If you factor in obsolescense will your computer have a new stat: "half-life"? As your computer ages your level decreases. *sheesh* brilliant idea people..
Actually no, this was a seperate experiment conducted by NASA while the experiment you are referring to was conducted by Australia. Both were scramjet flights, they were totally different designs though. The NASA experiment is the second of 3 flights. The first was aborted due to a failure with the control surfaces on the pegasus booster. The third is upcoming.
It should be noted that there is a difference between escape velocity and orbital velocity. Escape velocity is the delta V necessary to escape the gravity well. Orbital velocity is simply the V necessary to keep missing whatever object you're falling toward. All orbits are conic sections. A vehicle with a V greater than Vescape will be in an orbit with an open section (i.e. a hyperbolic orbit) and those under Vescape will be in a closed elliptical orbit.
To answer your question, Vescape for an object is the same regardless of altitude. The difference is that the initial V at higher altitudes is greater therefore the delta V necessary to reach Vescape is lower. The operational altitudes for a scramjet are so low that Vinitial is effectively zero compared to the delta V necessary to reach Vescape. Therefore, a scramjet doesn't get you close.
Also, Mach 1 is 760mph at a specific altitude only. As the altitude increases, the velocity corresponding to mach 1 decreases. M=V/a (a is speed of sound) a decreases as you rise because atmospheric density drops.
However, how much lift does it actually get? Is it possible to build a craft that can use wing lift all the way up to LEO? If so, could it then be possible to obtain a flight envelope on the way back down?
This depends entirely in how you define leo. In order to reach what is generally considered space (100km+) you will be outside 99% of the atmosphere. This means that the atmospheric density is extremely low. So low that the normal rules of fluid mechanics are invalid and you have to treat air as a rarified gas. This is statistics based rather than standard calculus based. The extremely low density effectively means that lift from the wings/lifting body is essentially zero unless you have an extremely large surface area. In fact, at this point, drag and the erosion from atomic oxygen and free hydrogen are much more prevalent than the force of lift. As a result, once you reach this point lift is essentially zero although the engines would continually accelerate you to the necessary orbital velocity.
In other words, lift would be dependent on your surface area of the wings. This will get you to the top of the atmosphere. At which point, you have to use pure thrust to reach orbit. In addition, once you reach a certain point the O2 levels drop to the point where a scramjet is useless and you need to use conventional rockets.
Orbit is more a function of speed than a function of lift or drag. ISS uses reboosts periodically to compensate for the fact that LEO actually exists within the upper atmosphere and it's subject to a drag force.
The simple answer is that scramjet engines are MUCH less susceptible to debris/bird impacts simply because they have essentially no moving parts. It's essentially a well modeled tube. The critter would fly straight through without physically impacting anything except the walls. Oh, and due to the extreme temperatures it'll probably be incinerated.
This course started a couple years ago.. It's a 1000 level course which is freshman level. I've met a few people that took it although most of them are film types. Most engineering majors and physics majors at UCF don't bother because it's virtually useless for our degree requirements.
Here's an article from our student newspaper from the fall 2002 semester.
Strangely, the course number listed in the article is for physical science. I don't know off hand what the real number is. Here's the O-P page from the latest online course catalog.
Well, finals ended for me yesterday (with my orbital mechanics final) so I'm going to die for 2 weeks until summer semester starts.
I'm curious about availability at major universities. Here at the University of Central Florida we have free access in most of the newer buildings and several outdoor areas. The coverage is growing and notable currently covered areas include the bookstore (which is run by Barnes and Noble and has the obligatory Starbucks), the Math and Physics building, the Student Union (along with areas surrouding it) and Engineering. Do other schools have widespread access for students and faculty?
I used it briefly and it was very nice. It takes a little getting used to but you adapt quickly and I generally like it. You can get it much more reasonably priced for educational purposes. The computer store on campus sells it for around $400.
Best of all, it was invented by an alumni of my university:-)
Here's another story about it from my local student newspaper.UCF Future
Daniel Davis Aerospace Engineering major University of Central Florida - Orlando
Interestingly, Time Warner appears to have spawned off or sold at least part of it's cable network. Locally it is now "Bright House" but in the Charlotte, NC area it is still TWC. I'm not sure how this will effect my bandwidth but so far I haven't noticed any change. Of course, at this point the only thing that has changed are the logos that are plastered on the trucks/buildings and the cable box's info guides.
This isn't the first time this concern has been voiced. Last time I checked though, the atomic tests during world war 2 didn't set off a chain reaction that burnt the biosphere off the planet.
Experiments like this do provide an interesting reason to set up extra-planetary colonies. It gives us a method of isolating the experiment as much as possible outside of Earth. If something goes wrong it would be at least an order of magnitude easier to contain (although not an easy prospect, it's much easier than on Earth where it'd be damn near impossible)
> The crystal structure of a silicon [jlab.org] wafer is the same as a carbon [jlab.org] diamond. Germanium [jlab.org], too, routinely grows in a diamond structure. But carbon also forms graphite, which is a sheetlike structure.
In a similar vein, there has been conjecture in the past about silicon and germanium being the basis of some forms of extraterrestrial life. Those elements have a lot of potential for research. The main reason we have focused on carbon is primarily it's accessibility to us. Organic molecules provided a lot of the initial inspiration that eventually made us start wondering what carbon was cable of.
My company is a small company (20+ employees) but we all got $500 christmas bonuses and our individual performance bonus for the year (mine was $500). Made for a nice addition. It helped me buy my books for the spring semester. (Engineering books can be very expensive)
Daniel Aerospace Engineering major University of Central Florida - Orlando
"Mars has a denser atmosphere than Earth. While spaceborne objects would be a nice explanation for these formations- if a bit uncreative- it forgets the element of the atmosphere, which is the only reason Earth doesn't get pounded into rubble every meteor shower."
Interesting. There's only one problem. You're incorrect. Mars' surface density is pretty close to the Earth's at 35000 meters. Roughly 0.015 kg/m3. Earth's at the surface (sea level) is approximately 1.2 kg/m3.
The martian figure is from Nasa (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat. html)
and the Earth figure is from any standard atmosphere chart available on the web. I don't have my texts with me so I just grabbed the one off USA Today's site. (http://www.usatoday.com/weather/wstdatmo.htm)
Even if it were, Mars' atmosphere is much thinner and has a much lower pressure than Earth's. Meteors entering Mars' atmosphere stand a much better chance at reaching the surface than they would on Earth. Combined with the ambient atmospheric temperature of the planet's atmosphere, even the density wouldn't prevent this.
The equation of state for an ideal gas shows this relationship. (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat. html)
"Admittedly, it's possible that the atmosphere was carried in a solid-frozen format on said bombardial objects, but that's even more of a stretch."
I have one word: "Comets" They are believed to be responsible for a large amount of the atmospheres of Venus, Earth, and Mars.
Anyway, just my $.02..:-)
Daniel Aerospace Engineering major University of Central Florida - Orlando
So we have an island full of scientists with no engineers. These are people who spend their lives figuring out how the universe works. Engineers spend their lives fixing/building things after the scientists are done screwing with it. They'll need at least one engineer just to figure out how to put the ideas into practice.
Umm.. why do they need to get the tank back into orbit or have it seperate during reentry? If you're going to try it, don't seperate it at all and just stay connected until you reach the station. At that point, seperate and the tank will be in orbit along with the shuttle and station.
Actually it's been done several times. If you go to Space.com or Spaceflightnow.com you can see archive clips of rocket launches. My personal favorites are of the Mars Odyssey 2001 launch.
It's really neat watching the rocket's SRBs seperate and spiral off.
Don't let anyone fool you. If you're rich and miserable you'll still be as unhappy as poor and miserable.
In my case, I started with computers when I was in high school and it seemed like a natural choice for college. I finished an associates degree and started working. 7 years of professional programming have taught me one thing. I hate computers. Or at least programming them. I thought long and hard and finally realized my true love is aircraft and space craft. I'm going to school part time (7 credit hours this semester) for an aerospace engineering degree while at the same time working full time as a programmer. (Oh and I'm married.)
First, decide what it is you want most to achieve happiness. Don't even start school until you decide that. Once you have, make achieving that goal your priority. Remember, we're talking about happiness here. If it means sacrificing some work here and there, it will probably be worth it in the long run.
>... is being able to walk about to your backyard and watch launches. It happened on our first not-rainy afternoon in quite a while and was beautiful. Not quite like the Shuttle beautiful, > but beautiful nonetheless.
Agreed.. I watched it from the window of the UCF library before my Calculus class. Always fun to watch. It's at least a small part of why I chose my major (Aerospace Engineering).
I grew up in Jax and my family still lives there. I have to agree with you. A local commute system is going to be very difficult to implement and still make a significant difference. I think the same holds for the whole state. I think finishing I-295 will be a lot more useful.
> Would be nice if they would run it along I4 (which they probably will, since it's the main artery from Tampa to Orlando)... traffic there is horrible.
> Assuming it's not too expensive to ride, I would see it getting alot of business from us college students in Orlando who have family along the routes... gas isn't exactly cheap for a 400 mile drive one way
I can safely say (as a resident of metro Orlando and a student at UCF) that I agree completely. I'd love to use it as a quick way to Busch Gardens in Tampa or out to the Cape (I'm studying Aerospace Engineering).
Slashdot Mirror
If you factor in obsolescense will your computer have a new stat: "half-life"? As your computer ages your level decreases. *sheesh* brilliant idea people..
I just knew my engineering education would come in someday. Just never expected it to be on slashdot. :-)
Actually no, this was a seperate experiment conducted by NASA while the experiment you are referring to was conducted by Australia. Both were scramjet flights, they were totally different designs though. The NASA experiment is the second of 3 flights. The first was aborted due to a failure with the control surfaces on the pegasus booster. The third is upcoming.
It should be noted that there is a difference between escape velocity and orbital velocity. Escape velocity is the delta V necessary to escape the gravity well. Orbital velocity is simply the V necessary to keep missing whatever object you're falling toward. All orbits are conic sections. A vehicle with a V greater than Vescape will be in an orbit with an open section (i.e. a hyperbolic orbit) and those under Vescape will be in a closed elliptical orbit.
To answer your question, Vescape for an object is the same regardless of altitude. The difference is that the initial V at higher altitudes is greater therefore the delta V necessary to reach Vescape is lower. The operational altitudes for a scramjet are so low that Vinitial is effectively zero compared to the delta V necessary to reach Vescape. Therefore, a scramjet doesn't get you close.
Also, Mach 1 is 760mph at a specific altitude only. As the altitude increases, the velocity corresponding to mach 1 decreases. M=V/a (a is speed of sound) a decreases as you rise because atmospheric density drops.
However, how much lift does it actually get? Is it possible to build a craft that can use wing lift all the way up to LEO? If so, could it then be possible to obtain a flight envelope on the way back down?
This depends entirely in how you define leo. In order to reach what is generally considered space (100km+) you will be outside 99% of the atmosphere. This means that the atmospheric density is extremely low. So low that the normal rules of fluid mechanics are invalid and you have to treat air as a rarified gas. This is statistics based rather than standard calculus based. The extremely low density effectively means that lift from the wings/lifting body is essentially zero unless you have an extremely large surface area. In fact, at this point, drag and the erosion from atomic oxygen and free hydrogen are much more prevalent than the force of lift. As a result, once you reach this point lift is essentially zero although the engines would continually accelerate you to the necessary orbital velocity.
In other words, lift would be dependent on your surface area of the wings. This will get you to the top of the atmosphere. At which point, you have to use pure thrust to reach orbit. In addition, once you reach a certain point the O2 levels drop to the point where a scramjet is useless and you need to use conventional rockets.
Orbit is more a function of speed than a function of lift or drag. ISS uses reboosts periodically to compensate for the fact that LEO actually exists within the upper atmosphere and it's subject to a drag force.
The simple answer is that scramjet engines are MUCH less susceptible to debris/bird impacts simply because they have essentially no moving parts. It's essentially a well modeled tube. The critter would fly straight through without physically impacting anything except the walls. Oh, and due to the extreme temperatures it'll probably be incinerated.
This course started a couple years ago.. It's a 1000 level course which is freshman level. I've met a few people that took it although most of them are film types. Most engineering majors and physics majors at UCF don't bother because it's virtually useless for our degree requirements.
Here's an article from our student newspaper from the fall 2002 semester.
Strangely, the course number listed in the article is for physical science. I don't know off hand what the real number is. Here's the O-P page from the latest online course catalog.
Well, finals ended for me yesterday (with my orbital mechanics final) so I'm going to die for 2 weeks until summer semester starts.
Daniel Davis
Aerospace Engineering major
University of Central Florida - Orlando
I'm curious about availability at major universities. Here at the University of Central Florida we have free access in most of the newer buildings and several outdoor areas. The coverage is growing and notable currently covered areas include the bookstore (which is run by Barnes and Noble and has the obligatory Starbucks), the Math and Physics building, the Student Union (along with areas surrouding it) and Engineering. Do other schools have widespread access for students and faculty?
Daniel
Aerospace Engineering major
I used it briefly and it was very nice. It takes a little getting used to but you adapt quickly and I generally like it. You can get it much more reasonably priced for educational purposes. The computer store on campus sells it for around $400.
:-)
Best of all, it was invented by an alumni of my university
Here's another story about it from my local student newspaper.UCF Future
Daniel Davis
Aerospace Engineering major
University of Central Florida - Orlando
Interestingly, Time Warner appears to have spawned off or sold at least part of it's cable network. Locally it is now "Bright House" but in the Charlotte, NC area it is still TWC. I'm not sure how this will effect my bandwidth but so far I haven't noticed any change. Of course, at this point the only thing that has changed are the logos that are plastered on the trucks/buildings and the cable box's info guides.
This tech has been posted on /. before.. Drive a Greasecar - DIY Biodiesel
This isn't the first time this concern has been voiced. Last time I checked though, the atomic tests during world war 2 didn't set off a chain reaction that burnt the biosphere off the planet.
Experiments like this do provide an interesting reason to set up extra-planetary colonies. It gives us a method of isolating the experiment as much as possible outside of Earth. If something goes wrong it would be at least an order of magnitude easier to contain (although not an easy prospect, it's much easier than on Earth where it'd be damn near impossible)
> The crystal structure of a silicon [jlab.org] wafer is the same as a carbon [jlab.org] diamond. Germanium [jlab.org], too, routinely grows in a diamond structure. But carbon also forms graphite, which is a sheetlike structure.
In a similar vein, there has been conjecture in the past about silicon and germanium being the basis of some forms of extraterrestrial life. Those elements have a lot of potential for research. The main reason we have focused on carbon is primarily it's accessibility to us. Organic molecules provided a lot of the initial inspiration that eventually made us start wondering what carbon was cable of.
Couldn't help but think of one of my favorite movie quotes.. "I say we take off and nuke the entire site from orbit. It's the only way to be sure."
Now, where did I put that REM disc?
The problem with this definition is that it would include brown dwarfs which are clearly stellar in nature.
My company is a small company (20+ employees) but we all got $500 christmas bonuses and our individual performance bonus for the year (mine was $500). Made for a nice addition. It helped me buy my books for the spring semester. (Engineering books can be very expensive)
Daniel
Aerospace Engineering major
University of Central Florida - Orlando
"Mars has a denser atmosphere than Earth. While spaceborne objects would be a nice explanation for these formations- if a bit uncreative- it forgets the element of the atmosphere, which is the only reason Earth doesn't get pounded into rubble every meteor shower."
. html)
. html)
:-)
Interesting. There's only one problem. You're incorrect. Mars' surface density is pretty close to the Earth's at 35000 meters. Roughly 0.015 kg/m3. Earth's at the surface (sea level) is approximately 1.2 kg/m3.
The martian figure is from Nasa (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat
and the Earth figure is from any standard atmosphere chart available on the web. I don't have my texts with me so I just grabbed the one off USA Today's site. (http://www.usatoday.com/weather/wstdatmo.htm)
Even if it were, Mars' atmosphere is much thinner and has a much lower pressure than Earth's. Meteors entering Mars' atmosphere stand a much better chance at reaching the surface than they would on Earth. Combined with the ambient atmospheric temperature of the planet's atmosphere, even the density wouldn't prevent this.
The equation of state for an ideal gas shows this relationship. (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat
"Admittedly, it's possible that the atmosphere was carried in a solid-frozen format on said bombardial objects, but that's even more of a stretch."
I have one word: "Comets" They are believed to be responsible for a large amount of the atmospheres of Venus, Earth, and Mars.
Anyway, just my $.02..
Daniel
Aerospace Engineering major
University of Central Florida - Orlando
So we have an island full of scientists with no engineers. These are people who spend their lives figuring out how the universe works. Engineers spend their lives fixing/building things after the scientists are done screwing with it. They'll need at least one engineer just to figure out how to put the ideas into practice.
Umm.. why do they need to get the tank back into orbit or have it seperate during reentry? If you're going to try it, don't seperate it at all and just stay connected until you reach the station. At that point, seperate and the tank will be in orbit along with the shuttle and station.
Actually it's been done several times. If you go to Space.com or Spaceflightnow.com you can see archive clips of rocket launches. My personal favorites are of the Mars Odyssey 2001 launch.
It's really neat watching the rocket's SRBs seperate and spiral off.
I thought he was being funny. I didn't think he was being serious at all.
Don't let anyone fool you. If you're rich and miserable you'll still be as unhappy as poor and miserable.
In my case, I started with computers when I was in high school and it seemed like a natural choice for college. I finished an associates degree and started working. 7 years of professional programming have taught me one thing. I hate computers. Or at least programming them. I thought long and hard and finally realized my true love is aircraft and space craft. I'm going to school part time (7 credit hours this semester) for an aerospace engineering degree while at the same time working full time as a programmer. (Oh and I'm married.)
First, decide what it is you want most to achieve happiness. Don't even start school until you decide that. Once you have, make achieving that goal your priority. Remember, we're talking about happiness here. If it means sacrificing some work here and there, it will probably be worth it in the long run.
>... is being able to walk about to your backyard and watch launches. It happened on our first not-rainy afternoon in quite a while and was beautiful. Not quite like the Shuttle beautiful, > but beautiful nonetheless.
Agreed.. I watched it from the window of the UCF library before my Calculus class. Always fun to watch. It's at least a small part of why I chose my major (Aerospace Engineering).
I grew up in Jax and my family still lives there. I have to agree with you. A local commute system is going to be very difficult to implement and still make a significant difference. I think the same holds for the whole state. I think finishing I-295 will be a lot more useful.
> Would be nice if they would run it along I4 (which they probably will, since it's the main artery from Tampa to Orlando)... traffic there is horrible.
> Assuming it's not too expensive to ride, I would see it getting alot of business from us college students in Orlando who have family along the routes... gas isn't exactly cheap for a 400 mile drive one way
I can safely say (as a resident of metro Orlando and a student at UCF) that I agree completely. I'd love to use it as a quick way to Busch Gardens in Tampa or out to the Cape (I'm studying Aerospace Engineering).