What would happen if I flew through a city at Mach 3?

Factual Questions
21

What I am saying is that obstacles, both moving and not moving, make it impossible to travel in a straight line at mach 3.

22

Is there any way to find out how fast the jet was going?

23

Short version is you don’t make sharp turns at Mach 3.

Longer version is the relevant equation is

    centripetal acceleration = speed^2 / turn radius.

Which in English says that when you are going stupid fast, you either pull insane Gs turning or have a ginormous turn radius. Those two factors trade off directly.

In American units, Mach 3 is roughly 3400 ft/second. Square that and you get ~11.5million ft^2/s^2. If you want a WAG 30 foot turn radius to stay over the curbside lane making a 90 degree turn on a street grid, you’re looking at a centripetal acceleration of 11.5M/30 or about 380,000 ft/s/s acceleration. Since normal familiar gravity is one G is 32 ft/sec/sec you’re looking at about 12,000G to make that turn.

So more or less the same amount of violence as a modern artillery shell experiences while being fired out of a modern cannon.

Any human subjected to that would simply be converted into a thin red mist slowly dispersing in the breeze. Superman? Who knows?

24

And a ginormous turn radius just isn’t possible in any city.

25

This is Superman we’re talking about here, right? I think he can take the g-forces.

As far as violating FAA rules, someone else will have to tell he’s doing that. Not my job to enforce those.†

† This statement applies to almost everyone, especially everyone he meets in the comics.

26

You don’t tug on Superman’s cape nor try to enforce FAA regulations on him either.

27

But is there a secondary effect from having a sonic boom from one angle smash into a sonic boom from another angle?

28

G-forces I expect.

Of course, any turn imposes some g-force. Usually not enough to notice with most forms of transportation. Probably more usual with airplanes.

A lot depends on turning radius. Also angle of bank.

I’m guessing that is you’re enough like Superman to fly at Mach 3 like that you have the require secondary powers to deal with any g-forces you may experiences while dodging obstacles.

Also, what @LSLGuy said.

29

I checked on their own website, and as near as I can tell they flew just fast enough to create a sonic boom, so I would have to assume (until shown otherwise) that they got nowhere near Mach 3. MythBusters Episode 123: Curving Bullets