The way I understand it the pod would bank, but its weight would prevent it from ensuring that all the G forces were in the subjective down direction. The alpha design has been done within the G forces that its designers have thought are comfortable. Let's hope those parameters were set by the Tesla part of the team, not SpaceX. ;-)
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Hyperloop
- Thread starter gg_got_a_tesla
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The way I understand it the pod would bank, but its weight would prevent it from ensuring that all the G forces were in the subjective down direction. The alpha design has been done within the G forces that its designers have thought are comfortable. Let's hope those parameters were set by the Tesla part of the team, not SpaceX. ;-)
I believe the design is that the cars would slide up on the wall of the tube to the outside of the curves as they entered curves. The curves would have to smoothly transition from straight to the final circular radius so the force the passengers feel would gradually increase and to avoid having the car slammed sideways up the tube wall, but that's not a big issue.
With the current route design, passengers would feel a smooth increase from their normal weight to about 1.12 times their normal weight, then at the end of the curve, their weight would smoothly decrease back to normal, at all times pressing in the direction they would think of as down. You've likely felt pretty close to what the Hyperloop will produce in an airliner when it banks fairly steeply to maneuver near an airport.
If you want to see how the curves are designed look at the alpha design pdf on the SpaceX site. It details how they are to be done.
Ben W
Chess Grandmaster (Supervised)
Yes, although the perceptual increase is that you will experience 1.5 times your normal weight (i.e. a net extra 0.5g's) in the turns, as well as in the initial acceleration and final deceleration. The 1.12g figure is purely the lateral acceleration, which when combined with 1g of vertical acceleration (gravity), gives a net 1.5g's. Go Pythagoras!
The curves shown on the route design are for .5 g centrifugal acceleration (e.g. 480 kph with a 3.67 km radius). The resultant force is the vector sum or (1^2 +.5^2)^.5 = 1.118. The atan of .5 is 26.5 degrees which is the bank angle.
Ben W
Chess Grandmaster (Supervised)
From Page 40 of the PDF:
These first of these figures correspond to 1.12g's laterally, 1.5g's net. The second corresponds to 2.44g's laterally, 2.64g's net, so is obviously a typo.
The central valley section of the hyperloop map shows a tight curve with roughly 8km radius south of Fresno, which at 1220kph works out to 1.47g's laterally, or 1.78g's net. The curve would have to be relaxed to radius 10.4km in order to limit lateral acceleration to 1.12g, and net acceleration to 1.5g.
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The table on pp 40 is clearly wrong and isn't matched by any of the actual curve data presented in the route section details. Based on their statements and the route tables' heading of .5g, my assumption is that that's what the curves are designed for and for tighter turns, the cars will slow down.
I think that document was put together with very little editing and it will be interesting to see if they ever revise it or pursue the design.
When they mention a larger design able to carry 3 cars, does that indirectly also mean that this larger version could have larger passenger pods with cabins that could have a small alley and a small airplane-like restroom?
(to avoid the Chlorox and Depends solution, and make possible longer trips on other routes or routes for which portions would be slower to navigate in urban topography)
(to avoid the Chlorox and Depends solution, and make possible longer trips on other routes or routes for which portions would be slower to navigate in urban topography)
Based on the stated goal of carrying 3 Model S sized vehicles and a frontal area of 4 m2, I think the dimensions would be about 2.5m wide and 1.6m high, about twice the width of the passenger version. That would allow a passenger only car to carry many more passengers if throughput were an issue.
Because of the accelerations I'm pretty sure there will be no moving around, everyone is going to have to remain belted in the entire trip just as you have to stay in your seat during landings and take offs. Anyway, the whole restroom notion seems like a red herring to me. There are many small commuter and short haul planes such as those that fly between Caribbean islands that have no aisle or restrooms and it doesn't seem to be an issue for them. There are also many stretches between exits on highways that are over a half hour apart, and it's very rare to see anyone in the bushes.
Ben W
Chess Grandmaster (Supervised)
Hyperloop idea: Star-Tours-like movies that track the capsule accel/decel/cornering. For onboard viewing, or for advance simulation.
As stated above, the capsules won't need restrooms, but they will certainly need barf bags. Think of it as a 35-minute amusement park ride. They should open up Six Flags locations around each terminal.
As stated above, the capsules won't need restrooms, but they will certainly need barf bags. Think of it as a 35-minute amusement park ride. They should open up Six Flags locations around each terminal.
jeff_adams
Member
I like that idea! Instead of San Fran to LA go from Great America to Magic Mountain. Huge parking lots, room for cabs and shuttles on each end. Include a special "hyperloop" ticket into the price. 2 amusement parks in 1 day.
Wouldn't there be a 10 minute stretch in the middle where you would have very little turning or acceleration, but just coasting along?
And if for various reasons the trip ends up in real life being closer to 40-45 minutes than 35, its more of an issue for more people, and a design with restrooms would allow the concept to be used between cities that are a bit farther apart than 35-40 min.
In a plane you must buckle up during take off and landing, but maybe its for better-safe-than-sorry-if-theres-an-emergency/hard landing rather than because the g force makes walking hazardeous? I dont know about that. ...and are you in buckle-seat-belts for more than 30 minutes? (I never timed it but it seams less than 30 min?)
For a 10 min, 15 min, 20 min trip it would be a red herring, if there was a mid-point station where the hyperloop stops for 2 min, it would be a red herring, a 25 min stretch well ok might still be red herring, or even maybe a 30 min might not be a deal breaker, but when you are pushing beyond 30 and 35+ min, imo a rest room is starting to be an accommodation that people would start to appreciate if only knowing its there, its starting to be an issue that a lot of people will find an inconvenience that would be better addressed than dismissed, imo.
nice indeed
Here is another concern I have about the concept: sag between pylons.
If there is just 5mm of sag in 30m (100ft) then the air bearing plates will experience a 10Hz vertical judder of 1g. If that were transmitted to the passengers, it would liquify thier innerds (or at least be really uncomfortable.)
I think it is clear that to maintain the passanger compartment vibration free while the air bearings are doing the watusi will require sophisiticated active control perhaps involving a linear motor with control laws based on knowledge of the upcoming sections of tube plus the ability to respond to unpredicatable situations.
However, a better solution would be continuous active adjustment of the vertical position of the tube using a number of actuators spaced between each pylon. Some sort of sensor array, perhaps laser based, would monitor the position of the tube along its length.
And while I have the floor, I think it is obvious there need to be interdigitated expansion joints at each pylon. And I am still nervious about the air bearings going over the relatively small (1 inch) joints.
Here I show my work:
Approximately 10Hz from the spacing and speed.
d= sag*0.5*sin(2*pi*10*t)
v= sag*0.5*(2*pi*10)*cos(2*pi*10*t)
a= sag*0.5*(2*pi*10)^2*sin(2*pi*10*t)
amax= sag*0.5*(2*pi*10)^2
a= 9.8m/s^2, sag= 9.8/(0.5*(2*pi*10)^2)
sag= 5mm
Note: I am thinking about things like this because I had the same (but less violent) issues with my own attempt at solving the world's transportation issues:
Patent US6202566 - High-speed high-capacity transportation system - Google Patents
Unfortunately, I am a starter and not a finisher and lost interest almost the same day I sent off the pattent application. I have now let it lapse.
If there is just 5mm of sag in 30m (100ft) then the air bearing plates will experience a 10Hz vertical judder of 1g. If that were transmitted to the passengers, it would liquify thier innerds (or at least be really uncomfortable.)
I think it is clear that to maintain the passanger compartment vibration free while the air bearings are doing the watusi will require sophisiticated active control perhaps involving a linear motor with control laws based on knowledge of the upcoming sections of tube plus the ability to respond to unpredicatable situations.
However, a better solution would be continuous active adjustment of the vertical position of the tube using a number of actuators spaced between each pylon. Some sort of sensor array, perhaps laser based, would monitor the position of the tube along its length.
And while I have the floor, I think it is obvious there need to be interdigitated expansion joints at each pylon. And I am still nervious about the air bearings going over the relatively small (1 inch) joints.
Here I show my work:
Approximately 10Hz from the spacing and speed.
d= sag*0.5*sin(2*pi*10*t)
v= sag*0.5*(2*pi*10)*cos(2*pi*10*t)
a= sag*0.5*(2*pi*10)^2*sin(2*pi*10*t)
amax= sag*0.5*(2*pi*10)^2
a= 9.8m/s^2, sag= 9.8/(0.5*(2*pi*10)^2)
sag= 5mm
Note: I am thinking about things like this because I had the same (but less violent) issues with my own attempt at solving the world's transportation issues:
Patent US6202566 - High-speed high-capacity transportation system - Google Patents
Unfortunately, I am a starter and not a finisher and lost interest almost the same day I sent off the pattent application. I have now let it lapse.
The design calls for a mechanical suspension between the skids and the car. The skids are very light, probably aluminum with carbon fiber struts. The suspension is designed to weight about 1.3T (I'm assuming the propulsion and emergency braking systems aren't on the skids). The capsule weights about 26 T, so the unsprung weight ratio will be on the order of 5% compared to around 15% for normal cars. With a low unsprung weight ratio, small excursions, low jerk, and predictable frequency, I'd think a simple spring/shock system could be designed to absorb pretty much all the vibration. The heat rejection in the shocks would have to be carefully calculated, but that doesn't sound overwhelming.
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Could you expand on why you think the exiting design wouldn't work?
The design is for no expansion joints anywhere in the system except at the ends where all the thermal expansion and contraction would be accommodated. The tube is designed to slid through the pylon joints, so the pylons must bend the tubes through the curves. The lateral forces required, assuming a minimum radius of 1.6 km and normal 30m pylon spacing, is about 75% of the lateral force of a car passing a pylon in a curve. If that was too much, halving the pylon spacing for such tight turns would reduce it by about 2/3. On more typical curves with 10km radius, the lateral force is reduced to 1/6 that amount. I don't think lateral support would be a big issue and don't really see any other significant problem. The ends of the tubes would move over 300m, but that could be done by a long sliding section at the end just before the airlocks. The cars will be moving at very low speed there so it seems like a tractable design problem.
Even if there were an expansion joint at each pylon, at maximum speed each 1.5m skid would cross it in 3 msec. To fall to the surface, assuming a 1mm altitude, the skid would have to accelerate at about 10g against the suspension dampers, even assuming it lost all lift. That's unlikely though since the aerodynamic lift wouldn't be affected much at all. At slow speeds, say 100 kph where the lift is all from pressurized air, the skid would cross in 54 msec and would have to accelerate at just under .1g assuming total loss of lift. However, if this were the design, simply providing more than one outlet orifice in the skid surface would mean that only a fraction of the skid would lose lift, so there'd be little danger of it hitting the surface.
Since the two skids that would be affected only comprise about 7% of the total lifting surface, a very small decrease in altitude of the other skids would make up for the loss of lift.
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Anyone else feel like mundane details like baggage and security could use some more attention?
As a consumer, my problem with getting to LA has nothing to do with the one hour travel time in the air, and everything to do with the way one hour of flight time takes over four hours of real time.
Some of the wasted time is getting to the station and getting from the station to your destination. I'm not really sure how to avoid that. I think hyperloop is likely to make the problem worse if it has fewer stations. (There are lots of airports in the Bay Area and in the LA area).
Some of the wasted time is adding in a safety buffer so that if I get stuck in traffic, I don't miss my flight. If hyperloop were to operate more like a subway where you just get on the next car, you could nix this safety buffer. but if seating is limited and the operator tries to fill every car, then you'd be required to arrive for your reserved car, and you'd need that safety buffer.
A lot of the wasted time is security. The proposal makes short mention of that saying that it would be similar to airport TSA screening. only airport TSA screening is terrible. The proposal seems to imply that with regular departures there wouldn't be much of a security problem. but airports have regular departures, and the lines are usually long. It seems like a simple problem to solve: add more screening capacity. Somehow airports don't seem to be doing that. Is there some technology that would allow screening to go faster? so far, it seems like we just keep making it slower (laptops out, then liquids out, then shoes off, now mm-wave machines that take 10X longer than metal detectors, etc.)
More wasted time is luggage handling. You need to be at the airport at least 30 minutes ahead of time for your luggage to get on the plane. It takes about 30 minutes from landing before you get your luggage. Does hyperloop have a solution to that?
An annoying amount of time wasted is just getting on and off of the stupid airplane. Hopefully this will be fixed by those huge doors that open wide open. (At SJC, they frequently bring stairs to the back of the airplane in addition to the jet bridge at the front. Why don't they always do that everywhere?) I hope anyone building hyperloop recognizes that while big doors are probably more expensive, they're important.
Anyway, for hyperloop to attract me as a consumer, the travel speed isn't important. Instead, I'll be comparing the total time which includes security, luggage, safety buffer, etc.
As a consumer, my problem with getting to LA has nothing to do with the one hour travel time in the air, and everything to do with the way one hour of flight time takes over four hours of real time.
Some of the wasted time is getting to the station and getting from the station to your destination. I'm not really sure how to avoid that. I think hyperloop is likely to make the problem worse if it has fewer stations. (There are lots of airports in the Bay Area and in the LA area).
Some of the wasted time is adding in a safety buffer so that if I get stuck in traffic, I don't miss my flight. If hyperloop were to operate more like a subway where you just get on the next car, you could nix this safety buffer. but if seating is limited and the operator tries to fill every car, then you'd be required to arrive for your reserved car, and you'd need that safety buffer.
A lot of the wasted time is security. The proposal makes short mention of that saying that it would be similar to airport TSA screening. only airport TSA screening is terrible. The proposal seems to imply that with regular departures there wouldn't be much of a security problem. but airports have regular departures, and the lines are usually long. It seems like a simple problem to solve: add more screening capacity. Somehow airports don't seem to be doing that. Is there some technology that would allow screening to go faster? so far, it seems like we just keep making it slower (laptops out, then liquids out, then shoes off, now mm-wave machines that take 10X longer than metal detectors, etc.)
More wasted time is luggage handling. You need to be at the airport at least 30 minutes ahead of time for your luggage to get on the plane. It takes about 30 minutes from landing before you get your luggage. Does hyperloop have a solution to that?
An annoying amount of time wasted is just getting on and off of the stupid airplane. Hopefully this will be fixed by those huge doors that open wide open. (At SJC, they frequently bring stairs to the back of the airplane in addition to the jet bridge at the front. Why don't they always do that everywhere?) I hope anyone building hyperloop recognizes that while big doors are probably more expensive, they're important.
Anyway, for hyperloop to attract me as a consumer, the travel speed isn't important. Instead, I'll be comparing the total time which includes security, luggage, safety buffer, etc.
The Economist on the Hyperloop:
http://www.economist.com/blogs/econ...st-explains-12?fsrc=scn/fb/wl/bl/ee/hyperloop
http://www.economist.com/blogs/econ...st-explains-12?fsrc=scn/fb/wl/bl/ee/hyperloop
Welcome to the 21st scarentury, Derek...
Unfortunately, your appropriate comparison is going to have to be against alternatives, not against ideals. What are the security measures discussed for the CHSR project?
This year I took my first plane trip in five years; it included checking baggage. While nothing in the procedure made me feel safer, let alone warm and cuddly against the privacy intrusions, I will concede that the process went smoothly, efficiently and fast.
Unfortunately, your appropriate comparison is going to have to be against alternatives, not against ideals. What are the security measures discussed for the CHSR project?
This year I took my first plane trip in five years; it included checking baggage. While nothing in the procedure made me feel safer, let alone warm and cuddly against the privacy intrusions, I will concede that the process went smoothly, efficiently and fast.
There was a suggestion on another site that since there's no danger of a hyperloop car crashing into a building that there be two lines, one for people wishing to travel in cars only with inspected passengers, the other for risk takers. The risk takers would have to pay an insurance fee to cover damage to the system in the event one of their member decided to blow up a car. The safety first people would have to pay for the inspection.
The hyperloop isn't like an airport because it's not a hub. It's connecting one city to another, with the odd diversion in between.
The closest analogy I can think of is a line in a subway system. Separate line with no other traffic, which allows for very efficient movement of people. It can get a little congested down there but that doesn't affect the train the way traffic affects cars.
In the Hyperloop you'd have a procession through security and into a car. The car fills up and off you go. The problem with planes is that you're dealing with 200 people and it only takes one bunch of muppets to be faffing around and bang goes the timely departure.* With the hyperloop they'd be managing a small group for a short trip and the crew would politely hurry people into their seats, buckle them in and jump off. Plus, given the city-pair travel you 'd have a lot regulars who just want to get to the destination.
* Can anyone who's ever flown on a scheduled flight be a Libertarian? It's a great example of how directed cooperation would be sooo much better. Sometimes you can be too polite. I think maybe they should call for "families with young children, people who need extra time to get to their seat and people who don't need extra time but will end up taking it anyway because their hobby is blocking the aisle of an airplane and delaying its departure."
The closest analogy I can think of is a line in a subway system. Separate line with no other traffic, which allows for very efficient movement of people. It can get a little congested down there but that doesn't affect the train the way traffic affects cars.
In the Hyperloop you'd have a procession through security and into a car. The car fills up and off you go. The problem with planes is that you're dealing with 200 people and it only takes one bunch of muppets to be faffing around and bang goes the timely departure.* With the hyperloop they'd be managing a small group for a short trip and the crew would politely hurry people into their seats, buckle them in and jump off. Plus, given the city-pair travel you 'd have a lot regulars who just want to get to the destination.
* Can anyone who's ever flown on a scheduled flight be a Libertarian? It's a great example of how directed cooperation would be sooo much better. Sometimes you can be too polite. I think maybe they should call for "families with young children, people who need extra time to get to their seat and people who don't need extra time but will end up taking it anyway because their hobby is blocking the aisle of an airplane and delaying its departure."
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