D40LF wrote:djlong wrote:1) It's not a vacuum.
It's basically a 99% vacuum, so if it fails, it'll be very similar to an actual vacuum failure.
The faster trains go, the higher the resistance from air.
Check out planes, and how altitudes effect the corresponding atmospheric pressure.
https://www.mide.com/pages/air-pressure ... calculator" onclick="window.open(this.href);return false;
-5000 feet 1.19 atm 17.55 psi
-4000 feet 1.15 atm 16.95 psi
-3000 feet 1.11 atm 16.36 psi
-2000 feet 1.07 atm 15.79 psi
-1000 feet 1.04 atm 15.24 psi
-500 feet 1.02 atm 14.96 psi
0 feet 1.00 atm 14.70 psi
500 feet 0.98 atm 14.43 psi
1000 feet 0.96 atm 14.17 psi
2000 feet 0.93 atm 13.66 psi
3000 feet 0.90 atm 13.17 psi
4000 feet 0.86 atm 12.69 psi
5000 feet 0.83 atm 12.23 psi
10000 feet 0.69 atm 10.11 psi
20000 feet 0.46 atm 6.75 psi
30000 feet 0.30 atm 4.36 psi
40000 feet 0.19 atm 2.72 psi
50000 feet 0.11 atm 1.68 psi
60000 feet 0.07 atm 1.04 psi
Between 30,000 and 40,000 feet above sea level is where most commercial jetliners fly, betwwn 1/4 and 1/5 atmosphere pressure, or if you want to look at it the other way around, between 75% and 80% vacuum. They could not reach the cruising speeds they fly at if there wasn't a partial vacuum. Trains can't either, hyperloop, meglev, or high speed rail.