My point is simply that scaling the airplane won't significantly reduce your drag per person. I'm sure you could get a 2% reduction, or even more, but before you get much more, you'll quickly hit physical limits.
As for cost, I guess we'll have to agree to disagree. You believe that there is a market for high-speed flights that cost several times more than regular flights. I do not.
Heh. As if Apple doesn't use the cheapest components they can find. Aside from the motherboard and CPU, a Mac is made completely of stuff you can find on pricewatch.
You're right that a turbojet has to deal with the same issues with its compressor, but its easier for the turbojet because the mass flow rate through the core is relatively small. Ie: the tips of the compressor blades don't hit supersonic flow nearly as quickly as the tips of a larger fan blade. Less total energy is also lost due the shock-waves because less air needs to be slowed down to achieve a given level of thrust.
Now, all of the engines you mentioned are turbofans, but they have two main characteristics:
1) They're really low bypass ratio, so the core still provides most of the propulsion. This is unlike a high-bypass turbofan where the core provides 80% of the propulsion. These are affected far less by a loss of fan efficiency.
2) None of these aircraft are designed to cruise at mach 2+. They can only burst to that speed using afterburners. If you look at something like the F-22's engine (the F119-PW-100), you'll see that it's designed for a supercruise mach number of only 1.58, and uses a very low bypass ratio (~0.2) in the process.
I don't think a 20-30% savings in fuel costs per mile vs the Concorde is enough to make it cost-effective now. In any case, fuel is more expensive now than it was for 15 years during the late 1980's and 1990s, and the Concorde wasn't cost-effective then either. You say the rich will finance this project, but there just aren't enough rich people that need to travel so much to finance this huge operation.
Wing drag is based on weight (heavyer objects need more wing) but the body needs to move the same amount of air out of it's path if it's 100' long or 300' long.
Drag isn't just caused by "pushing air out of the way". Drag is very complex, but in supersonic flight, you can identify four major contributors to drag: pressure drag, skin-friction drag, lift-induced drag, and wave-drag. Wave drag is further broken down into volume-induced wave drag and lift-induced wave drag. The equations describing these aren't very friendly to your argument. Let's break it down:
0) Pressure drag is due to the "pusning air out of the way". You're right, it is proportional to the frontal-area of the body, and will be similar for long and short bodies of equal frontal-area.
1) Skin-friction drag is proportional to wetted surface area. A fuselage 3x as long will have 3x the surface area and much higher skin-friction drag.
2) Lift-induced drag is proportional to lift, and thus to weight. A fuselage 3x as long will weigh 3x as much, and thus require a large increase in lift. This will cause a large increase in drag.
3.1) Volume-induced wave drag is proportional to volume and inversely proportional to the fourth power of length. So increasing the length of the body by 3x will actually result in a large reduction in volume-induced wave drag.
3.2) Lift-induced wave drag is proportional to the square of lift. So making the body 3x longer will require a 3x increase in the part of the lift used to support the body, causing a 9x increase in the drag caused by the body.
As I said, drag is a complex function of these elements, and at supersonic flight, total drag is a sum of all of these elements. However, if you look at the math, you'll see that making the body longer will greatly increase your drag, unless the overall drag is completely dominted by volume-induced wave drag (which it isn't).
But supercavitation-based designs don't heat up the incoming flow. Doing so would require a high energy investment. They use cavitation to flash-vaporize parts of the flow.
Not quite true - the engines for the F-22 Raptor are F119 Turbofans (http://www.pratt-whitney.com/prod_mil_f119.asp) which enable the aircraft to achieve supersonic flight without afterburner (quite an achievement).
It's completely true. I didn't say you couldn't have turbofans that operated at supersonic speeds. I said that turbofans:
a) cannot reach really high supersonic speeds b) are less efficient than turbojets at some mach number
This is all the result of the fact that airflow through the fan must be kept subsonic, or else there is a drastic loss of efficiency. If you look at supersonic turbofans like on the F-22, you'll notice the intakes I mentioned that slow down the flow to subsonic speeds before the air hits the fan blades.
A turbofan and turbojet are both turbine engines with a set of fan blades as the first thing the incoming air "sees" after the inlet. These aren't like propeller blades
Turbojets have no fan, they just have a compressor before the combustor. And the solidity ratio doesn't make that much of a difference, fans can be treated using the same theory as propellors. Like propellors, they suffer a drastic loss of thrust as the incoming air approaches sonic speeds.
Your description of turbofans versus turbojets is correct, but you have to consider why turbofans are more efficient. Basically, it's a result of the following two equations describing the jet exhaust:
As you can see, thrust increases linearly with both thrust and velocity, but the kinetic energy of the air increases quadratically with velocity and only linearly with mass. Any kinetic energy imparted into the exhaust air is basically wasted from the engine's point of view, so its desirable to minimize this residual energy. As you can see, you can double thrust by either doubling the mass-flow-rate or doubling the velocity. Both give you the same thrust, but the latter approach leaves twice as much residual energy in the exhaust.
Turbofans work on the principle of maximizing mass flow rate and minimizing exhaust velocity. Instead of moving a little bit of air at high speed through the core, they extract most of that core energy at the turbine, and use it to drive a fan that moves a lot of air at low speed through the bypass ducts. The result of this is that in a high-bypass ratio turbofan, the fan provides the vast majority of your thrust.
Now, it becomes obvious why turbofans don't work well at high supersonic speeds. The closer the flow through the fan gets to sonic, the less efficient the fan becomes at providing thrust. Since the fan provides most of the thrust of the engine, the engine suffers a drastic thrust loss.
In a big plane like this, yes it is. And while bragging rights may count for something, they don't count for the billions of dollars it'd cost to build this thing.
They simply doubled the price and people kept using the thing which is all about the users not a built in need to wait x years to turn a profet.
The number of people who will be willing to pay 4x as much to fly 2x faster will always be limited. The fact that every SST effort to date has so far proved unprofitable suggests that this limitation will continue to exist as long as the 4x cost differential exists.
Drag is a function of altitude, speed, shape, and weight.
You're getting away from the point. You said "a 300 passenger plane will have lower drag-per-person than a 100 passenger plane". That's not really true, because a 300 passenger plane will weigh close to 3x as much as a 100 passenger plane. See, weight is the critical part of the equation. More weight means more lift which means more lift-induced drag. Indeed, thrust-required is proportional to weight, at least at subsonic speeds. The ratio of wave-drag to lift-induced drag at supersonic speeds changes things slightly, but the point remains --- making the plane bigger is not a good way to reduce thrust required per passenger.
Geting a 16% savings from the engine and 2% from a better shape and 2% from a reduced weight would let them reach ~20% overall savings.
Is this thing coming out in 2035 or 2015? Because 16% by 2015 is incredibly optimistic. Even then, a 20% overall savings will likely not even overcome the increased cost of fuel by 2035. And in 2035, a supersonic transport will still use 4x as much fuel as a subsonic transport. That's the fundemental problem.
How do you get a bubble of air in a medium of air? It makes no sense. Hell, even if you had a bubble of air, they'd be no point --- the reason supercaviation makes things more efficient is that moving through water vapor is more efficient than moving through water. If you've got a bubble of air moving through air, you haven't gained anything.
Without the USSR, it's very likely that Germany would have won. Without the US, it's possible that Germany would have won, but more likely that Germany would ave taken a lot longer to beat. Japan is another story, but then again, Japan had no designs on continental Europe.
In any case, your point is well taken. That's precisely why the "we saved your asses" attitude is so stupid. The Russians can say the exact same thing to us ("we saved your asses by decimating Hitler's land forces"). The dick-waving is really kind of silly.
I seem to recall that the concord was operating at a profit though the last seveal years of it's life. The R&D costs where never paid back but at some point the they doubled the price and basicly nobody noticed.
First, the R&D costs on something like this are enormous. If those aren't recouped, there is no point. Second, if the Concorde was only operating at a profit decades after starting service, then that's hopeless. There is no way you could make up for all the losses in a reasonable timeframe. It's completely unrealistic. The thing would have to operate for 50 years just to break even.
Anyway, a ship that can take 300 people should have less drag per person than a ship that is built for 100 people.
It's not as big a difference as you'd think. The drag on a plane is a function of how much lift it produces. If you make the plane bigger (heaver), you need to increase the lift produced by the wing, which proportionally increases drag. In any case, a subsonic plane of the exact same size will still be 4x cheaper to operate in fuel costs alone.
And.52 is 16% more effecent than.62 which is a HUGE savings.
It's 16% over a period of over 30 years! Those numbers won't be enough to make a plane like this profitable in the future when the Concorde isn't profitable now. You'd be lucky if that 16% even offsets rising fuel costs.
Overall I think they can drop their fuel price per person mile down by 20-30% which should let them increase the things range.
If they can do that by 2015, it would be a fricking miracle.
I think a lot of people would be willing to spend ~5-10k to save 8 hours off of a trip.
The Concorde shows that apparently enough people are not willing to do that. Basically, you're paying 4x as much (or more if you want to recoup your R&D), to get somewhere twice as fast. It's not a winning combination for most people.
There is a reason turbofans aren't used on mach 2+ aircraft. The basic problem is that in order to operate a turbofan at supersonic speeds, you have to use an engine inlet that uses a shock wave (or a series of shock waves) to slow down the flow to subsonic speeds before it hits the fan blade. Fans, like all propellors, drastically lose efficiency as the incoming flow approaches supersonic speeds. This design causes the loss of some energy, so at a certain point, a turbojet actually becomes more efficient than a turbofan.
Supercavitation works by causing the fluid the object is traveling through to vaporize. In the case of air, the fluid is already vaporized, so what would form the bubble?
OK, admittedly I Am an Aerospace Engineer (IAAE?).
LOL. I'm an Aerospace Engineer in Training (IAAET?) I agree with you completely about the 787, and I alluded to as much when I pointed out that a lot of innovation went into the design of the 787. However, the pop-culture definition of "innovation" includes "revolutionary" in it. If you ask a lay-person whether they think the 787 is innovative, they'll say no. On the other hand, if you ask them other they think this supersonic airliner is innovative, they'll say yes. That'd be true even if the new airliner didn't use any technologies you couldn't find in a decades old Concorde.
Heh. And if it hadn't been for the Russians, the Germans would have won anyway, conquered continental Europe, consolidated all of its resources, and the Americans would have been powerless to stop them. Yet, Americans don't defer to the Russians very easily...
Shockwaves are caused by an object moving through a fluid faster than the speed of sound (ie: the speed of pressure wave propagation in the fluid). At subsonic speeds, pressure waves bouncing back from an object affect the incoming flow, basically "warning" it of the existance of the object. That's how the fluid can flow smoothly around the object --- the pressure waves caused the fluid's path to change long before it hit the object. At supersonic velocities, the pressure waves don't move fast enough to affect the incoming flow. So the fluid cannot flow smoothly around the object, and a shock wave is created where the fluid has to instantaneously react to the presence of the object.
I'm usually the first person to blame marketing, but in this case, your malaise is a bit misdirected. In the world of aerospace, it's really the physics that's more of a holdup than marketing.
Consider the CF6-50 (old 747-200 engine). It's fuel consumption at cruise (35,000 feet and mach 0.8-ish) is about 0.62 pounds of fuel per pound of thrust per hour. The Concorde engine's consumption at cruise (53,000 feet at mach 2.0) is 1.19 pounds of fuel per pound of thrust per hour. Now, consider that during supersonic cruise, your drag skyrockets by a factor of 2-3. So not only are you using 2x as much fuel for a given level of thrust, but your thrust needs to be twice as high to keep the plane flying!
Also, don't count on huge improvements in the above-mentioned figures. The CF6-50 is an engine designed in the 1960s. It's 0.62 figure at cruise was excellent for the time. The GE90 (the 777 engine), was designed in the 1990s. It's specific fuel consumption at cruise is 0.53. It's extremely efficient for a modern engine.
I'll take that bet. 2015 is ten years from now. Ten years ago was 1995. Consider how far we've come since then. Do you really think we'll come much farther in ten more years? My guess is that 2015 for this sort of thing is actually a bit optimistic. The physics of supersonic flight just don't lend themselves to cost-efficient aircraft, especially with today's escalating fuel prices.
Easy. You test the engine in a harness, find out how much thrust it develops, then use aerodynamic theory to figure out how fast a hypothetical plane could fly with it.
Yes and no. "Innovation" is a bit of a silly word in the engineering world. Engineering is mostly about "evolution" not "revolution". Occasionally, you see something like the SR-71, which break every existing mold, but such designs are few and far between. Consider something like the Boeing 787. It's claim to fame is a 20% increase in efficiency. To an aerospace engineer, that's huge. They'd trade their first-born for a 10% decrease in specific fuel consumption. To hit that 20%, a lot of innovations had to go into the design. But consider the big picture: is the 787, as a whole, really innovative? Not really.
Japan's aerospace industry in particular is very interested in technologies that even lay-people would see as "revolutionary". For example, if you research the field of hypersonic planes, a lot of that work is being done in Japan. In the United States, the focus is a bit different. Things have become not so much about "faster and higher", but "better, more efficient, and cheaper". Both are innovative in a way, but the former is more "sexy".
I don't know too much about Spanish food, but I'd point out that Indian food achieves most of its flavor buy using a wide variety of spices and ingredients. That presents quite a logistical issue when your're growing your own food on Mars...
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Ha ha ha. You should try reading the Anandtech forums sometime. You read some truely silly stuff in there.
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My point is simply that scaling the airplane won't significantly reduce your drag per person. I'm sure you could get a 2% reduction, or even more, but before you get much more, you'll quickly hit physical limits.
As for cost, I guess we'll have to agree to disagree. You believe that there is a market for high-speed flights that cost several times more than regular flights. I do not.
Heh. As if Apple doesn't use the cheapest components they can find. Aside from the motherboard and CPU, a Mac is made completely of stuff you can find on pricewatch.
You're right that a turbojet has to deal with the same issues with its compressor, but its easier for the turbojet because the mass flow rate through the core is relatively small. Ie: the tips of the compressor blades don't hit supersonic flow nearly as quickly as the tips of a larger fan blade. Less total energy is also lost due the shock-waves because less air needs to be slowed down to achieve a given level of thrust.
Now, all of the engines you mentioned are turbofans, but they have two main characteristics:
1) They're really low bypass ratio, so the core still provides most of the propulsion. This is unlike a high-bypass turbofan where the core provides 80% of the propulsion. These are affected far less by a loss of fan efficiency.
2) None of these aircraft are designed to cruise at mach 2+. They can only burst to that speed using afterburners. If you look at something like the F-22's engine (the F119-PW-100), you'll see that it's designed for a supercruise mach number of only 1.58, and uses a very low bypass ratio (~0.2) in the process.
I don't think a 20-30% savings in fuel costs per mile vs the Concorde is enough to make it cost-effective now. In any case, fuel is more expensive now than it was for 15 years during the late 1980's and 1990s, and the Concorde wasn't cost-effective then either. You say the rich will finance this project, but there just aren't enough rich people that need to travel so much to finance this huge operation.
Wing drag is based on weight (heavyer objects need more wing) but the body needs to move the same amount of air out of it's path if it's 100' long or 300' long.
Drag isn't just caused by "pushing air out of the way". Drag is very complex, but in supersonic flight, you can identify four major contributors to drag: pressure drag, skin-friction drag, lift-induced drag, and wave-drag. Wave drag is further broken down into volume-induced wave drag and lift-induced wave drag. The equations describing these aren't very friendly to your argument. Let's break it down:
0) Pressure drag is due to the "pusning air out of the way". You're right, it is proportional to the frontal-area of the body, and will be similar for long and short bodies of equal frontal-area.
1) Skin-friction drag is proportional to wetted surface area. A fuselage 3x as long will have 3x the surface area and much higher skin-friction drag.
2) Lift-induced drag is proportional to lift, and thus to weight. A fuselage 3x as long will weigh 3x as much, and thus require a large increase in lift. This will cause a large increase in drag.
3.1) Volume-induced wave drag is proportional to volume and inversely proportional to the fourth power of length. So increasing the length of the body by 3x will actually result in a large reduction in volume-induced wave drag.
3.2) Lift-induced wave drag is proportional to the square of lift. So making the body 3x longer will require a 3x increase in the part of the lift used to support the body, causing a 9x increase in the drag caused by the body.
As I said, drag is a complex function of these elements, and at supersonic flight, total drag is a sum of all of these elements. However, if you look at the math, you'll see that making the body longer will greatly increase your drag, unless the overall drag is completely dominted by volume-induced wave drag (which it isn't).
But supercavitation-based designs don't heat up the incoming flow. Doing so would require a high energy investment. They use cavitation to flash-vaporize parts of the flow.
Not quite true - the engines for the F-22 Raptor are F119 Turbofans (http://www.pratt-whitney.com/prod_mil_f119.asp)
which enable the aircraft to achieve supersonic flight without afterburner (quite an achievement).
It's completely true. I didn't say you couldn't have turbofans that operated at supersonic speeds. I said that turbofans:
a) cannot reach really high supersonic speeds
b) are less efficient than turbojets at some mach number
This is all the result of the fact that airflow through the fan must be kept subsonic, or else there is a drastic loss of efficiency. If you look at supersonic turbofans like on the F-22, you'll notice the intakes I mentioned that slow down the flow to subsonic speeds before the air hits the fan blades.
A turbofan and turbojet are both turbine engines with a set of fan blades as the first thing the incoming air "sees" after the inlet. These aren't like propeller blades
Turbojets have no fan, they just have a compressor before the combustor. And the solidity ratio doesn't make that much of a difference, fans can be treated using the same theory as propellors. Like propellors, they suffer a drastic loss of thrust as the incoming air approaches sonic speeds.
Your description of turbofans versus turbojets is correct, but you have to consider why turbofans are more efficient. Basically, it's a result of the following two equations describing the jet exhaust:
Thrust = mass-flow-rate * velocity
Kinetic energy = 1/2 mass-flow-rate * velocity^2
As you can see, thrust increases linearly with both thrust and velocity, but the kinetic energy of the air increases quadratically with velocity and only linearly with mass. Any kinetic energy imparted into the exhaust air is basically wasted from the engine's point of view, so its desirable to minimize this residual energy. As you can see, you can double thrust by either doubling the mass-flow-rate or doubling the velocity. Both give you the same thrust, but the latter approach leaves twice as much residual energy in the exhaust.
Turbofans work on the principle of maximizing mass flow rate and minimizing exhaust velocity. Instead of moving a little bit of air at high speed through the core, they extract most of that core energy at the turbine, and use it to drive a fan that moves a lot of air at low speed through the bypass ducts. The result of this is that in a high-bypass ratio turbofan, the fan provides the vast majority of your thrust.
Now, it becomes obvious why turbofans don't work well at high supersonic speeds. The closer the flow through the fan gets to sonic, the less efficient the fan becomes at providing thrust. Since the fan provides most of the thrust of the engine, the engine suffers a drastic thrust loss.
You can you make the air less dense? Supercavitation works through vaporization --- yo can't vaporize air.
Not all R&D is specific to a project.
In a big plane like this, yes it is. And while bragging rights may count for something, they don't count for the billions of dollars it'd cost to build this thing.
They simply doubled the price and people kept using the thing which is all about the users not a built in need to wait x years to turn a profet.
The number of people who will be willing to pay 4x as much to fly 2x faster will always be limited. The fact that every SST effort to date has so far proved unprofitable suggests that this limitation will continue to exist as long as the 4x cost differential exists.
Drag is a function of altitude, speed, shape, and weight.
You're getting away from the point. You said "a 300 passenger plane will have lower drag-per-person than a 100 passenger plane". That's not really true, because a 300 passenger plane will weigh close to 3x as much as a 100 passenger plane. See, weight is the critical part of the equation. More weight means more lift which means more lift-induced drag. Indeed, thrust-required is proportional to weight, at least at subsonic speeds. The ratio of wave-drag to lift-induced drag at supersonic speeds changes things slightly, but the point remains --- making the plane bigger is not a good way to reduce thrust required per passenger.
Geting a 16% savings from the engine and 2% from a better shape and 2% from a reduced weight would let them reach ~20% overall savings.
Is this thing coming out in 2035 or 2015? Because 16% by 2015 is incredibly optimistic. Even then, a 20% overall savings will likely not even overcome the increased cost of fuel by 2035. And in 2035, a supersonic transport will still use 4x as much fuel as a subsonic transport. That's the fundemental problem.
How do you get a bubble of air in a medium of air? It makes no sense. Hell, even if you had a bubble of air, they'd be no point --- the reason supercaviation makes things more efficient is that moving through water vapor is more efficient than moving through water. If you've got a bubble of air moving through air, you haven't gained anything.
Without the USSR, it's very likely that Germany would have won. Without the US, it's possible that Germany would have won, but more likely that Germany would ave taken a lot longer to beat. Japan is another story, but then again, Japan had no designs on continental Europe.
In any case, your point is well taken. That's precisely why the "we saved your asses" attitude is so stupid. The Russians can say the exact same thing to us ("we saved your asses by decimating Hitler's land forces"). The dick-waving is really kind of silly.
I seem to recall that the concord was operating at a profit though the last seveal years of it's life. The R&D costs where never paid back but at some point the they doubled the price and basicly nobody noticed.
.52 is 16% more effecent than .62 which is a HUGE savings.
First, the R&D costs on something like this are enormous. If those aren't recouped, there is no point. Second, if the Concorde was only operating at a profit decades after starting service, then that's hopeless. There is no way you could make up for all the losses in a reasonable timeframe. It's completely unrealistic. The thing would have to operate for 50 years just to break even.
Anyway, a ship that can take 300 people should have less drag per person than a ship that is built for 100 people.
It's not as big a difference as you'd think. The drag on a plane is a function of how much lift it produces. If you make the plane bigger (heaver), you need to increase the lift produced by the wing, which proportionally increases drag. In any case, a subsonic plane of the exact same size will still be 4x cheaper to operate in fuel costs alone.
And
It's 16% over a period of over 30 years! Those numbers won't be enough to make a plane like this profitable in the future when the Concorde isn't profitable now. You'd be lucky if that 16% even offsets rising fuel costs.
Overall I think they can drop their fuel price per person mile down by 20-30% which should let them increase the things range.
If they can do that by 2015, it would be a fricking miracle.
I think a lot of people would be willing to spend ~5-10k to save 8 hours off of a trip.
The Concorde shows that apparently enough people are not willing to do that. Basically, you're paying 4x as much (or more if you want to recoup your R&D), to get somewhere twice as fast. It's not a winning combination for most people.
There is a reason turbofans aren't used on mach 2+ aircraft. The basic problem is that in order to operate a turbofan at supersonic speeds, you have to use an engine inlet that uses a shock wave (or a series of shock waves) to slow down the flow to subsonic speeds before it hits the fan blade. Fans, like all propellors, drastically lose efficiency as the incoming flow approaches supersonic speeds. This design causes the loss of some energy, so at a certain point, a turbojet actually becomes more efficient than a turbofan.
Supercavitation works by causing the fluid the object is traveling through to vaporize. In the case of air, the fluid is already vaporized, so what would form the bubble?
Hmm, if one can't tell, does it really matter?
OK, admittedly I Am an Aerospace Engineer (IAAE?).
LOL. I'm an Aerospace Engineer in Training (IAAET?) I agree with you completely about the 787, and I alluded to as much when I pointed out that a lot of innovation went into the design of the 787. However, the pop-culture definition of "innovation" includes "revolutionary" in it. If you ask a lay-person whether they think the 787 is innovative, they'll say no. On the other hand, if you ask them other they think this supersonic airliner is innovative, they'll say yes. That'd be true even if the new airliner didn't use any technologies you couldn't find in a decades old Concorde.
Heh. And if it hadn't been for the Russians, the Germans would have won anyway, conquered continental Europe, consolidated all of its resources, and the Americans would have been powerless to stop them. Yet, Americans don't defer to the Russians very easily...
Completely wrong. What event horizon?
Shockwaves are caused by an object moving through a fluid faster than the speed of sound (ie: the speed of pressure wave propagation in the fluid). At subsonic speeds, pressure waves bouncing back from an object affect the incoming flow, basically "warning" it of the existance of the object. That's how the fluid can flow smoothly around the object --- the pressure waves caused the fluid's path to change long before it hit the object. At supersonic velocities, the pressure waves don't move fast enough to affect the incoming flow. So the fluid cannot flow smoothly around the object, and a shock wave is created where the fluid has to instantaneously react to the presence of the object.
I'm usually the first person to blame marketing, but in this case, your malaise is a bit misdirected. In the world of aerospace, it's really the physics that's more of a holdup than marketing.
Consider the CF6-50 (old 747-200 engine). It's fuel consumption at cruise (35,000 feet and mach 0.8-ish) is about 0.62 pounds of fuel per pound of thrust per hour. The Concorde engine's consumption at cruise (53,000 feet at mach 2.0) is 1.19 pounds of fuel per pound of thrust per hour. Now, consider that during supersonic cruise, your drag skyrockets by a factor of 2-3. So not only are you using 2x as much fuel for a given level of thrust, but your thrust needs to be twice as high to keep the plane flying!
Also, don't count on huge improvements in the above-mentioned figures. The CF6-50 is an engine designed in the 1960s. It's 0.62 figure at cruise was excellent for the time. The GE90 (the 777 engine), was designed in the 1990s. It's specific fuel consumption at cruise is 0.53. It's extremely efficient for a modern engine.
I'll take that bet. 2015 is ten years from now. Ten years ago was 1995. Consider how far we've come since then. Do you really think we'll come much farther in ten more years? My guess is that 2015 for this sort of thing is actually a bit optimistic. The physics of supersonic flight just don't lend themselves to cost-efficient aircraft, especially with today's escalating fuel prices.
I still love flying Thai airlines. ALl of the things you mentioned (including rather good food), plus hot stewardesses :)
Easy. You test the engine in a harness, find out how much thrust it develops, then use aerodynamic theory to figure out how fast a hypothetical plane could fly with it.
Yes and no. "Innovation" is a bit of a silly word in the engineering world. Engineering is mostly about "evolution" not "revolution". Occasionally, you see something like the SR-71, which break every existing mold, but such designs are few and far between. Consider something like the Boeing 787. It's claim to fame is a 20% increase in efficiency. To an aerospace engineer, that's huge. They'd trade their first-born for a 10% decrease in specific fuel consumption. To hit that 20%, a lot of innovations had to go into the design. But consider the big picture: is the 787, as a whole, really innovative? Not really.
Japan's aerospace industry in particular is very interested in technologies that even lay-people would see as "revolutionary". For example, if you research the field of hypersonic planes, a lot of that work is being done in Japan. In the United States, the focus is a bit different. Things have become not so much about "faster and higher", but "better, more efficient, and cheaper". Both are innovative in a way, but the former is more "sexy".
Don't forget how much you have to pony up for any of Rational's stuff!
I don't know too much about Spanish food, but I'd point out that Indian food achieves most of its flavor buy using a wide variety of spices and ingredients. That presents quite a logistical issue when your're growing your own food on Mars...
Ha ha ha. You should try reading the Anandtech forums sometime. You read some truely silly stuff in there.