I do have a distributed application in mind, and it would rely on Gambit-C / Termite. I was kicking around learning Erlang for this purpose as well, but I much prefer Scheme's syntax (though I admit I didn't look at Erlang in much depth - perhaps later).
I also thought is was a good idea to learn Scheme because I don't think I really got FP the first time around, and wanted to try again having used a bunch of imperative or hybrid languages first (C, C++, Python, Ruby). Now, Lisp / Scheme make much more sense to me. I do try to learn a new language once in a while as well.
I recently decided to learn Scheme (though I was exposed to LISP during an undergrad class a number of years back).
In addition to the SICP book (and video lectures), I highly recommend "The Little Schemer," "The Seasoned Schemer," and Dybvig's "The Scheme Programming Language." I found the the "Little / Seasoned Schemer" books to be useful after reading Dybvig's book. You wind up looking at some basic concepts again; however, the material is presented in a much different manner, and is meant to lead to insights as to what Scheme is all about, plus things like names, recursion, etc.
For the "Little / Seasoned Schemer" books, I recommend re-reading the part on the Y combinator from the first before reading the section in the latter about the imperative Y combinator. Similarly, re-read the last chapter in the first before reading the last chapter in the second.
No - it is not smaller aircraft in the sky that is the problem. It is the number of aircraft trying to use the limited number of runways at the major US airports (out of the 10,000 total airports in the US). This includes large and small aircraft.
Actually, the use of smaller planes opens up the possibility of using airports that aren't utilized right now, and reducing traffic at the major airports.
The current radar system is generally passive. That is, each aircraft allowed into class A or B airspace (above FL 180 or near one of the major airports, respectively) has to have a transponder. This transponder transmits a repsonse to the radar's ping. The range of the aircraft is determined based on the round trip time of that request / response. The altitude is reported by the aircraft itself, via an encoding altimeter.
With GPS, you can get altitude (in the cockpit, and then presumably off aircraft with a new GPS transponder system in the future), but it is generally not as accurate as pressure altitude from an altimeter. With WAAS, however, it is extremely accurate. Basically, you are adding an extra "GPS," but at the airport, that gives you a differential signal on top of the satellites which allows even more accurate altitude calculations. I don't know the exact numbers, but it is enough to do ILS-type precision approaches.
And while I love GPS, I'm also a little skeptical that it is going to solve congestion issues. Most people here probably are not aware, but something like 80-85% of *all* airline traffic goes through the major 25 airports in the country. Yet there are 10,000 airports in the US. The issue is not airspace - it is airspace and runway space around these major airports. Switching to a GPS navigation system will not get you more runways, better configured, at O'Hare airport. Nor will it take away fog in the Bay Area which prevents simultaneous ILS approaches from being run. I do think it will help, but it's not a panacea. Frankly, I think it's more useful for getting rid of costs associated with maintaining old VOR and NDB stations.
I'd be interested to know how much the FAA spends on ground based VORs, as well, as there are hundreds of those in the US. They have to be secured and maintained. I suspect that $40 billion may be a bargain once all those VORs can go away. That's just a guess though.
As far as comments regarding time and cost to upgrade - yes, that's a long time, but who gets to decide to force every airplane owner to buy $10k (for GA, probably much more for a commercial system) worth of equipment just so he can do what he did in the airspace the day before? Keep in mind, too, that a lot of the demands of the current system are created by the airlines, not GA, so it is not unfair that GA should have to upgrade immediately. Until last year, I was flying a plane that was close to 50 years old, so airplanes have a long life, and it's not just a matter of mandating new aircraft have the equipment, therefore the problem is solved in 5 years.
Really? And the software they'd write in a year would have 5 9's of reliability? And it'd comply with all the regulations which say how software written for aircraft has to be tested? Please.
When a life-ending asteroid is bearing down on the planet 500 years from, I hope your descendants still enjoy the fact that they decided to regress to becoming hunter gatherers, rather than participate in all those nasty polluting enterprises like spaceflight and building telescopes. Of course, they won't even see it coming...
A Cirrus SR-22 does about 175 kts. at 14 gph, which works out to be 14 mpg. The plane carries four people. Keep in mind that you can generally fly a smaller plane into and out of airports close to your location, thus avoiding the need for long travel by car to your ultimate destination (I've flown lots of places where I can *bike* from the airport to where I'm going).
Some newer diesel engines are promising almost twice the efficiency at the same horsepower, putting the plane on par with the mileage for an average car. You also have to remember a plane travels in a straight line vs. a winding road, so the effective mileage vs. a car is even higher.
I don't understand why it is extremely selfish to fly. The fact is, our society both relies on and produces technological progress. The innovations in the future that allow us to travel at 200 mpg, or eliminate oil altogether as a source of energy, will not come from people who refuse to consider the fact the energy is a fundamentally good thing. As an engineer, I couldn't complete my job without travel, electricity or oil. That doesn't mean I wouldn't like to see the day we can get rid of oil, but simply wishing it away won't work.
1) Yes, they do. But you have to consider the other effects of the hub and spoke travel system. In a small plane, I cna frequently travel to/from airports close enough to my destination that I don't need to take a taxi or rent a car.
2) True, but lost time waiting in an airport line costs money too. Ask anyone who has paid a lawyer to travel.
3) Well, probably, yes. But the accident statistics for charter jets and airlines are close. The biggest factor is the pilot. Small plane != unsafe. Charter pilots are commercial, IFR rated pilots.
4) Here you are only partially correct - they are slower *in the air.* However, I fly myself between two cities that are about 500 miles apart, from the same airports that have direct service from Southwest, and I almost *always* beat the airline flight in door-to-door time by flying in a plane that goes only 170 mph. The newer small planes go close to 200. You have to consider the total travel time. Plus, I'm not nearly as tired or frazzled from standing in endless lines and stripping in front of strangers.
Also, the airlines would like you to believe the ATC system would suffer, but the problem is not from small planes. It is the fact that 85% of all airline flights go through 25 of the 10,000 airports in the US. In a small plane, you could use many, many more airports that are tremendously underutilized. In other words, it is a problem with the runways, but from a relatively small number of runways!
You can't lump in charter service with GA. Keep in mind that charter pilots have *commercial* licenses, and are operated under a different set of FAA regulations. If you look at the statistics between airline flights and charter jets, then the two are actually not that far apart in accident rates. Of course, a twin engine jet is going to be safer than a single engine prop plane, but by far the most significant factor is the pilot.
If you look closely at the statistics, the bulk of the GA accidents are VFR pilots who inadvertently get into IFR conditions, and lose control of the airplane. Any charter pilot will have an IFR ticket, and lots more time than the average VFR pilot (not to mention recurrent training).
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I do have a distributed application in mind, and it would rely on Gambit-C / Termite. I was kicking around learning Erlang for this purpose as well, but I much prefer Scheme's syntax (though I admit I didn't look at Erlang in much depth - perhaps later). I also thought is was a good idea to learn Scheme because I don't think I really got FP the first time around, and wanted to try again having used a bunch of imperative or hybrid languages first (C, C++, Python, Ruby). Now, Lisp / Scheme make much more sense to me. I do try to learn a new language once in a while as well.
I recently decided to learn Scheme (though I was exposed to LISP during an undergrad class a number of years back).
In addition to the SICP book (and video lectures), I highly recommend "The Little Schemer," "The Seasoned Schemer," and Dybvig's "The Scheme Programming Language." I found the the "Little / Seasoned Schemer" books to be useful after reading Dybvig's book. You wind up looking at some basic concepts again; however, the material is presented in a much different manner, and is meant to lead to insights as to what Scheme is all about, plus things like names, recursion, etc.
For the "Little / Seasoned Schemer" books, I recommend re-reading the part on the Y combinator from the first before reading the section in the latter about the imperative Y combinator. Similarly, re-read the last chapter in the first before reading the last chapter in the second.
No - it is not smaller aircraft in the sky that is the problem. It is the number of aircraft trying to use the limited number of runways at the major US airports (out of the 10,000 total airports in the US). This includes large and small aircraft. Actually, the use of smaller planes opens up the possibility of using airports that aren't utilized right now, and reducing traffic at the major airports.
The current radar system is generally passive. That is, each aircraft allowed into class A or B airspace (above FL 180 or near one of the major airports, respectively) has to have a transponder. This transponder transmits a repsonse to the radar's ping. The range of the aircraft is determined based on the round trip time of that request / response. The altitude is reported by the aircraft itself, via an encoding altimeter. With GPS, you can get altitude (in the cockpit, and then presumably off aircraft with a new GPS transponder system in the future), but it is generally not as accurate as pressure altitude from an altimeter. With WAAS, however, it is extremely accurate. Basically, you are adding an extra "GPS," but at the airport, that gives you a differential signal on top of the satellites which allows even more accurate altitude calculations. I don't know the exact numbers, but it is enough to do ILS-type precision approaches. And while I love GPS, I'm also a little skeptical that it is going to solve congestion issues. Most people here probably are not aware, but something like 80-85% of *all* airline traffic goes through the major 25 airports in the country. Yet there are 10,000 airports in the US. The issue is not airspace - it is airspace and runway space around these major airports. Switching to a GPS navigation system will not get you more runways, better configured, at O'Hare airport. Nor will it take away fog in the Bay Area which prevents simultaneous ILS approaches from being run. I do think it will help, but it's not a panacea. Frankly, I think it's more useful for getting rid of costs associated with maintaining old VOR and NDB stations. I'd be interested to know how much the FAA spends on ground based VORs, as well, as there are hundreds of those in the US. They have to be secured and maintained. I suspect that $40 billion may be a bargain once all those VORs can go away. That's just a guess though. As far as comments regarding time and cost to upgrade - yes, that's a long time, but who gets to decide to force every airplane owner to buy $10k (for GA, probably much more for a commercial system) worth of equipment just so he can do what he did in the airspace the day before? Keep in mind, too, that a lot of the demands of the current system are created by the airlines, not GA, so it is not unfair that GA should have to upgrade immediately. Until last year, I was flying a plane that was close to 50 years old, so airplanes have a long life, and it's not just a matter of mandating new aircraft have the equipment, therefore the problem is solved in 5 years.
Really? And the software they'd write in a year would have 5 9's of reliability? And it'd comply with all the regulations which say how software written for aircraft has to be tested? Please.
When a life-ending asteroid is bearing down on the planet 500 years from, I hope your descendants still enjoy the fact that they decided to regress to becoming hunter gatherers, rather than participate in all those nasty polluting enterprises like spaceflight and building telescopes. Of course, they won't even see it coming...
A Cirrus SR-22 does about 175 kts. at 14 gph, which works out to be 14 mpg. The plane carries four people. Keep in mind that you can generally fly a smaller plane into and out of airports close to your location, thus avoiding the need for long travel by car to your ultimate destination (I've flown lots of places where I can *bike* from the airport to where I'm going). Some newer diesel engines are promising almost twice the efficiency at the same horsepower, putting the plane on par with the mileage for an average car. You also have to remember a plane travels in a straight line vs. a winding road, so the effective mileage vs. a car is even higher. I don't understand why it is extremely selfish to fly. The fact is, our society both relies on and produces technological progress. The innovations in the future that allow us to travel at 200 mpg, or eliminate oil altogether as a source of energy, will not come from people who refuse to consider the fact the energy is a fundamentally good thing. As an engineer, I couldn't complete my job without travel, electricity or oil. That doesn't mean I wouldn't like to see the day we can get rid of oil, but simply wishing it away won't work.
1) Yes, they do. But you have to consider the other effects of the hub and spoke travel system. In a small plane, I cna frequently travel to/from airports close enough to my destination that I don't need to take a taxi or rent a car. 2) True, but lost time waiting in an airport line costs money too. Ask anyone who has paid a lawyer to travel. 3) Well, probably, yes. But the accident statistics for charter jets and airlines are close. The biggest factor is the pilot. Small plane != unsafe. Charter pilots are commercial, IFR rated pilots. 4) Here you are only partially correct - they are slower *in the air.* However, I fly myself between two cities that are about 500 miles apart, from the same airports that have direct service from Southwest, and I almost *always* beat the airline flight in door-to-door time by flying in a plane that goes only 170 mph. The newer small planes go close to 200. You have to consider the total travel time. Plus, I'm not nearly as tired or frazzled from standing in endless lines and stripping in front of strangers. Also, the airlines would like you to believe the ATC system would suffer, but the problem is not from small planes. It is the fact that 85% of all airline flights go through 25 of the 10,000 airports in the US. In a small plane, you could use many, many more airports that are tremendously underutilized. In other words, it is a problem with the runways, but from a relatively small number of runways!
You can't lump in charter service with GA. Keep in mind that charter pilots have *commercial* licenses, and are operated under a different set of FAA regulations. If you look at the statistics between airline flights and charter jets, then the two are actually not that far apart in accident rates. Of course, a twin engine jet is going to be safer than a single engine prop plane, but by far the most significant factor is the pilot. If you look closely at the statistics, the bulk of the GA accidents are VFR pilots who inadvertently get into IFR conditions, and lose control of the airplane. Any charter pilot will have an IFR ticket, and lots more time than the average VFR pilot (not to mention recurrent training).