Hyperloop - Reinventing the Wheel
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- čas přidán 23. 07. 2024
- This is a technical discussion about Hyperloop, getting behind all the media hype, and looking at how it could actually work. Are the researchers heading in the right direction?
We look at Air skis, Maglev, and Wheels, and see which is the most suitable for high speed transportation. Which technology will be most achievable and give the best results?
Video snippets courtesy of Virgin Hyperloop One, Hyperloop Transportation Technologies, Ohio State Engineering, Luke Starkenburg
My comments about the progress of the commercial companies is my assessment, based on the limited technical information they publish.
My figures about maglev performance is a best estimate, after extensive research. It’s difficult because they have never published any technical data. If they were proud of their energy efficiency, they would let us know!
There are three choices of levitation for Hyperloop; Air skis, maglev, and wheels.
In this video I’m going to discuss the merits of each, look at what’s been done so far, and suggest a better way to make progress.
The air ski proposal would never produce enough air flow to lift the pod. This is a simple calculation, backed up by failed experiments by various teams. With air skis failing, Hyperloop researchers have now decided to use maglev. Once again, they have committed to one technology without really looking at the alternatives. Are they making the same mistake again?
So we’ll compare maglev and wheels to see which one is most suitable for Hyperloop.
Speed. The Blue Flame rocket car, in 1970 achieved an amazing 1014 km an hour using Goodyear pneumatic tyres. The fastest is Thrust SST at 1228 km, their ultimate speed was limited by the sound barrier, not their metal wheels.
We can see that wheels can perform reliably at double the maximum speed of the fastest maglev.
Modern car tyres are very efficient, with a 300:1 lift/drag ratio, and racing bicycle tyres are better at 500:1.
Traction efficiency. Traction is not often discussed, but it is very important as it’s the major cause of maglev’s high energy consumption. A high-speed pod will use a lot of energy to reach full speed, we need good efficiency to recover most of it on braking.
Maglev uses linear motors, the circular ring around the motor is rolled out along the full length of the track, which could be hundreds of kilometres long. Traction efficiency is compromised, because it’s too expensive to use the exotic materials and precision construction of a normal motor. Linear motors are 70% efficient, or less, compared to conventional motors driving wheels which are 90% efficient. So linear motors waste three times as much traction energy.
Mechanical wear is the one feature where maglev has the advantage. This is an important challenge for wheels, and the main focus for research. It’s inevitable that there will be running expenses due to wear of the wheels, but we need to minimise the effect on the overall operating expenses. Hyperloop is the most extraordinary project, why would anyone choose air skis and maglev, instead of the obvious choice of wheels? Maybe the attraction of hyper technology! Air cushion and maglev are not novel, futuristic concepts, they have both been researched for a very long time. The reason you don’t see them operating is because they don’t work very well and are too expensive.
So now we’ll look at how to develop wheels that are suitable for high speed transportation.
How do we keep the passengers comfortable when cornering? Aircraft do it by banking to the correct angle so the passengers feel upright but with some extra g-force. Wheels can do the same, the pod can run up the side of the tube at exactly the right angle, so that high speeds can be maintained in curves. This would be very difficult with maglev.
Surprisingly, pneumatic tyres are the best solution. The tyre is an incredibly strong structure, it can run at 1,000 kph, using the normal construction of polyester fibres, steel, but with very thin rubber.
With Kevlar and carbon fibre, the tyre would be structurally capable of running at 2,000 kph.
The pneumatic tyre is ideal for smoothing out bumps, it has good grip, and low rolling resistance.
We don’t need any dramatic new inventions, just a combination of existing technology to suit the purpose. We can reduce the rotational stress, and increase the speed with a large diameter tyre, 1.5 m (5ft) or larger.We need hard rubber to reduce wear, of course we don’t need wet grip like road tyres. The structure needs to be quite thin and flexible, using modern materials like Kevlar or carbon carbon fibre.There is a support ring for run-flat security, this also helps internal cooling because of the lack of outside air flow to keep the tyres cool. The running surface is important, the polished steel tube wall might be ideal, but we can research better options.It’s possible that a thin film of special lubricant on the tube would reduce tyre wear and still allow adequate grip. - Věda a technologie
Please visit my website for more technical information, and discussion of challenges and possible solutions.
www.hyperloopdesign.net/
You might want to check out thunderf00t channel - he debunked the idea of a vacuum tube through calculation and experiment. Hyperloop will never work.
Great presentation on a complex topic. Well worth watching.
I was at the 2016 design weekend at A&M :) Just looked over your website after seeing it posted on r/hyperloop. Happy to see you're still at it and a huge thank you for all the work you've put into this. I really hope every student team, Hyperloop One, and Elon himself sees your site.
Paul Gemperlein many thanks for your encouragement, I have really enjoyed contributing to Hyperloop over the years, and meeting people in Texas in 2016. But I do get a bit impatient, I hope this video encourages a broader view of Hyperloop’s options.
How enlightening to hear the voice of reason in this world of marketing nonsense. Thank you very much ! 🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻
Thanks Claire for your input, good to hear someone is still interested. It’s sad that Hyperloop research has ended up getting bogged with maglev research that never gets anywhere. I still think it’s a worthwhile project, a more energy efficient way to travel.
Grateful for your patient and dispassionate analysis on a question that seems to get a lot of people frothing.
Hi Dion, glad someone is still thinking about Hyperloop! I wonder why people people are frothing? Surely engineers should choose the most practical solutions, and not let their decisions be driven by emotion. Sadly the world has decided that Hyperloop is maglev, thereby consigning the project to endless, hi-investment research.
@@RichMac46
I think because Musk rubs certain people entirely the wrong way, while others view him as a second Hercules.
I'm a programmer myself, rather than an engineer, so I rely on others who are willing to put the boxing gloves aside and just present the arguments as best they can to help me form opinions. From my super subjective perspective, I find your case for wheels to be by far the most convincing. If a Hyperloop system based around a wheeled pod has a shorter route to market, surely some Arabic oil prince or crypto-zillionaire-zoomer can be persuaded to fund it. At least, I'd _hope_ so.
I think the problem is funding. Try to raise $millions for high-speed wheel research, and you would struggle. But a maglev project costing 10 times as much would be easier to fund, because maglev is “the future of transportation”. Ultimately, research projects pursue the technology that raises the most investment, so in fact it’s the bankers making the choice of technology. Dangerous! That’s where Musk is so good, he and his team make the technology decisions, not the investors.
@@RichMac46 Can't know until it's been tried! If I see it pop up on crowdcube I'll be sure to invest 1/1000th of $1M ;)
This is awesome, Richard.
Nice video
Hi, Richard,
You know me from the previous mail. Now I've just subscribed to your channel.
DdC.
Hey Richard!
I'm a board member on Gatorloop, a team competing in the SpaceX competition. Thanks for reaching out to us and for checking out our website. We have certainly considered all of these points in our design, and I think you're going to be very pleased and intrigued once we host our unveiling event for our 2019 pod. Stay tuned!
Go Gators! www.ufhyperloop.com
Rubbish web site
Gavin Mcinally how can we make it better
@@djragnar407 just went back to have a look. It worked the second time.also.i see 2 prototype s ,when i click on them nothing happens. Could stick some interesting info in there. Good luck.
Do you guys have a u tube channel?
@@gavinmcinally8442 Yes we do, though we have not posted any content in a few years. Working on new ideas here soon!
Can you post the link for your website please?
Air-skis sound really cool when you're smoking DMT though.
The high speed applications tires have been used for didn't have rubber-to-ground contact for thousands of miles per day. What evidence is there rubber tires wouldn't need to be changed daily or weekly at such high speeds?
Good question Flinx. We don’t really know, which is why somebody needs to build a rolling road. We know the tyres are structurally capable, we need to test a range of options to give acceptable wear rate.
Trucks spend less than 5% of total operating costs on tyres. 50,000 km would be ok, but we could get more, with hard rubber and an ideal running surface. Lubrication is possible, the metal-to-metal contact in your car engine has no wear because of a thin oil film. Maybe a Teflon tube surface would reduce wear and give adequate grip.
But we don’t know how the wear rate is affected by high speeds, there’s no cornering forces, and moderate acceleration and braking. We need to find out!
Wheel testing would be very low cost compared to maglev, and there’s a massive saving in initial. construction costs.
@@RichMac46 "We" don't know, but don't you think Goodyear knows from testing both sticky NASCAR tires, and firmer airliner tires? They probably have an idea what the wear rates would be like at 600 mph vs 200. They've probably consulted with hyperloop companies about this but we're not privy to that info.
I think your video overlooked emergency stopping and how lubricated tires would have too little grip to stop a pod safely unless the separation between pods is so large that overall passenger throughput greatly suffers.
Possibly tires wouldn't be used for braking. Instead eddy current brakes like some roller coasters use could be employed. But as far as I know those need proper alignment, which leads to tracks and either rails, or magnets. But they wouldn't be for propulsion.
Good point, a company like Goodyear would know a lot more. It would be great if a team or company had enough substance to persuade a tyre company to help. But Goodyear will have forgotten what they learned 50 years ago!
Most rolling roads only go to about 200kph, not much use. The Hyperloop tyre is different, because we don’t need high grip like motor-sport applications.
The land speed tyres all have high wear due to wheel-spin at 700 kph, on the loose salt. Blue flame of course was not wheel-driven, one of its tyres was used for all 27 runs.
@flinx Emergency braking. Normal braking will be limited to 0.3g, or whatever the electronics can handle. Emergency braking is different.
Normal disc brakes would overheat in the vacuum. Eddy current braking is complicated, as you say.
I’m thinking that friction brake pads onto the sides of the tube wall would work well for emergency braking, 1g or more. Because the steel would be cold, the brake pads wouldn’t overheat. With 1 g emergency braking, we can space the pods closer. What do you think?
@@RichMac46 Did you mean to elaborate on how well emergency braking with rubber tires will work and what the braking mechanism will be? Because I don't see an explanation. In a traditional car on a wet road, braking distance is about double that of a dry road. .3g in a traditional car on a wet road is already nearing the traction limit for regular tires. In a hyperloop with extra firm and durable rubber tires on an intentionally lubricated surface, I'm very skeptical there's enough traction to stop quickly in an emergency. As a result pods have to be spaced further apart, reducing passenger throughput.
This is an excellent presentation. Thank you.
How do you think hyperloops can get passengers in and out of trains quickly? On a regular subway or train, thousands of people can get in/out in a matter of seconds. You will need air locks at stations or some kind of vaccum seal on the doors, both of which seem very difficult.
You have made a really good point here, the design of stations is very important. With the vacuum, its structurally difficult to have side doors, and access will be from the ends. But the narrow pod will be slow to walk along, and passengers need to be seated before the pod moves.
My solution is described here www.hyperloopdesign.net/station. The passengers are seated in a mobile seating module, which rolls into the open pod at the airlock. This station would be far more efficient than a conventional rail station, or airport. The people can walk thru the ticket gate, and sit in a nearby seating module, which moves to the airlock when full. This design actually turns the loading challenges of the vacuum into a more efficient station.
@@RichMac46 Your idea is brilliant. I'm wondering why a tapered end is needed at all for the trains, since it runs in (mostly) a vacuum.
Janaka Goonasekera The aerodynamic drag depends a lot on what absolute pressure is used, so the need for streamlined ends is not really known. But what about aesthetics? If you make it look like a London Tube train, would anybody want to ride on it? Of course, Hyperloop needs to look sleek and fast, even if it’s not really needed to reduce drag.
@@RichMac46I totally get the esthetics of high speed trains - they are often prestige projects as well and become part of the landscape, so they need to be attractive. However, outside of presentations, nobody would actually see a hyperloop train running in a sealed tube I imagine. Even at stations, nobody would see the train, if they need to traverse some airlock system.
There is a lot of errors in this video:
1a: TGV don´t run comersially at 575km/h. That was a one time test. The comersial speed is 320km/h. That is also true for the 2 fasters expample. It was one time tests.
1b: The only reason maglev don´t go faster today is simply due to not having very long test track. 603 km/h was made on a 42km/h test track. The 575 atemt for TGV was made on a 150km/h track.
2a: Transrapid have active lifting track and there for no drag to lift ratio. For SC-maglev the ratio is about 1:200.
2b: Maglev uses more power simpy because the accelerate faster. NOTE POWER. Not energy. Still the numbers are wrong: Transrapid uses 20MW transformer, same as high speed rail. SC-maglev in Japan 25-30MW transformers so a bit more. This is mostly due to acceleration. maglev consume 30% less power at speed per passanger.
3a: Its not true that the biggest inefficency is in the air gap. While the airgap loses a bit of momentum, it don´t loses that much efficency. This is due to the magnet being larger in size, compensating for the larger airgap.
3b: Linjer motor can be much better than 70% efficent. This is typicaly the case for LIM engines. LSM engine is over 90% efficent. That is simular to induction and syncronus normal engine
4: Wheel can´t just run on the inside of the tube. That would wear down the tube and causes break.
5: Transrapid was not closed down in 2008. Actualy the developed there 9:th generation test train in 2009. That operated untill 2011 when the test track was closed down. The system was sold to a Swiss company in 2016. China and Korea both develop transrapid based maglev system today, and China built a factory for track production.
While maglev have been under development for quite a while, it have only existed commercially for a few years. The first full scale maglev train to finish commercial testing was Tranrapid in 2002. Then come the HSST in 2005 and the SC-maglev in 2012.
HSST and clones have been most successful making a total of 4 operating commercial systems today.
The reason why there is only 1 high speed system and 2 under construction (one in Japan and one new in China, started construction this year, also an aditionall one supose to start construction next year in the US). Is not due to commercial failure. There is only one country in the world that build high speed railway comersially today.. Japan, and they build maglev.
For the rest of the world, every single high speed railway built, have been built by the government. That is.. not commercially
Hi MatsV201. Thanks for your detailed comment! Sorry if there are any errors in my maglev story, it’s really hard to dig through the hype and get the facts. The two high speed trains have never published actual energy figures (I wonder why?), so you have to search thru unofficial engineer or media reports. Do you have actual energy figures? But the future of maglev looks uncertain, since China built the Transrapid, they have built 30,000 km of conventional rail.
Hyperloop will never be built if it’s too expensive, and the combined cost of the vacuum tube, and maglev, will be impossibly high. Which is why I’m promoting the wheels solution, which has the potential to reduce capital cost, and also running costs.
My proposal is pneumatic tyres running directly on the walls of the steel tube (no wear!). Tyres have been used at 1,000 km/h, 60 years ago, we need a research project now to see if they can be made reliable at that speed, with modern technology. The project would cost a fraction of maglev research. Wheels would have lower energy for moving, and better traction efficiency than any maglev system.
I think tyres could be developed with suitable reliability, but if not, the alternative is metal wheels running on a soft liner in the tube. This would be higher capital cost, but much easier to achieve, with less flex, heating etc. This would still be much cheaper than all the coils required for maglev!
@@richardmacfarlane8404 Actually both Transrapid and SC-maglev have published a whole string of numbers. Its not harder than google "transrapid energyconsumtion" and first hit is Swiss rapide page (that bought Transrapid in 2016)
www.swissrapide.com/htm/e_energieverbrauch.htm
There is also a substantial technical documentation behind that.
Its a bit harder för SC-maglev due to the best information being in Japanese.
"China built the Transrapid, they have built 30,000 km of conventional rail."
Well that is true.. What is also true is that the Chinese railway minister got jailed for corruption after taking over a billion dollars of bribes.
In the 2015 year 5 year plan they put aside funding for reserach of a new maglev train. The new train is finished now and is transrapid compatible.
The maglev elements of Transrapid cost about $2M/km. Most of the cost is guidway, engineering, access, transport and so on. The actually maglev is a very insignificant cost of the full system, just like the rails of a railway is very insignificant of the whole railway projekt.
The ware of the wheel increase by the square of the speed and distance (there for the cube of the speed and time). Having a wheel that works for 10 seconds at 1000km/h is doable. Making it work for 10 years is a totaly different story.
This is the main reason why high speed rail have a general top speed of 300km/h. Going over 300km/h the wear of the wheel increase so fast its totally uneconomical. A 300-320km/h high speed train need to swich the wheel axle every 2 years. Going to 350km/h, its every 6 month. Going to 400km/h its every month or so... Going to 575km/h, its literally a one time run. TGV V-150 that did the 575km/h run was on brand new axles when the run started. And gone directly to a shop for new axle after the run.
Transrapid have run 430km/h in Shanghai, every day for 15 years... the number of axels they switch out... zero.
The problem with maglev is not that its not commercially viable. The problem is that hardly any railway infrastructure is build commercially. Every single country that build high speed railway infrastructure today build it on a government based model, except one. Japan. As so happen build maglev.
@@matsv201 evul scuuuray gooberment
@@mreogromsdal415 Have you the dumb?
@@matsv201 It seems you're saying the problem of wear is related to the axles _rather than_ the tyres. Could magnetic bearings for the axles be a feasible solution?
If you use rotary motors you'll need many kg of batteries inside the pod. Unless you use a pantograph, which isn't feasible at high speeds due to wear (unless you use the newest materials).
Dibujo de Croquis Good question! Linear motors on the track provides external traction power, but with very high cost for the coils on the track, and low efficiency. The pod could be fully battery powered, but it’s difficult. The average power (for a 30 seat pod) is about 200 kW, but there is a peak of 3500 kW for acceleration, which needs to be recovered on braking. Lithium batteries don’t like quick recharge. My solution is supercapacitors for the peak power, and a power rail in the tube which provides the average power of 2-300 kW. The carbon brushes should last a while, and have an automated way to change them at the station.
Richard Macfarlane Thank you.
I feel it has really come down to the main innovation of the hyperloop is that the vehicle runs in a partial vaccume, which reduces air friction. Couldn't we get the same effect with an extremely streamlined vehicle (or some other kind of skin friction reduction technology). This way, we avoid all the tubing, vacume pumps, airlocks at the stations and the risks of destructive pressurization in case of accidents/terrorism
Vacuum is necessary to gain any speed or energy advantage over high speed rail. Aircraft gain by flying in lower density air, but travelling in a tube or tunnel really increases aerodynamic drag, unless the tube is very large and expensive. For an inter-city system, the added expense and complications of vacuum is justified to give the extra speed and low energy. There is a massive energy saving by eliminating aero drag. A lower speed, frequent stopping suburban service won’t use vacuum. Elon Musk’s Loop proposal has lower speeds, but easy entry to the tunnel without airlocks etc.
@@RichMac46 How do you imagine track ( or in this case tube) switching will happen? Does the wheels need to have some kind of steering?
Janaka Goonasekera Switching is really interesting. In the station, the pod could roll onto a section of track that’s moved sideways in one piece, to line up with the right airlock. Not too hard. But a full-speed switch would be much harder, you would need to have the lower part of the track in sections, that are moved sideways to give a smooth curve to the new tube. Everything would be in the vacuum, the tube would be double width at one end. At full speed this might be nearly 1km long, very expensive. At lower speeds, the switch could be shorter, I’m thinking about 3 sec transit time.
@@RichMac46 I imagine the vaccum must be a hard vaccum, otherwise there would not be much on an advantage over airplanes. i.e. if we reduce air pressure to around what is at 20000 meters, then the train can probably travel at airliner speeds, which is probably not enough to make it viable against airplanes.
Janaka Goonasekera We need to reduce the pressure in the tube to overcome the extra drag due to the tube, and the greatly increased speed. Once we have the sealed tube, airlocks etc, there’s not much extra pumping energy to make the pressure lower. 1kPa would reduce the drag 100 times, Hyperloop Alpha suggested 0.1kPa, 1000x less drag. I would think the optimum pressure to be somewhere between the two.
4:30
Transrapid uses *less* energy than a high speed train at 300 / 400 km/h:
large.stanford.edu/courses/2010/ph240/ilonidis2/
ICE 3 is the german high speed train.
Hi Andy. All the quoted energy consumption figures for the Transrapid are promotional figures before the Shanghai system was built, and are very understated. Its not fair to compare actual ICE numbers with Transrapid marketing. It's sad that rail doesn't publish energy performance data, where road and aviation publish their improved data to sell new products. It's really hard to get reliable HSR data, and virtually impossible for maglev. The only operating data for Transrapid puts it at about 3 times HSR energy, and there are references for 3-4 times for the SC maglev, although the source data is in Japanese.
@@RichMac46 Thanks for your competently description.
Hope some day we figure out the correct system for hyperloop ; )