Elon Musk, the entrepreneur who from time to time keeps the world hanging on a couple of his words, has long teased the world about what he calls the “Hyperloop” – the fifth mode of transportation, something never seen before that’s going to take its passengers with the speed of a bullet, safely, from San Francisco to LA, in just 35 minutes.
After working all night, Elon (and probably a team of his people) unveiled the details of the Hyperloop, with the reserve of “not too many mistakes.”
So, the Hyperloop, as envisioned by Elon Musk, is perfect for travel distances of up to 900 miles.
Around that inflection point, I suspect that supersonic air travel ends up being faster and cheaper. With a high enough altitude and the right geometry, the sonic boom noise on the ground would be no louder than current airliners, so that isn’t a showstopper. Also, a quiet supersonic plane immediately solves every long distance city pair without the need for a vast new worldwide infrastructure.
As some may have guessed before, the Hyperloop is all about controlling the physics of airflow, and the so-called Kantrowitz limit, which describes the speed at which an object (pod) can travel through a tube without choking the airflow. If the distance between the pod and the tube is too small, the system acts like a syringe, moving the entire column of air through, which means the tube has to bear immense pressures, which is “not good.”
According to the PDF document published by Elon, you can either go very slow or “very, very fast,” but the g-forces are very high – so the solution is somewhere in between, which means the Hyperloop is not a supersonic transport system.
But don’t get disappointed yet: the Hyperloop is able to travel at 700 mph. “Wheels don’t work well at that sort of speed, but a cushion of air does. Air bearings, which use the same basic principle as an air hockey table, have been demonstrated to work at speeds of Mach 1.1 with very low friction,” says the Alpha issue of the document Musk just tweeted about this afternoon (PDT).
Linear electric motors sharing the technology of those already in the Tesla Model S will accelerate the pod with external energy, and the pod itself will have a fan that will force the incoming air to exit through the rear. “This is like having a pump in the head of the syringe actively relieving pressure.”
Every 70 miles, the linear motors would provide additional boost to the capsule and the capsule itself will use little energy (stored in batteries) to propel the fan.
The cost of the Hyperloop will be significant, on the magnitude of hundreds of millions of dollars for pods and motors, and billions of dollars for the tube. However, when compared to the California Rail project which costs tens of billion, this is cheap.
The Hyperloop can be built on pylons over the ground or underground. The document published today takes care of a lot of aspects including technical and economical ones.
You can view the entire PDF document with in-depth economical analyses below: