Space Things

[Irace86.2.0]

Originally Posted by ZDan

Yeah, Virgin Hyperloops is just streaming along, eh?

Honestly, I've given it no more than 15 minutes of consideration to decide it is a stupid idea that is going nowhere. Others have invested years and 100s of millions of dollars to get us where?

I'm open to being surprised but so far I will stand by my for-free initial assessment. It is a dumb idea that won't work.

So you are admitting that before you spent all this time criticizing the concept of a hyper loop, you had only considered it for 15 minutes before deciding it was a stupid idea, and that you have never even read up on any of these proposals below? Interesting...for an aerospace engineer.

https://www.tesla.com/sites/default/...loop-alpha.pdf
https://www.rand.org/content/dam/ran...2008/P4874.pdf
http://et3.nl/images/upload/file/ET3...posal013au.pdf

I would be shocked if China or Dubai doesn't have a low-friction, low-pressure, tubed train under construction in the next five to ten years. Dubai is wanting to do an underwater train to India, and they want to do a train from Dubai to Abu Dhabi, with talks of both potentially being hyper-loop-style trains.

https://interestingengineering.com/t...t-train-mumbai

[Irace86.2.0]

@Spuds

"Also, the MagLev doesn't need a power supply to keep levitating. It will keep levitating as long as the speed is over 150km/h (93mph). So when it slows down, the tires will drop down, and the carriage will land as normal."

That statement is pretty interesting because the train clearly takes aerodynamics seriously with the shape of that nose, which seems like it would force the train's nose down, and yet such a heavy train is able to achieve lift at just shy of 100 mph. The Hyperloop proposal says up to 60% of the air would just pass through the fan system out the back, generating a little thrust, but ultimately it would only take a smaller percentage to generate lift, and considering the maglev train, even in a low-pressure tube, that seems reasonable.

[ZDan]

Originally Posted by Irace86.2.0

So you are admitting that before you spent all this time criticizing the concept of a hyper loop, you had only considered it for 15 minutes before deciding it was a stupid idea, and that you have never even read up on any of these proposals below? Interesting...for an aerospace engineer.

If anyone wants to pay me for my time I would be happy to investigate further.

Difficult to take your first link seriously, complaining about high speed rail plans but offering up magic dust as a superior alternative. Yeah, well, whaddya got? Nothing...

VHST concept from 1972 is cute. But geez, you'd think if it was workable we would have something by now?

OK, let's see what China and/or Dubai come up with.

Do I think it would be cool? Yeah. Do I think it's any kind of practical solution to moving humans around? No, I do not. Prove me wrong, children, prove me wrong!

[Irace86.2.0]

Tying things back to space, has anyone heard of MagLifter? NASA proposed using MagLev technology and a ramp to the top of a mountain to launch a rocket into space. This wasn't a new idea, as they discussed.

StarTram and others had their own ideas too. Enter ZDan here...

https://upload.wikimedia.org/wikiped...er_Mankins.pdf

[blsfrs]

In a slightly different vein, King's Dominion near Richmond has a roller coaster called the volcano. I'm sure it's common place now, but it used an electromagnetic propulsion system. It was really cool especially when you weren't expecting it. I heard aircraft carriers now use a similar catapult system. Make it big enough and you could do a space launch. IMHO

[Dadhawk]

Originally Posted by blsfrs

In a slightly different vein, King's Dominion near Richmond has a roller coaster called the volcano. I'm sure it's common place now, but it used an electromagnetic propulsion system. It was really cool especially when you weren't expecting it. I heard aircraft carriers now use a similar catapult system. Make it big enough and you could do a space launch. IMHO

Sadly Volcano has been decommissioned, but it was a great roller coaster. It wasn't maglev but as @blsfrs indicated was a linear induction driven vehicle. (no lift it rolled on wheels).

There are several of these in the US and around the world now.

https://en.wikipedia.org/wiki/Launched_roller_coaster

I worked at Kings Dominion before the mountain that was used for Volcano was repurposed for the ride. It originally contained three different rides of less intensity, including a floating boat ride similar to It's a Small World.

Amongst other things, I worked on the construction crew that built the Grizzly rollercoaster and was the first person to ride in it's back seat.

[Spuds]

Originally Posted by Irace86.2.0

@Spuds

"Also, the MagLev doesn't need a power supply to keep levitating. It will keep levitating as long as the speed is over 150km/h (93mph). So when it slows down, the tires will drop down, and the carriage will land as normal."

That statement is pretty interesting because the train clearly takes aerodynamics seriously with the shape of that nose, which seems like it would force the train's nose down, and yet such a heavy train is able to achieve lift at just shy of 100 mph. The Hyperloop proposal says up to 60% of the air would just pass through the fan system out the back, generating a little thrust, but ultimately it would only take a smaller percentage to generate lift, and considering the maglev train, even in a low-pressure tube, that seems reasonable.

I don't think it's aerodynamic lift the keeps the train up. My guess is the magnets on the train induce a current in the lifting coils as it passes by, which keeps it afloat by magnetic levitation. That works whether the train is being pulled or coasting on momentum. That's why you need wheels in the first place. Pretty clever.

As for the shape of the front and rear, keep in mind it has to go both directions, so it's a compromise. aerodynamically it would push the nose downward (to keep the nose in the guide at speed) but then there's a low pressure region behind that because air has momentum. As the front, this design keeps that lift point well behind the nose. As the rear, the same basic thing happens in reverse, plus it's tapered to reduce vortices and other drag effects.

[Irace86.2.0]

Originally Posted by Spuds

I don't think it's aerodynamic lift the keeps the train up. My guess is the magnets on the train induce a current in the lifting coils as it passes by, which keeps it afloat by magnetic levitation. That works whether the train is being pulled or coasting on momentum. That's why you need wheels in the first place. Pretty clever.

As for the shape of the front and rear, keep in mind it has to go both directions, so it's a compromise. aerodynamically it would push the nose downward (to keep the nose in the guide at speed) but then there's a low pressure region behind that because air has momentum. As the front, this design keeps that lift point well behind the nose. As the rear, the same basic thing happens in reverse, plus it's tapered to reduce vortices and other drag effects.

Aww thanks, I thought it was air lift by his phrasing that it didn't take extra energy input, which now sounds a little disingenuous, but he was maybe comparing it to the EMS-style suspension system.

[Spuds]

Originally Posted by Irace86.2.0

Aww thanks, I thought it was air lift by his phrasing that it didn't take extra energy input, which now sounds a little disingenuous, but he was maybe comparing it to the EMS-style suspension system.

Well, as I recall he just said it maintains lift without power, which is a completely true statement. It's just the lift coming from the coils, not aero. The act of moving the magnets on the train across the lifting coils causes an upwards force, without any additional power input. The energy source is the momentum of the train pulling a magnetic field across an unpowered coil, inducing a current in the coil, which produces it's own magnetic field that acts against that of the train. The superconductor magnets on the train will eventually lose their magnetic field without power to cool them, but I suppose it will last long enough for the train to stop.

Cool video.

[Irace86.2.0]

Originally Posted by Spuds

Well, as I recall he just said it maintains lift without power, which is a completely true statement. It's just the lift coming from the coils, not aero. The act of moving the magnets on the train across the lifting coils causes an upwards force, without any additional power input. The energy source is the momentum of the train pulling a magnetic field across an unpowered coil, inducing a current in the coil, which produces it's own magnetic field that acts against that of the train. The superconductor magnets on the train will eventually lose their magnetic field without power to cool them, but I suppose it will last long enough for the train to stop.

Cool video.
]

Yeah, I got that, and that video was a nice explanation. I was just being a little pedantic because the energy that is used to provide the force of linear motion forward also indirectly provides levitation, which yes, if energy is cut then the momentum of the train would still be providing lift, but I was also thinking without energy input to keep the train moving forward that the train would come to a quick stop from the eddy currents, similar to how my Keiser M3i stationary bike uses eddy currents to create resistance against the flywheel and abruptly stops the flywheel at a high setting without my input (I had read that the magnets themselves can act as resistance to impede top speed, whether that is thousands of mph only or not). Maybe the magnets don't cause fast braking inherently without energy input. Overall, I got your point. I was thinking it was semantics on whether someone could truly claim levitation didn't require energy when it actually required lots of energy, just not directly on a force resisting gravity.

Knowing they were superconducting magnets and when he said it takes no energy, I was thinking it was levitating in a quantum locking type of way with the assistance of air at speed to overcome gravity. I suppose if I was being pedantic about myself, the linear energy input of moving the train forward to achieve air lift and potential resistance that needed to be overcome to maintain motion would still be the same situation as the one above. No different I guess.

Like I said in my last post, he was likely comparing EMS MagLev trains that require constant inputs of energy to keep the train levitating, where this EDS system only needs energy of motion forward to levitate, so it is more energy efficient.

[bcj]

Sadam was getting set up with a boost system, but got shut down pretty hard.
Gerald Bull had it all worked out but other countries saw it as a military threat.
Seems Kim wasn't able to get hold of the IP.

edit: Saw this on Hacker News
Neumann Drive - Using a welding rod recycled from space junk to fuel your ion motor.
Suppose you could load up a bin full of MIG welding wire for fuel.

Hacker News Comments

Neumann Drive web site

[Irace86.2.0]

Static fire at SpaceX today for Flight 3 Starship.

https://www.space.com/spacex-starshi...-december-2023

EDIT: They are doing a static fire test tomorrow for Booster 10. I don't know when the FAA will approve them for IFT3, but I have to imagine it will be in mid January at the soonest because of the holidays, of course. Will they waste the ships or try for a landing, or will they try for a catch?

[Irace86.2.0]

I don't know if we have done this, but what is your favorite space/scifi movie or movie series? It can be whatever from a more technical and serious movie like Martian to a more fiction/fantasy movie like Star Wars to Guardians of the Galaxy. I don't care. It can be off world or specifically about space travel.

I'm looking forward to Dune 2 for 2024. Adam Sandler's Spaceman on Netflix might be decent, but I don't know how much it will involve space, as it looks to be more of an alien/earth movie.

My favorite space/scifi movie of all time? I'm a fan of Star Wars and Marvel, but when it comes to space movies, combine Christopher Nolan and Hans Zimmer with a great plot, and it is hard to beat:

INTERSTELLAR

[Spuds]

Favorite space movie of all time? I think I gotta say Apollo 13. At least it's a standard that I compare other movies to in my mind.

Movies more into the sci fi realm is harder. I watch a lot of science fiction but I think I prefer television series more than movies.