 miles from Paris, a cultivated field sells for about 150 Euros/sqm, about half a million dollars per acre, just because some day something might get built on it.
20 years ago, the cost of 1 mile of highway about 5 miles south from Paris was about 500 million dollars mostly because of the price of the real estate you had to build it through. The price today would probably be at least twice that, probably more like 3-4 times.
It's because of those costs that flights to London City airport are twice as expensive as the same flights to Heathrow.
That's why the trend in Europe is to build high-speed trains instead. There already are train stations inside cities.
There was also the fact that the planes were getting old and maintenance costs were escalating.
A Mach-2 plane requires a lot more attention than a subsonic one, and it's much more expensive to prolong its life.
There are conductorless subways already, and nobody seems to mind much.
There will be pilotless aircraft sooner or later.
There is a powerful incentive to design pilotless fighters:
Current AA missiles can maneuver at 30g and a piloted aircraft is limited to about 10g lest its pilot passes out. There will come a time when piloted aircraft will be sitting ducks for missiles.
Once the technology has been developped for the military, it will only be a matter of time for it to migrate to commercial planes, just as was the case for fly-by-wire a couple decades ago.
Escape velocity is the speed at which you must travel relative to the earth to escape its gravity field.
When you're in orbit, your speed isn't 0.
In fact, the higher your speed, the higher your orbit, until you reach escape velocity for which your orbit radius gets infinite.
A dual-decker TGV carries 510 passengers over 450km (280 miles) in 110mn.
.6 x 8.8 = 13.2 Mwh for the trip.
With a top speed of 300kph, we can assume it's using its max 8,800Kw for about 60mn and, say, on average 60% of that the rest of the time for a total 8.8 + 5/6 x
At 12 Mwh per ton of fuel, that's 1.1t. Diesel fuel weighs about 8 pounds per gallon so that's about 300 gallons.
Assuming our TGV is 80% full (that seems about typical from my experience), it's getting 280 x 510 x 0.8 / 300 = 380.8 miles per gallon per passenger.
ooops! I meant 800t of uranium and 1970t of thorium in 1982 alone.
Firstly, there is by definition no "cheap" way to make hydrocarbons out of CO2 and water. It's like making hydrogen out of water: what you must do is reverse the combustion process and somehow "put back" into the system the energy you got out of it when you burned the stuff, plus some overhead because no system is 100% efficient. For the system to make sense the energy source must of course not come from fossil fuels. It has nothing to do with ecology, it's just that if you use fossil fuel to make ersatz fossil fuel, you'll just end up with less fuel than you started with. Much as I am a staunch supporter of nuclear power, I must admit that this reverse manufacturing of hydrogen and hydrocarbons is one of the few areas where wind farms and solar electricity actually make sense. The main problem wind sun and wind as electricity sources is they're unreliable. By unreliable I mean that the production of a given plant depends on random factors and plugging a wind farm on an electricity distribution network causes load balancing headaches because electricity is almost impossible to store and production must at all times be equivalent to demand. If on the other hand you use your wind farm to extract hydrogen from water, for instance, output variations become much less troublesome. On a different note, even Greenpeace should favor nuclear over coal plants: Coal contains trace amounts of uranium and thorium. When you burn millions of tons of coal, however, those few ppm's of radioactive elements translate into very sizeable amounts: it's been estimated that coal plants in the US released 800t of Uranium and 1970t of thorium. So besides CO2, coal also produces large "nuclear" wastes - which are just as radioactive as nuclear plant byproducts but do not seem to receive much attention.
Oh, I see... It's not specific to the US, btw. And even if the practice is theoretically allowed it remains possible for a country to keep protecting domestic airlines by keeping a tight hand on airport slots. But that's mostly politics in my eyes.
So it was a purely technical reason that made it possible for a concorde to land and take off from JFK if the other airport was Heathrow or Charles De Gaulle, but impossible if that other airport was LAX???
years of uptime is what gets recorded for servers by netcraft. X does crash, yes, but the kernel? I've had exactly one instance that could be a kernel lockup: X hung and after a full hour I still couldn't get a console so I got fed up with waiting and rebooted. So there definetely was a problem. That's one lockup per roughly 5000 hrs of uptime and pretty taxing use. On the other hand, I have a hard time believing people who say they managed to run Word for weeks without rebooting on Win98. My experience is more on the lines of a day with just one reboot was worth remembering.
Nothing's wrong with that.
The problem was the implication that once you'd learned how to solve your problem you couldn't divulge the information to third parties, in other words help others.
Not only is this against the spirit of free software, it can arguably be a violation of the GPL:
Suppose you fork the project, but couldn't have written your mods without reading the documentation. Is this a violation of the NDA?
Or more bluntly, if for all practical matters the license terms forbid you to post a makefile if you've read the documentation before writing it, is this really free software?