That's a very naive point of view. People are perfectly and demonstrably capable of leading multiple lives, and acting in diametrally opposite ways in each of those lives. About the only problem with Mr. sleepin' around is that it's an exploitable weakness. You don't want someone high up the pooping pole who is so damn easy to be completely pwned.
Only if the said motor is acting in the direction of deflection of the important modes. It so happens, it won't. I'd like not to have to remind everyone that there are, like, um, engineers working on that thing. Presumably with some, like, structural experience with things that are notoriously difficult. Especially aerospace is kinda notoriously difficult, with good, quiet cars not far behind.
There are no linear motors. Well, um, yes, there are linear motors, if you look for them with a very good flashlight, that is. They cover about 1-2% of the length of the track. The words used in the fine description of the system are used for a reason. It's a mostly passive capsule, an almost ballistic system, with a compressor in the front of the capsule to provide compressed air to the air bearings and to bypass the plunger-in-a-syringe effect in a cheaper way than merely throwing a bigger tube at the problem. The linear motors reboost the capsule periodically. It will be coasting for about 29 out of 30 minutes. They also apply a force that doesn't give big reactions in the direction of easy to excite modes of the tube walls. After all, the motors push the capsule forward (or pull it backward); they should be symmetrically arranged so that there is no net pitching moment. Thus there is, to a first order at least, no excitation of the serious modes of the tube.
With one button, there isn't much to figure out, I'd hope. I mean, how simple can it get? A macbook, in addition to its keyboard and the screen latch, has exactly one extra button as well. Never had any problems with how to turn it on and off. Can you elaborate what exactly is your beef? (seriously, I'm all ears, no sarcasm intended)
I think that in the future the only option for gyros, barring new bearing material discoveries, would be fully non-contact operation with magnetic levitation bearings, operating in vacuum. Right now I think the gyros are at least temperature-conditioned, but yeah, the bearings are still a problem.
You are aware that the design literally calls the "cars" capsules, right? And that you'd be strapped down for the entire time into a shaped, reclined seat? 2g would be nothing much, you wouldn't even notice it most of the time. There's no walking and no peeing in the hyperloop, and I agree with this approach. With the capsules spaced 30s apart in rush traffic, you go pee, then you leisurely catch the next capsule.
Not even close. The friction losses on having a 500 mile long column of air going at 700 mph would be crazy. Scaling matters. Just because you can have it work in a bank or a big box store, or even in a downtown financial district, doesn't mean that you can willy-nilly both speed things up and increase the distance, by a factor of 100 no less.
Given that this system rides on 1mm thick air bearings inside of a smooth tube, I don't think that noise pollution is much of a concern on the outside of the tube. The air inside the tube is at roughly 1/1000 of atmospheric pressure, so the sound doesn't propagate all that efficiently inside of the tube. The only sources of acoustic noise is the vibration of the intake compressor at the front of the pod, transmitted through the thin air bearing cushion. This is relatively easy to mitigate, since rotating machinery running at a constant speed is about the easiest thing to deal with in terms of NVH (noise, vibration, harshness). An internal combustion engine is way harder to tame, and even that has been pulled off successfully:)
The tube/pylon system will of course be subject to excitation from the radial forces by the passing capsules. So far, the significant modes are around 2-4Hz, so that's not a big problem. There will be dampers between the pylon and the tube, those will keep the number of cycles of oscillation "low" (ideally: it'll be critically damped).
The point being that early aviation needed very little in the way of a supporting infrastructure.
That's IMHO very short-sighted. Yes, it needed very little except that it was in the times when the landscape was littered with machine shops, material depots and people capable of actually making things out of said material. A lot of this is mostly gone nowadays, replaced by dedicated logistical chains that are not in the spotlight, but are huge, critical operations. Airlines need lots, lots of support, it's just not the very visible tracks, roads and runways kind of infrastructure.
What do you crash into? There is a big difference between a head-on collision, and merely a slide along the tube without air cushioning. When you're in a tube, the only other thing you can crash into is another train that goes the same way (or has stopped). Since there's no on-board propulsion, there's no scenario in which a train can propulsively overtake and hit a train in the front. It can only happen if the train in the front brakes, and somehow this doesn't get the trains behind it to stop. Very, very unlikely. The braking systems would be entirely passive, so basically if you blow the fuses on all the on-board batteries, the thing mechanically brakes an in entirely passive fashion. Also, for the trains to stay unbraked, they must be in constant communications with the control center. Presumably if the communications are lost for more than a 100ms, the brakes come out.
Oh, and they are not stupid, they did plan the route in detail, with bend radii and speed profiles all included.
It's quite interesting to analyze what would happen should a bomb be brought into a capsule, and a capsule would explode. It's not clear if a charge small enough to destroy a capsule would be enough to repressurize the tube. Let's not forget that the tube sees a roughly 1 bar overpressure from the outside, the inside is pretty much vacuum when you look at the explosion-scale overpressures. Whatever overpressure is caused by an explosion in the capsule, can really only propagate through the air in the capsule, and uses whatever gas was generated in the explosion proper. Once you're in the tube, the pressure wave has really no medium to travel in (air at 0.75 Torr, ha ha), so as the explosive gasses expand, the pressure drops very quickly. It's very different from an explosion in normal atmosphere.
There's a rather large gap between the capsule proper and the tube, but only a tiny gap between the air bearings and the tube. Presumably if a capsule blows up, it'll scratch up the inside of the tube, perhaps even dent it here and there, but it would be rather quick to fix. I'd imagine they could be up and running again in a week or so. As soon as communications are lost with a capsule, everything else would stop, same as if an explosion-type local overpressure event was sensed (there are pressure sensors in the tube anyway!). It's all engineering, and very doable engineering. It'd be wicked cool to be on the team that works on all that.
Given that the deceleration phase recycles the energy into the system, and that the load/unload time is projected to be 5 minutes, I'd not think of it a big problem. The design can cope with frequent stops relatively well. A stop or two in each large state, should the system be used to go cross-country, would be OK, although it doesn't really make economical sense for it to go cross country anyway. Hyperloop only makes sense for short hops where you don't need to go potty.
Correct me if I'm wrong, but he seems to jump from idea that they already work in rotary engines and that MVA inverters are already commercialized (in mining equipment and trains) to the conclusion that they therefore will work in the linear configuration shown in the document. The wording there was sneaky.
An acquaintance has a small demo unit made as an (expensive) novelty item sitting on his desk. It's an aluminum pendulum and a 3 phase linear motor (just because, as he says). Runs off a couple AA rechargeable batteries. The pendulum is a disk and can be converted to a balanced disk by removing a weight. Once converted, you flip a switch and instead of going back-and-frth, it can spin up to 20kRPM in about a minute. The configuration is entirely immaterial, it's really a very basic thing, electrodynamically speaking. After you press the brake button, it similarly stops in about 40 seconds, while recharging the batteries.
There would be no attendant - what for, you can't walk inside of one anyway. Those are sit-only capsules. You probably can't exit your seat at all.
When it comes to emergency response, the default scenario is to reach the destination if mechanically possible. The whole system is designed to complete the journey of all capsules enroute with no external power and no sunlight - there's a lot of power-smoothing batteries at the accelerator sites. They have enough power not only for propulsion, but also to run all of the other systems, possibly for hours. If there was a local blackout, the stations would likely stay up as if nothing happened, the capsule traffic would merely be halted if there was no sunlight.
If further traver is not mechanically possible (many reasons here), the solution is to (mechanically) brake and crawl to the nearest station or emergency access point. There will be small electric motors and wheels to push you along at a modest pace (say 60mph?). The tube repressurization is a passive thing, so not a big concern - if a capsule signals that the onboard life support is down and the backups are down as well, a bunch of valves open and that's the end of it. Probably the repressurization could also be used as a stand-in for mechanical braking; the air-induced drag would surely stop the capsule rather quickly. A failure of the compressor would do the same thing although probably too slowly, there's storage for gas bearing air such that whatever braking mode is used, the gas bearings wouldn't run dry, so to speak. I'm sure the system would be engineered to behave. That's what engineering is for.
The whole "trapped passengers" issue is I'd think a bit overblown. The major active systems in a capsule are mostly not unlike those on a locomotive and on an airplane: a compressor, an electric motor, control and power electronics, a battery bank. Propulsion is external - the capsule merely has an aluminum stator sticking out from it. Due to low drag, the capsule is coasting without propulsion for 98% of the length of the route. For it to keep coasting, the compressor needs to keep on spinning, and you must have no leaks in the water coolant loops. They're not sure yet to what extent the active tilt control would be used.
The idea is nifty, and it's sorely needed. I think that if nobody else in the western world would pick it up, we'll end up seeing it somewhere in Asia. I'd like to be among the first passengers once it's open to the public:)
Just to give you an idea: a 2kW 40kRPM liquid cooled brushless motor is just a tad bigger than a D-size 1.5V battery. If you wanted it air cooled, it'd not only run hotter due to higher thermal resistances to the fins, but you'd need 4x+ the volume due to the size of the fins, and you'd be wasting another 100W to blow the air through those fins.
Oh, those are definitely possible to rebuild if you've got the right tools and can still get the parts. They are quite amazing to work on - rebuilding even a modern internal combustion engine is a downright boring thing after you've done a modern front wheel drive transmission.
In automation, you'd often use sealed brushless motors that are conduction or convection cooled through the case. Those have artificially low power densities since there's inadequate cooling of the stator. I can have a 2.5kW sealed servo brushless motor, or a 10kW-40kW (RPM-dependent) liquid-coooled motor in the same volume and roughly same mass. In cars, where weight and volume do matter, you need forced cooling for the motor. If your motor is under the car, and especially at the wheels, air cooling is out of the picture. You need liquid cooling.
I don't know where you got the idea that I imply that electric brushless motors somehow need maintenance. The only things that go bad on them are the bearings, and it doesn't take much to design those to outlast both the car and the owner.
As for the unsprung mass mattering only to race cars: ha ha ha.
Slashdot Mirror
You can always randomize it some more, you know :)
That's a very naive point of view. People are perfectly and demonstrably capable of leading multiple lives, and acting in diametrally opposite ways in each of those lives. About the only problem with Mr. sleepin' around is that it's an exploitable weakness. You don't want someone high up the pooping pole who is so damn easy to be completely pwned.
Cue some good fanfares. John Williams or somesuch. :) +1
Collecting all internet and telecom traffic is not the same as watching everything you do, unless it's by your own choice.
Said incremental progress brought it to a point where keeping the jets flying is much harder than actually flying them.
Only if the said motor is acting in the direction of deflection of the important modes. It so happens, it won't. I'd like not to have to remind everyone that there are, like, um, engineers working on that thing. Presumably with some, like, structural experience with things that are notoriously difficult. Especially aerospace is kinda notoriously difficult, with good, quiet cars not far behind.
There are no linear motors. Well, um, yes, there are linear motors, if you look for them with a very good flashlight, that is. They cover about 1-2% of the length of the track. The words used in the fine description of the system are used for a reason. It's a mostly passive capsule, an almost ballistic system, with a compressor in the front of the capsule to provide compressed air to the air bearings and to bypass the plunger-in-a-syringe effect in a cheaper way than merely throwing a bigger tube at the problem. The linear motors reboost the capsule periodically. It will be coasting for about 29 out of 30 minutes. They also apply a force that doesn't give big reactions in the direction of easy to excite modes of the tube walls. After all, the motors push the capsule forward (or pull it backward); they should be symmetrically arranged so that there is no net pitching moment. Thus there is, to a first order at least, no excitation of the serious modes of the tube.
With one button, there isn't much to figure out, I'd hope. I mean, how simple can it get? A macbook, in addition to its keyboard and the screen latch, has exactly one extra button as well. Never had any problems with how to turn it on and off. Can you elaborate what exactly is your beef? (seriously, I'm all ears, no sarcasm intended)
I think that in the future the only option for gyros, barring new bearing material discoveries, would be fully non-contact operation with magnetic levitation bearings, operating in vacuum. Right now I think the gyros are at least temperature-conditioned, but yeah, the bearings are still a problem.
You are aware that the design literally calls the "cars" capsules, right? And that you'd be strapped down for the entire time into a shaped, reclined seat? 2g would be nothing much, you wouldn't even notice it most of the time. There's no walking and no peeing in the hyperloop, and I agree with this approach. With the capsules spaced 30s apart in rush traffic, you go pee, then you leisurely catch the next capsule.
Not even close. The friction losses on having a 500 mile long column of air going at 700 mph would be crazy. Scaling matters. Just because you can have it work in a bank or a big box store, or even in a downtown financial district, doesn't mean that you can willy-nilly both speed things up and increase the distance, by a factor of 100 no less.
Even better: it's an evacuated closed tunnel, kept at 0.001 bar.
Given that this system rides on 1mm thick air bearings inside of a smooth tube, I don't think that noise pollution is much of a concern on the outside of the tube. The air inside the tube is at roughly 1/1000 of atmospheric pressure, so the sound doesn't propagate all that efficiently inside of the tube. The only sources of acoustic noise is the vibration of the intake compressor at the front of the pod, transmitted through the thin air bearing cushion. This is relatively easy to mitigate, since rotating machinery running at a constant speed is about the easiest thing to deal with in terms of NVH (noise, vibration, harshness). An internal combustion engine is way harder to tame, and even that has been pulled off successfully :)
The tube/pylon system will of course be subject to excitation from the radial forces by the passing capsules. So far, the significant modes are around 2-4Hz, so that's not a big problem. There will be dampers between the pylon and the tube, those will keep the number of cycles of oscillation "low" (ideally: it'll be critically damped).
The point being that early aviation needed very little in the way of a supporting infrastructure.
That's IMHO very short-sighted. Yes, it needed very little except that it was in the times when the landscape was littered with machine shops, material depots and people capable of actually making things out of said material. A lot of this is mostly gone nowadays, replaced by dedicated logistical chains that are not in the spotlight, but are huge, critical operations. Airlines need lots, lots of support, it's just not the very visible tracks, roads and runways kind of infrastructure.
Said someone who has no idea what kind of logistics and infrastructure it takes to support to modern jet-flying airlines.
What do you crash into? There is a big difference between a head-on collision, and merely a slide along the tube without air cushioning. When you're in a tube, the only other thing you can crash into is another train that goes the same way (or has stopped). Since there's no on-board propulsion, there's no scenario in which a train can propulsively overtake and hit a train in the front. It can only happen if the train in the front brakes, and somehow this doesn't get the trains behind it to stop. Very, very unlikely. The braking systems would be entirely passive, so basically if you blow the fuses on all the on-board batteries, the thing mechanically brakes an in entirely passive fashion. Also, for the trains to stay unbraked, they must be in constant communications with the control center. Presumably if the communications are lost for more than a 100ms, the brakes come out.
Oh, and they are not stupid, they did plan the route in detail, with bend radii and speed profiles all included.
It's quite interesting to analyze what would happen should a bomb be brought into a capsule, and a capsule would explode. It's not clear if a charge small enough to destroy a capsule would be enough to repressurize the tube. Let's not forget that the tube sees a roughly 1 bar overpressure from the outside, the inside is pretty much vacuum when you look at the explosion-scale overpressures. Whatever overpressure is caused by an explosion in the capsule, can really only propagate through the air in the capsule, and uses whatever gas was generated in the explosion proper. Once you're in the tube, the pressure wave has really no medium to travel in (air at 0.75 Torr, ha ha), so as the explosive gasses expand, the pressure drops very quickly. It's very different from an explosion in normal atmosphere.
There's a rather large gap between the capsule proper and the tube, but only a tiny gap between the air bearings and the tube. Presumably if a capsule blows up, it'll scratch up the inside of the tube, perhaps even dent it here and there, but it would be rather quick to fix. I'd imagine they could be up and running again in a week or so. As soon as communications are lost with a capsule, everything else would stop, same as if an explosion-type local overpressure event was sensed (there are pressure sensors in the tube anyway!). It's all engineering, and very doable engineering. It'd be wicked cool to be on the team that works on all that.
Given that the deceleration phase recycles the energy into the system, and that the load/unload time is projected to be 5 minutes, I'd not think of it a big problem. The design can cope with frequent stops relatively well. A stop or two in each large state, should the system be used to go cross-country, would be OK, although it doesn't really make economical sense for it to go cross country anyway. Hyperloop only makes sense for short hops where you don't need to go potty.
Correct me if I'm wrong, but he seems to jump from idea that they already work in rotary engines and that MVA inverters are already commercialized (in mining equipment and trains) to the conclusion that they therefore will work in the linear configuration shown in the document. The wording there was sneaky.
An acquaintance has a small demo unit made as an (expensive) novelty item sitting on his desk. It's an aluminum pendulum and a 3 phase linear motor (just because, as he says). Runs off a couple AA rechargeable batteries. The pendulum is a disk and can be converted to a balanced disk by removing a weight. Once converted, you flip a switch and instead of going back-and-frth, it can spin up to 20kRPM in about a minute. The configuration is entirely immaterial, it's really a very basic thing, electrodynamically speaking. After you press the brake button, it similarly stops in about 40 seconds, while recharging the batteries.
There would be no attendant - what for, you can't walk inside of one anyway. Those are sit-only capsules. You probably can't exit your seat at all.
When it comes to emergency response, the default scenario is to reach the destination if mechanically possible. The whole system is designed to complete the journey of all capsules enroute with no external power and no sunlight - there's a lot of power-smoothing batteries at the accelerator sites. They have enough power not only for propulsion, but also to run all of the other systems, possibly for hours. If there was a local blackout, the stations would likely stay up as if nothing happened, the capsule traffic would merely be halted if there was no sunlight.
If further traver is not mechanically possible (many reasons here), the solution is to (mechanically) brake and crawl to the nearest station or emergency access point. There will be small electric motors and wheels to push you along at a modest pace (say 60mph?). The tube repressurization is a passive thing, so not a big concern - if a capsule signals that the onboard life support is down and the backups are down as well, a bunch of valves open and that's the end of it. Probably the repressurization could also be used as a stand-in for mechanical braking; the air-induced drag would surely stop the capsule rather quickly. A failure of the compressor would do the same thing although probably too slowly, there's storage for gas bearing air such that whatever braking mode is used, the gas bearings wouldn't run dry, so to speak. I'm sure the system would be engineered to behave. That's what engineering is for.
The whole "trapped passengers" issue is I'd think a bit overblown. The major active systems in a capsule are mostly not unlike those on a locomotive and on an airplane: a compressor, an electric motor, control and power electronics, a battery bank. Propulsion is external - the capsule merely has an aluminum stator sticking out from it. Due to low drag, the capsule is coasting without propulsion for 98% of the length of the route. For it to keep coasting, the compressor needs to keep on spinning, and you must have no leaks in the water coolant loops. They're not sure yet to what extent the active tilt control would be used.
The idea is nifty, and it's sorely needed. I think that if nobody else in the western world would pick it up, we'll end up seeing it somewhere in Asia. I'd like to be among the first passengers once it's open to the public :)
I'd say 2g turns are OK.
You also need to buy the easements to allow passage of your track above all of the land it passes above. That space also belongs to the land owner!
Just to give you an idea: a 2kW 40kRPM liquid cooled brushless motor is just a tad bigger than a D-size 1.5V battery. If you wanted it air cooled, it'd not only run hotter due to higher thermal resistances to the fins, but you'd need 4x+ the volume due to the size of the fins, and you'd be wasting another 100W to blow the air through those fins.
Oh, those are definitely possible to rebuild if you've got the right tools and can still get the parts. They are quite amazing to work on - rebuilding even a modern internal combustion engine is a downright boring thing after you've done a modern front wheel drive transmission.
In automation, you'd often use sealed brushless motors that are conduction or convection cooled through the case. Those have artificially low power densities since there's inadequate cooling of the stator. I can have a 2.5kW sealed servo brushless motor, or a 10kW-40kW (RPM-dependent) liquid-coooled motor in the same volume and roughly same mass. In cars, where weight and volume do matter, you need forced cooling for the motor. If your motor is under the car, and especially at the wheels, air cooling is out of the picture. You need liquid cooling.
I don't know where you got the idea that I imply that electric brushless motors somehow need maintenance. The only things that go bad on them are the bearings, and it doesn't take much to design those to outlast both the car and the owner.
As for the unsprung mass mattering only to race cars: ha ha ha.