Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hyperloop lets you travel on a resonant acoustic wave?

conscienceofanentrepreneur.blogspot.com

Post reply on HN
Print view View original

31–40 of 93 posts

Re: Hyperloop lets you travel on a resonant acoustic wave?

#31

Post by nsh »

dhughes wrote: post #10

6,437km/h (4,000mph) to zero is going to be one hell of a stop.

I don't think it is as fast as you say. It is some where between 650-750km/hr. The image that this blog shows explains how that might look and work http://www.techcrump.com/travelling-the-world-in-6-hours-elo... but the fact that it is anti-crash is totally unimaginable if the traffic increases it is likely that the crashes would be reported, lets see what they put together i eagerly waiting for it to launch.Just a little too exited

Re: Hyperloop lets you travel on a resonant acoustic wave?

#32

Post by manmal »

jessriedel wrote: post #20
kyro wrote: post #9

For someone who has taken nothing more than undergraduate physics as a requirement for my degree, can someone explain the benefits/risks of using an acoustic wave system over others? Has anyone previously looked at this sort of system for travel? If the wave were to be disrupted and these capsules come to a screeching halt, how fast of a deceleration are we talking about? Never more have I wanted to crack open my phy…

This depends entirely on the drag coefficient of the train car. If the engines on a supersonic jet cut off, it's essentially a rock traveling at the speed of sound through still air. I don't believe the acceleration is cataclysmic for the occupants (although probably jolting). Remember also that normal commercial gets travel at like 80% of the speed of sound, and they can easily handle a loss of engine power. (Althou…

If the passenger cabin were smaller than the capsule, the cabin's movement could be softened by hydraulic dampers. This could also prevent casualties (e.g. through brain trauma, as often happens in train crashes) in case of an instant halt.

Re: Hyperloop lets you travel on a resonant acoustic wave?

#33

Post by bjornsing »

jessriedel wrote: post #19

I can't figure out how the OP proposal differs from Charles Alexander's. Low frequency (long wavelength) waves travel around the tube at the speed of sound. By traveling at the same speed, and correctly choosing a point along the wavefront, one can take advantage of significantly reduced apparent drag. It's implicit in Alexander's suggestion that either (a) the total length of the loop is an integer multiple of the w…

> I think it would require a calculation of how fast the wave would disperse in the tube, which OP has not done.

True. Two points though:

a) The rate of dispersion would be enormously dependent on the "stiffness" of the tunnel wall. If the wall is flexible at all a lot of energy would escape in its distortion. How much is a very complex calculation.

b) Ideal propagation for a ultra low frequency sound wave is probably very good. Why do I think so? I've heard that "shock waves" (actually their low frequency components) from various blasts often travel several times around the earth and are registered at least on their second lap. This knowledge has been incorporated in my gut and used to guide this "design".

Re: Hyperloop lets you travel on a resonant acoustic wave?

#34

Post by nonchalance »

moomin wrote: post #27

Not to be funny, but it seems like every other day has another "hyperloop uses acoustic waves" article. It's a good guess, but it doesn't even contain new speculation (another article went into detailed theorising about how cars would accelerate and decelerate). Seriously, until we have a solid info, or even a new guess, can we lay off Hyperloop?

Like with apple iPhone / iPad speculation, it garners pageviews. If this were forbes.com you would call it blogspam.

Re: Hyperloop lets you travel on a resonant acoustic wave?

#37

Post by dkrich »

dhughes wrote: post #10

6,437km/h (4,000mph) to zero is going to be one hell of a stop.

Yeah, where did you get those numbers? The distance from SF to LA is about 380 miles, and the speed of sound is about 760 mph. Whether or not the principles of sound movement are involved in Musk's plan, the speed is roughly equivalent if we're talking traveling back and forth in half an hour. Still a jolt, but you're talking about six times that.

Re: Hyperloop lets you travel on a resonant acoustic wave?

#38

Post by pjscott »

enko wrote: post #14
bjornsing wrote: post #7

Earlier quoted context omitted.

Drag? And by the way - the title doesn't end in a question mark. ;)

It does on HN : P Well, the acoustic idea wouldn't solve drag at all. The craft would still have to move through air.

I refer you to Charles Alexander's idea, which goes through a bit of the math for why traveling with the peak of an intense, low-frequency sound wave would give freakishly low drag.

http://charlesalexander2013.wordpress.com/2013/07/18/hyperlo...

Re: Hyperloop lets you travel on a resonant acoustic wave?

#39

Post by chatmasta »

speeq wrote: post #8

"Elon Musks final invention will be a time machine. It will only work once before exploding. Before entering it, Elon will turn around and tell us he has done his duty and given us many gifts, and now we must use those gifts to advance mankind. He hopes great things for us. We beg for him to stay and aid us further. He smiles sadly, He looks at us with his tired but happy eyes, shakes his head, and steps into the mac…

Did you just compare Elon Musk to Jesus?

Re: Hyperloop lets you travel on a resonant acoustic wave?

#40

Post by na85 »

chatmasta wrote: post #39
speeq wrote: post #8

"Elon Musks final invention will be a time machine. It will only work once before exploding. Before entering it, Elon will turn around and tell us he has done his duty and given us many gifts, and now we must use those gifts to advance mankind. He hopes great things for us. We beg for him to stay and aid us further. He smiles sadly, He looks at us with his tired but happy eyes, shakes his head, and steps into the mac…

Did you just compare Elon Musk to Jesus?

Yes. Everyone knows that Jesus had a time machine and appeared in the early 21st century.
Post reply on HN