How the Elon Musk Hyperloop Can Work

I've had my doubts about whether the Elon Musk Hyperloop approach could overcome inherent problems with stabilization. The problem with the approach, as it seemed to me, was that it committed to a tube pressure of 1 millibar, which seems to preclude aerodynamic stabilization.

The problem is that stabilization requires some kind of feedback loop. The capsule will tend to vibrate or oscillate, and there needs to be some mechanism that detects the vibration and counteracts it. My conjecture was that mechanical "damping" of vibrations could not react quickly enough at or near supersonic speeds.

I've realized, though, that the reaction speed required of the damping mechanism is reduced if the mass and rigidity of the capsule is increased. If, for example, the capsule is constructed with a 10 cm. thick steel shell, giving it a weight of some 20 tons, it seems that it would have sufficient mass and rigidity to reduce the damping reaction speed required. The damping force required would increase, but I'm guessing that's not as much of a problem as the reaction speed.

Constructing the capsule of heavy, hardened steel would also increase the protection of the occupants. Besides protecting against breach of the capsule, the increased mass also reduces the inertial forces inside the capsule in the event of unplanned deceleration or buffeting.

A heavy capsule requires more energy to accelerate, but the energy can be recaptured during deceleration.

People may be reluctant to travel inside what is essentially a bank vault, even though it would be much safer. Engineering psychology can be used to make people feel comfortable with the whole experience, though, which is already used to make people feel safe and comfortable in aircraft.