How big of a train? How long the tracks?

Would be a completely pointless waste of money even if possible. If you want a flying train, that’s called a plane.

Edit: they can go faster, but still seems pretty pointless tbh

@ShadowyZephyr are you familiar with https://en.wikipedia.org/wiki/Maglev? The point is a lack of friction.

@jamesoofou Maglev is hardly practical itself because of costs. I think regular rail can go fast enough while still being cheap enough.

@jamesoofou does anyone have a good back-of-the-envelope calc. on rolling resistance losses vs air drag losses for trains?