The vehicle was quite smooth in operation. It even sustained an explosion at takeoff on one flight (hydrogen leak before engine start), blowing out part of the aeroshell, and continued to its programmed landing as if nothing happened.
The DC-X vehicle was destroyed when someone at NASA (note, NOT the SDIO-sponsored group which actually built the thing in the first place) failed to reconnect a landing-strut unlock line after it was disconnected to check something else. Re-checking it wasn't on the checklist, for some reason. I personally would find an analysis of who omitted that step from the checklists to be extremely interesting.
I've studied physics for 6 years, so I know physics, OK?
I don't believe you. I cannot conceive of an educational institution with 6 years' worth of courses in physics, not flunking somebody who persists in making such elementary mistakes as failing to distinguish statics from dynamics. I only bothered staying in the university environment a bit over half what you appear to be claiming, and... well, I'll let the results speak for themselves.
Forces are transmittors of energy. You cannot apply a force to anything without also transferring energy.
Wrong on both counts. When you stand up, a force equal to your weight is applied upwards against your feet. What energy is carried by this force? What's the rate at which you gain energy from this force (the power)?
To be nit-picky, energy equals the integral of the dot-product of f and ds over the path s. If you don't have any motion, you don't have any energy transmitted. Excessive forces (even nominally static forces) exerted on a body can over-stress parts of it and cause damage, but a small force acting over a large distance will not cause overstress. Consider the amount of energy you acquire when you accelerate to highway speeds in a car. While the kinetic energy imparted is many times what you could attain by running, the acceleration is only a fraction of a G. The stresses on the body are less than you experience by standing up.
While your explanation is quite sound, it still does not answer the main gist of my argument, that the piston is powered by a combustion. It's not a question of evenly pumping in air in a pneumatic piston, it's a small explosion. Does this sound like an even accelleration to you? ... What I'm saying is that the energy from the combustion is quickly transferred to the leg via the piston and quite violently "shoots" you off the ground. What I'd like from you now, is an explanation as to why you think this is not true. How is the combustion transferred so evenly to the leg?
Ask the designers. If it were my design, I'd either have a low compression ratio to keep the peak forces down to a reasonable multiple of the average, or perhap separate the combustion chamber from the expansion piston and use a controllable valve between them to modulate the expansion. The Russians have been working on this concept for something like 20 years; they're bound to have figured out a few tricks.
Lets consider the combustion an ideal one. I never liked thermodynamics much but let's take a look.
I have no such prejudice against thermodynamics, so I'll be happy to expand on your numbers a bit.
p*V=n*R*T, this is the law of an ideal gas.
Actually, the isentropic adiabatic expansion of an ideal gas is described by the equation P*v^k = constant, where k is the ratio of the specific heats of the gas (the constant-pressure specific heat divided by the constant-volume specific heat). For typical combustion gases, k is between 1.27 and 1.3. Suppose I have a 2:1 expansion ratio (you assumed 6:1) and I want to average 2 G's of push over the 30 cm travel of the piston. Assuming k = 1.3 and v1 = 2*v0, P1 = P0 * 0.406. The average pressure over the travel is the integral from v0 to 2*v0 of C*v^(-1.3)*dv quantity divided by the delta volume (=v0) where C = P0*v0^(-1.3). Trying to simplify this without the benefit of being able to draw equations...
(integral(v0 to 2*v0 of (Cv^(-1.3)dv))) / v0 = (-10/3 C [(2v0)^(-0.3) - v0^(-0.3)]) / v0 = 0.626 C v0^(-0.3) / v0 {now expand C} = 0.626 P0 v0^(1.3) v0^(-0.3) / v0 {combine and cancel v0 terms) = 0.626 P0
So the peak thrust is only about 1/0.626 = 1.6 times the average thrust. For a 2-G average thrust, the peak would be a mere 3.2 G's. This would allow you to leap 60 cm in the air (1.2 times your figure) with a peak load of about 1/6 of what you calculated. If you were willing to take a 4.8 G peak acceleration, you could jump 90 cm. Being able to add energy equal to a 90 cm leap with every step would make running very, very easy. A 2:1 expansion ratio would make for a very inefficient engine, but efficiency does not appear to be the goal of the effort.
In short, I think you need to work on your analysis a little bit. My degree is not in physics, plus I'm very rusty after not using this stuff for years, and I am still running rings around you. I suggest you go brush up on some of the basics. -- Ancient Goth: Someone who overthrew the Roman Empire.
Unless the purchaser of the Toysmart.com (name/customer database) remains bound by the same privacy and usage agreement originally agreed to by Toysmart's users, then the sale might as well be the sale of dozens of copies. The FTC is right to intervene to make certain that the original agreement is obeyed, or the data destroyed. -- Ancient Goth: Someone who overthrew the Roman Empire.
Energy that has to travel up through your legs to set your body in motion.
Once again, you're confusing energy and force. Energy is force times distance, and the only large movement during a boot-powered launch is in the boot pistons themselves. This is where the energy is being produced. The only thing that travels up the body is force. Force is also being transmitted through your body from your feet up to your scalp when you do no more than stand up. If you bounce up on your toes, you may be accelerating yourself at 2 or even 3 G's. I doubt that you would consider the forces to be excessive. Continue a 3 G push for a distance of a foot, and you'll fly an additional 2 feet into the air before you start to come down again. Same force, greater distance.
This hardly sounds like a "equal force sustained over a longer distance" situation but rather as a short, strong impulse to send you off. He (the constructor) also says: "A person can move with significant jumps or strides" which means that it's not a case of normal forces but rather extraordinary forces that send you off the ground.
If it was the normal forces of a normal step over a longer distance you would not be able to jump higher, just take longer steps
If you're doing anything as energetic as skipping (let alone a trot or a run), you are spending some time flying through the air without either foot in contact with the ground. This is not a case of "extraordinary forces", it's quite normal.
Now try to follow me here. If you accelerate upwards during a normal step (and you pretty much have to), you are pushing with a force greater than gravity. If you sustain this greater-than-gravity acceleration over a longer distance, you'll accelerate to a higher speed and achieve a greater altitude during the step. Double the distance, you'll go about double the height and 1.4 times the speed. Quadruple the distance, you get 4x the height and 2x the speed. This is all without increasing the forces involved (F=ma, E=Fd, v=sqrt(2E/m)).
This is all first-semester physics. Haven't you studied it yet, or didn't you understand it well enough to apply it to problems that weren't on the tests? -- Ancient Goth: Someone who overthrew the Roman Empire.
one commentator during Hitler's reign said basically that he did't protest when the troops came for the disabled, or the elderly or the Jews and when they came for him there was nobody left to speak up for him.
The Rev. Martin Neimoller (or maybe Niemoller, I can't spell German worth a darn). -- Ancient Goth: Someone who overthrew the Roman Empire.
Energy is force times distance. As I mentioned before, if you can sustain a smaller force but over a much longer distance, you can impart more energy with less mechanical stress.
I think you're confusing several concepts. Every step is a "short sudden burst" of energy, as you come down on a foot (arresting the downward velocity) and then spring off again on it (leaving with upward velocity). If the boots can make each step smoother, you can have less stress than walking normally. A burst of speed as in a sprint involves several steps; unless you have greater stress in one or more of them individually, you won't have greater stress overall.
There don't seem to be any unusual postures or motions involved with using these boots, so I don't think the squatting analogy is relevant. When you push off with your shoe, the ground "pushes back". With the boots, there's an extensible mechanism that extends the push for a greater distance. Doesn't seem like a biggie. -- Ancient Goth: Someone who overthrew the Roman Empire.
1) If you absorb it your sail would quickly burn up.
You can't avoid absorbing some of the light. For a solar sail, this isn't a big problem. For a laser or microwave sail soaking up several KW per square meter....
One of the reasons for going to the carbon composite sail it that it's highly refractory (resists heat very well). If it radiates as a blackbody and it can tolerate a temperature of 1500 Kelvin (around 2200 F), it can dissipate about 290 KW per square meter - in each direction. If it can radiate both forward and aft, that's over half a megawatt per square meter. With that kind of radiating capability, it doesn't much matter if you reflect the incident power or absorb it (though it does affect your energy efficiency). -- Ancient Goth: Someone who overthrew the Roman Empire.
A laser's output is just as susceptible to scattering by dust or Rayleigh effects as anything else. An earth-bound laser will have a fair amount of its output bounced around randomly on its way out into space. However, it is only light. -- Ancient Goth: Someone who overthrew the Roman Empire.
If the photons have given up some of their velocity (momentum) does that mean they drop below the speed of light?
Nope. Photons have to travel at the (local) speed of light; they have no rest-mass, so they cannot exist unless v=c.
However, you are right to ask what happens to the momentum. Thing is, momentum is a vector; it has both magnitude and a direction. If the photon is absorbed by the sail, the sail takes on the momentum as well as the energy (where the momentum p equals e/c, where c is the good old speed of light). If the photon is reflected, things get interesting. You have a photon coming in and going out again, with more or less the same quantity of momentum - but a different direction. If the photon bounces directly back toward its source, the reflector absorbs twice the photon's momentum: the difference between the photon moving toward it and zero (e/c), and the difference between zero and the photon moving away in the opposite direction again (another e/c, total 2e/c). If you don't reflect directly back, multiply by cosine theta.
If you look at things in the frame of reference of the source (where the sail may be moving), you have additional complications due to Doppler shifting of the photon frequency (and thus an increase or decrease in its energy and also its momentum). When you're doing numbers on something like this, you have to be real careful about your reference frame or you risk getting complete nonsense. Ain't physics grand? -- Ancient Goth: Someone who overthrew the Roman Empire.
Do you have any idea how little energy a photon is?
A molecule of water is about 3*10^(-22) grams, but the oceans are still huge.
More to the point is the power levels required for a given amount of thrust. Momentum and energy of massless particles are related by the equation e=pc, so a gigawatt of photons will give you a force of about 3.3 Newtons (= 1e9 watts / 3e8 m/sec). If you have a perfect mirror and you're reflecting the beam straight back, you can double that.
Am I the only person who realizes that this puts Starwisp a lot closer? (I haven't read the whole thread yet, only downloaded through resp. #168.) -- Ancient Goth: Someone who overthrew the Roman Empire.
If Slashdot was truly concerned about their users' privacy from snooping, every Slashdot service would be available by https as well as http. As far as I can tell, https://slashdot.org doesn't work.
This goes double for services like Hotmail and Yahoo. You can protect your password on Yahoo mail via https, but your actual mail goes back and forth in the clear. They need to do something about this too. -- Ancient Goth: Someone who overthrew the Roman Empire.
It's not the landing I'm worried about, it's the sudden takeoff.
You miss the point. The piston can push for several times the distance that a person's toes can. Even with the same forces (and same acceleration, F=ma), you can get a lot more energy (E=force*distance) and thus a lot more speed. The takeoff doesn't have to be sudden at all, it's just sustained a lot longer. If you're coming down again on what amounts to a collapsible stilt, so's the landing. -- Ancient Goth: Someone who overthrew the Roman Empire.
Everyone move to Xenix? Man, how different the world would have been if THAT had actually come to pass. Among other things, Microsoft would have had to spank the nitwit who decided that "/" should be the option separator in the shell and the path separator had to be "\". We've been paying the bill in screwed-up keyboard layouts to work around this idiot's decision ever since.
One thing that really offends me about Microsoft is that they already had an OS in which so many things were actually done more or less right, and they deliberately decided to re-implement them wrong when they extended DOS. -- Ancient Goth: Someone who overthrew the Roman Empire.
How do you top a boot? Tep on the toe, tupid!
on
Gas-Powered Shoes?
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· Score: 2
One question though - how do you stop? The BBC article says the pistons are triggered by the foot hitting the ground...
Typical journalist who doesn't bother getting all the facts. If the thing fired as soon as it was compressed, it would throw you back when you landed after a step. The obvious trick is to have the piston be triggered when you unload your heel and push with your toe. This isn't something you do until you're already pushing away for the next step. If the piston turns a 300-pound, 3-inch stroke of your toe into a 300-pound, 12-inch stroke of the entire sole plate, you're going to get some serious distance from it.
If these guys have done their homework, the two boots are interlocked so that if one quits, the other shuts down too. I suppose it would be a shock to have a 12-foot stride suddenly followed by a 3-foot stride because of a fouled sparkplug. -- Ancient Goth: Someone who overthrew the Roman Empire.
The boots have what, about a 12" stroke? Force = energy / distance; if you have an extra foot of travel to soak up the impact of landing, it's not at all obvious to me that you'll have any increased forces (longer time, but perhaps even lower forces). The fuel supply is the least of it, 25 minutes is probably the endurance using tanks on the boots themselves. Consider the capacity of a canteen on the belt...
The next question is, what does this enable? If average people can run at 25 MPH with these boots on (and presumably carrying a load), it looks like they could handle a suit of composite armor. All of a sudden the powered-armor-clad Mobile Infantry of Starship Troopers doesn't look so far-fetched. -- Ancient Goth: Someone who overthrew the Roman Empire.
One of the selling points of this concept is that a person on foot (with internal-combustion boots or not) can go places inaccessible by cars. Doing it at 20+ MPH is new.
This invention has been in the pipeline for a long time; I remember reading about gas-powered boots many years ago. But it's not surprising that cheap microcontrollers and actuators are finally making them a reality. -- Ancient Goth: Someone who overthrew the Roman Empire.
Run off several hundred copies of the card on card stock, using the throwaway account and whatever snail-mail address you like (vacant lots might be good).
Mail. Each batch of cards could be worth, oh, $20-$30 in postage.
Here are the evil consequences:
If M$ weeds the list against the USPS's database, they'll have to cut the vacant lots out of their numbers.
If M$ doesn't weed the list, they'll be sending snail-mail to addresses that bounce. This is a recurring cost. If they use address correction it's only a one-time cost, but it's a healthy fraction of a dollar per address.
But you know the Congresscritters that M$ has bought will still cite the inflated numbers. So will uncritically pro-M$ newspapers like the Wall Street Journal. A few hundred thousand in postage is pocket change to M$; if they win the court battles and get permission to expand their monopoly, it's worth $billions. I'm still not sure it's worth it; at best, it's an ant nibbling on the elephant's foot. The ant may feel it's doing a terrific job, but the elephant isn't going to notice. -- Ancient Goth: Someone who overthrew the Roman Empire.
Swell their ranks. It'll cost 'em something to send out snail mails.
E-mail address is one of the required fields, so you'll either have your card tossed in the trash or you'll just be giving them carte blance to spam you (either way, at negligible cost to M$). Plus, they'll be able to cite higher numbers when trying to sway Congresscritters to vote their way. Signing up isn't going to help you one bit, and may hurt. I wouldn't. -- Ancient Goth: Someone who overthrew the Roman Empire.
It sure doesn't look like the open source community is worried about losing the freedom to innovate, either.
A great many (myself included) are worried about losing that freedom due to the encroachment of patents. That's what the League for Programming Freedom (http://lpf.ai.mit.edu/ is about. -- Ancient Goth: Someone who overthrew the Roman Empire.
Remember that the more fuel you use, the more fuel you need also to provide acceleration for the fuel itself, and then the fuel for that, etc (I think of it as recursive fuel).
If you can handle algebra, just think of it as the rocket equation.
The rocket equation is one reason why ion drives are so attractive for interplanetary space missions. If you need 14,000 m/sec of delta-V, doing it with xenon ions screaming out the back at 50 kilometers per second takes a lot less mass than doing it with superheated steam at a mere 4500 meters per second. -- Ancient Goth: Someone who overthrew the Roman Empire.
What happened to the Mars lander we sent out there? Did we ever regain control of it again?
Which lander? Mars Polar Lander? The latest analysis I've seen is that it almost certainly crash-landed and was destroyed. As for the other landers, the little one with the Sojourner rover was a success (but would have been a hell of a lot more useful if it had carried nuclear generators instead of chemical batteries, to keep everything alive through the cold Martian nights), and the Viking landers were phenomenal successes. -- Ancient Goth: Someone who overthrew the Roman Empire.
I would think that if one wanted public awareness increased, they would not hold demos in the most god-forsaken spots on earth.
I have this funny feeling that, news coverage aside, a demo on the beach at Waikiki wouldn't be taken seriously as a dry run for the Red Planet. -- Ancient Goth: Someone who overthrew the Roman Empire.
We'll never actually set foot on Mars. We, being the USA.
Space hardware is getting cheaper all the time. If some outfit like Roton gets into the business, the price of launches is going to drop drastically as well. Sooner or later, a Mars mission is going to be within reach of a private membership organization. Like, say, the Mars Society?
It doesn't matter extremely if the US government doesn't go, as long as somebody goes. I'd prefer Mars to be settled by people from a culture of democratic institutions and a recent frontier, but in a pinch anything will do. -- Ancient Goth: Someone who overthrew the Roman Empire.
Considering how long it took for hybrid cars to finally be produced... I have a bad feeling that one of the oil companies will try their hardest to prevent genetic algorithms from improving the average cars engine.
You don't understand how much such an advance is worth to Detroit. If Ford could increase fuel efficiency by 15% overnight, it could immediately shift its auto production away from the small, low-profit models to heavier, high-profit models and still meet its CAFE requirements. The technology is worth a lot more to Detroit than to Exxon.
Hybrids aren't doing anything that's exactly new. The Honda Insight gets 70 MPG, but the Geo Metro and Chevy Sprint were both capable of around 50 MPG. That didn't make them sell any better; they weren't what people wanted. The Insight, in particular, is a dog performance-wise; its batteries and little sustainer engine don't have the guts to accelerate it quickly. Expect to see buyer resistance from people who feel that getting up to traffic speeds, or the ability to pass, are more important than cutting $10 a week from their gasoline bill. Fixing this will require another technology, such as flywheels instead of batteries for energy storage. I hope that the public image of hybrids isn't completely soured before this happens.
Of course, a crisis which kicks the price of gasoline up to $4/gallon would change the equation pretty quickly. The clown who paid $38,000 for a huge honkin' SUV might not care that his fuel bill went from $2000 to $4000, but most people would. If you affect the buying preferences of most people (and by extension, the used-car market beginning about 2 years down the road), you'll have made a big difference. -- Ancient Goth: Someone who overthrew the Roman Empire.
Slashdot Mirror
--
Everyone now knows
The soi-disant Anti-Troll
Is but a troll himself.
--
To be nit-picky, energy equals the integral of the dot-product of f and ds over the path s. If you don't have any motion, you don't have any energy transmitted. Excessive forces (even nominally static forces) exerted on a body can over-stress parts of it and cause damage, but a small force acting over a large distance will not cause overstress. Consider the amount of energy you acquire when you accelerate to highway speeds in a car. While the kinetic energy imparted is many times what you could attain by running, the acceleration is only a fraction of a G. The stresses on the body are less than you experience by standing up.
Ask the designers. If it were my design, I'd either have a low compression ratio to keep the peak forces down to a reasonable multiple of the average, or perhap separate the combustion chamber from the expansion piston and use a controllable valve between them to modulate the expansion. The Russians have been working on this concept for something like 20 years; they're bound to have figured out a few tricks. I have no such prejudice against thermodynamics, so I'll be happy to expand on your numbers a bit. Actually, the isentropic adiabatic expansion of an ideal gas is described by the equation P*v^k = constant, where k is the ratio of the specific heats of the gas (the constant-pressure specific heat divided by the constant-volume specific heat). For typical combustion gases, k is between 1.27 and 1.3. Suppose I have a 2:1 expansion ratio (you assumed 6:1) and I want to average 2 G's of push over the 30 cm travel of the piston. Assuming k = 1.3 and v1 = 2*v0, P1 = P0 * 0.406. The average pressure over the travel is the integral from v0 to 2*v0 of C*v^(-1.3)*dv quantity divided by the delta volume (=v0) where C = P0*v0^(-1.3). Trying to simplify this without the benefit of being able to draw equations...(integral(v0 to 2*v0 of (Cv^(-1.3)dv))) / v0
= (-10/3 C [(2v0)^(-0.3) - v0^(-0.3)]) / v0
= 0.626 C v0^(-0.3) / v0 {now expand C}
= 0.626 P0 v0^(1.3) v0^(-0.3) / v0 {combine and cancel v0 terms)
= 0.626 P0
So the peak thrust is only about 1/0.626 = 1.6 times the average thrust. For a 2-G average thrust, the peak would be a mere 3.2 G's. This would allow you to leap 60 cm in the air (1.2 times your figure) with a peak load of about 1/6 of what you calculated. If you were willing to take a 4.8 G peak acceleration, you could jump 90 cm. Being able to add energy equal to a 90 cm leap with every step would make running very, very easy. A 2:1 expansion ratio would make for a very inefficient engine, but efficiency does not appear to be the goal of the effort.
In short, I think you need to work on your analysis a little bit. My degree is not in physics, plus I'm very rusty after not using this stuff for years, and I am still running rings around you. I suggest you go brush up on some of the basics.
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Ancient Goth: Someone who overthrew the Roman Empire.
Unless the purchaser of the Toysmart.com (name/customer database) remains bound by the same privacy and usage agreement originally agreed to by Toysmart's users, then the sale might as well be the sale of dozens of copies. The FTC is right to intervene to make certain that the original agreement is obeyed, or the data destroyed.
--
Ancient Goth: Someone who overthrew the Roman Empire.
Now try to follow me here. If you accelerate upwards during a normal step (and you pretty much have to), you are pushing with a force greater than gravity. If you sustain this greater-than-gravity acceleration over a longer distance, you'll accelerate to a higher speed and achieve a greater altitude during the step. Double the distance, you'll go about double the height and 1.4 times the speed. Quadruple the distance, you get 4x the height and 2x the speed. This is all without increasing the forces involved (F=ma, E=Fd, v=sqrt(2E/m)).
This is all first-semester physics. Haven't you studied it yet, or didn't you understand it well enough to apply it to problems that weren't on the tests?
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Ancient Goth: Someone who overthrew the Roman Empire.
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Ancient Goth: Someone who overthrew the Roman Empire.
I think you're confusing several concepts. Every step is a "short sudden burst" of energy, as you come down on a foot (arresting the downward velocity) and then spring off again on it (leaving with upward velocity). If the boots can make each step smoother, you can have less stress than walking normally. A burst of speed as in a sprint involves several steps; unless you have greater stress in one or more of them individually, you won't have greater stress overall.
There don't seem to be any unusual postures or motions involved with using these boots, so I don't think the squatting analogy is relevant. When you push off with your shoe, the ground "pushes back". With the boots, there's an extensible mechanism that extends the push for a greater distance. Doesn't seem like a biggie.
--
Ancient Goth: Someone who overthrew the Roman Empire.
One of the reasons for going to the carbon composite sail it that it's highly refractory (resists heat very well). If it radiates as a blackbody and it can tolerate a temperature of 1500 Kelvin (around 2200 F), it can dissipate about 290 KW per square meter - in each direction. If it can radiate both forward and aft, that's over half a megawatt per square meter. With that kind of radiating capability, it doesn't much matter if you reflect the incident power or absorb it (though it does affect your energy efficiency).
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Ancient Goth: Someone who overthrew the Roman Empire.
A laser's output is just as susceptible to scattering by dust or Rayleigh effects as anything else. An earth-bound laser will have a fair amount of its output bounced around randomly on its way out into space. However, it is only light.
--
Ancient Goth: Someone who overthrew the Roman Empire.
However, you are right to ask what happens to the momentum. Thing is, momentum is a vector; it has both magnitude and a direction. If the photon is absorbed by the sail, the sail takes on the momentum as well as the energy (where the momentum p equals e/c, where c is the good old speed of light). If the photon is reflected, things get interesting. You have a photon coming in and going out again, with more or less the same quantity of momentum - but a different direction. If the photon bounces directly back toward its source, the reflector absorbs twice the photon's momentum: the difference between the photon moving toward it and zero (e/c), and the difference between zero and the photon moving away in the opposite direction again (another e/c, total 2e/c). If you don't reflect directly back, multiply by cosine theta.
If you look at things in the frame of reference of the source (where the sail may be moving), you have additional complications due to Doppler shifting of the photon frequency (and thus an increase or decrease in its energy and also its momentum). When you're doing numbers on something like this, you have to be real careful about your reference frame or you risk getting complete nonsense. Ain't physics grand?
--
Ancient Goth: Someone who overthrew the Roman Empire.
More to the point is the power levels required for a given amount of thrust. Momentum and energy of massless particles are related by the equation e=pc, so a gigawatt of photons will give you a force of about 3.3 Newtons (= 1e9 watts / 3e8 m/sec). If you have a perfect mirror and you're reflecting the beam straight back, you can double that.
Am I the only person who realizes that this puts Starwisp a lot closer? (I haven't read the whole thread yet, only downloaded through resp. #168.)
--
Ancient Goth: Someone who overthrew the Roman Empire.
This goes double for services like Hotmail and Yahoo. You can protect your password on Yahoo mail via https, but your actual mail goes back and forth in the clear. They need to do something about this too.
--
Ancient Goth: Someone who overthrew the Roman Empire.
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Ancient Goth: Someone who overthrew the Roman Empire.
One thing that really offends me about Microsoft is that they already had an OS in which so many things were actually done more or less right, and they deliberately decided to re-implement them wrong when they extended DOS.
--
Ancient Goth: Someone who overthrew the Roman Empire.
If these guys have done their homework, the two boots are interlocked so that if one quits, the other shuts down too. I suppose it would be a shock to have a 12-foot stride suddenly followed by a 3-foot stride because of a fouled sparkplug.
--
Ancient Goth: Someone who overthrew the Roman Empire.
The next question is, what does this enable? If average people can run at 25 MPH with these boots on (and presumably carrying a load), it looks like they could handle a suit of composite armor. All of a sudden the powered-armor-clad Mobile Infantry of Starship Troopers doesn't look so far-fetched.
--
Ancient Goth: Someone who overthrew the Roman Empire.
This invention has been in the pipeline for a long time; I remember reading about gas-powered boots many years ago. But it's not surprising that cheap microcontrollers and actuators are finally making them a reality.
--
Ancient Goth: Someone who overthrew the Roman Empire.
- Scan the card (both sides).
- Create a throwaway Hotmail account (or fifty).
- Run off several hundred copies of the card on card stock, using the throwaway account and whatever snail-mail address you like (vacant lots might be good).
- Mail. Each batch of cards could be worth, oh, $20-$30 in postage.
Here are the evil consequences:- If M$ weeds the list against the USPS's database, they'll have to cut the vacant lots out of their numbers.
- If M$ doesn't weed the list, they'll be sending snail-mail to addresses that bounce. This is a recurring cost. If they use address correction it's only a one-time cost, but it's a healthy fraction of a dollar per address.
But you know the Congresscritters that M$ has bought will still cite the inflated numbers. So will uncritically pro-M$ newspapers like the Wall Street Journal. A few hundred thousand in postage is pocket change to M$; if they win the court battles and get permission to expand their monopoly, it's worth $billions. I'm still not sure it's worth it; at best, it's an ant nibbling on the elephant's foot. The ant may feel it's doing a terrific job, but the elephant isn't going to notice.--
Ancient Goth: Someone who overthrew the Roman Empire.
--
Ancient Goth: Someone who overthrew the Roman Empire.
--
Ancient Goth: Someone who overthrew the Roman Empire.
delta-V = V(exhaust) * (ln( M(init)/M(final) ) - 1 )
The rocket equation is one reason why ion drives are so attractive for interplanetary space missions. If you need 14,000 m/sec of delta-V, doing it with xenon ions screaming out the back at 50 kilometers per second takes a lot less mass than doing it with superheated steam at a mere 4500 meters per second.
--
Ancient Goth: Someone who overthrew the Roman Empire.
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Ancient Goth: Someone who overthrew the Roman Empire.
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Ancient Goth: Someone who overthrew the Roman Empire.
It doesn't matter extremely if the US government doesn't go, as long as somebody goes. I'd prefer Mars to be settled by people from a culture of democratic institutions and a recent frontier, but in a pinch anything will do.
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Ancient Goth: Someone who overthrew the Roman Empire.
Hybrids aren't doing anything that's exactly new. The Honda Insight gets 70 MPG, but the Geo Metro and Chevy Sprint were both capable of around 50 MPG. That didn't make them sell any better; they weren't what people wanted. The Insight, in particular, is a dog performance-wise; its batteries and little sustainer engine don't have the guts to accelerate it quickly. Expect to see buyer resistance from people who feel that getting up to traffic speeds, or the ability to pass, are more important than cutting $10 a week from their gasoline bill. Fixing this will require another technology, such as flywheels instead of batteries for energy storage. I hope that the public image of hybrids isn't completely soured before this happens.
Of course, a crisis which kicks the price of gasoline up to $4/gallon would change the equation pretty quickly. The clown who paid $38,000 for a huge honkin' SUV might not care that his fuel bill went from $2000 to $4000, but most people would. If you affect the buying preferences of most people (and by extension, the used-car market beginning about 2 years down the road), you'll have made a big difference.
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Ancient Goth: Someone who overthrew the Roman Empire.