Dr. Zev

MagLev Vs Hyperloop

Oct 02, 2013

Part one of series on why Elon Musk and his new team should use MagLev technology instead of the proposed Hyperloop.

Introduction

Let me first introduce you to our “cast of characters” — the different technologies that are vying to replace current transportation systems:

Hyperloop[2] is Elon Musk’s recent proposal for a high-speed transportation system linking Los Angeles and San Francisco, using a pair of partially-evacuated transportation tubes.

The California High-Speed Rail Authority[3] hopes to build a 200-mph high-speed conventional rail line linking Los Angeles and San Francisco by 2029.  Elon Musk thinks he can do better, faster, and cheaper with Hyperloop.  I feel that the California HSR (High-Speed Rail) proposal is simply the latest incarnation of a 200-year-old technology that best be put to rest.  I agree with Mr. Musk that we should not be wasting money on conventional HSR, when therefore are other, better ways to provide transportation.  I just disagree with him about what the better system is, prefering Magnetic Levitation (MagLev).

LeviCar and RoboTrail[4][5] are my own proposals for high-speed transportation, for both passengers (LeviCar) and freight (RoboTrail).  LeviCar involves having passenger cars being driven, on roads, to local depots, where they are deposited on a Magnetic-Levitation (MagLev) rails.  They then travel at 300 mph to another depot, from whence they are driven, on roads, to their final destinations.  It is preferable to use modular cars.  RoboTrail is LeviCar’s big brother, doing much the same for freight, using the same MagLev network, but with different depots.  The network is based on the concept that it is more useful to provide shorter door-to-door transit times to most people, than to provide really fast transportation between select cities.

LeviCar and RoboTrail are heavily dependent on the Danby-Powell superconducting MagLev architecture [6].  This is unique among MagLev systems in that vehicles can instantaneously switch from one rail to another.  It is also relatively low-cost, because the superconducting coils are on the vehicles, not the rails; the rails contain inexpensive aluminum loops.

Now that we know who’s who and what’s what, we can look to see why MagLev is superior to Hyperloop, and how it might be possible to combine the best features of both.

The Top-Ten Countdown List

10) Hyperloop is inflexible

Hyperloop goes only from one specific point to another specific point and back, meaning that if you need to get from somewhere else to somewhere else, you need to spend extra time just getting to the first station, and also just getting from the destination station to your final destination.

MagLev, using the hexOgrid[7] configuration, will have rails in an 18-mile hexagrammoid grid, with depots within ten miles, by road, from any point in a built-up (urban or suburban) area.

9) Maintaining even a partial vacuum at this scale is difficult and expensive.

Hyperloop uses a huge partially-evacuated transportation tube.  Maintaining even a partial vacuum would be difficult.  A catastrophic loss of air would shut down the whole thing.

MagLev systems generally run in the open air, resulting in a simpler, cheaper architecture, at the expense of increased air resistance.

8) Hyperloop uses large, noisy fans in front of each pod.

A Hyperloop pod has a large suction fan in front.  Its purpose is to reduce the air resistance, even though the pod is moving through a partial vacuum; and to provide air to lift the pod's “skis” off the bottom inner surface of the tube, forming an “air bearing”.  (The skis support the pods.)  This suction fan is sure to make a lot of noise, probably overwhelming any sound insulation.

MagLev uses traditional methods to minimize air resistance and noise, such as streamlining and platooning, the latter being when several vehicles travel in a closely-spaced convoy so that they “draft” off of each other, the lead vehicle bearing most of the wind resistance.

7) There is too little clearance between the pods and the tube's inner walls.

In Hyperloop, the pods are supported by “skis”, which receive air from the suction fan, and use this air to push against the inner walls of the transportation tube to levitate the pod.  The clearance between the skis and the inner wall of the tube is only 0.020" to 0.050" (about 0.5 mm to 1.3 mm), far too small.  Any slight irregularity in the inner walls of the tubes, or any sudden movements of the tubes due to accident or seismic activity, could result in a damaging high-speed collision between the skis and the tube’s walls.

MagLev (of the Danby-Powell architecture) uses clearances of 4" to 6" (about 100 mm to 150 mm), and is well able to tolerate such displacement, including any expansion joints.

6) Switching between tubes is impractical.

Hyperloop relies on the curved lower surface of the tube to keep the pod aligned properly.  In order to have two tubes join, there has to be an irregularity and discontinuity if the curvature of the tubes where they meet.  It is impractical to expect the skis to adjust to this change instantaneously.  This precludes the use of intermediate depots.

MagLev:  Most MagLev systems use either heavy monorails, or otherwise use troughs, and switching between rails is ther very slow, or is so difficult as to be impossible for moving vehicles.  The Danby-Powell MagLev architecture is unique among MagLev systems in that it provides for instantaneous switching between rails.  This allows individual vehicles to be switched off onto other rails, or onto sidings.  The same strong superconducting magnetic fields that levitate the vehicle, also stabilize it in the double-rail configuaration.[8]

5) Hyperloop pods tend to roll, which might also damage the motors.

Hyperloop lacks any system to provide stability on a continuing basis.  This means that the pods may roll (rotate about the axis of travel), and might travel upside-down.  This also means that the “rotors” on the pods may collide with the stators protruding from the inner was of the tube. 

• With Danby-Powell MagLev, you don’t have to worry if banking will cause a collision with your propulsion system, or how you are going to detect and correct any banking.  The constant drive force makes for a smoother ride.

4) Hyperloop pods are cramped.

Hyperloop  The individual seating inside a Hyperloop pod is reminiscent of a Mercury space capsule.  You cannot get up and move around.  If someone falls ill and needs emergency assistance from another passenger, there might be little room in which to provide it, unless medical equipment (like a defibrillator) is built into each seat.  More medical assistance would have to wait until the end of the trip.  The trips, though, are mercifully short, so it is unlikely that you’d get Deep-Vein Thrombosis (DVT).

MagLev offers a variety of seating.  LeviCar offers the same seating as a private automobile.  The MagLev network could also carry vans and buses, which would have more spacious seating.  In case of a medical emergency, the vehicle can be diverted to the nearest hospital without waiting to complete the trip.  MagLev portals directly beside a hospital emergency room would place the patient within a few feet of help.

3) Hyperloop cannot carry some of the larger standard freight containers.

Hyperloop  is specified with two different pod sizes, and, correspondingly, two different transportation tube diameters.  (These were the passenger-only pod, and the passenger plus vehicle pod.  Each has its own diameter, and its own requirement for the diameter of the transportation tube.)  At first, it seemed to me that the intention was to have two different-sized pods traveling in the same tube, as long as both satisfy the Kantrowitz Limit.  However, further reading indicated that each size needs its own tube, and, given the cost constraints, only one size tube can be built.  It looks like only half-height containers would fit.  It is important to be able to carry freight, because that is where the money is.

MagLev, because it operates in open air, has a lot more flexibility as to the size of the freight containers it can accommodate.  In the event that the 300-mph MagLev system is supplemented by adding vactrain-like shortcut tubes, or wormholes, to the hexOgrid, then the wormholes could be for passenger vehicles only, while freight would travel only on the 300-mph grid.

2) Escaping from a transportation tube can be a dicey experience.

Hyperloop  is supposed to use solid steel transportation tubes, but these are to be equiped with escape hatches.  These hatches could be a problematic source of leaks.  Also, the hatches must not be where the skis are in near-contact with the walls, because that would produce irregularities in the walls that can cause collisions with the skis.

MagLev, again because it operates in open air, does not have these problems.

… and the final reason why Elon Musk should use MagLev:

1) Tesla is the best company to manufacture LeviCars.

The LeviCar system, in addition to the MagLev rail component, also features modular cars.  There are many reasons to use such modular cars.  They make it so only car body, with passengers and luggage, need to ride the MagLev rails.  By not including the drivetrain, wheels, and batteries or fuel tanks, we can reduce the mass that is transported, and enhance safety by eliminating concentrated stores of energy.  They are also much easier to repair.  If something goes bad in either the front or rear chassis, simply swap the chassis with another equivalent rebuilt one, and later rebuild the swapped-out chassis and give it to another customer.

Of all the automobile manufacturers in America, the one best equipped to built LeviCars is (drumroll, please) Tesla, Elon Musk’s company.  So, backing the LeviCar / RoboTrail MagLev system can be a very smart business move for Mr. Musk.  Tesla owns the IP (Intellectual-Property) rights to many of the components that can be used in a LeviCar vehicle, and even if Tesla does not have the capacity to manufacture all of them, they certainly could license the technology to other companies, and make millions from the royalties.

[1] Levin, Joshua Zev, Top Ten Reasons why Elon Musk should use MagLev instead of, or as part of, Hyperloop (Accessed October 2, 2013)
http://Hyperloop.LeviCar.com/

[2] Musk, Elon, Hyperloop Alpha (Accessed October 2, 2013)

http://www.Hyperloop.com

[3] California High-Speed Rail Authority (Accessed October 2, 2013)

http://www.hsr.ca.gov/

[4] Levin, Joshua, LeviCar Website (Accessed October 2, 2013) www.LeviCar.com

[5] Levin, Joshua, A Perfect Synthesis (Accessed October 2, 2013)
http://www.evworld.com/article.cfm?storyid=744

[6] Maglev2000 Web Site (Accessed October 2, 2013)
http://www.Maglev2000.com

[7] Levin, Joshua Zev, hexOgrid Network for Magnetic-Levitation and Other Transportation Systems (Accessed October 2, 2013)
http://www.hexOgrid.com/

[8] Maglev2000, How Maglev Works (Accessed October 2, 2013)
http://www.maglev2000.com/works/how.html

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