I am most excited about the possibility of same day shipping from amazon, to be honest.
I am most excited about the possibility of same day shipping from amazon, to be honest.
Other baller-as-fuck stuff Elon does every day:
Intentional diversion from a straight up-and-down path, then sticking the landing back in the center of the pad.
Reusable rockets. This shit is crazy.
Mighty high praise for an alleged visionary that can't even make a car that fits in a garage.
DAMN
From my cousin. She is currently working with Boeing and is doing her graduate studies in aeronautical engineering at MIT.
I have not read through the entirety of the technical section, and I cannot say I have read it in depth as I have been skimming it at work, but my input would be the following...I did. It's pretty cool. Although I have some doubts about his cost estimates and the safety of the system. The main concern I have is that I think he is seriously underestimating how catastrophic a loss in cabin pressure could be. Since the tube is kept at .001 atmospheres, the pressure gradient between the inside and outside of the capsule is about 300 times greater than that between the inside and outside of a commercial aircraft at cruising altitude. You wouldn't have time to reach for your oxygen mask. Actually, if the leak was big enough and the capsule totally depressurized your lungs and the capillaries in your eyes would explode. Air Bus did a study on how this apparently...
There also seems to be a lot of subsystems necessary for operation...it's not actually that simple when you get down to it. Mechanical braking system, water cooling, air tank, deployable wheels, etc.
I haven't looked closely at his energy calculations yet, but I have a hard time believing that at .001 atm with a 20:1 compression ratio they can generate enough static thrust to hover the thing (33,000 lbs) when it's not moving. At speed it's probably fine.
I realize its an alpha design, but I find the paper super hand-wavy and I think there are still a lot of things they haven't addressed. That being said, it's super cool and I think it would be awesome if it actually happened!
What do you think?? I'm looking at this from a very aerospace perspective so I would be interested to hear what someone with more knowledge about transportation infrastructure thinks...
I'm actually concerned about the dampening system and the pylons he believes will support the system. It seems his ideas about the cost are based on placing the system completely above-ground, but can he really say that the support system for this will be so simple to create and maintain? They are talking about a dampening system that moves in all directions (x,y, & z) at each point to withstand earthquakes as well as the weight of the system + any eventual cargo load. The material cost alone for proper reinforcement and concrete needed for these "pylons" will be high. Not having any idea as to what the ground conditions are under the system, I would have to think that these structures would be less of trees and more of piers; maybe half the above-ground size of the Alexander Hamilton Bridge abutments in NYC. The steel pipe he proposes for the tube structure also raises an eyebrow for me. A 7.5' diameter steel pipe with only a .8 to .9in diameter wall? Our 12" diameter Ductile Iron we use for NYC standard storm sewer has a .6in wall thickness. The steel pipe is clearly a better material, but the pipe is going unsupported for maybe 80' (100' o.c. from pier to pier - width of supported section of pipe by the pier). You have the difference in air pressure from the outside to the inside plus the weight of the material and the system. I have not run any kind of numbers, but it seems too thin. As another subject of comparison; we installed 36” steel water main in John F. Kennedy International Airport. The 36” pipe had a wall thickness of .75-.875”. How can a steel pipe of a much larger diameter be the same wall thickness? The factor of safety that should be included in the design should be much higher than that for water main.
Not to mention having 100' sections of steel pipe made with a 7.5' and 10'-10" diameter for a total of 350+ miles is going to cost a small fortune; I am doubting the "less than $650 million dollars" estimate. 12" Ductile Iron costs us $82.80/lf in 20' sections (20' sections is the norm). That would be $153 million for a 12" DIP in 20' sections. To have a specialty sizing made will cost more. This can be up to the fabricator and his supply line, though. If they are exclusive suppliers for this project, and are making 350 miles, they can give a decreased price as this will probably be all their manufacturing line is producing for the duration of the project and then some for replacement parts. I will give him credit for estimating the cost to be double for the larger sized tube, but I would still venture to guess the $1.2 billion estimate is low.
You need to be able to account for not only the reinforcement for the entire system against damage due to earthquakes, which especially in California can be quite severe, but for the vibration of the system as a whole. We're now talking about, in the best case, large spread foundations which would take up even more space than the abutment. I doubt a caisson/pylon that could support the system would be a shallow and simple design, not to mention the earthquake effects on the caisson/pylon itself. Structural-soil interaction is a large focus of Civil Engineering right now. Between the increased focus on adapting tunnels over bridges and finding new, better ways to build foundations to resist earthquakes I'm not sure we can safely say the entire system can be supported properly in an area of high magnitude earthquakes. Admittedly, my expertise in this area is very low. I find Geotech to be enjoyable and fascinating, but have only some graduate level experience with earthquake design for the Northeast region of the US.
Another thought that occurred to me would be elevation changes. How flat is this area in California? I'm from NY and only been out there twice before, but around here you will not have any kind of level surface to allow for a constant elevation. Will the air cushion provided by the cars be enough to also redirect and maintain grades, both positive and negative? If this thing is travelling several hundred miles per hour the grade changes would have to be incredibly gradual and long. The problem will be the same with bridges; needing more space to reach the elevation of the bridge decks than the bridge itself takes up. This is one of the major problems they have with replacing the Tappan Zee Bridge between Westchester and Rockland Counties just north of NYC. He mentions 20, 50, and 100 foot tall pillars to support the tube over varying areas. The cost of the higher pillars, as well as the foundations required for something of that height to resist earthquake and lateral loading, appears to be left out. Are the 20' pillars the lowest they will go? Either way, building 25,000 pillars of varying heights across a 350 mile distance is not something to scoff at.
If the system were to be moved underground the increased cost for tunneling would be enormous. The 2nd Avenue Subway project running in NYC is $17 billion dollars to go 8.5 miles. This includes laying track and making stations & connections. The California Rapid Rail is going to cost $300 billion? At the same price per mile, to connect LA and San Francisco would be almost $700 billion, over double the cost of the CRR. Not only would you still have this large cost with tunneling, but you will still need the dampening system which is not of a large concern here in NY. I'm not sure what his estimated tunneling costs are based upon (size of cuts, length of cuts, type of soil/rock, etc.), but this would be a large cost concern.
Granted, if the contractors that win this project have such a distance to cover they may decrease their bid knowing they can still make a steady profit over a long term. Not only that, but they would gain a HUGE marketing ploy as well. As with all contractors, the cost is going to be based on how long the project will go on and how stable the income will be as well as the % profit earned. For example, one of the projects I run is a simple 8 month project worth a couple million. Right now, it is running at 40% profit which is something we would take all day, every day. Normally, we are looking at 15-20% on longer term projects. With long term projects we not only have a good revenue stream, but we are also keeping our crews employed and working for long stretches rather than having to move them constantly or having some periods of no work and having to lay people off temporarily.
As my cousin said, I know this was an alpha design, but I think a further look at the ground conditions as well as the cost of the actual material, labor, and equipment to build should be reevaluated before any further designs come forward. And yes, holy wall of text.
EDIT: Also; what up Rhinoz? How you been?
EDIT2: Wrong bridge named for a president.
The exploded lungs/eyeballs is a gross exaggeration, by the way.
Why don't we have some sort of deal with inmates who are sentenced to life/death to test cool stuff like this?
"Hey buddy, you're going to die in a couple of years, you have no family, etc, would you mind if we shot you in to space and threw you out of the door naked to see what happens? We'll drug you up since we'll have 100s of probes attached to you so you don't have to report anything, just have fun out there! PS. You will be honored for this task by having your name in sciencey stuff. Thanks."
easy. make robot facehuggers equipped with oxygen masks that pop out of the car the moment it senses a drop in pressure below safety thresholds.
Have you every burst the blood vessels in your eyes? I have. It is more than bloodshot eyes. The white part of your eye (don't know its name) is dyed red for a few weeks and can also screw with your vision. This depends on how many of the blood vessels burst of course.
Broken capillaries in your skin is indeed a bruise though. Anyway, it doesn't matter much. The real problem is if the cabin depressurizes you likely will die before you can get an oxygen mask to your mouth.
No, you'll pass out first. Then you'll die a few minutes later. Also, as the video noted, you have about 10-15 seconds before you pass out. That makes it quite likely you'll pass out (and subsequently die, unless someone else can help you), but by no means is it guaranteed.
edit: misread - didn't notice you said it was "likely". We agree on that, the technicality that you aren't actually dead notwithstanding.