Hacker News Reader

Comment by kamjam | Hacker News Reader

I wonder what the security checkpoints would be like on the HyperLoop if it ever got built? They are saying capsules could depart 30 seconds apart. Imagine is there was an attack in on of them, with several others travelling at high speed just behind.

http://www.bbc.co.uk/news/world-us-canada-23677205

I'm sure there some contingency has been thought of, unfortunately it's just the world we live in these days :(

View on HN

Forget about an attack. The system would need to be robust against simple malfunctions which could also result in a massive pile-up.

If they turn off the compressor there's a giant air cushion in front of them and the capsule no longer has air bearings. It probably lands on wheels and can then engage the breaks. A small capsule has low inertia as well.

Most likely safer than a train.

Unfortunately the passengers inside still have high inertia. It doesn't matter if the capsule stops without damage if all the people inside are crushed by G-forces.

This is covered in some detail in the proposal. The capsules will be able to stop in the event of an emergency without hitting capsules in front or crushing passengers.

This system would seem very weak to criminals / terrorists / whatever firing bullets at it. It would be exceptionally difficult to track where the shot/s came from, and it would cause serious pressure problems.

As opposed to aircraft sitting on the tarmac, which are not subject to such problems?

Aircraft sitting on the tarmac doesn't have to take off if it has been shot at. In the process of taking off could be more of a problem, I suppose. On the other hand, at least airports are a relatively small area to keep secure.

Presumably the Hyperloop isn't actually in danger when shot at. The cars just slow down when depressurization occurs. Thought I read that somehow.

I responded to concern over the Hyperloop shutting down for hours whilst the damage is repaired.

And, if someone fired a few pot shots into a taxing A380 at LAX, I have to imagine that the whole place would be shut down for a few hours.

Airplanes leak so much air that a couple more half-inch holes would not affect overall integrity. Most control systems are implemented with redundancy, so taking out a control point would just failover to a backup. Occupants aside, there little such damage could do to an airplane; noting the occupants, worst case is a couple casualties, not loss of everyone on board. And, of course, you could simply choose to not take off.

As mhandley noted, Hyperloop might be more susceptible, as the concern is more like your airplane flying an inch off the ground and hitting a stationary large brick.

...which reminds me of an old analogy: Back when large-capacity (ooh! 10MB!) hard drives were becoming common, I recall hearing the comparison that the read head was akin to a 747 traveling Mach 3 just 1 inch off the ground. Perhaps Elon wondered how this might work in real life, and so came up with Hyperloop.

Aircraft are actually supposed to leak air. In non-bleedless aircraft, the engine compressors pressurize air to be used in the A/C unit, which then sends all the pressurized air throughout the cabin. To prevent excess pressure buildup, valves are opened partially most of the flight with a veinlike network of tubes venting air to the exterior of the aircraft.

Of course, if any damage occurred on the ground, this would be a non-issue entirely as the aircraft wouldn't be pressurized at all.

Even if the pressure problems could be countered, a bullet hole is likely to leave a pretty ragged profile on the inside of the steel tube. The specification calls for the air bearing skis to ride 0.5 to 1.3mm off the tunnel wall. They'd need to be pretty robust to take hitting the ragged edge of a bullet hole at 700mph.

I think that a bullet hole in the type of tube that supports this much weight is unlikely. Oil pipeline tubes would typically be thinner (less weight to support) and the concept of a bullet piercing those tubes is unlikely.

I wonder - could you line the high-speed part of the tube with half an inch of soft wax or something similar? Then any dents or imperfections caused by bullets would rapidly be smoothed out again, and the damage to the skis would be minimized by vaporizing the wax you hit.

The specification for the tube is inch-thick steel. Most bullets not meant for tanks would leave a dent, not a hole.

The Shanghai maglev has no security at all... or at least not last time I went on it. Neither do any of the European HSR systems I've been on.

Remember a big part of TSA isn't to protect the people on the planes, but to protect other people from the planes themselves. It's pretty hard to weaponize a vehicle that's stuck inside a tube or on rails.

The pdf mentioned something like tsa, only streamlined.

Reply on news.ycombinator.com