What confuses me is why are there so few RBC's - compared to the meson bomb they should be far easier to manufacture (given that beam technolgoy is known and used for years and that this meson thing is new)
Just because beams are a well known technology doesn't mean that they are cheap or easy to make.
Furthermore the Mjolnir beam was new. We've never seen anything anywhere near that powerful in a ship that size before.
a) the Mljonir is not a ship - it's a weapon platform. No crew quaters, no storage areas, no engines, no corridors.
It's a bit smaller than a cruiser, but given the free volume, packing a bigger beam than a Leviathan could carry is more than reasonable.
And what I menat to say - it's most definately cheaper and easier to make than a meson bomb - so if they had stuffed two Orion full of those things, they could have produced more than enough RBC's by that time to make a realyl effective node blockade.
For your consideration; cost of patriot missile unit - US$170m. Cost of F15 - US$30m (approx wavy handed stuff)
As another aside; historically, it's not usually cheaper to buy autonomous units (at least, not reliable ones). That's why, shockingly, people still fly planes.
As another, final aside; all a mesom bomb needs to be (in a primitive simplified sense) for what it's used for in FS2 is a fissile devices and a trigger - click, bank, done - losing control is a desired thing. An RBC needs to be reusable, reliable, autonomous, and also of course requires to be able to warm up and cool down - losing control is a bad thing. It's worth noting it's generally easier to let energy overload and explode than to control it - after all, how many weapons nowadays are based on energy (reusable, soft-state i.e. not bang-then-done), and how many on explosive action (i.e. bullets)?
Ah... one other thing. Normally, new technology is less reliable than old technology; it would be very dangerous for the GTVA to (for example) devote their reliable fighter, cruiser, etc building materials for what are untested weapons during wartime.