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University Students Made a Working Model Hyperloop
derekmead writes: Elon Musk's Hyperloop gets people excited. Promise the ability to travel from San Francisco to Los Angeles in less than an hour, and you're going to get people salivating. But for as much as we've heard about it, we've had scarcely little to see—until a team of students at the University of Illinois decided to build their very own miniature hyperloop.
Mechanical engineering students at the university built a functioning 1:24 scale model of the Hyperloop, a "fourth mode of transportation" that sends pods through a partially pressurized tube at very high speeds, as part of a senior design project. It was designed to test some of the key components of Musk's design, which was outlined in a much-read, open source whitepaper (PDF) published in August of 2013. That said, there are several key differences, which keep this from truly being a proof-of-concept as to whether or not the Hyperloop will ultimately work.
Mechanical engineering students at the university built a functioning 1:24 scale model of the Hyperloop, a "fourth mode of transportation" that sends pods through a partially pressurized tube at very high speeds, as part of a senior design project. It was designed to test some of the key components of Musk's design, which was outlined in a much-read, open source whitepaper (PDF) published in August of 2013. That said, there are several key differences, which keep this from truly being a proof-of-concept as to whether or not the Hyperloop will ultimately work.
Planes generally average around 500mph, and the average plane flight time between SF and LA is... roughly 57 minutes. You'd have to hit much higher speeds to not be survivable. You're just going to be spending the last 15 minutes slowing down gradually.
"LaForge to bridge: Captain, the inertial dampeners are offline. Do NOT drop out of warp."
Pretty sure my bank has one of these. How is this news?
LOL ... well, I'll accept my being a moron as the problem here ... despite reading it, and knowing where those cities are located ... my brain was treating that as a "coast to coast in an hour", like New York to LA.
You are utterly correct.
Lost at C:>. Found at C.
Let's do the math. To travel from San Francisco to Los Angeles in an hour requires an average speed of 166 m/s. Accelerating at 1 G (9.8 m/s), it would take 17 seconds to reach that speed. If that's too much acceleration for you, do half the acceleration for 34 seconds. Either way, no puree.
Is one of the key differences that it is twenty-four times too small?
How long does a plane take to travel between both places ?
There's barely 560 km between both locations. An hyperloop device accelerating at the same speed a Tesla P85D does (lets say 33 km / h / s) would reach 600 km/h in 18 seconds. And a Tesla does't tend to splatter it's occupant on acceleration. If the environment is stable and safe and the vacuum is tight and the suspension is magnetic, it's easy to think about 2 minutes of acceleration, cruise and rotate the seats, 2 minutes of deceleration (which would feel like 2 minutes of acceleration)
Back of the hand calculations yields a speed of 3960 km/h reached after 66km (2 minutes in), 6 minutes 30 of cruise, and 2 minutes of deceleration. for a total of 10:30 without dangerous forces being used( provided the path is straight... yeah)
They could still do so. It'd just take about 4 years from warp 2 to reach a stop... ;)
I don't read AC A human right
Actually it's very achievable.
I'm going to use metric system because I'm most used to it.
Distance between SF and LA is 644 km.
An object accelerating constantly for 1800 seconds which would travel half the distance (322 km) in 1800 seconds only needs an acceleration of 0.2006 m/s^2 (0.02046g). It needs to decelerate constantly by the same rate for the rest of 1800 seconds to make the whole trip in 1h.
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
>>>> travel from San Francisco to Los Angeles in less than an hour
>> I am exceedingly skeptical this would be survivable by humans.
Turn in your geek card. Here's an easy back-of-the-envelope calculation for you.
Let's start with a gentle rate of acceleration and deceleration at 1mph/sec (e.g., "zero to sixty in 2 minutes"). That means that the vehicle is at a maximum speed of 420mph in 7 minutes, during which time it travelled about 24 miles. The distance between SF and LA is about 400 miles, so assume we have 350 miles to cover at top speed. That happens in 50 minutes, which when added to 7 times two is about 64 minutes. In other words, we can achieve this trip with less-than-elevator acceleration in about an hour.
It must have been fun and I'm sure the students learned a thing or two, but this model uses physical roller bearings, instead of air pressure. So there is one problem with the model straight away. The second is they built it into an oval shape, which is another challenge the hyperloop faces: how to negotiate deceleration through a sharp corner, yet still maintain a high rate of speed to make this a viable mode of transit. I understand these design flaws are limitations imposed by the scale of the model, but really if you can't model something properly, then your experiments within this model will yield unusable data. Still, it was probably a fun project no less.
I was pretty surprised when I heard about Tesla or SpaceX's half-scale test track. It seems like a much better idea to start off at a smaller scale like this. If I was in charge, I would start off with whatever scale I could source the cheapest components for. Like, start at 1/32 scale, then go to 1/16, then 1/8, etc. That way economies of scale will help make the cost of the prototypes negligible.
The Second Decree: No more pollution. No more car exhaust or ocean dumpage! From now on, we'll travel in TUBES! Get the scientists working on the Tube Technology immediately!
Taking guns away from the 99% gives the 1% 100% of the power.
When I was little, I found a book in our bookshelf about the future. The book was from the early sixties. All with floating at sea nuclear plants, automatic farming, synthetic meet, maglev trains, and trains running through tubes. Propelled either by a propeller at the back or by magnets in vacuum. So Elon Musk just had a similar book in his youth and now tries to build the stuff. Some is great, but that tube thing sucks. It is expensive, it will require a lot of resources even compared to bullet trains.
...isn't this basically just a model train in a tube? It sounds like the only thing from the hyperloop they are actually using is the "electromagnetic motors." It's using roller bearings, and the tube is not depressurized. As far as I know, those are the two most important things about the hyperloop, which speak to the goal of increasing speed by reducing drag. The speed is 160mph, which is less than half the speed of the fastest trains currently operating. Using electromagnetic acceleration is pretty cool, but I remember riding on roller coasters that used this method of acceleration back in the 90s. I don't fault the students for doing a cool engineering project, but the headline chosen by the journalist is more than a little disingenuous.
It is much better when public transport is run by the city and state. Have a look at many European countries, they have working modern and secure public transport systems.
Most of the time it is coasting, so a power loss would not cause it to stop. If one does get stuck, they have emergency air, and the capsules behind the stuck one would drive themselves back to the station with onboard motors. The life support systems are battery powered. And why would it take 5-6 hours for emergency help to arrive? This thing is not in the middle of nowhere, it is following I-5 between LA and SF.
When the damn thing turns. Maglev trains for people are actually slower then the ones for freight because the freight trains don't have to worry about grandma surviving the trip. If they were going straight the whole way that wouldn't be a problem, altho there's some time for slower acceleration and deceleration they the hyperloopies don't seem to add in. But to get from LA to San Fran you can't go straight, you have to go up and down hills, around mountains, over rivers, etc.
A big part of the reason for Hyperloops cost advantage on rail is that Musk insists that a Hyperloop track can be cheaper. He says it would be more analogous to a oil pipeline then a rail track, and have cheaper construction, more abrupt bends, etc., which leads to higher G-Forces; this is a an even bigger problem problem for actual implementation of the idea then it would be for alternatives.
Mark my words: every trial of this will be successful until they put people in it. By the time they've smoothed out the turns, upped construction standards to virtually eliminate accidents, and reduced speed to something grandma can survive it will probably cost more then rail. It's brand-new technology and first generation check is never cheaper then the stuff it's replacing. I suspect there will be significant energy savings, and possibly some speed advantage, due to the fact that a hyperloop operates in a vacuam and there's no wind resistance, but the price advantage ain't gonna last.
Coast to coast still wouldn't be that big of a deal. The SR-71 Blackbird flew from LA to Washington DC in 64 minutes 20 seconds.
They didn't design a hyperloop. They designed something that tested some aspects that would get used by a hyperloop.
Do editors even work here?
BeauHD. Worst editor since kdawson.
But planes essentially go straight except for the very beginning and ending of the flight. They don't have to dodge the Mountains of the Southern Coast Range. And they aren't doing it at Mach I.
So you wouldn't be plastered to the back windows, but the side windows would be a wee bit of a problem.
NY to LA is 2448 miles - at an acceleration of 1g (~22 (Miles per hour) per second) it would take 102 seconds (1.7 minutes) to achieve a speed capable of going from LA to NY in an hour. As long as there aren't any sharp curves, or things to hit along the way, there aren't any forces that would prevent a 1hr trip from LA to NY. Hell the SR-71 made the trip from NY to London in 1hr 40 minutes, and that's 1000 miles farther at ground level - let alone at the 80k - 90k feet the SR71 flew at.
Sorry, but I'm having trouble imagining such a facility being run by a typical American for-profit entity. Bad morale, low standards, high staff turnover, no loyalty to the employee, so no loyalty from the employee back to looking after the public.
So how's about we agree, that we'll make the operating entity an crown (or state) owned utility (not for profit) and run with a well paid, well trained, workforce ?
If only we could fall into a woman's arms without falling into her hands
Their proposed route never exceeds 0.5g in any direction, and the capsules can bank.
Floating at sea nuke plants? Fukushima came pretty damn close, eh? Not to mention all those nuke subs and carriers. Maglev trains are out there. Some of them even run through tubes (and/or chunnels). And synthetic meet? Kids these days just call it "social networking."
Eloi are stupid, throw morlocks at them!
It's O scale or no scale.
Reference please. All I have seen is a mention of following I5.
Good lord a correction that didn't descend into mudslinging on the internet. It really *must* be a new era.
Except that their projected travel time is 35 minutes, which is quicker than a plane. And it is supposed to use about 1/10th the energy per person to make that trip. And instead of 'dozens' of flights a day, it leaves every 2 minutes (every 30 seconds during peak time).
Their whitepaper, starting on page 39.
The "Hyperloop" concept - putting a capsule with seats in a tube and having it speed between cities - has been around for decades. I have seen concepts for it in old engineering books from the 1950s. Somehow, this becomes "new" and Musk gets his name on it.
I really don't get this cult of personality around Musk. He must have a god for a publicist.
If it's state run that's fine, just make sure it's not a "jobs program" where people are never fired or held accountable for their actions. I don't want something like TSA where people are rummaging through luggage for SWAG
I'm glad you people weren't around when the Wright bros were doing their thing. Or the Panama Canal. Or the Hoover Dam.
Eventually, this will be a viable project. Decades at the very earliest, before the first shovel full is dug. And then decades later before the first mile mile is complete. Gotta let the enviroweenies have their say.
But one of these will be built. Eventually.
My issue is with turn radius. Using your example and constraining the maximum perceived gforce to 1.5 we come up with the following.
With a downward force of 1G the maximum centripetal acceleration would be 1.1G. 1.5^2 = 1^ + x^2.
The equation for centripital acceleration is A = v^2/R. Therefore 1.1 = (166)^2/r Therefore r = (166)^2/1.1 = 25km. That is a very big turning radius. To put it another way, it would take 4.3 Km of tube to change direction 10 degrees. Interstate 5 turns a lot sharper than that so I think the the "following I5" idea is a pipe dream.
In theory, there is nothing whatsoever wrong with the idea of a hyperloop. Pneumatic-powered transportation has been in the prototype stage for a very long time (a century or so, IIRC.)
But a line like this between SF and LA? The finances required for such construction are daunting enough with "simple" high-speed rail line. Constructing hundreds of miles of something far more finicky and complex? I suppose if one wanted to construct such a line across the great plains (not exactly a high-demand market) that could work. But a not-flat region of CA? His estimated construction costs are for raw trackage, and do not include the extensive system of bridges and tunnels that would be absolutely required, not to mention the expensive right-of-ways. And for what? Yes, there is a lot of air traffic between LA and SF, but not so much the construction of this boondoggle makes any sense whatsoever.
Outside of the Northeast Corridor, passenger rail in the US makes no sense whatsoever. The distance between viable markets, even with high-speed trains, is simply far too large to make the extensive capital costs worth it.
And why would it take 5-6 hours for emergency help to arrive? This thing is not in the middle of nowhere, it is following I-5 between LA and SF.
A couple of fender benders during rush hour on the Wednesday before Thanksgiving and it will take 5-6 hours to go 4 car lengths. ;-)
That is not much detail at all. Those two page do not show a detailed route or investigations into any of the trouble spots along the way. Drawing a line on a map is very easy. Here is a quote from the article;
This can be achieved by deviating from the current highway system, earth removal, constructing pylons to achieve elevation change or tunneling.
That sounds a lot like "we'lI think about it later". think they will be deviating from the current highway system a lot.
Cool. When I was at university, all I made was a bong out of a half-gallon milk bottle.
It was a pretty sweet bong, though.
You are welcome on my lawn.
I want SkyTran: http://www.skytran.us/
I think your math is off. According to their whitepaper, the turning radius at 1220km/h (339m/s) is 23.5km. Plugging that into your formula gives a centripetal acceleration of 4.9m/s^2, or 0.5g.
While they are mostly following I-5, they deviate when necessary to smooth the turns. That is one of the reasons it is built on pylons.
Read more than 2 pages. Pages 44-50 show the details, including the turning radii and the deviations from I-5.
An hour to get from New York to San Francisco, an hour and a half to get through the TSA inspection and baggage handling. An enclosed tin can would be a perfect environment for a terrorist attack, and even if it wasn't the TSA would want to stick their noses in for the sake of empire building.
Also in Musk's published photos, they'd have a hard time fitting in the disabled access and public toilets which would be demanded by regulators and pressure groups.
Depending on cost and energy requirements, the Hyperloop may be better suited to goods transport. High acceleration and deceleration forces would not be a problem for goods shipments.
Godel_56 posting anon. due to mod points.
It would actually take about 8 years.
As we all know, humans are not capable of traveling at speeds faster than 30 mph. It was common knowledge in the 18th Century.
Obviously hyperloops can't work either.
-- Tigger warning: This post may contain tiggers! --
I was off by a factor of 9,8.
Now that I look at it more, that math is a big WTF. The 'A' in that formula is not in units of 'G's, it is in m/s^2. Since 1G is about 9.8m/s^2, the correct formula is 10.78 = (166)^2/r or r=(166)^2/10.78, or 2.5km.
Instead of just assuming you know what they are doing, and using bad math to prove them wrong, why not actually READ the document and see what they are ACTUALLY proposing?
I finally did read the rest but it never states how much land outside the I5 right of way it would need.
"And why would it take 5-6 hours for emergency help to arrive? This thing is not in the middle of nowhere, it is following I-5 between LA and SF."
Because it's California, and that's probably how long it would take to file all the required statements of environmental impact and get a court's okay, even with the expedited procedures I'm sure would be put in place if Hyperloop were actually built.
Scale is off.
And guess what ? You should know better than to rely on time or speed to make such a guess. You should rely on force and acceleration. 1 G is perfectly survivable by human , and within 1 minutes you are already at 60 meter per seconds, and in 10 minutes 600 meter per seconds or about 2160 kmh. At that sped you do paris new york in 2 and half hour and the 400 miles between los angeles and san francisco in about 15 minutes. Naturally the speed we are talking about are not even 1/4 of that, and the acceleration much lower. But still it shows you that when it comes to beeing squished, you are way way underestimating how much it would take.
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visit randi.org
Dude, if they're on the I5 Right of Way the are turning in 3D too much. It's got a legendary "grapevine grade" in Kern County.
If they take over a lane, or the median, and build a viaduct a couple stories high, they may be able to beat things like the Grapevine Grade. But then they have to deal with mountains and hills the I5 tunneled through, overpasses, etc. And it's kinda easy to say "we'll take over the median," but I suspect the supports for the huge towers you'd need to make the grapevine grade survivable are gonna be pretty damn expensive.
I'd be a whole lot more sympathetic to their arguments if they didn't boil down to "we costed out the stuff that doesn't cost much, and it doesn't cost much; and clearly nothing else will be relevant because we don;t want it to be relevant."
The drive through at my old credit union had a similar scale hyperloop prototype in about 1985. We never thought of sending anything but deposit slips through it back then. . .
I made a mistake. Sorry. The document is still pretty vague. I would like to be able to actually see how far from the right of way the proposed route actually is. The map is not detailed enough for that.
For that matter, at 1g for the entire duration of the ride (1g acceleration halfway, 1g deceleration the other half) it would only take a bit over 21 minutes.
And if we want to talk about human survivability, Wikipedia tells me that humans can generally tolerate up to 5g before blacking out. At that rate it would take about 9.5 minutes one way.
And if we're just looking to get there in an hour, 1/8 g would do the trick.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
Oops, forgot that it was the cube, not the square. I figured on 4C, not 2C.
Then again, if one figures that their gravity generators aren't broken(just the inertial comp.), and they can manage to negate 2G sufficiently, it'd still only take 4 years. ;)
I don't read AC A human right
Doesn't pretty much every bank have a model hyperloop?
... surely these people know we've used pneumatic tubes before, no?
I've decided to stop wasting my time responding to AC trolls/sockpuppets... so if you want a response from me... login.
New Zealand is about 20000km from where i currently live. at 0.2g max acceleration you can cover that distance from stationary starting to stationary stop in less than two hours (6300seconds). So your idea of forces involved for high speed are quite false. Of course in this example top speed would be 6232m/s, or about 15% below orbital speed. quite impractical for a plane, or even this concept. But it illustrates the point.
In short your top speed is what matters. There are no inherent forces that kill you at speed and acceleration can be very mild.
The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
I can slow down for the sharper corners. Like High speed rail does you know. Since its a v^2 term you don't need to slow down much.
The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
Aviation speed records are typically overflown, and are measured point to point. The Blackbird circled far enough over the Pacific to allow it to cross back over LA at cruising speed; it also overflew DC and then slowed and circled back.
(BTW, any practically any pilot can set a record - just find a point to point run that hasn't been declared yet.)
Not every correction descends into mudslinging, you insensitive clod!
And they aren't doing it at Mach I.
Maybe not Mach 1.00, but Mach 0.80 to Mach 0.85 (airliner cruising speeds) aren't that far off.
What if the replacement viaduct took the i5 over the grapvine grade as well as the hyperloop?
There are a lot of roads where a viaduct over a valley would save considerable time, money and fuel over the current norm of terrain-following. Just because that's the way stagecoaches did it doesn't mean that it's appropriate for newer technologies.
Unlike rail, the hyperloop vehicles are able to bank inside the tubes so that cabin gravity is always apparently floorwards. (In fact if the CoG is low, then the banking comes for free, assuming a cylindrical profile.)
That in turn allows much tighter bend radii than rail where the limitations are mechanical stresses on the tube from passing pods and how much vertical G forces you're prepared to subject your passengers to (3G for 30 seconds is quite tolerable from my own experience deliberately spiral diving aircraft. More than that and passengers will probably complain loudly)
It's worth pointing out that HSR systems in the EU use bend radii in the region of 4-5 MILES for full-speed direction changes, and as with rail, the right-of-way only needs to be 30 feet wide for hyperloop.
Robert A Heinlein germane.
What will happen during a hyperloope worker's strike or revolt?
Tracy Johnson
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BT
Hyperloop's maximum speed is projected to be 760 MPH, Mach I at sea level is 761, and Mach numbers go down as elevation goes up.
Viaducts never save construction money. The reason is pretty simple: the road-bed you build on the viaduct has to be equivalent of the one you'd build on the dirt, which means the only way to save money is on digging the hole the road-bed would go into. And that's only cheaper if you're in a magical place with easily diggable dirt patches located precisely where you need them.
In the long-term they tend to save money as manageable grades reduce fuel consumption and the need for specialized equipment, but Hyperloop isn't in that phase yet.
The banking thing is interesting, but you totally destroy your credibility with the 3.0 Gs thing.
Hyperloop is not supposed to be a mode of travel grandma can't use. 0.2G is roughly what the competition is doing, and Musk's proposed 0.5 G would actually be comparable to a roller coaster.
This is an idea that'll work great and be near or under cost at scale, but that's because people won't be in it. I am not saying it's a bad idea, or that it's not possible that we'll be zipping our way around on Hyperloops in 2100, but this is a new technology. It's not software. It is pretty much impossible for it to be all three of faster, cheaper, and better without a few more years of aggressive development.
They also have unions, but the relationship between unions and companies is usually less angry and pathetic as in the US.
Could you imagine a hyperloop system being run by unions? Look at places like Washington DC where their mass transit *union run* has resulted in trains crashing into each other and trains going into a tunnel that's on fire only to lead to someone dying of smoke inhalation. This would be so much worse.
When you say *union run* do you mean that the staff are in a union? I assume that, being the US, you're not talking about some workers' co-operative actually owning it?
To have a right to do a thing is not at all the same as to be right in doing it
It's top speed may be pushing Mach 1, but the elevation is not an issue. Fighter planes see higher (not lower) Mach numbers with increasing altitude because the speed of sound decreases with altitude (and I think that that is what you meant). However, it is the lower temperature at higher altitudes that is the cause - not the reduced pressure. The temperature in the Hyperloop tube s/b the same (or slightly) higher than its surroundings.
Textbook case of disproving a minor point. Whether it's the speed of sound in the air around the tube, or the speed of sound from a table doesn't really change the argument.
My point is that this thing's going significantly faster then anything we let your grandma ride in today, that it's also supposed to make turns in the same radius as a car, all three dimensions (20-100 ft elevation means that you're going up and down relative to the roadbed, which itself goes up and down), etc. It's designed to have a lateral g-force of 0.5 Gs, which is comparable to roller-coasters.
This is not an idea that's likely to actually work without a whole lot more development.
Textbook case of disproving a minor point. Whether it's the speed of sound in the air around the tube, or the speed of sound from a table doesn't really change the argument.
It may seem to be a minor point, but you were the one to bring it up! The top speed of around 760 mph is quite obviously chosen so that it remains subsonic (or did you think it wouldn't pull 765?).
My point is that this thing's going significantly faster then anything we let your grandma ride in today,
And my point is that it is very close to typical jet speeds - which my grandma, were she alive today, would be quite comfortable with. It isn't speed you feel, it is acceleration. Its only practical speed limit is the speed of sound, which also limits your airliner speed. And speaking of acceleration . . .
that it's also supposed to make turns in the same radius as a car,
No, not even close. The route mostly follows the I-5, but deviates to keep the turning radii large enough to limit inertial acceleration forces to 0.5g - which is described as the most that a person can comfortably sustain for short periods.
all three dimensions (20-100 ft elevation means that you're going up and down relative to the roadbed, which itself goes up and down), etc.
The pylons are sized so as to keep the tube as level as possible. It is the road (and ground) that go up and down, not so much the tube.
It's designed to have a lateral g-force of 0.5 Gs, which is comparable to roller-coasters.
That is simply off by an order of magnitude. Here are some of the high force coasters; here's some milder Disney rides. Airliners tend to be a bit lower than 0.5 but not by much - and can readily exceed that number if need be.
So you're arguing that it's not going Mach 1 because it's designed to only go Mach .99868593955. Apparently you don't believe in rounding to significant digits. As for typical Jet Speeds, those are below Mach .9, and typically in the Mach 0.8 range. Mach 0.15-0.2 is a pretty significant difference.
Moreover you are talking about a different G-Force measurement then either me or the standard Musk has designed. When taking turns the relevant measure is the lateral G-Force measure, and Coasters don't go too high on that because if they did 6 Gs laterally a 200 lb dude would be exerting 1200 pounds of pressure on the side of their roller-coaster, and it probably can't handle that. They top out at 0.5 Gs lateral. Aircraft don't do a lot of lateral Gs either, partly because they have to go straight really fast or fall from the sky, partly because they have even less structural strength to resist extra pressure on the fuselage, but mostly because people start throwing the fuck up once you break 0.2 lateral. They try to stay below 0.15 laterally unless something has gone horribly wrong.
The whole plan is vintage Musk -- equal parts brilliant engineering, pooh-poohing the standards literally everyone else uses (0.2 Gs laterally is what everything in transportation, except Hyperloop, does), unwarranted financial optimism (his $700 Million tunneling budget won't get him all the way through a single mountain, and Cali has a couple ranges of the damn things), and excellent spin (for example, his planned route technically does not go from LA to San Fran, it goes from 30 miles from LA to the San Francisco Bay, which reduces his costs by roughly 75%, but nobody calls him on it). Given some development the engineering could be very interesting, but you really need a lot of that development.
> you totally destroy your credibility with the 3.0 Gs thing.
If you want to mess about with aircraft there are planes you can do this in, and places you can have the altitude to do it. It's harder to lift your arms but not intolerable. In general, unless the passengers are warned in advance it's best not to exceed 0.5G in banked turns and exceeding 2G may pull the wings off some models of light aircraft.
> actually be comparable to a roller coaster.
Roller coasters are deliberately designed to repeatedly throw people around in different directions in order to heighten the sense of danger. High speed banked turns in hyperloop (or anything comparable) are in no way comparable to the feeling of a roller coaster, more like riding in a widebodied air transport (note there that the apparent cabin gravity is also always floorwards thanks to banked turns.)
Anyone who tries to make out that passengers will feel substantial lateral forces is barking up the wrong tree. Even the original vacuum train proposals made use of banking in turns and european HSR systems make extensive use of banking to avoid the same effects (You can feel the apparent gravity pushing you into the seat a little harder in some spots on the Paris-Amsterdam run).
Any credibility loss is borne by those who try to compare the ride quality of a high speed transport system to a roller coaster. The ride on rails is comparable to that of a ship or an aircraft (without pitching and rolling) and in a tube will be even smoother than that of a maglev (try the shanghai airport shuttle sometime. It's like a magic carpet.)
I didn't say you couldn't do 3.0 Gs. I said that your credibility is destroyed when you bring that into a discussion of mass transportation. Mass transportation is not supposed to be that jerky because mass transportation is supposed to be used by all the people you specifically agreed you weren't when you signed that contract before the pilot took you up.
As for your comparison to current modes of transport, you're not comparing a current hi-spoed transport system with other current hi-speed systems. You're comparing a theoretical system designed by people whose job is to Fail Fast by cutting corners, and no education in transit, with those systems. The current systems you're talking about have been carefully calibrated to have 0.2 Gs lateral max, because when you cut that corner your customers put "Vomit Comet" on all your Yelp Reviews. The theoretical system is designed at 0.5 lateral Gs, which is roughly equivalent to what you get on a roller coaster.