From what I’ve read about the various “tube train” hyper high- speed proposals the acceleration/decelleration phases are supposed to take place over a long distance and period of time so the G forces acting on passengers would supposedly not be excessive. Of course, that may pose some difficulty if there is a high volume of traffic in the tube you are traveling in, a “rear ender” would be ugly, to say the least…
Elon said that it is a Concorde and railgun and with an air hockey table. That suggests to me that it is a Mach 2 aircraft mounted on a railgun with an air cushion and launched in a hyperloop, high altitude ballistic loop, to the target city. It could land conventionally like the space shuttle, or even better, align with the target city’s railgun and recharge the railgun’s supercapacitors.
Elon Musk strikes me as a dreamer who is enamored of “Gee Whiz” technology and thinks that human progress occurs only when that technology is developed, whether there is a demand for it or not. He has opined that human progress slipped when the Concorde was retired from commercial airline service and a replacement supersonic airliner had not been developed.
They said the same about the Wright Brothers and their various contemporaries who so very foolishly proposed to fly people through the air at hundreds if not thousands of feet above the ground. Imagine that, and from two high school dropouts who owned a bicycle repair shop. If anything, Musk may be slightly ahead of his time. This will happen, IMHO.
As Larry (Tree) remarked almost a month ago, there is the problem of acceleration and deceleration that seems to be ignored in the promotion of this means of transit. I saw nothing of it in the account in this morning’s paper.
The design Musk is promoting has a top speed of around 750 MPH which is barely transonic (MACH 1), the G-load would not require “Space Shuttle harnesses” for the passengers…
As far as some hypothetical far future 3,000 MPH “transatlantic tubetrain”, it would have to be designed with long acceleration/deceleration phases, it could not launch out of the station like a horizontal Saturn V rocket…
Regardless, the technological and financial obstacles that must be overcome for any such system to be built are so huge that we may as well be debating Starship designs…
While I realize ‘passengers’ would not accept it, Top Fuel and Funny Car drag racing cars routinely accelerate from 0 to in excess of 300 MPH in less than 1000 feet and under 5 seconds. (because of the speeds being reached by these top class cars - the competitive track has been reduced from 1320 feet {1/4 mile} to 1000 feet several years ago). Needless to say, such acceleration would not be conducive to breaking out one’s personal electronics and accesing Wi-Fi.
It used a linear induction motor to get things moving with occasional mid-route boosts. Lots of roller coasters do this. Nothing weird or new about it. Acceleration can be as gentle as needed. Actually, gentle is easier - lower power requirement.
It uses suspension like an air bearing. Nothing weird or new here, either. Just bigger.
It uses a suspended tube for a guideway. This is new. It needs the guideway to be partially evacuated. This is really new. It uses a compressor on the front end to “suck” in the air in front of the train and push it out the back through the air suspension, so the thing essentially coasts with little friction between induction motor boosts.
The suspended tube guideway is designed for easy alignment and to be earthquake tolerant.
There are a gazillion details where the devil can pop up. He’s thought through a bunch of them but has “wave the hands” kinds of answers. Fair enough. This isn’t a complete design - just a concept/feasibility study at this point.
It’s pretty wild…but not crazy. I think I’d rather spend the day and drive than climb aboard…but that’s what people said when RRs first appeared, too.
After every lawyer in America is dead this possibly has a chance, science not withstanding. We will all be NIMBYs when they want your house, your town, your city because a support is need right there as it has the tube needs to be in a straight line. I’d be willing to bet the approval process to move power lines, national parks, lakes, and who knows what will take a century at least. And how noisy will it be on the outside as it whizzes by at 600+mph?
Two ways. You can use the linear induction motor in reverse. Or, there is an emergency friction brake of some sort. Either way, you don’t want to do more than about 0.1G for regular service braking.