Quote from: GORDAP on 06/24/2018 04:18 pmIf the transport vehicles can be charged during the short but frequent stops for taking on and off passengers, I wonder if 'supercaps' would be a superior solutions vs batteries. I think supercaps charge faster than batteries and have better cycle lifetimes, both of which would be important in this use case. Their drawback is energy density, but with a fairly short and fixed route such as this one, I'd think energy capacity would be much reduced, hence undercutting batteries advantage here. Thoughts?Economies of scale are kicking in for batteries. Vehicles and power storage are doubling the world capacity for this storage technology about annually. Someday, super-capacitors might have a role, but they don't now. Why is 'quick' charging an ask?
If the transport vehicles can be charged during the short but frequent stops for taking on and off passengers, I wonder if 'supercaps' would be a superior solutions vs batteries. I think supercaps charge faster than batteries and have better cycle lifetimes, both of which would be important in this use case. Their drawback is energy density, but with a fairly short and fixed route such as this one, I'd think energy capacity would be much reduced, hence undercutting batteries advantage here. Thoughts?
Quote from: AncientU on 06/24/2018 04:45 pmQuote from: GORDAP on 06/24/2018 04:18 pmIf the transport vehicles can be charged during the short but frequent stops for taking on and off passengers, I wonder if 'supercaps' would be a superior solutions vs batteries. I think supercaps charge faster than batteries and have better cycle lifetimes, both of which would be important in this use case. Their drawback is energy density, but with a fairly short and fixed route such as this one, I'd think energy capacity would be much reduced, hence undercutting batteries advantage here. Thoughts?Economies of scale are kicking in for batteries. Vehicles and power storage are doubling the world capacity for this storage technology about annually. Someday, super-capacitors might have a role, but they don't now. Why is 'quick' charging an ask?re: "quick charging" If charging is sufficiently quick, it could be accomplished during the brief time the vehicle is docked putting off and taking on passengers - eliminating the need to take the vehicle out of service or swap batteries.
Any kind of induction charging while still or moving is unlikely, Elon's not a fan on account of the inefficiency of it.Most likely when the battery gets low, the pod will be automatically routed out of service and then either perform some kind of battery swap with some sort of automated system or simply charge with a supercharger style connection (but one that doesn't require a human to plug in).The supercharger method will be easier to implement I suspect, though I wouldn't entirely rule out a battery swapping system (depends on whether having extra pods for the supercharging method is more expensive than implementing the battery swap system on fewer pods, I imagine).
The tunnel system is the most expensive part and the way they can save on tunnel is ludicrous acceleration for the Pods. Every departure a zero to 120 mph in 6 second launch. Slower acceleration means longer on-ramp tunnels.
Quote from: Ludus on 06/24/2018 11:15 pm The tunnel system is the most expensive part and the way they can save on tunnel is ludicrous acceleration for the Pods. Every departure a zero to 120 mph in 6 second launch. Slower acceleration means longer on-ramp tunnels. No need to accelerate hard. Constant gentle accel for half of the trip, constant gentle deceleration for the other half. Matthew
Regarding boarding: Have you seen this picture? This is what TBC has in mind...
Quote from: RedLineTrain on 06/21/2018 08:36 pmAs for Autopilot, it is currently being used on millions of miles of driving at speeds up to 90 miles per hour. An auto safety expert explained to me recently that the fact that these autopilots are programmed to allow the cars to break the speed limit is a sign that their manufacturers are not taking safety seriously. - Ed Kyle
As for Autopilot, it is currently being used on millions of miles of driving at speeds up to 90 miles per hour.
Quote from: jpo234 on 06/25/2018 08:56 amRegarding boarding: Have you seen this picture? This is what TBC has in mind...That's an updated depiction of Chicago's Block 37 boondoggle Super-station, which was partially completed at a cost of $400m for a failed similar project. AIUI, TBC will take it over and finish what they need. News expose...
Deviating from the mean traffic velocity (i.e. 'the sped everyone else is going at') increases risk of an accident, and almost equally in both directions of deviation*. i.e. going 10 under the mean velocity is just as risk as going 10 over. If you insist on travelling at the speed limit when everyone else is going 10-15 over, then YOU are the hazard.
[Can't do that with there being multiple cars/pods and multiple points of entry along the tunnel. Tunnel traffic needs to maintain constant and equal speed. But it seems there might be a way to use gravity to aid acceleration. V=at, so a 6-second drop gives 60 meters/sec, or 134 mph, less friction losses. How deep is the tunnel? Looks like it would need to be 180 meters deep for this to work, so electric powered acceleration would also be necessary. Point is, gravity acceleration wouldn't have such a serious effect on the passengers excepting of course the case where the drop was truly vertical, then freefall could disrupt stomaches.
Quote from: aero on 06/25/2018 03:51 am[Can't do that with there being multiple cars/pods and multiple points of entry along the tunnel. Tunnel traffic needs to maintain constant and equal speed. But it seems there might be a way to use gravity to aid acceleration. V=at, so a 6-second drop gives 60 meters/sec, or 134 mph, less friction losses. How deep is the tunnel? Looks like it would need to be 180 meters deep for this to work, so electric powered acceleration would also be necessary. Point is, gravity acceleration wouldn't have such a serious effect on the passengers excepting of course the case where the drop was truly vertical, then freefall could disrupt stomaches.I really like this idea. The cars exiting the main path go off at full speed onto a ramp that curves up to almost fully vertical, then flop over to horizontal just at the surface. The on ramp is the reverse, the car is tilted forward to almost vertical, drops to gather speed, then the ramp curves back to horizontal just before reentering the main path.Kind of like a hammerhead turn in an aircraft.
QuoteDeviating from the mean traffic velocity (i.e. 'the sped everyone else is going at') increases risk of an accident, and almost equally in both directions of deviation*. i.e. going 10 under the mean velocity is just as risk as going 10 over. If you insist on travelling at the speed limit when everyone else is going 10-15 over, then YOU are the hazard. In this future nirvana that the autonomous vehicle crowd wants us all to live in, the controlled traffic will slow down to the speed limit, or near the limit.
You got the idea. But note that the ramps don't need to go vertical or even near vertical. Discounting friction losses, potential energy converts to kinetic energy per unit of vertical displacement, independently of whether the drop is vertical or on a grade. It's true that the more nearly vertical the ramps, the shorter they would be, and the lower the friction losses would be. But overcoming friction losses is much of what the electric motors do anyway.The neat thing as I see it is that the cars use gravity to accelerate to cruise, electric energy to maintain steady cruise, and gravity to decelerate to stop giving up only the energy that would otherwise be mostly recovered by regenerative braking. Can anyone come up with a more energy efficient method to accelerate and decelerate the cars?
Quote from: aero on 06/26/2018 04:14 amYou got the idea. But note that the ramps don't need to go vertical or even near vertical. Discounting friction losses, potential energy converts to kinetic energy per unit of vertical displacement, independently of whether the drop is vertical or on a grade. It's true that the more nearly vertical the ramps, the shorter they would be, and the lower the friction losses would be. But overcoming friction losses is much of what the electric motors do anyway.The neat thing as I see it is that the cars use gravity to accelerate to cruise, electric energy to maintain steady cruise, and gravity to decelerate to stop giving up only the energy that would otherwise be mostly recovered by regenerative braking. Can anyone come up with a more energy efficient method to accelerate and decelerate the cars?But the lower the slope of the ramps the more space they take at shallow depth, which interferes with things like utilities and also requires a larger entrance, cosine and all that. I suppose they could do a double spiral ramp, up and down, but it still needs more surface space for a larger entrance.To avoid the weightless effect. the car could accelerate at say .5G going down and brake at the same .5 G going up on nearly vertical ramps. That would also allow shallower tunnels.There would still need to be occasional elevators or something similar in case the cars had a failure that didn't allow them to run at full speed.
Quote from: edkyle99 on 06/24/2018 03:11 pmQuote from: RedLineTrain on 06/21/2018 08:36 pmAs for Autopilot, it is currently being used on millions of miles of driving at speeds up to 90 miles per hour. An auto safety expert explained to me recently that the fact that these autopilots are programmed to allow the cars to break the speed limit is a sign that their manufacturers are not taking safety seriously. - Ed KyleI'd question their credentials as an 'auto safety expert'. Deviating from the mean traffic velocity (i.e. 'the speed everyone else is going at') increases risk of an accident, and almost equally in both directions of deviation. i.e. going 10 under the mean velocity is just as risky as going 10 over. If you insist on travelling at the speed limit when everyone else is going 10-15 over, then YOU are the hazard.
Quote from: edzieba on 06/25/2018 12:48 pmQuote from: edkyle99 on 06/24/2018 03:11 pmQuote from: RedLineTrain on 06/21/2018 08:36 pmAs for Autopilot, it is currently being used on millions of miles of driving at speeds up to 90 miles per hour. An auto safety expert explained to me recently that the fact that these autopilots are programmed to allow the cars to break the speed limit is a sign that their manufacturers are not taking safety seriously. - Ed KyleI'd question their credentials as an 'auto safety expert'. Deviating from the mean traffic velocity (i.e. 'the speed everyone else is going at') increases risk of an accident, and almost equally in both directions of deviation. i.e. going 10 under the mean velocity is just as risky as going 10 over. If you insist on travelling at the speed limit when everyone else is going 10-15 over, then YOU are the hazard.Go ahead, good luck making that argument at traffic court.The way I see it, allowing autopilot to break the speed limit has to do with the fact that humans are not involved therefore a different standard can be applied. As more and more cars adopt the technology, and eventually humans are completely removed from the equation, speed limits will probably be non-existant and the only goal will be how efficient, safely and fast can automated vehicles get you to a destination. Once global transportation accidents go down to something like once or twice every 3-5 years, then the only goal in transportation is efficiency.