Really? If so that is just ridiculous, the Blackstone Fortresses were created by the pre-Fall Eldar at their height and you need three of them to destroy a star. The Planet Killer is a Warp-spawned monstrosity and that can only kill planets.
Something that can also be done (as of Deathwatch, though which book it was in I forget atm) by a single unmanned stealth spacecraft smaller than a Viper class scout frig. So what the point of building the Planet Killer was I have no idea.
That I have less problem with, I'm sure the Imperium has giant orbital complexes that would dwarf a Ramilies as well, we just don't hear much about them.
Actually we do. Luna is no moon (anymore), It's a Space Station. The Imperium has a tendency to hollow out moons and very large asteroids and then arm them. The Bulwark in The Frozen Reaches is a good example of this, though somewhat small.
That makes me laugh a little. I am of the general inclination that the Mechanicus do know how they work, though the senior tech priests who do would probably not be manning a warship.
You'd think though that the Techpreist Senoris would know though, as they are (in theory) high ranking members of the admech and would have a very good reason to know. Being they are in charge of fixing broken ones. To fix something like that, you have to know at least the basics of how and why it works.
But then again, I've been very, very frequently told that 'realism' is a dirty word when dealing with anything to do with 40k, even in the role playing. Pointing out that tanks have more than four actual facings and that tank armor works better at an angle, and that
no one needs to be
ordered to use cover in combat... gah.
