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Comment by m4rtink | Hacker News Reader

Silent supersonic cruise missiles!

Doesn't seem like it would be important for a supersonic missile to be silent since you wouldn't hear it before it hits you regardless.

When attacking things the size of country, sensors near the borders can detect the sound of supersonic aircraft and transmit that information at the speed of light to waiting air defense systems. Silence still has some value.

Doesn't really make sense to me. For one, it's not silent, just quieter than you'd normally expect from a supersonic aircraft. It's not stealthy; radar will see it. It can't fly low and still be fast, so it can't hide from radar behind terrain. It's much slower than ballistic missiles, hypersonic glide vehicles, etc.

Quiet is good. The B-2 is engineered to be low observability not just in radar cross section, but in infrared, visual, and auditory. https://www.popularmechanics.com/military/aviation/a24484/b-...

A high-flying stealth subsonic cruise missile can be as silent as the airliners you see everyday flying silently overhead at 30k feet. Sonic booms are dramatically less stealthy.

If it had a very small radar cross section then it could be an interesting cruise missile, and if it had a robust pressure hull it could be a submarine. It doesn't. This conversation is stupid.

Nothing about the XB-1 design is optimised for boom reduction.

The Overture airliner, with an entirely different configuration, will also only operate supersonically over oceans.

What advantage does this have over ICBMs?

Ballistic missiles, being ballistic, have limited accuracy. It's also easier to detect them (flying higher and with larger radar signature) and tell where they're heading.

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