You run H2 rich fuel mixtures to lower the average molecular weight of your exhaust stream, which increases the exhaust speed for a given combustion temperature. Exhaust speed is proportional to Isp, and high Isp is good.
I get that figure from the Space Shuttle and Saturn systems. Though I believe that there are some 1:6 ratios out there these days.
Keep in mind it's a matter of tradeoffs. 1:9 gives you smaller tankage, but lower Isp. Higher fuel:oxidizer ratios increase the size of the fuel/oxidizer tanks, but increase Isp. SO you aim for the "ideal" balance, and we seem to have settled around 1:5 as our ideal point.
Yah, they'll make some things possible that aren't possible now. I doubt they'll make anything that we already have more effective.
Keep in mind that one primary characteristic of military missiles is storability. Having to fuel it up just before launch (which you have to do with LH2) pretty well defeats the purpose.
At least, when it comes to consumables. A hypersonic stealth bomber (if it's possible at all) might be neat.
All you are doing is arguing why A) Tobacco pays off the government and B) Tobacco should be under the FDA.
No, I'm arguing HOW tobacco pays off the government. It's not the lobbyists, it's the taxes.
All I'm doing is pointing out the FDA SHOULD have control over tobacco, they had to specifically exempt it for them not to. It then follows the reason they exempted them is because people want tobacco and because tobacco pumps a lot of money into government coffers. Lobbyists aside, tobacco revenue and taxation are what make it very hard to ban tobacco.
I thought I was saying that very thing. With the addition that the government will NOT do that, because they don't want to shoot themselves in the foot. You don't want them to either, though you may not be aware of it. Trust me, having every government in the USA suddenly looking about for a MAJOR source of new revenue at the same time won't be fun.
It should be noted, by the way, that tobacco growers are highly regulated. They have strict allotments they are allowed to grow in any given year (my father bought a piece of property in Tennessee a few years back, and was quite surprised to find that it had a tobacco allotment attached to it. Not in a bad way, mind, since he found out when someone offered to buy the allotment from him.)
Having been in the military, and watched some of the things they do, I can see your point.
However, one must remember that missiles/shells are "consumables".
And expensive consumables cut into training budgets in big ways. The Navy doesn't fire too many torpedoes in training (they cost too damn much, even if they are mostly recoverable), but the Army shoots a lot of artillery shells out their tubes (because, by comparison, an HE shell is cheap).
A scramjet will make a Patriot missile look like pocket change, and not be especially more capable. So it won't happen.
you only need to carry up ~1/9 of your propellant mass
one sixth. Typical H2/O2 rockets use a five to one ration of oxidizer to fuel. It's still a huge advantage, though.
All things being equal (they aren't, but it gets you in the timezone), an H2/O2 rocket massing 1000T at launch would mass only about 340T by the time it reached Mach 15. A 1000T scramjet would mass about 830T at the same point. From Mach 15, the flight profiles of both would be about the same (both using rockets from that point on, of course), and they'd both burn up ~55% of their remaining mass to get to orbit. So the pure rocket puts ~150T into orbit, the scramjet-rocket hybrid puts ~370T into orbit.
Note: Ignoring friction. Ignoring the atmosphere when convenient, and including it when helpful to do so. Ignoring the details of staging and such, and the extra mass of the airframe built around the scramjet stage. Ignoring the need of the scramjet to reach some high speed before it begins combusting. Ignoring [physical reality as much as possible]....
Ahh. It didn't start at Earth escape speed, it started at Earth orbital speed (~8kps for a low orbit).
It accelerated constantly in direction of travel, thus adding to speed.
Which changed the orbit so the spacecraft went up.
Which slowed it down, as kinetic energy was converted to potential energy.
Thing to remember is it started at ~70% escape speed, and ended up at ~200% escape speed.
Unfortunately, one of the downsides of very low acceleration is that deltaV required for escape is twice orbital speed, rather than sqrt(2) times orbital speed for high acceleration mode.
Given the Isp advantages, it still makes sense to use an ion engine, so long as you aren't in a real hurry to get anywhere.
I'm not saying it should be banned. I'm saying that the belief that banning it would cause the associated revenues to vanish in complete and utter violation of the second law of thermoeconomics is ludicrous. If you ban automobiles, every family now has tens of thousands to dollars to spend on walking shoes and iPods.
Umm, no. Tobacco taxes are a bit higher than "everything else". Except possibly alcohol. If we stop spending $1T (or whatever the actual figure is) on cigarettes, we lose that difference. Tobacco taxes range from $0.07 per pack in South Carolina to over $2 per pack in New Jersey, last I checked. This is in addition to the usual sales taxes (that everything is taxed with).
Add in $0.39 federal taxes on a pack, and you'll get tax rates of $0.46 to ~$2.40 per pack.
Add in local cigarette taxes, and the numbers start getting high. Over $3.40 a pack in some places.
Are high cigarette taxes a bad thing? Only if it encourages your government to depend on that revenue, which our's do. Because all that money is GONE if cigarettes are illegal.
Sure, people now have thousands of more dollars to spend every year. But the things they buy now won't be taxed at around 50% like cigarettes are. They'll be taxed closer to 10%. So assume that imaginary $1T spent on cigs. Half that goes to diverse governments around the nation. The other half goes to the tobacco companies, growers, distributors, truck drivers, etc. If people don't buy cigs with that trillion, they still spend it. But only 10% of it goes into government coffers (not necessarily a bad thing, in my opinion).
So the governments are out $400B. Which they built their budgets around. Which they use to provide services. Which services they won't necessarily be able to afford, without raising other taxes. A lot.
Every time I see an otherwise indefensible industry defended with this reasoning, I can't help but think that it's a closed system; money previously spent on smokes would then be spent on other things. It's like saying that if Ford went under, Americans would spend 14% (or whatever their market share is) less on cars, and our economy would suffer.
Shutting down Phillip Morris would be akin to shutting down Ford. Properly regulating tobacco would be more akin to making automobiles illegal.
This is more like saying that if ALL automakers went under, we'd spend less on cars. And there'd be this massive recession when all the former employees of the auto companies were laid off. And the people who sold cars. And the people who maintained cars. And the people who made and distributed gasoline. and....
Realistically, banning tobacco would not have those effects. Marijiuana growers would switch to tobacco, and people would buy black-market tobacco. The recession as a huge chunk of our economy (bigger than the dot.Bombs) went belly-up overnight wouldn't help. And the tax revenues from tobacco would go from frighteningly large to zero, thus tossing 50 state budgets into crisis, and exacerbating the Federal deficit....
Note that I am a non-smoker, whose wife is allergic to tobacco smoke. I have no love for the tobacco industry or government dependence on it. But I am realistic enough to recognize that bringing tobacco under the FDA would be disastrous, without a looooong period of weaning our governments from those tobacco taxes.
Either that, or the FDA regulates tobacco, and destroys its own credibility by keeping it legal (things with minute cancer risks have been banned - how can they justify NOT banning something as dangerous to people's health as tobacco?).
Tobacco is not under the purview of the FDA because Congress specifically exempted it from such regulation.
Congress did NOT do this because BIG TOBACCO was paying them off. Congress did this because tobacco couldn't possibly be legal as an over-the-counter drug (delivery system) under FDA regulation, since it is a carcinogen (not just a little bit of a carcinogen, but a "you will get cancer if you use this long enough" sort of carcinogen), and tobacco pays an ENORMOUS amount of federal and state taxes.
Note that none of the States that blackmailed the tobacco industry into giving the states $250B wanted tobacco regulated by the FDA. And none of them have regulated or banned tobacco sales, either (other than the same "over 18" they had for decades before the settlement). Same reason - their budgets would go belly-up in a big way if no tobacco taxes were paid.
Tobacco continues to be legal in this country because Prohibition failed in a big way. It is quite clear to the various governments that bringing tobacco under proper regulatory control (banned by the FDA, in other words) would mean a loss of enormous amounts of revenue, a loss of large numbers of jobs in the tobacco industry (and the related industries in the production/distribution chain) with more revenue lost as a result, and a thriving black market such as existed during Prohibition.
Congress isn't sensible (or silly, depending on perspective) enough to remove Prohibition for other "recreational drugs" (marijiuana, cocaine, heroin, etc) but they're plenty sharp enough to realize that adding 1/3 the American public to the consumers of illegal drugs by making the second most popular (or third, if you count caffeine) "recreational drug" illegal as well is a really bad idea.
Alright. 2x10^-4 m/s^2 is ~2x10^-5 G. I'd weigh about 1/14th of an ounce. Most of you would be a bit lighter.
To give a real-world reference, you'd weigh about 2/3 the weight of an American dime.
Which is another way of saying you'd be effectively weightless. Note that if you were in such an acceleration field, and dropped your coffee cup, you'd have a couple minutes before it reached the deck. Letting go of your coffee cup while you typed a quick post to/. and getting it back in hand before it spilled would be quite practical.
That seemed like a ridiculous amount of accelleration, though, so I checked further, and the spacecraft's final velocity is given by the esa [esa.int] as 2737 m/s, not km. Interestingly, that's actually less than the earth's escape velocity by a good margin. My best guess at this point, then, is that the 2737m/s figure is the velocity imparted to the craft by the engine, not counting the initial velocity it was given by the rocket it was strapped to.
Actually, it is almost twice escape speed - the spacecraft was at the moon when it reached its "final velocity". Earth escape speed is only 1400 m/s or so at the altitude of the moon.
Assume Isp ~3000 for an ion drive. Could be lower, could be higher.
Assume a deltaV of 10% of lightspeed. Not really relativistic, but it'll give you an idea.
Assume a 10 Kg spacecraft, before you load the reaction mass aboard.
mass ratio = e^(deltaV/(9.8 * Isp)), which, in this case, is about 7x10^442. So your 10 Kg spacecraft would need 7x10^443 Kg reaction mass.
It's been a long time since I checked, but that's about a bazillion times the mass of the entire universe (10^394 times, give or take a couple-three orders of magnitude).
If by relativistic speeds, you mean 80% or so of lightspeed, then increase the reaction mass to something like 10^3550 Kg or thereabouts.
So, as has been said, ion drives (at least as currently conceived, won't be doing relativistic trips anytime soon).
He didn't? He took 70 tons of silver from one of the ships he captured. And back then, 70 tons of silver was a lot of money.
Re:Probably not the most important cabinet positio
on
Colin Powell Resigns
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· Score: 1
"My local TV news described it as the most important position to resign so far. Isn't Secretary of State the most important cabinet position, period?"
No. Common misconception
Well, no. Secretary of State is higher in the Presidential succession order than any other Cabinet Officer, behind VP, Speaker of the House, and President of the Senate pro tempore.
Secretary of Defense is two places farther down, behind Secretary of the Treasury, which puts him third of the three "important" Cabinet positions. I define "important" here as Secretaries ahead of the Attorney General in the succession order. All other Cabinet Secretaries come in after Attorney General (with Homeland Security at the bottom of the list).
Never thought it was impossible. Well, a qualifier - converting an existing aircraft to H2 burner is most likely impossible.
Designing a plane from scratch to use H2 is possible, and worth doing, once we have an infrastructure that supports H2 everywhere the plane might have to fly.
747-ER carries 240,379 L, according to Boeing. Using your assumptions, that version of the 747 would require an extra 240 m^3 of fuel.
Looks like a 747-400 carries 67,000L of fuel, which is somewhat more achievable without too adverse an effect on passenger capacity.
Note that changing the shape of a wing has a non-trivial effect on performance, and that most of the fuel is carried in the wing (apparently, the 747-400 also carries fuel in the horizontal stabilizers). So the extra 40-odd to 240 Kl will be coming out of the body...
Yah, it's just engineering. It's not a trivial exercise, however.
Most airplanes don't really use fuel cells all that much. They use jet engines, mostly.
I'm none too confident that we could develop a fuel-cell powered jet engine
That said, using liquid hydrogen (which has other issues as a replacement for avgas), if you could get 90% efficiency, if a jet engine gets 30% efficiency, if you want about the same range, then you're still talking quadrupling the size of the fuel tanks. a 747 would need an extra 720,000 liters of fuel tankage.
Since a 747 has 865,000 liters of passenger space, that amount of fuel would reduce passenger space by 83%, leaving them about one sixth the passenger space.
Assuming, just for grins, that half that extra fuel could come out of cargo space (the 747 doesn't actually have 360,000 liters of cargo space), then we'd only reduce the passenger capacity by 42%.
And this doesn't even count the fuel cells, which aren't known as high-density electrical generation devices.
Umm, if that's a high guess, must be nice where you live. We have to run A/C 24/7 ten months a year where I live.
That said, neither solar nor wind are 24/7, so you'd get rather less than you might think out of such a system. Try one third rated output, for a conservative guess - so 7% of your electric bill, maybe?
That said, by your guesstimate, it would cost less than $10,000 dollars to remove yourself from the Grid entirely. Have you done so, and if not, why not?
I mean, who would really but up to such a challenge of giving up everything they have here on Earth? Obviously living on Mars, you would lose so many of the conviences and luxuries you are used to here on Earth. Most likely no more TV, broadband internet, or junk food. You would have to spend your entire life inside a building or in a space suit when you wanted to get out and stretch your legs or explore (if you are authorized to do such things). It would definately take some serious courage to change your life so drastically.
Yep. I'd go in a heartbeat, if it were possible. No more TV - I dont' watch it now. No more broadband internet - that would be annoying. No more junk food - I'm kicking that habit even as I type this - three weeks without a burger, and counting.
Spending my entire life in a building? My current job puts me in a building from just after sunrise to just after sunset right now. It'll be better when summer rolls around again of course. But a desk job here is the next best thing to spending my entire life in a building. Space suit wouldn't bother me, I don't think. Depends on the design of the suit, I guess.
Seriously, it's a chance to be away from the...stuff... I put up with now. Different...stuff... there, of course, but at least it has the virtue of being different.
Only thing that would make me think twice is that likely enough my daughter would want to remain here. Which defeats the whole purpose of colonizing, doesn't it?
The average straight-line distance is ~73 million km, but, of course, spaceships never travel in straight lines. So, I guesstimate that the actual "kilometers traveled" would be 145M km. And, because it's a round trip, double it to ~300M km.
The average straight-line distance is considerably more than 73 Gm. 73 Gm is very close to the MINIMUM straight-line distance. Average is a lot closer to 240 Gm.
Actual distance travelled in a Hohmann transfer orbit (which is a poor choice for a manned mission) is ~600 Gm. Doubled for a round-trip to 1200 Gm.
But colonists won't be coming back, so we can ignore the round-trip figure. Starting from the Moon, chemically-fueled ships can make Mars in six months on a free return trajectory, with a reasonable mass-ratio. Which is short enough that the radiation shielding issue wouldn't be prohibitive and artificial gravity isn't required.
And if you simply MUST have artificial gravity, then take two ships, tether them together with a long line once they enter their transfer orbit, and spin them about their common axis. It's not an insurmountable problem.
I'd like to see a bigger push in requiring all new homes, especially here in CA, to have one of the following to offset the ever growing energy needs and to help desentralize the power grid and to protect from terrorism and the large companies looking to squeeze us with their schemes.
A 80-400watt windmill very small easy to use. (Less than $1500)
or 100watts of solar panels (Less than $1000)
Two of your three options involve spending more than $1000 dollars for the ability to run one (1) lightbulb. Not really terribly attractive.
Now, requiring some amount of solar water-heating is a good idea. Should be added to building codes everywhere it's practicable.
Sounds like part of the money-laundering section, then. Which was authored by...Senator John Kerry (and proudly advertised as his contribution to PATRIOT during the recent Presidential campaign).
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You run H2 rich fuel mixtures to lower the average molecular weight of your exhaust stream, which increases the exhaust speed for a given combustion temperature. Exhaust speed is proportional to Isp, and high Isp is good.
I get that figure from the Space Shuttle and Saturn systems. Though I believe that there are some 1:6 ratios out there these days.
Keep in mind it's a matter of tradeoffs. 1:9 gives you smaller tankage, but lower Isp. Higher fuel:oxidizer ratios increase the size of the fuel/oxidizer tanks, but increase Isp. SO you aim for the "ideal" balance, and we seem to have settled around 1:5 as our ideal point.
Keep in mind that one primary characteristic of military missiles is storability. Having to fuel it up just before launch (which you have to do with LH2) pretty well defeats the purpose.
At least, when it comes to consumables. A hypersonic stealth bomber (if it's possible at all) might be neat.
No, I'm arguing HOW tobacco pays off the government. It's not the lobbyists, it's the taxes.
All I'm doing is pointing out the FDA SHOULD have control over tobacco, they had to specifically exempt it for them not to. It then follows the reason they exempted them is because people want tobacco and because tobacco pumps a lot of money into government coffers. Lobbyists aside, tobacco revenue and taxation are what make it very hard to ban tobacco.
I thought I was saying that very thing. With the addition that the government will NOT do that, because they don't want to shoot themselves in the foot. You don't want them to either, though you may not be aware of it. Trust me, having every government in the USA suddenly looking about for a MAJOR source of new revenue at the same time won't be fun.
It should be noted, by the way, that tobacco growers are highly regulated. They have strict allotments they are allowed to grow in any given year (my father bought a piece of property in Tennessee a few years back, and was quite surprised to find that it had a tobacco allotment attached to it. Not in a bad way, mind, since he found out when someone offered to buy the allotment from him.)
However, one must remember that missiles/shells are "consumables".
And expensive consumables cut into training budgets in big ways. The Navy doesn't fire too many torpedoes in training (they cost too damn much, even if they are mostly recoverable), but the Army shoots a lot of artillery shells out their tubes (because, by comparison, an HE shell is cheap).
A scramjet will make a Patriot missile look like pocket change, and not be especially more capable. So it won't happen.
one sixth. Typical H2/O2 rockets use a five to one ration of oxidizer to fuel. It's still a huge advantage, though.
All things being equal (they aren't, but it gets you in the timezone), an H2/O2 rocket massing 1000T at launch would mass only about 340T by the time it reached Mach 15. A 1000T scramjet would mass about 830T at the same point. From Mach 15, the flight profiles of both would be about the same (both using rockets from that point on, of course), and they'd both burn up ~55% of their remaining mass to get to orbit. So the pure rocket puts ~150T into orbit, the scramjet-rocket hybrid puts ~370T into orbit.
Note: Ignoring friction. Ignoring the atmosphere when convenient, and including it when helpful to do so. Ignoring the details of staging and such, and the extra mass of the airframe built around the scramjet stage. Ignoring the need of the scramjet to reach some high speed before it begins combusting. Ignoring [physical reality as much as possible]....
I imagine that a scramjet is a bit too expensive to make it worthwhile in that sort of application. A (cheap) rocket will do quite nicely.
It accelerated constantly in direction of travel, thus adding to speed.
Which changed the orbit so the spacecraft went up.
Which slowed it down, as kinetic energy was converted to potential energy.
Thing to remember is it started at ~70% escape speed, and ended up at ~200% escape speed.
Unfortunately, one of the downsides of very low acceleration is that deltaV required for escape is twice orbital speed, rather than sqrt(2) times orbital speed for high acceleration mode.
Given the Isp advantages, it still makes sense to use an ion engine, so long as you aren't in a real hurry to get anywhere.
Umm, no. Tobacco taxes are a bit higher than "everything else". Except possibly alcohol. If we stop spending $1T (or whatever the actual figure is) on cigarettes, we lose that difference. Tobacco taxes range from $0.07 per pack in South Carolina to over $2 per pack in New Jersey, last I checked. This is in addition to the usual sales taxes (that everything is taxed with).
Add in $0.39 federal taxes on a pack, and you'll get tax rates of $0.46 to ~$2.40 per pack.
Add in local cigarette taxes, and the numbers start getting high. Over $3.40 a pack in some places.
Are high cigarette taxes a bad thing? Only if it encourages your government to depend on that revenue, which our's do. Because all that money is GONE if cigarettes are illegal.
Sure, people now have thousands of more dollars to spend every year. But the things they buy now won't be taxed at around 50% like cigarettes are. They'll be taxed closer to 10%. So assume that imaginary $1T spent on cigs. Half that goes to diverse governments around the nation. The other half goes to the tobacco companies, growers, distributors, truck drivers, etc. If people don't buy cigs with that trillion, they still spend it. But only 10% of it goes into government coffers (not necessarily a bad thing, in my opinion).
So the governments are out $400B. Which they built their budgets around. Which they use to provide services. Which services they won't necessarily be able to afford, without raising other taxes. A lot.
Shutting down Phillip Morris would be akin to shutting down Ford. Properly regulating tobacco would be more akin to making automobiles illegal.
This is more like saying that if ALL automakers went under, we'd spend less on cars. And there'd be this massive recession when all the former employees of the auto companies were laid off. And the people who sold cars. And the people who maintained cars. And the people who made and distributed gasoline. and....
Realistically, banning tobacco would not have those effects. Marijiuana growers would switch to tobacco, and people would buy black-market tobacco. The recession as a huge chunk of our economy (bigger than the dot.Bombs) went belly-up overnight wouldn't help. And the tax revenues from tobacco would go from frighteningly large to zero, thus tossing 50 state budgets into crisis, and exacerbating the Federal deficit....
Note that I am a non-smoker, whose wife is allergic to tobacco smoke. I have no love for the tobacco industry or government dependence on it. But I am realistic enough to recognize that bringing tobacco under the FDA would be disastrous, without a looooong period of weaning our governments from those tobacco taxes.
Either that, or the FDA regulates tobacco, and destroys its own credibility by keeping it legal (things with minute cancer risks have been banned - how can they justify NOT banning something as dangerous to people's health as tobacco?).
Congress did NOT do this because BIG TOBACCO was paying them off. Congress did this because tobacco couldn't possibly be legal as an over-the-counter drug (delivery system) under FDA regulation, since it is a carcinogen (not just a little bit of a carcinogen, but a "you will get cancer if you use this long enough" sort of carcinogen), and tobacco pays an ENORMOUS amount of federal and state taxes.
Note that none of the States that blackmailed the tobacco industry into giving the states $250B wanted tobacco regulated by the FDA. And none of them have regulated or banned tobacco sales, either (other than the same "over 18" they had for decades before the settlement). Same reason - their budgets would go belly-up in a big way if no tobacco taxes were paid.
Tobacco continues to be legal in this country because Prohibition failed in a big way. It is quite clear to the various governments that bringing tobacco under proper regulatory control (banned by the FDA, in other words) would mean a loss of enormous amounts of revenue, a loss of large numbers of jobs in the tobacco industry (and the related industries in the production/distribution chain) with more revenue lost as a result, and a thriving black market such as existed during Prohibition.
Congress isn't sensible (or silly, depending on perspective) enough to remove Prohibition for other "recreational drugs" (marijiuana, cocaine, heroin, etc) but they're plenty sharp enough to realize that adding 1/3 the American public to the consumers of illegal drugs by making the second most popular (or third, if you count caffeine) "recreational drug" illegal as well is a really bad idea.
To give a real-world reference, you'd weigh about 2/3 the weight of an American dime.
Which is another way of saying you'd be effectively weightless. Note that if you were in such an acceleration field, and dropped your coffee cup, you'd have a couple minutes before it reached the deck. Letting go of your coffee cup while you typed a quick post to /. and getting it back in hand before it spilled would be quite practical.
Actually, it is almost twice escape speed - the spacecraft was at the moon when it reached its "final velocity". Earth escape speed is only 1400 m/s or so at the altitude of the moon.
Assume Isp ~3000 for an ion drive. Could be lower, could be higher.
Assume a deltaV of 10% of lightspeed. Not really relativistic, but it'll give you an idea.
Assume a 10 Kg spacecraft, before you load the reaction mass aboard.
mass ratio = e^(deltaV/(9.8 * Isp)), which, in this case, is about 7x10^442. So your 10 Kg spacecraft would need 7x10^443 Kg reaction mass.
It's been a long time since I checked, but that's about a bazillion times the mass of the entire universe (10^394 times, give or take a couple-three orders of magnitude).
If by relativistic speeds, you mean 80% or so of lightspeed, then increase the reaction mass to something like 10^3550 Kg or thereabouts.
So, as has been said, ion drives (at least as currently conceived, won't be doing relativistic trips anytime soon).
He didn't? He took 70 tons of silver from one of the ships he captured. And back then, 70 tons of silver was a lot of money.
No. Common misconception
Well, no. Secretary of State is higher in the Presidential succession order than any other Cabinet Officer, behind VP, Speaker of the House, and President of the Senate pro tempore.
Secretary of Defense is two places farther down, behind Secretary of the Treasury, which puts him third of the three "important" Cabinet positions. I define "important" here as Secretaries ahead of the Attorney General in the succession order. All other Cabinet Secretaries come in after Attorney General (with Homeland Security at the bottom of the list).
Designing a plane from scratch to use H2 is possible, and worth doing, once we have an infrastructure that supports H2 everywhere the plane might have to fly.
Based on the systems he's used for the cabin, and estimates he's made for his house, a better guesstimate would be $30,000.
And expect to be paying a pretty penny to replace batteries every five-ten years also...
Alas, I have this really big oak tree shading my house (and reducing my A/C load dramatically), so solar power is not practical for me...;(
747 Maximum Fuel Load: 43,625 L
747-ER carries 240,379 L, according to Boeing. Using your assumptions, that version of the 747 would require an extra 240 m^3 of fuel.
Looks like a 747-400 carries 67,000L of fuel, which is somewhat more achievable without too adverse an effect on passenger capacity.
Note that changing the shape of a wing has a non-trivial effect on performance, and that most of the fuel is carried in the wing (apparently, the 747-400 also carries fuel in the horizontal stabilizers). So the extra 40-odd to 240 Kl will be coming out of the body...
Yah, it's just engineering. It's not a trivial exercise, however.
I'm none too confident that we could develop a fuel-cell powered jet engine
That said, using liquid hydrogen (which has other issues as a replacement for avgas), if you could get 90% efficiency, if a jet engine gets 30% efficiency, if you want about the same range, then you're still talking quadrupling the size of the fuel tanks. a 747 would need an extra 720,000 liters of fuel tankage.
Since a 747 has 865,000 liters of passenger space, that amount of fuel would reduce passenger space by 83%, leaving them about one sixth the passenger space.
Assuming, just for grins, that half that extra fuel could come out of cargo space (the 747 doesn't actually have 360,000 liters of cargo space), then we'd only reduce the passenger capacity by 42%.
And this doesn't even count the fuel cells, which aren't known as high-density electrical generation devices.
That said, neither solar nor wind are 24/7, so you'd get rather less than you might think out of such a system. Try one third rated output, for a conservative guess - so 7% of your electric bill, maybe?
That said, by your guesstimate, it would cost less than $10,000 dollars to remove yourself from the Grid entirely. Have you done so, and if not, why not?
Yep. I'd go in a heartbeat, if it were possible. No more TV - I dont' watch it now. No more broadband internet - that would be annoying. No more junk food - I'm kicking that habit even as I type this - three weeks without a burger, and counting.
Spending my entire life in a building? My current job puts me in a building from just after sunrise to just after sunset right now. It'll be better when summer rolls around again of course. But a desk job here is the next best thing to spending my entire life in a building. Space suit wouldn't bother me, I don't think. Depends on the design of the suit, I guess.
Seriously, it's a chance to be away from the ...stuff... I put up with now. Different ...stuff... there, of course, but at least it has the virtue of being different.
Only thing that would make me think twice is that likely enough my daughter would want to remain here. Which defeats the whole purpose of colonizing, doesn't it?
Say, about as large as the passenger compartment. Counterproductive, eh?
The average straight-line distance is considerably more than 73 Gm. 73 Gm is very close to the MINIMUM straight-line distance. Average is a lot closer to 240 Gm.
Actual distance travelled in a Hohmann transfer orbit (which is a poor choice for a manned mission) is ~600 Gm. Doubled for a round-trip to 1200 Gm.
But colonists won't be coming back, so we can ignore the round-trip figure. Starting from the Moon, chemically-fueled ships can make Mars in six months on a free return trajectory, with a reasonable mass-ratio. Which is short enough that the radiation shielding issue wouldn't be prohibitive and artificial gravity isn't required.
And if you simply MUST have artificial gravity, then take two ships, tether them together with a long line once they enter their transfer orbit, and spin them about their common axis. It's not an insurmountable problem.
A 80-400watt windmill very small easy to use. (Less than $1500)
or 100watts of solar panels (Less than $1000)
Two of your three options involve spending more than $1000 dollars for the ability to run one (1) lightbulb. Not really terribly attractive.
Now, requiring some amount of solar water-heating is a good idea. Should be added to building codes everywhere it's practicable.
Sounds like part of the money-laundering section, then. Which was authored by...Senator John Kerry (and proudly advertised as his contribution to PATRIOT during the recent Presidential campaign).