Even aircraft are heavy. A loaded F/A18 tips the scales at about thirty tonnes.

What would you gain from having a flying carrier?

More fiction then science, But do you remember Sky Base from Captain Scarlet, they seem to pop up from now and then.

You could probably fit a battery of 155mm guns.

COIN-only though.

"I'd quite like to see a heavy-lift airship, like the Skycat or Lockheed P791 tooled up as an AC130 writ large."

That's exactly what I was thinking. It might really be effective for night operations, quiet, hard to see. The only thing that scares me is triple A, but  big systems are unlikely in the scenarios we're talking about here. At any rate once they start shooting  they'd be subject to quick counter strikes, and insurgents aren't likely to have big radar guided triple A stuff, not like the Zeus. Consider something like that for border patrol in Iraq along the Syrian and Iranian borders, or in Afghanistan in the mountains or near Pakistan. In Popular Mechanics I read this article about this new hybrid airship design that is built like a giant wing (or something like that), so this shape generates even more lift. They're thinking about using it to haul cargo into remote areas that don't have any decent landing strips for heavier lift aircraft. This would offer obvious military applications.

Treadgar