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Comment by bornfreddy | Hacker News Reader

What about guns? Relative speed against the enemy is the same no matter if you shoot forward or backward. Or am I missing something?

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You need a backward facing radar for modern fire control targeting calculating a solution. These are heavy and large and will interfere with engine placement.

Bullets don't move at the speed of light.[1] Shoot a bullet backwards off a bullet train, that bullet's ground speed is less than if shot from the ground while stationary. Similarly, shoot a bullet forward off a bullet train, that bullet's ground speed is more than if shot from the ground from a stationary position. Shoot bullets backwards off a jet moving Mach 3 (just sayin') those 1700mph bullets will still be moving in the forward direction of the jet at 600mph relative to the ground.

[1] They should use rear-facing lasers!

But the bullet will still hit the plane following you at roughly 1700mph (you could say, the plane will crash into the bullet at that speed, but it‘s the same result), because it‘s also moving at Mach 3.

Good luck trying a Cobra with a Blavkbird, a plane that needs a third of the US to make a 180 turn at full speed.

That's true in the ground's frame of reference.

But in the plane's frame, where both planes are roughly stationary and the wind is moving 100s of mph backwards, bullets fired backwards move faster.

And for aerial combat I would argue the plane's frame is the important one.

But the guy that is pursuing you will still be going after you in around Mach 3 so he will go through your bullets like they would be traveling his direction at 600mph.

Yeah but your enemy is also moving forward because they’re trailing you.

This really only applies if shooting at a target behind you that is either stationary or moving much slower than you.

If the target is moving at (or nearly at) the same speed as you then those velocities effectively cancel out

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