Correct. You may have to go through a background check depending on the airport you fly out of, but once you are through that process it is pretty close to the same experience in jumping into your car to go someplace.
It's not cheap, and not as safe and reliable as using the airlines, but it's a much nicer experience. I keep waiting for DHS/TSA to try to interfere with it the way they have the airlines.
While I generally agree with the direction of your comments, the government has indeed been directly involved in greatly increasing the safety of airline travel. The NTSB/CAA/FAA have been instrumental in determining the causes of accidents and promulgating regulations intended to prevent reoccurrence of those accidents.
While the system has many flaws, if you compare the risks of airline flight in the 50s with today, there has been a huge increase in safety. Some would have happened without the intervention of the government, but a lot of it might have been delayed or never happened without government intervention.
The DHS and TSA on the other hand, are the worst thing to happen to US aviation ever.
As a helicopter pilot who flies a helicopter with an autopilot... it's not as difficult as you make it out to be, especially with the miniaturization of computer systems.
There are two bigger problems that I see: The smaller the area producing downwash, the less efficient the craft is. Think Harrier versus a typical helicopter. A typical helicopter has a rotor system 25-40 feet in diameter, while a Harrier engine outlet is only a few feet across. There's a reason why the fuel line for the Pegasus engine is as big as your arm. The noise is also related, again think Harrier versus a helicopter. A helicopter isn't necessarily quiet, but compared to a Harrier they're silent!
The other problem is engine failure. Although BRS to some degree addresses that problem, that adds weight which is going to adversely affect range, power, etc. Also, even BRS systems have parts of the envelope they can't protect you in - a friend watched a guy die in an ultralight - the structure failed too close to the ground. The BRS deployed, but did not inflate in time to reduce the vertical impact.
If you look at a lot of work that got done right after WWII on personal sized helicopters, they tried to address a lot of these issues. Notice that we still don't see a lot of man portable helicopter systems!
I can't answer your question, but it is true that currently barometric altimeters are more precise than GPS altitude. GPS is not currently capable, even with WAAS, of meeting TERPS requirements for precision approaches, but there are precision approaches that use barometric altitude to indicate glide slope.
GPS has always had lousy altitude resolution compared to position over the ground. I've always thought it was both satellite geometry and earth model problems, but I can't really say for sure.
In any case, grandparent is currently correct: baro altitude is more precise than GPS.
In the aircraft I fly, GPS altitude is not nearly as accurate as GPS position over the ground. I believe this is a combination of less optimal satellite geometry, and the resolution of the terrain map or earth model being used to set the position in space of the ground.
Another thing that people are ignoring here is that GPS is incredibly easy to jam. A few years back someone turned on a single jammer someplace in France and disabled GPS for a large percentage of that country. Sole source navigation & separation is a risky business. The current ATC system is designed to be a very redundant system - the pilot can lose his communications radios, or his navigation radios, or ATC can lose their RADAR (so, you can lose any 1 of the three), and it is still possible to get aircraft to their destinations safely.
I'm wondering what will happen if all airline traffic is navigating and being separated by GPS when someone turns on a GPS jammer in the middle of a city like Los Angeles or New York?
Personally I think RADAR is an important piece of the ATC system I'd rather not have go away.
I have to disagree, having worked a bit on avionics. The key is writing the code in a way that will be testable, and then testing it.
In the case of Class A software, every conditional branch needs to be tested in all possible combinations, even in combinations which in theory can't happen. In our parent company, this was done using a special (hardware) debugger so that conditional branches could be forced to go in ways they wouldn't normally go. The combinatorial explosion of possible outcomes caused strict limits on how many levels deep of conditional code they would allow (I think it was no more than 2 levels deep, but it's been a while). It took about a year to test one major release of code because of the complexity of testing. You can get a copy of DO-178B to understand what the government requires for testing hardware and software in flight critical situations.
An ex-student of mine worked on testing the Boeing 777 flight control software and he said their testing was much more comprehensive than ours.
I would say that the average software engineer woefully underestimates the level of effort it takes to write code that the aerospace industry considers flight worthy.
I'm surprised to hear people saying the teachers and school should get sued. I think felony charges and jail time would be a much better reaction to this incident.
If it's as simple as this, I'm disappointed. How is the aircraft controlled in roll and pitch? Watching the aircraft fly, it appears that the operator is controlling the aircraft in pitch and roll, and perhaps in yaw. How? (it looks like the moving vanes would control yaw).
If the Coanda effect is simply being used to attach the flow around the surface of the craft, I don't see how pitch and roll control are maintained, nor how you would produce lateral displacements. The flow would be mostly uniform, and the craft would hover but not controllable in pitch and roll. Yet in the video, it certainly appears as if the operator is able to control the craft much as you would a helicopter.
I was assuming that some of the air is being ducted through a slot or something so that the flow could be attached in a non-uniform way around the body of the aircraft, and that these non-uniform flows would then result in different directions of thrust at various points around the craft, thus allowing pitch and roll control.
In the MDHC Notar, there is a jet of air which is forced out along one side of the tail boom, and this attaches the main rotor down wash to that side of the boom. If Coanda was just about the shape of the surface, MDHC would not have gone to all the trouble it did to pressurize air inside the tail boom - they would have simply built a tail boom with a specific shape.
I find the Wikipedia article a bit confusing. On the one hand, they define Coanda effect as:
Method and apparatus for deviation of a fluid into another fluid
and this is consistent with the MDHC usage of Coanda - they introduce one flow of air into another to attach the first flow. The Wikipedia article gives the example of the spoon in the flow of water. If the flow of water is the first fluid, where is the second fluid?
How is the spoon example different than what happens when air flows over an airfoil? Are we saying that is also an example of Coanda?
There are two different mechanisms used to yaw a helicopter, depending on whether we are talking about in forward flight, or in a hover.
In forward flight, the main rotor thrust is tilted which pulls the helicopter to the side. As the helicopter moves to the side, the vertical fin at the rear of the helicopter provides weathercock stability, much like the fins on an arrow. This yaws the helicopter in the pro-turn direction. Some helicopters need a little bit of pro-turn anti-torque pedal, but this is a minor correction to keep the aircraft in trim. Most of the yawing force in forward flight is being provided by the (fixed) vertical stabilizer.
In a HOVER, a conventional helicopter uses tail rotor thrust to yaw the aircraft. As a previous poster pointed out, this is done by changing the angle of attack of the tail rotor, not by changing the speed. As he pointed out, in full size helicopters, the main rotor and the tail rotor are connected by drive shafts and transmissions, meaning their speed is always at a fixed relationship to each other. This is done so that during unpowered flight (autorotation) the main rotor can keep the tail rotor turning, to give the pilot yaw control during the glide and landing.
Also, you are incorrect about how counter-rotating helicopters generate yaw forces. A tandem rotor helicopter like the CH-46 and CH-47 generate yaw forces by tiling the front and rear rotors in opposite directions. To yaw left, the front rotor is tilted to the left, and the rear rotor is tilted to the right. Coaxial and intermeshing helicopters generate yaw forces by changing the relative pitch of the rotors. This causes the rotor turning in one direction to generate an increased torque force, while the rotor turning in the opposite direction generates decreased torque forces. The imbalance causes a yawing force. Note that these systems need to work backwards when in autorotation. I've never flown one of those systems, so I only know what I've read - someone who has flight experience in a Kaman or Kamov might comment?
Back to the particular device in the article, the anti-torque force seems to be generated by a combination of fixed fins around the circumference (note how they are all bent in the anti-torque direction) and the (4?) moving fins which are probably there to provide yaw control to the operator.
I beg to differ - I think the parent was probably correct about what the author meant. First of all, the design did NOT look that stable. Also, the fact that the fan is ducted means gentle collisions won't destroy the rotor system which is a pretty good feature for a small UAV. It also has a safety benefit if the rotor is ducted.
As for the stability of helicopters, if you look at the designs in the 50's and 60s, stability was a big goal. Look at Stanley Hiller's demonstration of hands off hovering of his helicopters. Over the years stability appears to have been less and less of a goal. Look at how the flybar on the Bell rotor systems has disappeared. I'm not sure why this has happened, but I'm guessing that agility has won out over stability, especially since stability can easily be added by electronic means.
I read the article, but I wasn't quiet sure how the Coanda effect was utilized by this design. I'm guessing that rather than tilt the rotor there are places where the downwash is attached (or not) and thus generate sideways thrust? I saw the little vanes moving, but assumed that was more for anti-torque - if you noticed, most of the vanes were fixed with a little bend in the direction of anti-torque (and, like the MDHC Notar the anti-torque force would be proportional to downwash and thus to torque). A few of them moved to give you the ability to rotate the machine and account for minor yawing forces not exactly countered by the fixed vanes.
Did anyone else notice where/how Coanda effect was used? Perhaps the moving vanes really are implementing the Coanda effect, but if so it's in a fairly different way than the MDHC Notar system. Did I miss something?
Mercury Computer was the second largest shipper of PPC processors, second only to Apple. After the Apple switch to Intel, I would expect that Mercury is probably the largest consumer of PPC. Mercury makes very interesting massively parallel machines for realtime signal processing. Their machines range from a handful of processors up to 1,000 processors, all connected by a high speed proprietary switched fabric. You can check them out at MC.com
Another big consumer of PPC processors is the embedded market. They're much smaller processors (IBM 8xx and Freescale 8xxx) but they're full PPC processors and I'll be they ship in huge quantities.
If you think you want a 3 button mouse buy one. It will work fine with OSX and do exactly what you expect.
I personally don't like the mice that Apple ships. I like the Macally mice with three buttons and a wheel. Works great and does exactly what you would expect.
So, in that sense, Apple does listen and support what people ask for. They just don't promote it by selling those kinds of mice themselves.
Agreed - Target Disk Mode is incredibly useful, and I've used it to save my own butt several times, as well as the butts of others!
I was at a course where the Macs were mis-behaving and nobody could save their data. Everything was going to be wiped when we left for the day, losing hours of work. The files were too big to move even on CD. I booted up my laptop using TDM, and everybody stored their data on my laptop. Next day we were able to pull it all back off the laptop the same way.
I also agree that it would be nice if it was supported on USB...
While modern airplanes have great automation available, your statement that pilots do very little is an exaggeration. Most (all?) takeoffs and most approaches are hand flown. Most systems configuration changes in flight are done by the pilot. The crew most certainly does not sit there and watch the automated system making decisions. Most pilots enjoy flying; that's why they chose the profession in the first place. While navigation enroute has made great automation strides (mostly because of microprocessors and GPS) most approaches in bad weather are still done based on 1950's technology (ILS) and the majority of those are hand flown.
While autoland systems are used overseas, I do not believe they are used in the U.S (but they probably will be someday).
While the technology may be available to allow pilots to do very little, that's not how it's done in practice. The last 3 times I flew jump seat (Dash-8, CRJ, Boeing-777) most of the flying was hand flying, with the exception of the cruise portion of the flight. The safest system is probably the track that we are on: automation to do the boring parts, and a wealth of information presented by computer to the pilot in a way humans can easily interpret (so, for instance a HUD with computer synthesized imagery so the human can see through fog, night, etc.).
And, to answer your question about kernels, I'd feel fine with Linux if it passed DO-178B Level A certification, but that's probably not going to happen anytime soon;-)
I beg to differ. Almost no airspace over US cities is prohibited airspace. Washington DC has a lot of prohibited airspace, but most other cities have none. As a former traffic helicopter pilot I can tell you that there are not many restrictions on where you can fly, except good judgement. San Francisco is one exception that I know of.
Exactly my experience late last year on my motorcycle. Cop turns on his lights about 1/8 mile from the exit I'm planning on using. I know there's a gas station right at the bottom of the ramp, so I signal, go to the bottom of the ramp, and pull into the gas station.
The cop rants for a bit about how HE gets to decide where I pull over, not me, blah, blah, blah. Maybe because my bike can do 185 he thinks I'm gonna run? Dunno, and I was close to telling him off, but restrained myself and said "yes sir" all the while thinking that of course in the future I'll continue to pull over when it's safe for both him and I.
I wish there was a way to select cops who aren't likely to have the power trip gene.
The company was an unfortunate combination of bleeding edge and inadequate funding. At the time, 100BT Ethernet had just come out, and people were getting 5-6MB/sec over it. We were using Fiber Channel to get gigabit ethernet speeds over the network. There was only one card at the time, from Emulex, and I don't think they considered us worth their effort at first. When we started demonstrating what we could do, they got much more helpful. Certainly had we not reverse engineered their DMA engine, they never would have given us the time of day.
The other half of the project was the actual server hardware. It was a project another company did, and when it was cancelled they sold the assets for cheap. I think this looked like a good deal to the president and CTO of our company. In retrospect, it was probably a bum deal. We could have done better by starting with PC hardware running an RTOS, and then later done our own boards. At the time, it looked like a cool piece of hardware. Problem was that the CTO didn't perform due diligence.
I've certainly learned over the years that you almost NEVER want to do bleeding edge, or if you do it needs to be ONE THING, with everything else conservative, and you better have a backup plan too!
All that said, there are certainly times it's cheaper or faster to reverse engineer someone else's work, rather than try to reinvent it from start.
Amazingly, we got the hardware and software to work. And, the customers loved the product. The company simply ran out of money before they could become profitable.
With 30 years as a software engineer, it's only very recently that I've ever seen "reverse engineering" used in the context of reading source code. In the past we called that.... um... "reading the source code". I can understand this interpretation, and it fits in with the general idea of "deduce design by observing details" but I think this particular interpretation trivializes the term a bit. Can you imagine someone saying they "reverse engineered a book" because they read it and understood what the author intended?
Throughout most of my career, I've understood reverse engineering to be what you do when you DON'T have the source code. I think the wikipedia entry mentions that this is the most common interpretation. It can be extremely difficult and time consuming. I've done it on major projects a few times in my career. It is neither easy nor efficient, but sometimes the only choice you have.
It's also common to talk about reverse engineering hardware, where the innards of a chip may be deduced by observing its inputs and outputs. I worked on a project at a startup where we had to do that, because the original hardware developers were long gone, and no VHDL could be discovered, yet we had to write drivers for their (buggy) chips in order to make a deadline. At the same company we had to reverse engineer the workings of a (buggy) Fiber Channel PCI card, because the manufacturer would not give us the support we needed to make our deadlines. They were rather surprised when we talked to them about the details of their (proprietary, embedded in an ASIC) DMA engine that we deduced via logic analyzers and oscilloscopes.
Those projects were SO difficult compared to reading (even obscure) code, that I really think that using the one phrase for both activities is confusing and sometimes even deceptive.
If I leave a DVD lying around my house when you visit, laptop in hand, am I guilty of making copyrighted material available for copying? Do I need to keep my DVDs under lock and key to insure you don't pop 'em in your laptop and make copies?
If I watch a movie on my TV with the shades open, so that you could potentially sit outside my house and videotape the movie, have I violated the intent of this law?
Actually, I believe there are two reasons that yokes became adopted (hate 'em myself - much prefer a stick)
1) I've read that you can put more force on a yoke. Seems wrong to me, but that's what I've read. WWII bombers had yokes, whereas lots of the fighters still had sticks. The Bell X-1 had a yoke, as well.
2) In General Aviation, there was a move (in the 50's I think) to make airplanes more like cars, as a way to get better public acceptance. "Steering wheels" versus a stick, don'tcha know?
2) Not being able to modify this code is not at all akin to being unable to change a lightbulb in your own house. When you buy a house, you OWN the house. When you buy a piece of software, you do not OWN the code.
Ok, so it's like renting an apartment in which you are not allowed to change the lightbulbs yourself, instead you are supposed to call the landlord when a light goes out. But whenever you do he tries to convince you that the bulb isn't really out, and then tries to talk you into renting a new apartment that has all working bulbs. So you do, and the new apartment has bulbs already broken when you move in. And you complain, but he's not listening, he's already telling you about this new apartment he has...
When Hollywood makes films do they pay owners for using footage of the outside of their buildings? I don't believe this is usually the case so why should it be illegal to make footage of their footage? It would seem a building costs far more to product than some tape.
Actually, they do. I've been told in photography classes that you can't take a picture that includes a building unless you get permission. Apparently the architectural firms own copyright to the likeness of the building. Do I think that's stupid? Yup.
On the Fight Club DVD, they talk about the end scene where they blow up some buildings - totally done in CG - having to be buildings that the studio owned. I guess you can get into trouble for blowing up the likeness of someone else's building?
Personally I think it might be time for copyright to go away, or at least drastically morph so that most information becomes free.
I was thinking the same thing: do the students HAVE to have a computer at school? Can you opt out of the entire computerized classes thing? Would a terms-of-usage agreement have any basis if you are compelled to have a computer and you must sign the agreement in order to have a computer? What is your alternative to signing?
Personally I think computers in school is a terrible idea. Then again, I don't think current schools are a very good way of teaching. Not sure I have great alternatives, though.
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It's not cheap, and not as safe and reliable as using the airlines, but it's a much nicer experience. I keep waiting for DHS/TSA to try to interfere with it the way they have the airlines.
While the system has many flaws, if you compare the risks of airline flight in the 50s with today, there has been a huge increase in safety. Some would have happened without the intervention of the government, but a lot of it might have been delayed or never happened without government intervention.
The DHS and TSA on the other hand, are the worst thing to happen to US aviation ever.
There are two bigger problems that I see: The smaller the area producing downwash, the less efficient the craft is. Think Harrier versus a typical helicopter. A typical helicopter has a rotor system 25-40 feet in diameter, while a Harrier engine outlet is only a few feet across. There's a reason why the fuel line for the Pegasus engine is as big as your arm. The noise is also related, again think Harrier versus a helicopter. A helicopter isn't necessarily quiet, but compared to a Harrier they're silent!
The other problem is engine failure. Although BRS to some degree addresses that problem, that adds weight which is going to adversely affect range, power, etc. Also, even BRS systems have parts of the envelope they can't protect you in - a friend watched a guy die in an ultralight - the structure failed too close to the ground. The BRS deployed, but did not inflate in time to reduce the vertical impact.
If you look at a lot of work that got done right after WWII on personal sized helicopters, they tried to address a lot of these issues. Notice that we still don't see a lot of man portable helicopter systems!
GPS has always had lousy altitude resolution compared to position over the ground. I've always thought it was both satellite geometry and earth model problems, but I can't really say for sure.
In any case, grandparent is currently correct: baro altitude is more precise than GPS.
Another thing that people are ignoring here is that GPS is incredibly easy to jam. A few years back someone turned on a single jammer someplace in France and disabled GPS for a large percentage of that country. Sole source navigation & separation is a risky business. The current ATC system is designed to be a very redundant system - the pilot can lose his communications radios, or his navigation radios, or ATC can lose their RADAR (so, you can lose any 1 of the three), and it is still possible to get aircraft to their destinations safely.
I'm wondering what will happen if all airline traffic is navigating and being separated by GPS when someone turns on a GPS jammer in the middle of a city like Los Angeles or New York?
Personally I think RADAR is an important piece of the ATC system I'd rather not have go away.
In the case of Class A software, every conditional branch needs to be tested in all possible combinations, even in combinations which in theory can't happen. In our parent company, this was done using a special (hardware) debugger so that conditional branches could be forced to go in ways they wouldn't normally go. The combinatorial explosion of possible outcomes caused strict limits on how many levels deep of conditional code they would allow (I think it was no more than 2 levels deep, but it's been a while). It took about a year to test one major release of code because of the complexity of testing. You can get a copy of DO-178B to understand what the government requires for testing hardware and software in flight critical situations.
An ex-student of mine worked on testing the Boeing 777 flight control software and he said their testing was much more comprehensive than ours.
I would say that the average software engineer woefully underestimates the level of effort it takes to write code that the aerospace industry considers flight worthy.
I'm surprised to hear people saying the teachers and school should get sued. I think felony charges and jail time would be a much better reaction to this incident.
If the Coanda effect is simply being used to attach the flow around the surface of the craft, I don't see how pitch and roll control are maintained, nor how you would produce lateral displacements. The flow would be mostly uniform, and the craft would hover but not controllable in pitch and roll. Yet in the video, it certainly appears as if the operator is able to control the craft much as you would a helicopter.
I was assuming that some of the air is being ducted through a slot or something so that the flow could be attached in a non-uniform way around the body of the aircraft, and that these non-uniform flows would then result in different directions of thrust at various points around the craft, thus allowing pitch and roll control.
In the MDHC Notar, there is a jet of air which is forced out along one side of the tail boom, and this attaches the main rotor down wash to that side of the boom. If Coanda was just about the shape of the surface, MDHC would not have gone to all the trouble it did to pressurize air inside the tail boom - they would have simply built a tail boom with a specific shape.
I find the Wikipedia article a bit confusing. On the one hand, they define Coanda effect as:
and this is consistent with the MDHC usage of Coanda - they introduce one flow of air into another to attach the first flow. The Wikipedia article gives the example of the spoon in the flow of water. If the flow of water is the first fluid, where is the second fluid?How is the spoon example different than what happens when air flows over an airfoil? Are we saying that is also an example of Coanda?
In forward flight, the main rotor thrust is tilted which pulls the helicopter to the side. As the helicopter moves to the side, the vertical fin at the rear of the helicopter provides weathercock stability, much like the fins on an arrow. This yaws the helicopter in the pro-turn direction. Some helicopters need a little bit of pro-turn anti-torque pedal, but this is a minor correction to keep the aircraft in trim. Most of the yawing force in forward flight is being provided by the (fixed) vertical stabilizer.
In a HOVER, a conventional helicopter uses tail rotor thrust to yaw the aircraft. As a previous poster pointed out, this is done by changing the angle of attack of the tail rotor, not by changing the speed. As he pointed out, in full size helicopters, the main rotor and the tail rotor are connected by drive shafts and transmissions, meaning their speed is always at a fixed relationship to each other. This is done so that during unpowered flight (autorotation) the main rotor can keep the tail rotor turning, to give the pilot yaw control during the glide and landing.
Also, you are incorrect about how counter-rotating helicopters generate yaw forces. A tandem rotor helicopter like the CH-46 and CH-47 generate yaw forces by tiling the front and rear rotors in opposite directions. To yaw left, the front rotor is tilted to the left, and the rear rotor is tilted to the right. Coaxial and intermeshing helicopters generate yaw forces by changing the relative pitch of the rotors. This causes the rotor turning in one direction to generate an increased torque force, while the rotor turning in the opposite direction generates decreased torque forces. The imbalance causes a yawing force. Note that these systems need to work backwards when in autorotation. I've never flown one of those systems, so I only know what I've read - someone who has flight experience in a Kaman or Kamov might comment?
Back to the particular device in the article, the anti-torque force seems to be generated by a combination of fixed fins around the circumference (note how they are all bent in the anti-torque direction) and the (4?) moving fins which are probably there to provide yaw control to the operator.
As for the stability of helicopters, if you look at the designs in the 50's and 60s, stability was a big goal. Look at Stanley Hiller's demonstration of hands off hovering of his helicopters. Over the years stability appears to have been less and less of a goal. Look at how the flybar on the Bell rotor systems has disappeared. I'm not sure why this has happened, but I'm guessing that agility has won out over stability, especially since stability can easily be added by electronic means.
I read the article, but I wasn't quiet sure how the Coanda effect was utilized by this design. I'm guessing that rather than tilt the rotor there are places where the downwash is attached (or not) and thus generate sideways thrust? I saw the little vanes moving, but assumed that was more for anti-torque - if you noticed, most of the vanes were fixed with a little bend in the direction of anti-torque (and, like the MDHC Notar the anti-torque force would be proportional to downwash and thus to torque). A few of them moved to give you the ability to rotate the machine and account for minor yawing forces not exactly countered by the fixed vanes.
Did anyone else notice where/how Coanda effect was used? Perhaps the moving vanes really are implementing the Coanda effect, but if so it's in a fairly different way than the MDHC Notar system. Did I miss something?
Another big consumer of PPC processors is the embedded market. They're much smaller processors (IBM 8xx and Freescale 8xxx) but they're full PPC processors and I'll be they ship in huge quantities.
I personally don't like the mice that Apple ships. I like the Macally mice with three buttons and a wheel. Works great and does exactly what you would expect.
So, in that sense, Apple does listen and support what people ask for. They just don't promote it by selling those kinds of mice themselves.
I was at a course where the Macs were mis-behaving and nobody could save their data. Everything was going to be wiped when we left for the day, losing hours of work. The files were too big to move even on CD. I booted up my laptop using TDM, and everybody stored their data on my laptop. Next day we were able to pull it all back off the laptop the same way.
I also agree that it would be nice if it was supported on USB...
Paul
I should be denied a job because someone stole my identity and wrecked my credit rating?
While autoland systems are used overseas, I do not believe they are used in the U.S (but they probably will be someday).
While the technology may be available to allow pilots to do very little, that's not how it's done in practice. The last 3 times I flew jump seat (Dash-8, CRJ, Boeing-777) most of the flying was hand flying, with the exception of the cruise portion of the flight. The safest system is probably the track that we are on: automation to do the boring parts, and a wealth of information presented by computer to the pilot in a way humans can easily interpret (so, for instance a HUD with computer synthesized imagery so the human can see through fog, night, etc.).
And, to answer your question about kernels, I'd feel fine with Linux if it passed DO-178B Level A certification, but that's probably not going to happen anytime soon ;-)
I beg to differ. Almost no airspace over US cities is prohibited airspace. Washington DC has a lot of prohibited airspace, but most other cities have none. As a former traffic helicopter pilot I can tell you that there are not many restrictions on where you can fly, except good judgement. San Francisco is one exception that I know of.
The cop rants for a bit about how HE gets to decide where I pull over, not me, blah, blah, blah. Maybe because my bike can do 185 he thinks I'm gonna run? Dunno, and I was close to telling him off, but restrained myself and said "yes sir" all the while thinking that of course in the future I'll continue to pull over when it's safe for both him and I.
I wish there was a way to select cops who aren't likely to have the power trip gene.
The other half of the project was the actual server hardware. It was a project another company did, and when it was cancelled they sold the assets for cheap. I think this looked like a good deal to the president and CTO of our company. In retrospect, it was probably a bum deal. We could have done better by starting with PC hardware running an RTOS, and then later done our own boards. At the time, it looked like a cool piece of hardware. Problem was that the CTO didn't perform due diligence.
I've certainly learned over the years that you almost NEVER want to do bleeding edge, or if you do it needs to be ONE THING, with everything else conservative, and you better have a backup plan too!
All that said, there are certainly times it's cheaper or faster to reverse engineer someone else's work, rather than try to reinvent it from start.
Amazingly, we got the hardware and software to work. And, the customers loved the product. The company simply ran out of money before they could become profitable.
Throughout most of my career, I've understood reverse engineering to be what you do when you DON'T have the source code. I think the wikipedia entry mentions that this is the most common interpretation. It can be extremely difficult and time consuming. I've done it on major projects a few times in my career. It is neither easy nor efficient, but sometimes the only choice you have.
It's also common to talk about reverse engineering hardware, where the innards of a chip may be deduced by observing its inputs and outputs. I worked on a project at a startup where we had to do that, because the original hardware developers were long gone, and no VHDL could be discovered, yet we had to write drivers for their (buggy) chips in order to make a deadline. At the same company we had to reverse engineer the workings of a (buggy) Fiber Channel PCI card, because the manufacturer would not give us the support we needed to make our deadlines. They were rather surprised when we talked to them about the details of their (proprietary, embedded in an ASIC) DMA engine that we deduced via logic analyzers and oscilloscopes.
Those projects were SO difficult compared to reading (even obscure) code, that I really think that using the one phrase for both activities is confusing and sometimes even deceptive.
If I watch a movie on my TV with the shades open, so that you could potentially sit outside my house and videotape the movie, have I violated the intent of this law?
1) I've read that you can put more force on a yoke. Seems wrong to me, but that's what I've read. WWII bombers had yokes, whereas lots of the fighters still had sticks. The Bell X-1 had a yoke, as well.
2) In General Aviation, there was a move (in the 50's I think) to make airplanes more like cars, as a way to get better public acceptance. "Steering wheels" versus a stick, don'tcha know?
Paul
Ok, so it's like renting an apartment in which you are not allowed to change the lightbulbs yourself, instead you are supposed to call the landlord when a light goes out. But whenever you do he tries to convince you that the bulb isn't really out, and then tries to talk you into renting a new apartment that has all working bulbs. So you do, and the new apartment has bulbs already broken when you move in. And you complain, but he's not listening, he's already telling you about this new apartment he has...
Actually, they do. I've been told in photography classes that you can't take a picture that includes a building unless you get permission. Apparently the architectural firms own copyright to the likeness of the building. Do I think that's stupid? Yup.
On the Fight Club DVD, they talk about the end scene where they blow up some buildings - totally done in CG - having to be buildings that the studio owned. I guess you can get into trouble for blowing up the likeness of someone else's building?
Personally I think it might be time for copyright to go away, or at least drastically morph so that most information becomes free.
Personally I think computers in school is a terrible idea. Then again, I don't think current schools are a very good way of teaching. Not sure I have great alternatives, though.