KenV, with respect I think you are mixing the different types of formation,and manoeuvres within those formations.
Close Formation- like the T`Birds,Arrows,PdeFrance etc; you use references such as wingtip/nose/rudder to give you spacing and position,and you hold that `picture` following the leader`s every move.that `picture should stay in it`s relative position irrespective of whether you are in a turn,level,rolling or looping.
Tactical- a much broader /longer gap between aircraft,and usually done in sections seperated by maybe a couple of miles.This allows full freedom of movement of each aircraft to manoeuvre/checking for hostiles and avoiding,and using natural features for cover/radar shadow.
I am talking about a tactical formation in airlifters with a longer gap between aircraft, but not separated by miles. When the formation turns, the guy on the outside of the turn cannot climb to stay aligned with the lead's roll axis. He stays at the same altitude while rolling with the lead and speeds up to maintain his position relative to the lead. Think of it as a turn in 2 dimensions rather than 3. Based on what I read here, you guys would call it a "flat" turn. Formation flat turns are routine in airlifters. And it requires that you have eyebrow windows, and that is exactly why the vast majority of tactical airlifters have eyebrow windows. I'm just wondering how the A400 gets by without them.