w****e
发帖数: 2210 | 1 http://current.com/technology/89042567_plans-for-a-4-000mph-und
"Vacuum Tube Train: A 4,000-mph magnetically levitated train could allow you
to have lunch in Manhattan and still get to London in time for the theater,
despite the 5-hour time difference. It’s not impossible: Norway has
studied neutrally buoyant tunnels (concluding that they’re feasible, though
expensive), and Shanghai is running maglev trains to its airport. But
supersonic speeds require another critical step: eliminating the air—and
therefore air friction—from the train’s path. A vacuum would also save the
tunnel from the destructive effects of a sonic boom, which, unchecked,
could potentially rip the tunnel apart." "As envisioned by Frankel and Frank
Davidson, a former MIT researcher and early member of the first formal
English Channel Tunnel study group, sections of neutrally buoyant tunnel
submerged 150 to 300 feet beneath the surface of the Atlantic, then anchored
to the seafloor–thereby avoiding the high pressures of the deep ocean.
Then air would be pumped out, creating a vacuum, and alternating magnetic
pulses would propel a magnetically levitated train capable of speeds up to 4
,000 mph across the pond in an hour. As Frankel and Davidson say, it's
doable. "We lay pipes and cables across the ocean every day," says Frankel.
"The Norwegians recently investigated submerged, floating tunnels for
crossing their deep fjords, and were only held back by the costs."-Carl
Hoffman | b********6
发帖数: 35437 | | w****e
发帖数: 2210 | 3 btw, the sound speed is about 750 mph. | b*********n
发帖数: 5846 | |
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