See what I did there…“pipe dream”…lol…Ahem. Sorry.
Here’s a little snippet for those that haven’t seen the promise of 30 min cheap transportation between LA and SF:
Anyway. Hyperloop will never ever be safe or cost-effective. I cannot for the life of me figure out why media organizations on ALL sides are being duped into believing this fantasy. It really demonstrates the severe lack of simple science knowledge in the media and the public in general.
To create a hollow tube made of steel several hundred miles long (a single peice of steel welded together) that runs above ground and pump almost all the air out of it is beyond ridiculous.
There are a few technical problems and a few practical problems that will prevent it from ever happening.
First, unlike pipelines that carry liquids the tube will be empty and exposed to the sun. The sun will heat the steel on the side it faces. This will create expansion on the hot side that will cause it to swell, Since the heating will only occur on the hot side, it will want to bend and curve (as opposed to stretch uniformly). In a tube with liquids, the liquid helps to cool the walls of the pipe and absorbs the heat and makes heating of the pipe by the sun more uniform. Pipelines are smaller tubes and larger tubes don’t have anywhere near the pressure of a near vacuum.
Train tracks are a good example of what happens when steel gets hot (Remember that SoCal can be crazy hot at times).
An 1800-foot length of rail will expand almost one foot with an 80-degree change in temperature, for example.
The tube will be hundreds of miles long and even if it expanded 1 foot for every mile between LA and SF (one-quarter of what a railroad track would expand) that’s still just shy of 400ft of expansion. If it expands at the same rate as a railroad track, we’re talking 1000’ of expansion.
A railroad track is comparatively strong and is more uniformly heated than a tube with an 8-10’ diameter. The problem for the tube is it will have large temperature gradients between the hot and cool sides. If the prototypes I’ve seen are any indication of how it’s made, the bottom of the tube will be filled with concrete, creating a flat surface for the vehicle to ride on inside the tube. The concrete will act as a sink for heat making the gradient problem even worse.
The tube will be close to a total vacuum. There’s talk of building them between LA and SF and DC and NYC.
Now, the LA to SF idea will effectively create the largest vacuum chamber in the world. The idea is to put several hundred, perhaps even thousands of people in these vacuum chambers and send them at close to the speed of sound through them.
A single failure in the tube would result in everyone in the tube being killed as a wall of air rushes into the tube and the cars inside slam into it. It would become an undefendable target for terrorists. Assuming “1/2 thick steel walls a .50 caliber Green (if I remember this round is M903 SLAP), a black or red tip could easily penetrate. The Green tip can penetrate over 1”@500yrds depending on the hardness of the steel. Homemade tannerite or fertilizer explosions could also breach the tubes if set up correctly.
When you cut a train track or blow up a plane, you don’t kill everyone on the same track or everyone in the air. Everyone in the tube would likely be killed or severely injured. And if they did survive, the tube would have to have escape ports, but the ports could only be opened if the tube were pressurized. Creating pressure doors through the length of the tube would be cost prohibitive, create points for vacuum leaks and stress points.
Musk is either an idiot or if you read the fine print on the competitions he holds, a genius. When teams build “pods” for test tracks. Musk get’s to keep all of the technologies that engineering teams around the world bring and compete with. So if someone does come up with something groundbreaking, he get’s to keep the idea and owes no one anything.