Limits Of Magnetic Acceleration Tubes

[Spacescifi]

Suppose some company decided to build magnetic coil tubes that have a vacuum inside on earth?

 

The idea is extremely fast overland travel, basically accelerate at 1g to 2g for an hour or a few or less, and wind up across the country faster than if you flew.

 

Is this viable theoretically?

 

I can't care about the ridiculous cost because I am a dreamer... not Elon.

Elon would shed man tears over this lol.

Edited May 17, 2022 by Spacescifi

[kerbiloid]

A vacuum tunnel in air doesn't differ from the same one underground.

[razark]

1 hour ago, Spacescifi said:

magnetic coil tubes

What does this mean?

 

1 hour ago, Spacescifi said:

The idea is extremely fast overland travel

How? Without knowing what "magnetic coil tubes that have a vacuum inside" means, how does one even approach an answer to this part?

 

1 hour ago, Spacescifi said:

1g to 2g for an hour or a few or less

What? So the lower limit is "1 g for less than an hour", and the upper limit is "2 g for a few hours". That's a pretty wide range, and damn near meaningless.  Is there a difference between 1g for 12 seconds and 2 g for 56 hours? Probably, but unless you actually define your terms, how do you expect an answer?

 

1 hour ago, Spacescifi said:

Is this viable theoretically?

Not at this point.

[Gargamel]

1 hour ago, Spacescifi said:

 

The idea is extremely fast overland travel, basically accelerate at 1g to 2g for an hour or a few or less, and wind up across the country faster than if you flew

Which country?   I would think you could bike across Lichtenstein quicker than getting on an airplane (Do they have more than one airport?).   
 

Kidding aside, I believe the real limitation to rail gun tech, which this basically is, is how fast and accurately the magnets are switched on and off.  This limits your max speed.  You probably won’t be able to accelerate at 1g continuously.   There’d come a point where they couldn’t keep up.   Others here know more of the specifics of this than I.  
 

But who wants to accelerate at 1g on a train? That’s uncomfortable.   Why not accelerate at .25g or some such until you hit cruising speed?   We’re not losing the force of gravity, so the force vectors are going to get a little wonky for the average passenger.  
 

But... what if you had two trains, and the first one to leave the station did your 2g run, and the second one did the .25g run.    That way you could have two services for a variety of passenger needs.  Those who want the faster train would know what they’re getting Into, while those who want a more comfortable ride can do so. 
 

Your intuition is sound though, where you figure a constant acceleration train would be much faster than flying.    If you had a hole in the ground that went straight through the Earth’s core to the antipodal other side, and you jumped in, you’d accelerate halfway there, and decelerate the other half, and literally step out on the other side, 48 (?) minutes later.   Of course, ignoring  the absurdity of it.   Your train would make a New York to LA, Perth to Sydney, etc, run much faster than any other means. 

1 minute ago, razark said:

What does this mean?

 

How? Without knowing what "magnetic coil tubes that have a vacuum inside" means, how does one even approach an answer to this part?

 

What? So the lower limit is "1 g for less than an hour", and the upper limit is "2 g for a few hours". That's a pretty wide range, and damn near meaningless.  Is there a difference between 1g for 12 seconds and 2 g for 56 hours? Probably, but unless you actually define your terms, how do you expect an answer?

 

Not at this point.

Ignoring costs, deployment, infrastructure needs, and other such trivialities, I think it’s theoretically possible, but not realistic. 

[razark]

2 minutes ago, Gargamel said:

I think it’s theoretically possible, but not realistic. 

I think it's way too vague to ascribe any possibility to.

[kerbiloid]

A boring maglev.

[KSK]

Just for comparison purposes, according to Wikipedia, the world Maglev speed record is 603 km/h, achieved on an 18.4 km track. That's from rest to full speed and back to rest.

A little bit of back-of-the-envelope maths gives me an acceleration of approximately 0.15g and a time to reach maximum speed of 110s or just under 2 minutes.

Put a Maglev in a vacuum tube so that it can keep accelerating and you very quickly get to some pretty ridiculous speeds  even at .15g.  

Again, for comparison, commercial passenger jets travel at about 600 mph (from a quick online search) or 965 km/h.

The above Maglev in a vacuum tube would hit passenger jet speed in about 3 minutes and about 14 km into its journey, assuming my arithmetic checks out. In that context, accelerating at 1 or 2g looks a bit like overkill.  

 

Edit:  This is a very rough calculation of course - for one it ignores air resistance completely and, for two, it assumes a constant acceleration to the half way point and then constant braking to rest. But I think it gets the main points across - it should only take a relatively modest constant acceleration for a vacuum tube train to comfortably beat out commercial air travel for raw speed, and those kinds of acceleration are quite achievable with current technology.

Whether a vacuum tube train can be made as reliable and safe as commercial air travel is another matter.

Edited May 17, 2022 by KSK

[Spacescifi]

3 hours ago, Gargamel said:

Which country?   I would think you could bike across Lichtenstein quicker than getting on an airplane (Do they have more than one airport?).   
 

Kidding aside, I believe the real limitation to rail gun tech, which this basically is, is how fast and accurately the magnets are switched on and off.  This limits your max speed.  You probably won’t be able to accelerate at 1g continuously.   There’d come a point where they couldn’t keep up.   Others here know more of the specifics of this than I.  
 

But who wants to accelerate at 1g on a train? That’s uncomfortable.   Why not accelerate at .25g or some such until you hit cruising speed?   We’re not losing the force of gravity, so the force vectors are going to get a little wonky for the average passenger.  
 

But... what if you had two trains, and the first one to leave the station did your 2g run, and the second one did the .25g run.    That way you could have two services for a variety of passenger needs.  Those who want the faster train would know what they’re getting Into, while those who want a more comfortable ride can do so. 
 

Your intuition is sound though, where you figure a constant acceleration train would be much faster than flying.    If you had a hole in the ground that went straight through the Earth’s core to the antipodal other side, and you jumped in, you’d accelerate halfway there, and decelerate the other half, and literally step out on the other side, 48 (?) minutes later.   Of course, ignoring  the absurdity of it.   Your train would make a New York to LA, Perth to Sydney, etc, run much faster than any other means. 

Ignoring costs, deployment, infrastructure needs, and other such trivialities, I think it’s theoretically possible, but not realistic. 

 

2 hours ago, KSK said:

Just for comparison purposes, according to Wikipedia, the world Maglev speed record is 603 km/h, achieved on an 18.4 km track. That's from rest to full speed and back to rest.

A little bit of back-of-the-envelope maths gives me an acceleration of approximately 0.15g and a time to reach maximum speed of 110s or just under 2 minutes.

Put a Maglev in a vacuum tube so that it can keep accelerating and you very quickly get to some pretty ridiculous speeds  even at .15g.  

Again, for comparison, commercial passenger jets travel at about 600 mph (from a quick online search) or 965 km/h.

The above Maglev in a vacuum tube would hit passenger jet speed in about 3 minutes and about 14 km into its journey, assuming my arithmetic checks out. In that context, accelerating at 1 or 2g looks a bit like overkill.  

 

Edit:  This is a very rough calculation of course - for one it ignores air resistance completely and, for two, it assumes a constant acceleration to the half way point and then constant braking to rest. But I think it gets the main points across - it should only take a relatively modest constant acceleration for a vacuum tube train to comfortably beat out commercial air travel for raw speed, and those kinds of acceleration are quite achievable with current technology.

Whether a vacuum tube train can be made as reliable and safe as commercial air travel is another matter.

 

Interesting... I was considering a large country on par with the USA or Russia.

Anyways, spoiler alert!

I wanted to know if it was theoretically possible because theoretically possible is MORE than good enough to make something a 'reality' in scifi.

Furthermore I intended to use such magnetic linear tubes to 'fuel' a new scifi drive for space travel I had in mind.

Infinity Drive: So called because you could almost use it to accelerate for infinity, but realistically you would not and could not.

Normal rocket based engines require fuel, but this scifi drive is literally fueled by converting stored past accelerstion into current acceleration.

How it works: Set the vessel to charge mode, put it inside a 4g magnetic tube, a really long one, since you will want as much acceleration you can get if you are going to want near torchship levels of delta v.

Before the vessel begins decelerating, cut off the 'charge mode' and the vessel's acceleration rate will be locked at 4g for a max time of however long the tube was before it decelerated the vessel.

Next crew enter the vessel, belly chemical rocket thrustere VTOL it as it tilts it's nose skyward at an angle and then it engages it's scifi drive and begins accelerating at 4g nose first into the sky.

How? By the vessel splitting in two with a gap between the halves and one half chasing the other...  it's a kind of diametric drive that is literally fueled by the last charge rate of acceleration that was NOT using the ship's scifi drive that nonetheless accelerated the ship for a length of time.

One can even steer with RCS while accelerating even though the halves are separated, since they are so attracted and repelled by each other that they keep alignment as if they were joined together when steering. To cut acceleration you just cut it off and the ship joins together again. In so doing you will save 'charge' until you decide to use it again.

Limitations: You are locked in at your acceleration rate, so you want 4g to quickly get to orbit and escape earth's gravity, but the scifi drive cannot be throttled down so you would merely use it to get up to a certain coasting speed desired by the crew and then begin coasting.

Implications: 'Fueling' these not-a-torchship-but-just-as-good vessels is relatively easy on a homeworld with magnetic vacuum acceleration tubes. Refueling in space is a whole other kind of level of hard though and virtually impossible unless some long linear magnetic tubes are already built on various airless moons.

 

Coincidentally, apart from missiles becoming far more potent using this scifi drive, it makes manned spaceflight easier but not too OP either, since obviously comfortable long accelerations at 1g are not happening because you need higher than 1g to escape Earth's gravity anyway.

And the technology of the entire setting would be considered far future as well, such as secondary aces of humanity created for certain purposes, one of them designed with a melding of the human abilities of intuition  and reason combined with the computational ability to process and calculate information quickly. So that if you played one of them at chess they would absolutely slaughter you... since they have both computer level processing and human reasoning to their advantage. Which means while a normal human can only see a relatively small number of outcomes of a given move, this descendant of humanity can literallly think of hundreds and understand how each might occur.

 

 

Edited May 17, 2022 by Spacescifi

[farmerben]

If we bore directly through the center of the planet, we don't need maglev.  Gravity will accelerate us and slow us down.  It takes about 43 minutes to transit the diameter of the Earth with it's gravity.  If we take some off center chord line it takes the same amount of time, assuming no friction.  

On an internally dead body like the Moon or Mars tunneling through the center is a viable possibility, travel times vary depending on the planet.

[KSK]

You’d need a very big tube if I’m understanding your description correctly.

Let’s assume a 40,000 km acceleration tube (circumference of the Earth to a reasonable approximation). Let’s assume constant 4g acceleration and deceleration, so half of that tube is used for charging the Drive.

Starting from rest,  s = 1/2 at^2.

Solving for t, I get 1000 seconds, approximating 4g to 40ms^2.

So a fully charged Drive can accelerate for 1000s at 4g. So what delta-V does that give?

Delta-v = a.delta-t

Solving for v, I get 40km/s.

Thats… curiously unimpressive for the infrastructure involved. So much so that if someone could check my maths, that would be appreciated.

For reference, the Saturn V could accelerate the Apollo CSM+LM stack to around 10km/s.

 

[kerbiloid]

1. Any ground movement would destroy the superlong superpipe. Better put it on trusses.

2. Excavation would cost enormously. Better put it on trusses.

3. Service & Repair would cost a lot. Better put it on trusses.

4. Rocks add stress. Better put it on trusses.

5. No need in putting it underground outside of the metropolitan areas. Better put it on trusses.

 

Finally we have the classics.

Spoiler

 

Oops, a wrong slide...

This one.

Spoiler

 

Spoiler

And no, pressing the pipe with rocks won't reinforce it.

[CFYL]

18 hours ago, KSK said:

the world Maglev speed record is 603 km/h, achieved on an 18.4 km track.

just mentioning: a TRAIN with ground contact, CRH380AM-0204, reached 605km/h in testing condition. that's not on a real track, and maglev do run faster than trains.

19 hours ago, Gargamel said:

 If you had a hole in the ground that went straight through the Earth’s core to the antipodal other side, and you jumped in, you’d accelerate halfway there, and decelerate the other half, and literally step out on the other side, 48 (?) minutes later.

Actually the rotation of the Earth screws it up. The hole would need to be bended into a set shape to allow "real" freefall without touching the walls.

Vacuum pipe for acceleration is a fairly nice idea.

There is a US firm called spinlaunch. Their way of launching rockets is to "spin to speed up". I would called it a suborbital cannon which lauches an upper stage.

Now create a new firm "pipelaunch"?

Then the pipelaunch company will find it extra hard to convince the nations on the equator (mainly, Africa, South-Eastern Asia, South America) to let the company build large metal structure, vacuum machines, power plants and other infrastructure---which do little good to the local economy, tourism put aside.

...

Now that pipelaunch has solved ALL political and economic issues. ALL OF THEM. Let's hit the technological side.

Excavating on land isn't easy. Putting metal in sea water is even harder. Corrosion happens. You have to put a huuuge Zinc panel in sea water and connect it to iron structures with a cord, and frequently replacing the Zinc panel. Or attach a super battery to your iron structure and use an insoluble anode. (The "Zinc panel" method will put a lot of Zn²⁺ to sea water, so environmental NGOs may be knocking at pipelaunch's door.

Then you need power plant for all the electricity you need. A nuclear power plant won't be enough. Pipelaunch needs several reactors. They had better build more reactors so that they could sell electricity, to compensate for the unit cost.

...

Now that pipelaunch has solved ALL technological issues. ALL OF THEM. Let's hit the application side.

I wonder what sort of payload would such a facility launch? I don't quite understand the "split into halves" part. But for a cruiser...

Spoiler

YES I LIKE IT!!!

 

[mikegarrison]

This idea of running trains in vacuum tubes has been around for a long time now.

Musk's hyperloop using a partial vacuum is kind of an interesting twist on it, actually. It allows using an air cushion instead of maglev.

One thing that is usually glossed over is how the stations work. Obviously people can't board the train in a vacuum, or else very few of them would volunteer for that experience. And none of them would volunteer more than once. So somehow you need to have a way to get either the people onto the train or the train into the vacuum tunnel.

Side note, I've ridden on a maglev train. Way back in 1986, at the Vancouver World's Fair. https://www.highspeedrailcanada.com/2018/05/when-canada-had-magnetic-levitation.html

[magnemoe]

Idea is possible but get the problem with maglev and hyperloop, only benefit over hyperloop is that its an train who can carry more passengers. Other benefit is that its very fast. 
And yes its velocity limits because you will need to switch the magnets fast, however this is not an gun firing an small bullet down an short barrel, its an train so the magnets will be larger and farter apart. 
I assume you could reach hypersonic velocity. 

One obvious issue is that line has to be very straight 

[CFYL]

On 5/18/2022 at 9:22 AM, mikegarrison said:

So somehow you need to have a way to get either the people onto the train or the train into the vacuum tunnel.

What about slowing the train down, and build an airlock on the track? It would cost less to vacuum a smaller room.

54 minutes ago, magnemoe said:

One obvious issue is that line has to be very straight 

Someone once proposed an idea of line, starting from US west coast, passing Canada, across Bering Straight, passing east Siberia, passing Beijing to Shanghai. That's, (more or less a coincidence,) almost a "large circle" on the Earth. So it only bends towards the ground, with little sideways bend. Of course it has to tunnel into some mountains.

Point is... even passenger jets can't have all their seats filled on intercontinental flights, which is a major reason of abandoning further A380 production. Antonov 225 is gone, Airbus 380 won't be produced any more. We simply don't need such giant passenger jets. (although cargo jets can be useful)

For such a maglev, it would cost a lot to maintain its state of vacuum, whether you run it or not, because re-vacuuming it can cost even more. The total amount of passengers of intercontinental travel is more or less a fixed number. Of course a cheaper way of travelling can harvest more passengers, while a higher cost can discourage some passengers, either way it's not gonna be a great change. I doubt that this maglev is more costly than an airplane although it's faster. This makes it even harder to squeeze enough money out of it to make ends meet.

Also about safety. As of 2021, we have seen 146 launches (51 by the US and 55 by China), of which 92.5% are successful. 22 astronauts have lost their lives in accidents, and more casualties are recorded for ground crew. 1960 SS7 accident killed half of USSR missle experts. 1996 CZ-3B accident killed 8 and injured 57. The 2 Space shuttle accidents killed 14. Rockets simply aren't safe enough to be used by the lot of people--even if the cost is minimal. 

In contrast: As of 1959-2016, Boeing 727 records an average of 1.24 hull losses per MILLION departures, and 0.73 hull losses that kills passengers/crew per MILLION departures. That means, one accident which causes penalty per 1.4MILLION departures, or a total success rate of (1,000,000-1.24)/1,000,000=99.9999876%. Each nine stands for decades of hard work, and thousands of lives that are lost in previous accidents, which warns us of safety, and pushes us into making new rules and coming up with new safety measures.(Data by Boeing.)

It takes a long time to make a new means of tranportation as safe as established ones. An accident on a vacuum maglev would possibly be as fatal as a rocket failure -- high speed, poor maneuverability, in vacuum. How to stop a maglev from hitting the walls of the tube when its moving at 1km/s and out of control? Also a single accident will cause the entire facility to be out of service--breaks the tube and fills it with air. What about the train that leaves a few minutes after the one that suffers an accident? stop it. How will passengers come out of the tube? I don't know. Scatter airlocks along the tube and spend another billion dollar for this.

Edited May 19, 2022 by CFYL
The OP says cost can be ignored. But I don't think that rules out safety issues---they probably can't be solved even with an infinite fund.

[Vanamonde]

Accelerating at 1g for an hour would be quite a feat in itself, but assuming you got the thing going that fast, I suspect that as it followed the curvature of the earth's surface the centrifugal force would turn the passengers to a red smear on the ceiling of the car. I am too lazy to re-teach myself the math to check that, though. 

[mikegarrison]

1 hour ago, Vanamonde said:

Accelerating at 1g for an hour would be quite a feat in itself, but assuming you got the thing going that fast, I suspect that as it followed the curvature of the earth's surface the centrifugal force would turn the passengers to a red smear on the ceiling of the car. I am too lazy to re-teach myself the math to check that, though. 

The SF writer James P Hogan once pointed out in one of his books that if you got the train moving fast enough you wouldn't have to levitate it at all, because it would be in orbit.

I could look up the equation, but Google tells me orbital velocity at sea level is 7.9 kps.

[Nuke]

8 hours ago, CFYL said:

What about slowing the train down, and build an airlock on the track? It would cost less to vacuum a smaller room.

Someone once proposed an idea of line, starting from US west coast, passing Canada, across Bering Straight, passing east Siberia, passing Beijing to Shanghai. That's, (more or less a coincidence,) almost a "large circle" on the Earth. So it only bends towards the ground, with little sideways bend. Of course it has to tunnel into some mountains.

Point is... even passenger jets can't have all their seats filled on intercontinental flights, which is a major reason of abandoning further A380 production. Antonov 225 is gone, Airbus 380 won't be produced any more. We simply don't need such giant passenger jets. (although cargo jets can be useful)

For such a maglev, it would cost a lot to maintain its state of vacuum, whether you run it or not, because re-vacuuming it can cost even more. The total amount of passengers of intercontinental travel is more or less a fixed number. Of course a cheaper way of travelling can harvest more passengers, while a higher cost can discourage some passengers, either way it's not gonna be a great change. I doubt that this maglev is more costly than an airplane although it's faster. This makes it even harder to squeeze enough money out of it to make ends meet.

Also about safety. As of 2021, we have seen 146 launches (51 by the US and 55 by China), of which 92.5% are successful. 22 astronauts have lost their lives in accidents, and more casualties are recorded for ground crew. 1960 SS7 accident killed half of USSR missle experts. 1996 CZ-3B accident killed 8 and injured 57. The 2 Space shuttle accidents killed 14. Rockets simply aren't safe enough to be used by the lot of people--even if the cost is minimal. 

In contrast: As of 1959-2016, Boeing 727 records an average of 1.24 hull losses per MILLION departures, and 0.73 hull losses that kills passengers/crew per MILLION departures. That means, one accident which causes penalty per 1.4MILLION departures, or a total success rate of (1,000,000-1.24)/1,000,000=99.9999876%. Each nine stands for decades of hard work, and thousands of lives that are lost in previous accidents, which warns us of safety, and pushes us into making new rules and coming up with new safety measures.(Data by Boeing.)

It takes a long time to make a new means of tranportation as safe as established ones. An accident on a vacuum maglev would possibly be as fatal as a rocket failure -- high speed, poor maneuverability, in vacuum. How to stop a maglev from hitting the walls of the tube when its moving at 1km/s and out of control? Also a single accident will cause the entire facility to be out of service--breaks the tube and fills it with air. What about the train that leaves a few minutes after the one that suffers an accident? stop it. How will passengers come out of the tube? I don't know. Scatter airlocks along the tube and spend another billion dollar for this.

according to that graph the only way to die on a 767 is to intentionally fly it into a structure. 

[Spacescifi]

Well the reasoning is certainly interesting. since it shows that reaching ever increasing speeds inside a vacuum coil tube has it's own challenges.

 

Which can still be surmounted by the way.

 

1. How to reach increasing speeds with coils?

 

Simply space them out at spots where you know the speed will so high that it will require more spaced out coils for acceleration to work.

 

2. How to avoid becoming a red smear? Just limit the max speed. I also think going to orbital speed at the equator inside a vacuum chamber tube would be awesome. Just hope an accident would not happen. That would be terrible.

[CFYL]

4 hours ago, Nuke said:

according to that graph the only way to die on a 767 is to intentionally fly it into a structure. 

Did some research. This makes my doubt if the graph is correct.

Spoiler

1983 Air Canada 143, B767-233, fuel outage, glided to safety

1991 Lauda Air 004, B767-3Z9ER, disintegration, killed 223 of 223.

1996 Ethiopian Airlines 961, B767-260ER, hijacked, sea landing, killed 123 of 175.

1999 Egypt Air 990, B767-366ER, crashed in the Atlantic, killed 217 of 217.

2001 terrorists killed 157 in the air and 2650 on the ground.

2002 Air China 129, B767-200ER, crashed into terrain in South Korea, killed 128 of 167.

2011 Polish Airlines 016, B767-300ER, gears cannot deploy, landed safely and saved 231.

2015 Transaero airlines UN8888, B767-300, wrong course / too low in Beijing, no major malfunction, safely landed in Moscow.

28/10/2015 American Airlines, B767, caught fire in Chicago when refueling, injured 20.

29/10/2015 Dynamics Airways, B767-200, caught fire in Florida when taxiing, burnt the left wing.

28/11/2015 American Airlines, B767-300ER, cockpit window broke, landed safely in London.

24/1/2015 American Airlines, B767, encountered turbulence, injured 7 of 203

2019 Air Zimbabwi UM642, B767, engine caught fire in flight, landed safely

2019 Atlas Air 3591, B767-300ERF, crashed into the sea near Houston, killed 3 of 3.

2019 All Nippon Airways 246, B767, engine failure, landed safely, saved 278 of 278.

2022 Japan Airlines, B767, wobble in flight, broke the bones of an air hostess.

"B767" means, I don't know the exact type.

 

[Nuke]

9 hours ago, CFYL said:

Did some research. This makes my doubt if the graph is correct.

  Hide contents

1983 Air Canada 143, B767-233, fuel outage, glided to safety

1991 Lauda Air 004, B767-3Z9ER, disintegration, killed 223 of 223.

1996 Ethiopian Airlines 961, B767-260ER, hijacked, sea landing, killed 123 of 175.

1999 Egypt Air 990, B767-366ER, crashed in the Atlantic, killed 217 of 217.

2001 terrorists killed 157 in the air and 2650 on the ground.

2002 Air China 129, B767-200ER, crashed into terrain in South Korea, killed 128 of 167.

2011 Polish Airlines 016, B767-300ER, gears cannot deploy, landed safely and saved 231.

2015 Transaero airlines UN8888, B767-300, wrong course / too low in Beijing, no major malfunction, safely landed in Moscow.

28/10/2015 American Airlines, B767, caught fire in Chicago when refueling, injured 20.

29/10/2015 Dynamics Airways, B767-200, caught fire in Florida when taxiing, burnt the left wing.

28/11/2015 American Airlines, B767-300ER, cockpit window broke, landed safely in London.

24/1/2015 American Airlines, B767, encountered turbulence, injured 7 of 203

2019 Air Zimbabwi UM642, B767, engine caught fire in flight, landed safely

2019 Atlas Air 3591, B767-300ERF, crashed into the sea near Houston, killed 3 of 3.

2019 All Nippon Airways 246, B767, engine failure, landed safely, saved 278 of 278.

2022 Japan Airlines, B767, wobble in flight, broke the bones of an air hostess.

"B767" means, I don't know the exact type.

 

the graph seems dated, there are no 737 maxes.  it says its from 2016.

also according to the graph boeing are a bunch of liars. 

Edited May 20, 2022 by Nuke

[mikegarrison]

For that chart hijackings, terrorist attacks, military shootdowns, and intentional crashes are not considered "accidents". Also, crashes during flight testing are not included.

That excludes 9/11, the Ethiopian 767 hijacking, and the Egyptian 767 murder/suicide.

The 767 fatal hull losses are then the Lauda Air mid-flight thrust reverser deployment and the Air China CFIT crash. The 2019 incident with the Atlas Air frighter happened after that chart was made.

Edited May 20, 2022 by mikegarrison

[wumpus]

23 hours ago, mikegarrison said:

The SF writer James P Hogan once pointed out in one of his books that if you got the train moving fast enough you wouldn't have to levitate it at all, because it would be in orbit.

I could look up the equation, but Google tells me orbital velocity at sea level is 7.9 kps.

Doesn't that effectively mean "at re-entry speeds near sea level"?  Granted, aero losses of trains are dominated by the losses along the side (probably excepting the fastest and shortest trains), so this might not be as bad as it sounds.  Like "ground launch to orbit", it sounds like something that might work  well on the Moon, but probably not even Mars.

I think the US has higher passenger rail deaths than air deaths, although that might have been during a spike of rail accidents and can't include general aviation but is almost certainly true on a per-passenger basis.  Also note that while the US passenger rail service might appear miserable to other industrial countries, rail *freight* is heavily used (often much more than said other industrial countries) and typically has control of the rails and thus makes upgrading passenger rail next to impossible.  That and Americans tend to drive further, and when its too far to drive go straight to planes.

 

PS: getting back to the subject at hand, I remember hearing about an upper limit (on the order of the speed of sound) for this type of thing thanks to back EMF produced by the rail car.  I've never seen what would cause it (I'm reasonably familiar with Maxwell's Equations), but it seemed taken for granted in a group of fairly well informed space enthusiasts.

Edited May 20, 2022 by wumpus
added the postscript

[mikegarrison]

22 minutes ago, wumpus said:

Doesn't that effectively mean "at re-entry speeds near sea level"?  Granted, aero losses of trains are dominated by the losses along the side (probably excepting the fastest and shortest trains), so this might not be as bad as it sounds.

Vacuum tube, remember? No air, no issues.

(Well, OK, lots of issues, but not that issue.)

Edited May 20, 2022 by mikegarrison

[kerbiloid]

We may build a 7.9 km/s vacuum tunnel at 100+ km altitude. It's called orbit.

Known advantages: doesn't need walls, doesn't need magnets.