Sigh...he's a cutting edge type of guy w/ a PHD in physics...try this:
Elon's largest obstacle will not be the physics behind this idea—it will the politics (this coming from experience). He will meet resistance from politically entrenched contractors demanding they be part of the action or else they will stifle his efforts.
Wow! Great work!
Maybe the capsule can slightly rotate in anticipation of a turn (assuming the capsule is cylindrical in shape). In that case, you won't be pulled to the side during cornering much like banked turn of an aircraft.
As soon as I saw Concorde, a railgun and an air hockey table, I thought of Ekranoplans. http://en.wikipedia.org/wiki/Ekranoplan
So Elon Musk throws some vague ideas out to fuel interest about a futuristic transport system.
Serious engineers and scientists around the world gather to solve the puzzle of the mysterious machine.
The think tank comes up with a few viable solutions to the problem.
Elon Musk appears before the audience, takes the results and picks one to satisfy everyone's desire for an answer. :b
This is the actual Hyper-loop that Elon has put his own physics in to improve efficiency.
Wheels in the tube would cause drag unless they are supposed to magically pop out when needed. High pressure coming in from the side will not create a smooth airflow going forward. The concorde is made for high speed so it could be that a concorde nosed capsule will push air out of the way and magnets will propel it or the magnets will levitate it and wind will push it forward?
Why not just go with a vacuum?
Northrop-grummman had a concept for a ground based ekronoplane with a launch mechanism.
called TTWIG-TRACK TETHERED WING IN GROUND EFFECT- ANOTHER WAY OUT IMPOSSIBL CONCEPT.
My guess is something similar to a maglev train, except that it rides on an air cushion instead of a magnetic field.
This would eliminate the very high cost per mile for maglev track, as the air cushion track could just be plain old concrete with an electrified rail for power.
The issues would be the noise and vibration generated by the air cushion, plus all of the usual right-of-way problems faced by trains.
Having perforated walls would allow air flow to bypass a capsule in the event that one stopped ahead of the other. This scenario could allow a crash. Unless you had a significant amount of check valves....
Great write-up. If current trains would simply split into two as they approach the station, the front half could enter the station and stop while the back half bypasses the station. A train full of passengers that recently left that station could slow down until the bypassing section caught it, connected to it on the run then continue on. Passengers would then reposition in the train dependent on if they planned to bypass the next station. As such passengers could travel non-stop at 100+ MPH. Simple and inexpensive. firstname.lastname@example.org for my 503 other ideas.
The design is by Alexander Bolonkin and its the Hyper-sonic Ground Electric AB Engine design.
This is the design that Elon has been talking about and its just about the only one that fits his description.
The above is a very interesting conversation of what the hyper-loop might be.
If we didn't worry about speed so much we could probably have a safe, reliable and cheapish form of transport already.
Friction is the problem.
Either go up really high or seal yourself in a tube.
Both fraught with danger as we can't survive in those conditions should something bad happen.
That's bad mmmkay.
So use the air to our advantage.
Make a track, (like a c channel or a t section or something neat that you can lift off/propel off perhaps too) sit a nice aerodynamic shaped train on it, use ground effect to lift it, go as fast is efficient/safe/practical.
It's all the other little gizmo's/tricks that you can then use on that base vehicle to make it better, I like the air/air cushion idea, i don't know if/how it'd work on a large vehicle in the open air, might be ok if you're going really fast.... or just golf ball dimple the whole thing and don't worry about air jets.
Ask the Russians, they have whole giant aircraft that skim over water, they've probably got some neat maths on it ;)
All in all I'm very glad Elon Musk is making some noise about it, he's an interesting chap, most billionaires only seem interested in... well I don't know, trapeze artists on their superyachts I guess, they don't make much noise or benefit the world much as far as I can tell.
Do something with your money, be interesting, advance something, cure something, just DO SOMETHING.
If you cannot, I'll happily do it in anonymity in your most exalted name.
Calculate the kinetic energy of the air in the tube and have a laugh.
Oh Dear God !! PLEASE NOT ANOTHER 'BULLET TRAIN' FOR CALIFORNIA !!! The one propsed now is contoversial, Some farmers don't want it on their land,some counties don't want it at all. It is supposed to reach 200 mph, however if a train from Sacramento tops out at 200 mph, it will have to hit its brake fast or wind up in Bakersfield instead of Stockton, Merced or Fresno. From S.F to L.A. would take about 2-1/2 hours. Okay for through traffic, but local traffic would extend that time by hours. Take a plane.
Being located on a major earthquake fault doesn't thrill me much either.
Also the system proposed is to be built by the Chinese, who can't seem to keep their own 'bullet train' system working right.
Hey ! I just thought of another great idea.
A giant circus cannon in San Francisco (maybe Treasure Island) and a gigantic net over Griffith Park.
Survivors can pop in to a Dodgers game.
(On my t-shirt = 'Sanity is Overrated')
A simple tracked hovercraft without a linear motor assist would work up to 400 km/h. About half the target speed. If the air were already moving at a high speed the speeds would multiply not just add. A linear motor could double it again. If the tracks were banked around corners then curvature under 9 km (5.6 mile) are possible.
Nice article! It has to be a track or tube system in order to achieve that kind of door to door timing. Beyond that, in order to remove the massive aerodynamic costs at sea level, you need reduced air pressure or no air pressure. Either that or minimal friction and super efficient propulsion. How that is achieved via cost effective infrastructure is the question I guess.
After watching those space x grass hopper videos, I'm taking this guy much more seriously. He has runs on the board and the money to put ideas into practise.
Space will be conquered by private industry, because pure research, as noble as it sounds, doesn't pay the bills.
He's succeeded when others have said he won't, Tesla is outselling some luxury cars and Space X speaks for itself. I'm sure this will succeed also
Seems like vacuum tube since it uses pneumatic like those old message tubes in banks etc.
Same idea only scale up.
In order not to become a high speed ball of compost, should one of several systems fail, the design will have to be in the form of a central tube (rail), on which the passenger vehicle rides; all enclosed in a second (larger) tube which can be used to manage air resistance and interface with stops and stations.
If the passengers are carried beneath the horizontal center line, the passenger compartment will naturally tip in the direction of corners, without having to worry about banked corners (and their coffee won't spill).
In order to synchronize passengers senses with physical forces acting on the capsules, a set of LED screens will need to act as the "windows"; providing visual clues (possibly a representation of the actual cityscape or countryside) and a feeling of familiarity. That will result in less clean-up of "ejected" stomach contents.
Or maybe, he's throwing out requirements for what it must do and getting ideas from everyone else's speculation.
The model you propose is very much a machine that moves air and suffers from very high frictional losses at these speeds.
The Concorde at altitude operated in a partial vacuum with significant reductions in frictional losses.
It would seem that you did not include the need for differential support air jet pressures in order to compensate for operational loading.
It's a tube system which inventors from Goddard (his last patent was a maglev vacuum train) to Terraspan's rocket scientist all agree is the best performing and most environmentally friendly (very low energy- lower then Ocean freight costs) is the safest, most beneficial long range travel method.
Of course when you really do the math on the need for personal road transport in SF and L.A., add in the very high energy cost of the Musk guesstimate proposal you are better off or at least nearly the same by driving Highway 5 (if you are lucky in a Tesla).
Let's not forget Musk has never proposed or executed on any new technology. Be careful.
What's the big hurry?? How can one enjoy the scenery at 350 mph? This is fine for carrying cargo, but people should conduct business online and travel for pleasure.
Keith Lofstrom here. It's launch loop, not Lofstrom Loop, which is what my intestines do after a great Mexican dinner. If Musk plans a launch loop segment, I'll be out front of his house with a picket sign - loop tech is great for space launch, but lousy for near-city safety.
Brian Dodson's speculations are interesting, but miss three important points - drag, maintaining track alignment in Seismofornia, and twisty topograpy like the grapevine north of LA. Land surface tracks can't go very fast.
But in fawning appreciation of Brian sticking his neck out, I will stick out mine, embellishing a clever idea from my buddies at stratosolar.com . Here's my (literal) trial balloon:
Imagine a an aerostat (balloon) track floating at 12km altitude, above most commercial aircraft, tethered to the ground with well marked power cables. Assume (we'll be doing a lot of that) a track mass of 50 tonnes per kilometer, including a 5 meter wide strip of sun-tracking solar cells (I'm a solar skeptic, but we're having fun here). We are above the clouds and most scattering, in the 1300W/m² insolation zone, so a 15% efficient array generates a megawatt per kilometer, most of which feeds the grid in daytime.
Assume our small passenger vehicle weighs m = 1000kg, moves at v = 300m/s, has a drag coefficient Cd = 0.4, and a frontal area of A = 1m². Air density rho is 0.3kg/m³. Drag power is ½rhoCdAv³, or 1.6 megawatts (on the ground it would be 6.5MW and make a hell of a lot of noise). We can draw that from the track before and aft, and turn it into hand-waving motor power.
Vehicle passage deflects the track downwards, about 0.7 m/s trailing. That can be restored by temporarily releasing tension in the tether anchor motors.
Vertical and horizontal alignment is critical. A 10cm sinusoidal variation over 100meters (0.1%) results in tooth-loosening 0.4 gee 3 Hz shaking. We will need to damp out all perturbations before another vehicle passes, and that may limit passenger rates to less than airline rates.
OTOH, if we skip the silly "no vacuum" claim, an evacuated steel tube running below the surface of the ocean from Daly City, past Pt. Arguello, to El Segundo makes more sense. ½mv² = 45MJ, 12.5 kilowatt-hours, most of which you can recover when you stop. With other vehicles behind you, don't stop too soon!
P.S. My first posting. I assume UTF-8 characters work. If not, (½) = 1/2, (²) = exponent 2, (³) = exponent 3. Where's the preview button? Why does the edit page time out? What are you kids doing on my lawn? Grumble, grumble.
Assuming this is how it works and that it is built, the efficiency will never even pay the interest on the loans to finance the construction of the track.
What is commendable about Musk is that he is using his money to do something that we are already doing ,.. better and creating excitement. So when others call him a genius or revolutionary it is just the Americans boasting about there own, a self projection. There are ideas but likely one that will work is the one imagined by someone unknown today and if Musk finds it and takes it of - hats of to him.
You have heard that "everything works on paper" - now you can add - everything works in the minds of Billionaires! There is nothing like money to cloud one's judgement and there is little hope for progress when there is NO money.
The author describes an air tube delivery system with air moving past its enclosing tube at 600 odd MPH that has the friction made acceptably low by pumping air into the tube through perforations.
Has he done any back of the envelope calculations to see whether that make the energy requirements any less that powering, say, all of Metro LA? Obviously not.
Elon Musk may just merely try to divert public attention from forthcoming air transport solutions -- much in line with DOT and other government-sponsored anti-GA policies.
There's indeed a pending opportunity out there for GA ultra-light aircraft builders, when mass-produced EVs will make electric power units (motor & battery) available at an affordable cost -- remember the similar opportunity that had occurred decades ago with VWs air-cooled flat four-cylinder boxer engine? And since noise is currently the main practical obstacle to mass-use of personal aircraft, electric GA aircraft will definitely change the game.
If Elon Musk were really a visionary, he would anticipate the sole survivor of the automobile era in the longer run, i.e. the urban mini-EV embodied by the detachable cockpit of an ultra-light electric VTOL aircraft, to drive downtown with after landing at the urban periphery...
A man from the Isle of Wight,
Could travel much faster than light.
He departed one day - in a conventional way,
And returned on the previous night.
There once was a man named Musk
Who spoke in a manner most brusque:
"Give your problems to me - I'll solve them for free,
And have you there and back home before dusk".
Keith Lofstrom has it right, vacuum or near vacuum is the way to go.
In all fairness to Elon Musk we must not judge his proposal until we actually hear the details from Musk himself.
Brian Dodson took a good shot at second guessing Musk's proposal but I'm sure he would be first to call for the details from Elon. After all Brian ends by telling us the actual plans will come to the public in late July or August.
ET3 patents (the first one is US 5,950,543 from 1999) disclose a system that exceeds Musk's claims for 'hyperloop'. PTT (pneumatic tube transport) has extremely high drag at high speed and /or long distance (unless helium or hydrogen is used as the working fluid -- and then the drag is still much greater than ET3). see www.et3.com
Under the heading "there's nothing new under the sun", here's your Hyperloop... it's been done before not quite 150 years ago in NYC and London. Here's some interesting links:
and a five part article about the London pneumatic train, starting with part 1 here: http://www.ianvisits.co.uk/blog/2012/11/26/londons-lost-pneumatic-railways/
Of special note is the sevice concept for the London train which was show up / on demand (like Hyperloop) rather than strictly scheduled.
Pneumatic tube - high velocity air moving through low friction metal tube. Cars are un-powered most of the time - pushed by moving air.
(Conventional so far. But next...)
Cars are made to travel somewhat slower than the air around them, via permanent magnets inducing a current in the tube walls to create a bit of drag. This causes air to move past and around the car at high pressure and velocity. Small wings in that airstream carry the weight of the car - with the magnets at their outer tips.
However, with such close tolerances between the walls and potential for air turbulence shaking, a second mechanism is needed for control. The same magnets that induce drag are run in metal channels so that induced magnetic repulsion keeps them centered in the channel, keeping the car from oscillating up/down/left/right or rolling - and also providing banking control for curves.
Near stations, the tube will be wider, reducing the air pressure and velocity. Coming into a station, the car will brake enough (magnetically) to stay slower than the airflow, maintaining the necessary lift until the car is moving slow enough to roll on a track - probably a direct extension of the channels the magnets ride in.
Leaving a station, the car is simply rolled into the narrowing tube, where it is accelerated by the air and soon lifts off the track again.
if the high pressure air is injected into the tube to levitate the 'carriages', wouldn't there be an ever increasing pressure inside the tube? you would need some sort of blow off valve to relieve pressure, can't see that working.
Here's a chance for all the really smart kids to shine!
The Hyperloop looks to be an exciting option for fast distance traveling, but similar to current public transportation options like San Jose’s light rail system or Caltrain, it relies on the public to travel to and from specific destinations. Our BiModal Glideway would be a better solution as it would provide the same high speed distance travel, but allow drivers the freedom to go from door to door during their commute.
Why not a Gauss tube?