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[...] An anonymous source, identified as a former Dynex exec, told The Sunday Times that the acquisition of Dynex Semiconductor by Chinese railway firm Zhouzhou CRRC Times Electric in 2008 "could have helped the development" of the Chinese navy's new railguns.
Dynex produces, as its name suggests, semiconductors, in particular insulated-gate bipolar transistors (IGBTs). These can be used as critical components in railguns and similar catapult-type technologies thanks to their very high voltage and current ratings.
"In these big electronic systems... you need to be able to turn on and off big power very, very quickly. And your standard power switches are too slow," the former Dynex exec told the newspaper.
The basic principle behind a railgun is that a current passed between two rails via a sliding armature generates an electromagnetic field that flings a projectile carried in the armature out into the great beyond. A little lateral thinking easily turns this into an electromagnetic catapult. To make it work you need seriously high currents and voltages – sufficient to generate 160MJ, if this paper is taken at face value.
[...] The national security implications of this tech transfer are obvious, and troubling. Britain's post-Brexit answer to maintaining national prosperity is to go full throttle into cutting-edge technologies, racing ahead of other countries to commercialise and license the technologies we develop. If that comes into conflict with our strategy of using Chinese capital to cover the upfront costs, and the result is that British advanced technologies find their way into Chinese weapon systems, that will not only make the world a less safe place, it will potentially harm Britain's standing with its allies – particularly the US, which is keen to confront Chinese challenges to its hegemony.
(Score: 0) by Anonymous Coward on Tuesday March 06 2018, @06:53AM (8 children)
The hyperloop is an almost-vactrain with an electric fan. An obvious alternative is maglev, but what about a rail gun?
(Score: 2) by takyon on Tuesday March 06 2018, @07:04AM (2 children)
https://www.nextbigfuture.com/2018/03/test-track-has-33-times-lower-air-pressure-as-progress-towards-4000-kilometer-per-hour-trains.html [nextbigfuture.com]
https://www.nextbigfuture.com/2018/02/spinlaunch-is-using-large-centrifuges-to-accelerate-to-payloads-into-space-target-500000-per-launch.html [nextbigfuture.com]
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(Score: 0) by Anonymous Coward on Tuesday March 06 2018, @09:08AM (1 child)
Spinlaunch - 500kg payload at a maximum acceleration of 10000g = 5000 weight-tons. Imagine the force in the bearings just before launch.
The track used for this acceleration will be heavy as hell - the energy efficiency is going to be abysmal - even with regenerative braking.
I have a feeling this is more spin than launch.
(Score: 2) by Immerman on Tuesday March 06 2018, @02:33PM
That is indeed some serious loading, but they do mention using "plasma bearings" to lubricate the projectile, rather than mechanical ones. I imagine that functions something like the pressure-melted layer of water under the blades of your ice skates, and can't "wear out" in any meaningful sense since it's being constantly replenished.
I don't see what the weight of the track has to do with anything - yeah, it'll take some serious energy to get up to speed, but it's not like you have to do that for every launch - it's loaded *after* it spins up, so just get it up to speed and spend the next month continuously launching payload. You only need to replace the energy lost to your payload and friction - and considering how astoundingly inefficient rockets are that seems like a potentially good deal.
Seems to me the real challenge in the whole thing is the moment your projectile transitions from the very-rapidly-spinning spiral track to the motionless "barrel" - a transition conveniently left out of the artists concept drawing, along with the loading mechanism. Seems like that would require some pretty impressive coordination and a relatively seamless transition to avoid ripping things apart.
It seems to me that the real benefit of such a device would not be launching from Earth so much as in space, where there's no air resistance to overcome. It basically eliminates the crippling non-linearities of the rocket equation, so you could launch raw materials from your moon or asteroid mining facility without wasting any energy on accelerating a rocket and propellant - or at least only needing a much smaller rocket for navigation refinement and braking purposes. Of course you'd need to impart a balancing momentum to your asteroid if you didn't want to propel it into an ever-larger orbit (assuming your targets are all inside that orbit), but maybe that's not really a problem you care about. Even if it is, ion drives or other high-efficiency low-thrust engines could do the job quite nicely.
(Score: 2) by takyon on Tuesday March 06 2018, @07:27AM (2 children)
https://arstechnica.com/cars/2018/03/is-it-time-to-take-the-hyperloop-seriously/ [arstechnica.com]
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(Score: 0) by Anonymous Coward on Tuesday March 06 2018, @09:22AM (1 child)
Expensive to build, expensive to maintain, speed doesn't necessary equate with throughput,. I doubt the Hyperloop will qualify as mass-transit.
(Score: 2) by Grishnakh on Tuesday March 06 2018, @05:54PM
Hyperloop isn't trying to compete with traditional trains I think, it's to compete with airplanes. Would you consider jetliners to be "mass transit"? Didn't think so. Hyperloop is much the same: not that many passengers per trip, higher costs, but higher speed. Hyperloop should be a competitor to airplanes, offering even higher speeds, and probably greater throughput (more cars, more frequently), and better reliability and safety (underground tunnels are more predictable and generally safer than the atmosphere at 10-30k feet; there's no bad weather in a tunnel). It might cost more than a Delta or United flight though, but hopefully it'll just be competitive. If things were working properly in this country, the cheapest way of getting around (at least around the northeast corridor where cities are close together) would be by regular heavy rail.
(Score: 2) by c0lo on Tuesday March 06 2018, @08:54AM (1 child)
What a fan would be useful for in almost-vac?
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Grishnakh on Tuesday March 06 2018, @05:58PM
As I understand it, it's for moving what little air there is from the front of the vehicle to the rear of the vehicle. If this were a true vac-train, it'd be unnecessary, but this isn't a vacuum, only a partial vacuum.