Tightness is highly
relative, airplane sizes vary and the "tightest" maneuver the Tbirds fly is anything Trail- (that's where the 18 inches is possible). That's really the Thunderbirds' forte, as they fly each one Trail maneuver in each inclination; in a turn, a roll and a loop! ...and to add a twist to it
, they even make the diamond transition mid-maneuver each time.
If you want to see a really tight formation, you should look at the Blues or Tbirds in the A-4's or T-38's respectively. Even though in some ways they appear further apart (stacked in the case of the Blues or the Tbirds with lateral clearance); however, technically the pilots sat a lot closer to each other in the air than they do in today's aircraft. Plus, both the A-4's and T-38's had really fast roll rates and neither was fly-by-wire...
I have respect for all present and past, but I'll tell you this much; since learning to appreciate aerobatic formation flying, what really sets apart a good team is their ability to always look uniform and maintain their station as planned. To the average viewer, I realize this may be somewhat transparent as most people look and see only how close two objects appear to one another, but it takes great discipline to hold ones position, unshakably, even further out on the wing too...
