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Comment by theamk | Hacker News Reader

I question if it is even possible to build the cannon with 50x longer range than the current ones. And if it possible, will the system be more efficient that a missile-based one.

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It really does sound like bullshit at first glance. Just the most basic projectile motion shows you need a muzzle velocity of something like 5km/s, without factoring in drag, friction, etc. With those, you probably need more like double that. What kind of projectile is going to handle being accelerated to that speed over the length of even a very long gun barrel, in sea-level air? 10kg at 10km/s is 500 megajoules of kinetic energy. What the hell is going to be propelling that thing?

I mean it's going to be accurate. I think from a cost stand point it's a lot cheaper to lob a shell than fire a cruise missile from the same range. Also it would be impervious to ECM as there's no guidance system (That's if they don't put anything in the shell)

What kind of accuracy can it have? It will have to pass through many different layers of air, moving very fast. Even a small nudge will be magnified when you multiply it by 1,000 miles.

I assume that they'll have models that correct for all of that, and I assume they'll have satellite weather included for up-to-the-minute data on all of the factors involved. (Either that or I'm guessing wrong about the effects of those things.)

Assuming all of that... what kind of precision are we talking about? Can they hit a building? A tank?

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