I got my nano a few weeks ago, and managed to avoid all problems with screen scratches by using a screen protector bought for my palm pilot. I had to trim the protector to fit on the nano, but it's barely noticeable that it's on there and I have not had a single scratch on the screen.
True, I shouldn't have to do that; maybe Apple should have used a better material for the screen. In the end I see this as another frivolous lawsuit that's destroying this country.
The existance of NASA (and NACA) is based on the idea that they are to examine high risk concepts and develop them to the point that they can be transfered to industry. Working for a few years now on the aeronautics side of things, I've seen it done several times. This is at the center of the Boeing/Airbus dispute. We accuse them of getting direct subsidies from the European governments to fund their aircraft development, while they accuse Boeing of getting subsidies in terms of research done by NASA.
Due to the high cost of space flight, at least when it's handled by the government, the traditional space launch systems corporate entities have not yet decided to get into the manned flight buisness without government funding. At least that's my poinion. I can see your point of NASA holding on to it for longer than it should.
I don't agree with your assessment of the TPS damage and the O-Ring problem, these were not a problem that creeped up over the years. The O-ring/temperature problem was ignored by management so that they could keep schedule; while the risk of the foam shedding was always there and known by NASA, but was downgraded as more flights were not seriously affected by it and no easy fixes were available.
Lastly, I'm not sure if the shuttle could be handled by other agencies, or at least any better. It's an experimental aircraft, never ment for long term use. While a fantastic peice of engineering, I don't see it as practical in its current form.
Actually, it depends on the reference frame you're in. When dealing with air flowing over the rotor blade, we always do the analysis in the rotating frame attached to the rotor blade. Conventional airfoils are designed to operate in air flowing from the nose to tail. On the retreating side of the rotor disk, the airflow over the section of the rotor inboard of the "stand still point" will be backwards relative to the blade. In this case, the entire blade is in the reverse flow region on the retreating blade side of the rotor disk. Achieving that, even with a compound helicopter (having auxiliary lifting and propulsive devices) is not easy. Typically, helicopters fly at an mu (advance ratio) of 0.4 at most.
I agree with you on not permitting the use of calculators in school. It defeats the purpose of a math education. I went to a deli a while ago, asked the kid for a 1/3 of a pound of turkey, and after thinking for a while he had to take out a calculator to figure out that it's about 0.3 pounds! Of course, that's just one isolated incident, but it illustrates the point.
I'd go as far as to say that computers should not be allowed in the classroom except for subjects that specifically require them, like typing, drafting, etc. Schools have been trying to use technology to replace skilled teachers, and some studies indicate that it may not be working. Basic math skills will let you know if the result spat out by the calculator makes sense.
You can take this a step further. Coming from an engineering background, I've known people who complained in school about having to learn how to do problems using closed form solutions, since they're are so idealized that you'd never use them in real life. The point is that those solutions are the basis for all sophisticated analyses. Without going through those exercises, you can't understand the shortcomings of the tools you're using to make sure your answers make sense (and not blindly trusting the computer/calculator). Such a basic lack of understanding can have disastrous consequences. Computers and calculators are tools to be used once you are proficient in the subject.
I generally don't agree with the Patriot Act. I would rather have the guy prosecuted under charges other than terrorism. It will be interesting to see how they plan on making the terrorism charges stick. I'm sure you can easily get him on reckless endangerment of all on board, or probably something worse for trying to maim the pilots. Most of the articles that I read on the subject say that you could "temporarily blind" the pilots. Working around lasers, I know it doesn't take much for it to be much worse than just temporary blindness, depending on the power and proximity. Based on the altitude, the lasers must have a fair bit of power, just don't know whether they're still in range to do serious, long term damage.
The reason why people expect things to work perfectly the first time around is due to a lack of understanding of the engineering involved. People think that with the current computational tools engineers can understand any problem completely. The reality is that the theory behind the analytical tools is often based on approximations and fudge factors. When you push designs to extremes of current technology, the assumptions that the analysis are based on begin to break down. That leaves you with three choices that I can think of: 1. beef up the factors of safety, if applicable, 2. create a new analysis based on assumptions that your design will not break (of course that's simpler said than done, and requires lots of testing of the analysis) 3. weigh the risks of using the analysis and try to mitigate them by modifying your design
The method employed by an orthithopter to generate lift and propulsive force is very different than what an insect uses. This is how I understand it: because of the small Reynolds numbers or ratio between the aerodynamic forces and inertial forces of the wings, the air seems a lot more viscous to an insect. It doesn't produce lift in a traditional sense that a bird or an airplane does. As its wings flap, the motion generates a vortex and the spinning motion of the air produces low pressure inside the vortex. During each stroke of a wing, the flapping motion of the insect is such that the vortex moves across the upper surface of the wing. This vortex imparts a large pressure differential between the lower and upper surface. At the scale of an insect, the amount of lift produced is much larger than what you could produce by having a stationary wing with an airfoil-type cross-section. But it doesn't efficiently scale up to anything larger than a humming bird, at least not in air. You'd need a denser, probably more viscous gas/fluid. I've seen mineral oil used as a medium to study mechanical equivalents of insect wings since it's density and viscosity lets you slow down the time scale. I've been to a presentation by the professor in charge of the ornithopter program. They did some amazing research to figure out how to make this concept work. It has to do with correctly coupling the elastic flapping motion of the wings with twisting motion. But unlike an insect, lift is produced by the forward motion of the aircraft, just like in a normal airplane. The thrust is produced by the flapping and twisting motion pushing the air back.
"The only role that government should play is in funding pure-science projects." I guess you don't work at a NASA center. There's significant pressure on NASA researchers to bring in outside customers to cover their salaries and costs of running facilities, which implies not doing pure-science research. There's some interesting dynamics playing out: government researchers trying to get funding from the private sector while the private sector tries to get funding from the government.
It's more than just calculations and trying to account for every scenario. What most people don't realize who don't do R&D is that all designs are based on approximations and assumptions. You can never be completely certain of their consequences; that's why there are factors of safety. On top of that, you can never be certain of the exact material strength and composition. We don't understand all the non-linear effects that arise in even simple systems, let alone something extremely complicated as most aerospace systems.
I agree, human error is always a major contributor to these disasters. Management short sightedness and narrow-mindedness as well as penny-pinching had a role in all of them too. But at the same time you have to consider the logistics of these operations and and making do with often less than adequate resources. Try coordinating hundreds, if not thousands, of people across the country, probably the world, in the design and manufacture of a device that has thousands of parts that all have to work together. It's not as simple as the reporters would like everyone to believe. They like to sensationalize things, since that makes people read or listen, and gets them paid. I don't see that changing anytime soon
Sorry, I'm not that familiar with dragonfly anatomy. My expertese is helicopters, and I work with some people who do bio-inspired flight. I won't even venture a guess since I have nothing to base it on.
Rotors are much easier to build: just a revolute joint. While a flapping wing would be a more efficient way to produce lift for a small aircraft, it would be incredibly challenging to produce an actuator which can produce the required motion of a bee's wings, particularly at the proper frequency and scale. The wings actually flap and then twist, or flip over, at the end of each stroke. This way they use the vortex that is shed during the previous stroke to provide a boost in lift on the return stroke because the vortex passes over the upper surface of the wing. This produces a much greater pressure differential than just a regular airfoil in a free stream, because the core of the shed vortex has a much lower pressure than what can be produced by an airfoil due to it's shape. Let's not forget the control system which would probably be a challenge to design.
Interesting idea, but I'm not so sure of it, at least based on my intuition. Ground effect is caused by a change in induced velocity due to the proximity of the surface. By having a second smaller rotor underneath a larger one will affect the induced velocity near in the inner section of the upper rotor, but they seem to have a large root cutout, if I recall correctly, so it shouldn't really matter too much. Besides, it's the outer section of the blade that provides most of the lift. As a general rule of thumb, you're in ground effect in hover if you're within two rotor radii of the ground. Since they didn't take off, the difference in its effectiveness should be minimal. But everything on helicopters is non-intuitive, as I keep finding out over and over again. So you may be right.:)
As far as the spacing between the two rotors is concerned, I would be very disappointed if they didn't take that into consideration. Helicopter rotors are controllable and fatigue resistant ONLY due to the ability of the rotor blades to flap (and lag for fatigue). Since they were only required to hover, they only needed to account for coning which can be predicted fairly accurately.
This is probably another example of how the smallest design details can have a huge impact on the vehicle. For all we know, they built the blades and messed up where the elastic axis or tension center is with respect to the aerodynamic center, that's easy to do and that could have done disastrous consequences.
4.1.4 No devices for storing energy either for takeoff or for use in flight shall be permitted. Rotating aerodynamic components, such as rotor blades, used for lift and/or control are exempt from consideration as energy storing devices.
It's a good idea for just a short hop, but not for sustained flight. As soon as you would put in collective pitch to increase the angle of attack, your drag/torque would increase, with a further increase due to the extra weight of the fly wheel. Then the pilot would have an increased work load to sustain the aircraft in flight.
"the atmospheric conditions caused a dangerous imbalance in the craft's two rotor blades: the bottom blade was producing lift while the top blade wasn't." Sounds to me that what really happened was that they tried to save weight and didn't make the upper blades, which are longer, torsionally stiff enough. This caused a phenomenon similar to aileron reversal: as you produce lift, you produce a nose-down pitching moment which can elastically twist the blades, and may be capable of reversing the direction of lift. If this is what happened, then I can easily see the upper blades flapping down into the lower set of blades.
This aileron reversal effect is actually a fairly hot research topic in the rotorcraft community. People are trying to exploite it by using embeded actuators to control trailing edge flaps to create a pitching moment to twist rotor blades and thereby eliminate the swashplate for primary control.
I agree completely. On top of that, the part count on the car goes up, since now the bolts are assemblies, which means more thngs can go wrong. The aerospace industry, which I work for, is trying to reduce part count not increase it. Also, another improtant point to consider is that you have to power them. How will that be done? More wiring in the car? that will be a gold mine for the car dealers. I had the oxygen sensor go bad twice on my last car (a Dodge Neon) due to broken wires. Now multiply that by a hundred or more. It seems that this will be good primarely for the car makers and dearlers.
First of all, let me say that I'm a civil servent (CS) at NASA, but not working for NASA. All CS were instructed to read the report today and make recommendations to their bosses. After reading the report, I have to say that I wasn't thrilled with it. It made some good points while others I wouldn't agree with, but more often than not it stated very obious conclusions that you could get just by talking to most NASA engineers for 5 minutes.
I have to agree with the educational outreach, such as the space academy and more training for teachers. I had plenty of teachers who could teach the material, but didn't know what it is used for in the real world. That's what makes people interested, in my opinion, by showing them how it apples to their lives. There also needs to be a change in attitudes towards failing students who are not doing well. I was a TA in college, and I and other TA's have been told to rescale the grades on homeworks and exams because not enough students were passing. You could blame the bad grades on us and the teachers, but I couldn't force students to come to my office hours if they didn't want to either. But the point is, if you pass students due to education board pressures or just to get them out of your hair, it doesn't do society any good. I had a teacher retire because he was sick of being foreced to make the classes easier over the years; so it's not just my opinion.
Among other points in the report that I took note of was the retiring of the workforce and need to hire new engineers. Everyone has been talking about the upcoming "brain drain" at NASA. But if the plan (and the current trend) is to contract everything out, there will be no pressing need to hire more engineers. I just heard today that my center has a large number of CS currently not funded by a project for FY06 due to the restructuring and aeronautics program cutbacks. So I don't see this as a problem, but maybe that's just the aeronautics side.
There were two points that struck me as odd. One was the recommendation that NASA shouldn't be doing work that can be done by industry. I thought that always was the mandate: to do the work that the private sector can't or won't do due to high cost/risk/timescale/lack of facilities/etc. Along the same line, they recommended the formation of an organization to do high risk/high payoff research. To me, that's the point of NASA. It seems to me that that has been lost somewhere along the way.
Yes, CNN is definitely slipping. They reported that it may be now possible to reduce the flight time from New York to London to less then 5 hours. The Concord, first built in the late 60's, was able to accomplish the same flight in 3 hours. Based on CNN's reporting, aerospoce technology seems to be making incredible steps forward.:)
Ah yes, the 126p, or "Maluch" meaning Little One in Polish. The car was a riot. I got to ride in one last time I was in Poland. My cousin picked me up in it and it didn't want to start. He had a hammer just for such an occasion that he used to bang on the engine block to get it started. Also, no fuel guage, just a dipstick. Air cooled, so when we went on an overnight trip since the thing had no real trunk space, we put some luggage on the roof and that produced enough drag so that the engine overheated every 50 km or so. The whole car was so small that I think it could have fitted in the cabin of my old Dodge Neon. And then there was the Neon, but we won't go into all the noises it made...
The problem with the metric system in the US is that the conversion process would be incredibly pricy and lets's face it, companies will do anything they can to avoid additional costs.
Another issue that results in the english/metric unit problems is lack of intuition by engineers. Working with english units most of my life, until recently, I never had to design anything with metric units. Length and mass, I can deal with that. But when you throw stiffness, preasures, damping, etc., I can't look at the numbers and say "that seems right" or "that's physically not possible."
The US will have to make the leap eventually, but it will take a major change in political and economic environment to make that happen.
True, the ISS is a financial mess, but in my opinion, politics have played a major role in that. (Such as bringing in the cash strapped Russians in as partners.) You're forgetting about one of the major reasons for the space station: long term micro-gravity experiments. Can't do that on the moon.
I agree that NASA needed a long term goal and as much as I don't care for Bush's policies, I do like the fact that he's scrapping the shuttle. It should have been done a while ago. Going back to the moon is the next logical step after the space station, but with record deficits, I can't see how it's justified.
The whole topic of NASA's space objectives and plans brings up another question: does NASA really have a long term plan for the aeronautics side?
First of all, NASA's budget for FY04 is approximately $15.47 billion according to NASA's website, not $17 billion. That's a pretty big difference. NASA's entire aeronautics budget is a bit less than a billion if you want something for comparison. I'd love to see an increase in NASA's budget. It benefits me since I work in the aerospace sector. But I can't agree with this initiative at a time when we're facing record deficits.
It's nice to see that NASA is finally getting some sorts of long term goal (the aeronautics side needs one still). It seems like there hasn't been one in a while. I also wonder what programs will be cut or scaled back to reallocate the $11 billion that Bush mandated that NASA pull from programs that do not support the moon initiative. Since much of NASA's budget gets outsourced, has anyone considered the impact on the companies (and local economies) that have NASA contracts?
I personally feel that this will fizzle just like Bush Sr.'s push for Mars. I'm sure there will be a lot of noise and excitement about this for the next few months, but when all is said and done, it will prove to be too costly. If Bush doesn't get reelected, I think it will probably go away, if he does and he keeps pushing it, it will become another albatross around NASA's neck like the space station. On the other hand, I'm sure someone is considering China's ambitions and their impact on our prestige.
I once got a change to meet Francis Rogallo, the inventor of the hang glider. He told me that he envisioned it originally as a wing for cars that you'd deploy, fly where you needed to go, then stow it after you land and park the car.
Flying cars... there's a scary idea. People have a hard enough time dealing with motion in two dimensions, now let's bump that up to six and see what kind of mess that would cause. You'd definitely have to let a computer do all the real work and sit back and enjoy the ride. Not sure how many people would go for that in their personal vehicle; relenquishing that much control to a box. It would definately have to be a lot more sophisticated and idiot proof than the autopilot in let's say a 747.
You're forgetting that this is the government that we're talking about. It's slow to change or react even when it comes to something like this. There must be committees and subcommittees to investigate everything. Contracts and rules must be strictly adhered to (usually.) This is what I think is the most likely scenario that is being played out here:
A program proposal was written up to get funding approval, and they projected a maximum of 20 groups showing interest. Based on that forecast, they set up timelines and budgets. A thorough evaluation of five times as many entrees as the planned for would probably put them over their deadlines and budget constraints. So the logical thing is to do a cursory evaluation of the entrees to down select the candidates. I'm not saying the selection criteria were correct, but these days the government, like much of business in the US is short sighted, and short term monetary savings are the bottom line.
People seem to forget that the military is no longer on a seemingly limitless budget. We're fighting two wars, (even though they're supposedly over) are involved in some other policing actions, and Ronald Regan is no longer in office.
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I got my nano a few weeks ago, and managed to avoid all problems with screen scratches by using a screen protector bought for my palm pilot. I had to trim the protector to fit on the nano, but it's barely noticeable that it's on there and I have not had a single scratch on the screen.
True, I shouldn't have to do that; maybe Apple should have used a better material for the screen. In the end I see this as another frivolous lawsuit that's destroying this country.
The existance of NASA (and NACA) is based on the idea that they are to examine high risk concepts and develop them to the point that they can be transfered to industry. Working for a few years now on the aeronautics side of things, I've seen it done several times. This is at the center of the Boeing/Airbus dispute. We accuse them of getting direct subsidies from the European governments to fund their aircraft development, while they accuse Boeing of getting subsidies in terms of research done by NASA.
Due to the high cost of space flight, at least when it's handled by the government, the traditional space launch systems corporate entities have not yet decided to get into the manned flight buisness without government funding. At least that's my poinion. I can see your point of NASA holding on to it for longer than it should.
I don't agree with your assessment of the TPS damage and the O-Ring problem, these were not a problem that creeped up over the years. The O-ring/temperature problem was ignored by management so that they could keep schedule; while the risk of the foam shedding was always there and known by NASA, but was downgraded as more flights were not seriously affected by it and no easy fixes were available.
Lastly, I'm not sure if the shuttle could be handled by other agencies, or at least any better. It's an experimental aircraft, never ment for long term use. While a fantastic peice of engineering, I don't see it as practical in its current form.
Actually, it depends on the reference frame you're in. When dealing with air flowing over the rotor blade, we always do the analysis in the rotating frame attached to the rotor blade. Conventional airfoils are designed to operate in air flowing from the nose to tail. On the retreating side of the rotor disk, the airflow over the section of the rotor inboard of the "stand still point" will be backwards relative to the blade. In this case, the entire blade is in the reverse flow region on the retreating blade side of the rotor disk. Achieving that, even with a compound helicopter (having auxiliary lifting and propulsive devices) is not easy. Typically, helicopters fly at an mu (advance ratio) of 0.4 at most.
I'd go as far as to say that computers should not be allowed in the classroom except for subjects that specifically require them, like typing, drafting, etc. Schools have been trying to use technology to replace skilled teachers, and some studies indicate that it may not be working. Basic math skills will let you know if the result spat out by the calculator makes sense.
You can take this a step further. Coming from an engineering background, I've known people who complained in school about having to learn how to do problems using closed form solutions, since they're are so idealized that you'd never use them in real life. The point is that those solutions are the basis for all sophisticated analyses. Without going through those exercises, you can't understand the shortcomings of the tools you're using to make sure your answers make sense (and not blindly trusting the computer/calculator). Such a basic lack of understanding can have disastrous consequences. Computers and calculators are tools to be used once you are proficient in the subject.
I generally don't agree with the Patriot Act. I would rather have the guy prosecuted under charges other than terrorism. It will be interesting to see how they plan on making the terrorism charges stick. I'm sure you can easily get him on reckless endangerment of all on board, or probably something worse for trying to maim the pilots. Most of the articles that I read on the subject say that you could "temporarily blind" the pilots. Working around lasers, I know it doesn't take much for it to be much worse than just temporary blindness, depending on the power and proximity. Based on the altitude, the lasers must have a fair bit of power, just don't know whether they're still in range to do serious, long term damage.
The reason why people expect things to work perfectly the first time around is due to a lack of understanding of the engineering involved. People think that with the current computational tools engineers can understand any problem completely. The reality is that the theory behind the analytical tools is often based on approximations and fudge factors. When you push designs to extremes of current technology, the assumptions that the analysis are based on begin to break down. That leaves you with three choices that I can think of:
1. beef up the factors of safety, if applicable,
2. create a new analysis based on assumptions that your design will not break (of course that's simpler said than done, and requires lots of testing of the analysis)
3. weigh the risks of using the analysis and try to mitigate them by modifying your design
The method employed by an orthithopter to generate lift and propulsive force is very different than what an insect uses. This is how I understand it: because of the small Reynolds numbers or ratio between the aerodynamic forces and inertial forces of the wings, the air seems a lot more viscous to an insect. It doesn't produce lift in a traditional sense that a bird or an airplane does. As its wings flap, the motion generates a vortex and the spinning motion of the air produces low pressure inside the vortex. During each stroke of a wing, the flapping motion of the insect is such that the vortex moves across the upper surface of the wing. This vortex imparts a large pressure differential between the lower and upper surface. At the scale of an insect, the amount of lift produced is much larger than what you could produce by having a stationary wing with an airfoil-type cross-section. But it doesn't efficiently scale up to anything larger than a humming bird, at least not in air. You'd need a denser, probably more viscous gas/fluid. I've seen mineral oil used as a medium to study mechanical equivalents of insect wings since it's density and viscosity lets you slow down the time scale.
I've been to a presentation by the professor in charge of the ornithopter program. They did some amazing research to figure out how to make this concept work. It has to do with correctly coupling the elastic flapping motion of the wings with twisting motion. But unlike an insect, lift is produced by the forward motion of the aircraft, just like in a normal airplane. The thrust is produced by the flapping and twisting motion pushing the air back.
"The only role that government should play is in funding pure-science projects." I guess you don't work at a NASA center. There's significant pressure on NASA researchers to bring in outside customers to cover their salaries and costs of running facilities, which implies not doing pure-science research. There's some interesting dynamics playing out: government researchers trying to get funding from the private sector while the private sector tries to get funding from the government.
It's more than just calculations and trying to account for every scenario. What most people don't realize who don't do R&D is that all designs are based on approximations and assumptions. You can never be completely certain of their consequences; that's why there are factors of safety. On top of that, you can never be certain of the exact material strength and composition. We don't understand all the non-linear effects that arise in even simple systems, let alone something extremely complicated as most aerospace systems.
I agree, human error is always a major contributor to these disasters. Management short sightedness and narrow-mindedness as well as penny-pinching had a role in all of them too. But at the same time you have to consider the logistics of these operations and and making do with often less than adequate resources. Try coordinating hundreds, if not thousands, of people across the country, probably the world, in the design and manufacture of a device that has thousands of parts that all have to work together. It's not as simple as the reporters would like everyone to believe. They like to sensationalize things, since that makes people read or listen, and gets them paid. I don't see that changing anytime soon
Sorry, I'm not that familiar with dragonfly anatomy. My expertese is helicopters, and I work with some people who do bio-inspired flight. I won't even venture a guess since I have nothing to base it on.
Rotors are much easier to build: just a revolute joint. While a flapping wing would be a more efficient way to produce lift for a small aircraft, it would be incredibly challenging to produce an actuator which can produce the required motion of a bee's wings, particularly at the proper frequency and scale. The wings actually flap and then twist, or flip over, at the end of each stroke. This way they use the vortex that is shed during the previous stroke to provide a boost in lift on the return stroke because the vortex passes over the upper surface of the wing. This produces a much greater pressure differential than just a regular airfoil in a free stream, because the core of the shed vortex has a much lower pressure than what can be produced by an airfoil due to it's shape. Let's not forget the control system which would probably be a challenge to design.
Interesting idea, but I'm not so sure of it, at least based on my intuition. Ground effect is caused by a change in induced velocity due to the proximity of the surface. By having a second smaller rotor underneath a larger one will affect the induced velocity near in the inner section of the upper rotor, but they seem to have a large root cutout, if I recall correctly, so it shouldn't really matter too much. Besides, it's the outer section of the blade that provides most of the lift. As a general rule of thumb, you're in ground effect in hover if you're within two rotor radii of the ground. Since they didn't take off, the difference in its effectiveness should be minimal. But everything on helicopters is non-intuitive, as I keep finding out over and over again. So you may be right. :)
As far as the spacing between the two rotors is concerned, I would be very disappointed if they didn't take that into consideration. Helicopter rotors are controllable and fatigue resistant ONLY due to the ability of the rotor blades to flap (and lag for fatigue). Since they were only required to hover, they only needed to account for coning which can be predicted fairly accurately.
This is probably another example of how the smallest design details can have a huge impact on the vehicle. For all we know, they built the blades and messed up where the elastic axis or tension center is with respect to the aerodynamic center, that's easy to do and that could have done disastrous consequences.
It's against the rules:
4.1.4 No devices for storing energy either for takeoff or for use in flight shall be permitted. Rotating aerodynamic components, such as rotor blades, used for lift and/or control are exempt from consideration as energy storing devices.
It's a good idea for just a short hop, but not for sustained flight. As soon as you would put in collective pitch to increase the angle of attack, your drag/torque would increase, with a further increase due to the extra weight of the fly wheel. Then the pilot would have an increased work load to sustain the aircraft in flight.
"the atmospheric conditions caused a dangerous imbalance in the craft's two rotor blades: the bottom blade was producing lift while the top blade wasn't." Sounds to me that what really happened was that they tried to save weight and didn't make the upper blades, which are longer, torsionally stiff enough. This caused a phenomenon similar to aileron reversal: as you produce lift, you produce a nose-down pitching moment which can elastically twist the blades, and may be capable of reversing the direction of lift. If this is what happened, then I can easily see the upper blades flapping down into the lower set of blades.
This aileron reversal effect is actually a fairly hot research topic in the rotorcraft community. People are trying to exploite it by using embeded actuators to control trailing edge flaps to create a pitching moment to twist rotor blades and thereby eliminate the swashplate for primary control.
I agree completely. On top of that, the part count on the car goes up, since now the bolts are assemblies, which means more thngs can go wrong. The aerospace industry, which I work for, is trying to reduce part count not increase it. Also, another improtant point to consider is that you have to power them. How will that be done? More wiring in the car? that will be a gold mine for the car dealers. I had the oxygen sensor go bad twice on my last car (a Dodge Neon) due to broken wires. Now multiply that by a hundred or more. It seems that this will be good primarely for the car makers and dearlers.
First of all, let me say that I'm a civil servent (CS) at NASA, but not working for NASA. All CS were instructed to read the report today and make recommendations to their bosses. After reading the report, I have to say that I wasn't thrilled with it. It made some good points while others I wouldn't agree with, but more often than not it stated very obious conclusions that you could get just by talking to most NASA engineers for 5 minutes.
I have to agree with the educational outreach, such as the space academy and more training for teachers. I had plenty of teachers who could teach the material, but didn't know what it is used for in the real world. That's what makes people interested, in my opinion, by showing them how it apples to their lives. There also needs to be a change in attitudes towards failing students who are not doing well. I was a TA in college, and I and other TA's have been told to rescale the grades on homeworks and exams because not enough students were passing. You could blame the bad grades on us and the teachers, but I couldn't force students to come to my office hours if they didn't want to either. But the point is, if you pass students due to education board pressures or just to get them out of your hair, it doesn't do society any good. I had a teacher retire because he was sick of being foreced to make the classes easier over the years; so it's not just my opinion.
Among other points in the report that I took note of was the retiring of the workforce and need to hire new engineers. Everyone has been talking about the upcoming "brain drain" at NASA. But if the plan (and the current trend) is to contract everything out, there will be no pressing need to hire more engineers. I just heard today that my center has a large number of CS currently not funded by a project for FY06 due to the restructuring and aeronautics program cutbacks. So I don't see this as a problem, but maybe that's just the aeronautics side.
There were two points that struck me as odd. One was the recommendation that NASA shouldn't be doing work that can be done by industry. I thought that always was the mandate: to do the work that the private sector can't or won't do due to high cost/risk/timescale/lack of facilities/etc. Along the same line, they recommended the formation of an organization to do high risk/high payoff research. To me, that's the point of NASA. It seems to me that that has been lost somewhere along the way.
Yes, CNN is definitely slipping. They reported that it may be now possible to reduce the flight time from New York to London to less then 5 hours. The Concord, first built in the late 60's, was able to accomplish the same flight in 3 hours. Based on CNN's reporting, aerospoce technology seems to be making incredible steps forward. :)
Ah yes, the 126p, or "Maluch" meaning Little One in Polish. The car was a riot. I got to ride in one last time I was in Poland. My cousin picked me up in it and it didn't want to start. He had a hammer just for such an occasion that he used to bang on the engine block to get it started. Also, no fuel guage, just a dipstick. Air cooled, so when we went on an overnight trip since the thing had no real trunk space, we put some luggage on the roof and that produced enough drag so that the engine overheated every 50 km or so. The whole car was so small that I think it could have fitted in the cabin of my old Dodge Neon. And then there was the Neon, but we won't go into all the noises it made...
The problem with the metric system in the US is that the conversion process would be incredibly pricy and lets's face it, companies will do anything they can to avoid additional costs.
Another issue that results in the english/metric unit problems is lack of intuition by engineers. Working with english units most of my life, until recently, I never had to design anything with metric units. Length and mass, I can deal with that. But when you throw stiffness, preasures, damping, etc., I can't look at the numbers and say "that seems right" or "that's physically not possible."
The US will have to make the leap eventually, but it will take a major change in political and economic environment to make that happen.
True, the ISS is a financial mess, but in my opinion, politics have played a major role in that. (Such as bringing in the cash strapped Russians in as partners.) You're forgetting about one of the major reasons for the space station: long term micro-gravity experiments. Can't do that on the moon.
I agree that NASA needed a long term goal and as much as I don't care for Bush's policies, I do like the fact that he's scrapping the shuttle. It should have been done a while ago. Going back to the moon is the next logical step after the space station, but with record deficits, I can't see how it's justified.
The whole topic of NASA's space objectives and plans brings up another question: does NASA really have a long term plan for the aeronautics side?
First of all, NASA's budget for FY04 is approximately $15.47 billion according to NASA's website, not $17 billion. That's a pretty big difference. NASA's entire aeronautics budget is a bit less than a billion if you want something for comparison. I'd love to see an increase in NASA's budget. It benefits me since I work in the aerospace sector. But I can't agree with this initiative at a time when we're facing record deficits.
It's nice to see that NASA is finally getting some sorts of long term goal (the aeronautics side needs one still). It seems like there hasn't been one in a while. I also wonder what programs will be cut or scaled back to reallocate the $11 billion that Bush mandated that NASA pull from programs that do not support the moon initiative. Since much of NASA's budget gets outsourced, has anyone considered the impact on the companies (and local economies) that have NASA contracts?
I personally feel that this will fizzle just like Bush Sr.'s push for Mars. I'm sure there will be a lot of noise and excitement about this for the next few months, but when all is said and done, it will prove to be too costly. If Bush doesn't get reelected, I think it will probably go away, if he does and he keeps pushing it, it will become another albatross around NASA's neck like the space station. On the other hand, I'm sure someone is considering China's ambitions and their impact on our prestige.
I once got a change to meet Francis Rogallo, the inventor of the hang glider. He told me that he envisioned it originally as a wing for cars that you'd deploy, fly where you needed to go, then stow it after you land and park the car.
Thanks, you're right. Forgot about rotation in a plane.
Flying cars... there's a scary idea. People have a hard enough time dealing with motion in two dimensions, now let's bump that up to six and see what kind of mess that would cause. You'd definitely have to let a computer do all the real work and sit back and enjoy the ride. Not sure how many people would go for that in their personal vehicle; relenquishing that much control to a box. It would definately have to be a lot more sophisticated and idiot proof than the autopilot in let's say a 747.
You're forgetting that this is the government that we're talking about. It's slow to change or react even when it comes to something like this. There must be committees and subcommittees to investigate everything. Contracts and rules must be strictly adhered to (usually.) This is what I think is the most likely scenario that is being played out here:
A program proposal was written up to get funding approval, and they projected a maximum of 20 groups showing interest. Based on that forecast, they set up timelines and budgets. A thorough evaluation of five times as many entrees as the planned for would probably put them over their deadlines and budget constraints. So the logical thing is to do a cursory evaluation of the entrees to down select the candidates. I'm not saying the selection criteria were correct, but these days the government, like much of business in the US is short sighted, and short term monetary savings are the bottom line.
People seem to forget that the military is no longer on a seemingly limitless budget. We're fighting two wars, (even though they're supposedly over) are involved in some other policing actions, and Ronald Regan is no longer in office.