Hyperloop Technologies

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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choff
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Re: Hyperloop Technologies

Postby choff » Wed Feb 18, 2015 8:55 pm

I'm partial to inductive track maglev trains if they ever build one, competitive costwise with conventional freight. Have to live with very expensive skytrain where I live, which, while electric is firmly grounded.
CHoff

GIThruster
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Re: Hyperloop Technologies

Postby GIThruster » Wed Feb 18, 2015 9:01 pm

paperburn1 wrote:In my opinion the only reason cars and trucks are preferred is the age old problem of point to point transport. It convenient and cheap until you leave the area. then it a pain to get yourself or goods to your destination.
This is the reason I prefer to drive than fly if the drives are less than ten hours. It works out to be faster in most cases. two hours early to leave or catch your flight, get a rental car if one is available. shuttle buses.,

This is one of the reasons Europeans in general, have longer work days than Americans but put in far fewer work hours. There are huge masses of people especially in eastern Europe, who walk miles to the nearest train station and then miles again from the station to work, and the same to get home. 14 hour days for 8 hours work is quite common. The answer is not "mass transit". It cannot be. This is why I'm a proponent of flying cars, because they really do offer a wonderful solution, so long as there is no down exhaust, so long as the cars are computer controlled so we don't constantly have stuff falling on our heads, etc. The driverless vehicle technology being tested today will find its best use in piloting flying cars in the future.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

krenshala
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Re: Hyperloop Technologies

Postby krenshala » Wed Feb 18, 2015 9:19 pm

DeltaV wrote:Which reminds me, why is it called "parallel parking"? It should be called "serial parking".

Because you are parking parallel, instead of perpendicular, to the curb.

GIThruster wrote:This is one of the reasons Europeans in general, have longer work days than Americans but put in far fewer work hours. There are huge masses of people especially in eastern Europe, who walk miles to the nearest train station and then miles again from the station to work, and the same to get home.

Its a 30 to 45 minute drive to work for me. I believe it would be a 20min train ride, however, I would have to drive 5 to 10 minutes to nearest parking, then catch a shuttle to the station (another 10 minutes at least), then once downtown walk for about 20 minutes to get to my office, for at least a 60 minute trip. No thanks. Now, if I could fly over here in a car, whether I'm controlling it or not, it would probably take at most 20 minutes for me to get to work (assuming "highway" ground-speeds of ~60mph for the flight).

KitemanSA
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Re: Hyperloop Technologies

Postby KitemanSA » Fri Feb 20, 2015 8:52 pm

ladajo wrote: I can't see an economical pure physical gap suspension system, and at the proposed speeds any contact is going to mechanically dramatic at the contact points.

InducTrack II. I've read that there is an InducTrack III under development, but I prefer my SpInducTrack. Well, not for this, it is for slower speed cargo, though I guess it could be revised to handle high speed with hybrid.
Last edited by KitemanSA on Fri Feb 20, 2015 9:07 pm, edited 5 times in total.

KitemanSA
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Re: Hyperloop Technologies

Postby KitemanSA » Fri Feb 20, 2015 8:59 pm

krenshala wrote:
DeltaV wrote:Which reminds me, why is it called "parallel parking"? It should be called "serial parking".

Because you are parking parallel, instead of perpendicular, to the curb.

I was told it was because you are supposed to pull up parallel to the car in front of your spot, then back in. Hmmm.

AcesHigh
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Re: Hyperloop Technologies

Postby AcesHigh » Sat Feb 21, 2015 8:23 pm

if you have enough space, you can parallel park driving ahead, no need to stop and drive in reverse. And you will still park parallel (because it´s in relation to the curb)

Also, remember there is "oblique parking", where you park in the diagonal. Once again, it´s oblique related to the curb.
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DeltaV
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Re: Hyperloop Technologies

Postby DeltaV » Sun Feb 22, 2015 8:38 pm

krenshala wrote:
DeltaV wrote:Which reminds me, why is it called "parallel parking"? It should be called "serial parking".

Because you are parking parallel, instead of perpendicular, to the curb.

That was just one of a plethora of such banalities that the EEs subjected me to in engineering school (they always said "series" not "serial").

My refusal to use emoticons is leading to extra posts and unnecessary carbon liberation. Brrrrr.

Scupperer
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Re: Hyperloop Technologies

Postby Scupperer » Sun Mar 01, 2015 12:57 pm

Construction begins 2016 for Hyperloop on five-mile stretch

Will be interesting to see if they can deliver and keep it as inexpensive as they believe.
Perrin Ehlinger

cc
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Re: Hyperloop Technologies

Postby cc » Wed Mar 04, 2015 11:23 pm

DeltaV wrote:The main reason is the low rolling resistance of steel wheels on steel rails under heavy loads.

The inline aerodynamics helps, but it's lower rolling friction, not lower air friction, where the real advantage is.

The low rolling resistance on steel rail is often misrepresented and there is an error concerning it on the Inductrack wikipedia page. It is only impressive at low speed, beyond which mechanical losses become considerable. See page 39 (3-13) of the ECCO report, for comparisons with and without aerodynamic drag. Inductrack electromagnetic drag is essentially constant, while steel rail surpasses it at <30m/s and continues to grow. At higher operating speeds, there would be no comparison. (edit: the Inductrack III performance is even more striking.)

Overcoming aerodynamic drag requires power proportional to the cube of the velocity, and it is not insignificant at higher speeds, even if it can be amortized over the length of a train. Even on that point though, any maglev has the potential for significantly improved aerodynamics over a wheeled train.

A comparison of hyperloop and Inductrack in a vacuum would be interesting. It is uncertain wether the cheaper track of the former would offset the simplicity and higher operating efficiency of the latter.

ladajo
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Re: Hyperloop Technologies

Postby ladajo » Thu Mar 05, 2015 6:04 pm

It would more than likely play as an economy of scale function. Initial builds, not so much, later and larger builds, more so.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

choff
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Re: Hyperloop Technologies

Postby choff » Fri Mar 06, 2015 8:04 pm

One problem I see with hyperloop, travelling in a vacuum tube, lets say the cabin suddenly springs a leak while underway. By the time the train has slowed down and normalized atmospheric pressure in the tube to a breathable cabin pressure would be how long? Maybe the leak never gets detected until the train arrives in station full of dead people.
CHoff

GIThruster
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Re: Hyperloop Technologies

Postby GIThruster » Fri Mar 06, 2015 8:35 pm

The air isn't evacuated so much as moving. It's the air that moves the cars. The trouble is in moving air supersonically without dissipating all your energy in turbulence and shock wave generation. And if they get a standing shockwave, kiss the tunnel good-by.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

raelik
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Re: Hyperloop Technologies

Postby raelik » Fri Mar 06, 2015 10:51 pm

Doing a back-of-the-envelope calculation, to achieve laminar flow (a Reynolds Number less than 2300) in, let's say a 10 ft. diameter tube at 60 deg. F, with the air moving at 760 mph, would require the air to be evacuated down to about 25 milliTorr, which is a fairly substantial vacuum, but not outside the realm of possibility. Of course, 10 ft. diameter is probably not realistic except in a prototype demonstrator. A larger diameter is probably going to be necessary for a commuter car, though maybe not by much since the car would need to essentially seal the tunnel. A larger diameter will require more vacuum for the flow to stay laminar. This also assumes that the tunnel is as perfectly smooth as possible, and that the front and back of the car have the correct geometry to avoid establishing vortices.

erblo
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Re: Hyperloop Technologies

Postby erblo » Sun Mar 08, 2015 11:31 am

GIThruster wrote:The air isn't evacuated so much as moving. It's the air that moves the cars. The trouble is in moving air supersonically without dissipating all your energy in turbulence and shock wave generation. And if they get a standing shockwave, kiss the tunnel good-by.

It might have changed some from the original concept but what you're describing is not hyperloop. The air is stationary at ~100 Pa and the capsules are periodically accelerated by linear induction motors and coast most of the way on air bearings. The tube diameter, which is dictated by the Kantrowitz limit and the wish to avoid supersonic flow around the capsule, is reduced by reducing the effective diameter of the capsule using a battery powered compressor. This compresses and ducts a large portion of the incoming airflow through the capsule and provides pressurized air for the bearings.

choff wrote:One problem I see with hyperloop, travelling in a vacuum tube, lets say the cabin suddenly springs a leak while underway. By the time the train has slowed down and normalized atmospheric pressure in the tube to a breathable cabin pressure would be how long? Maybe the leak never gets detected until the train arrives in station full of dead people.

The capsule life support will be completely self contained and sized to handle small to medium leaks (with supplemental oxygen if necessary) - large leaks will activate emergency breaking and flooding of the whole tube to atmospheric pressure which will probably take a matter of seconds.

Example: A port should experience choked flow until the pressure is > 0.5 atm (~5.5 km altitude). This means that (arbitrary numbers) a port 1/40th the tube cross sectional area every 500 m will raise the pressure of the tube to this (breathable) level in t=0.5*500m/(343m/s*1/40)=29.2s.

So it should be possible to design an emergency pressurization system so that the explosive decompression is the most dangerous part of a complete loss of pressure event (i.e.requiring something like a hatch malfunction or a bomb). As for not detecting a leak - well that's a problem experienced by every jetliner on every flight right now...

Aero
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Re: Hyperloop Technologies

Postby Aero » Sun Mar 08, 2015 3:48 pm

Since we're talking about emergency pressurization scenarios, what happens if a car is speeding along and an earth quake or some other disaster rips the tube completely apart some few miles ahead of the car? The air will rush in, the speeding car will slam into the inrushing air and quickly decelerate. What level of deceleration would that be. Would it amount to hitting a brick wall, or hitting a water surface from 3 feet - 10 feet - 100 feet altitude?

In this scenario, the relative air speed at near atmospheric pressure would be supersonic.
Aero


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