From: Sydney, Australia
This is from memory so should be substantially correct.
In basic terms, air battles are firstly between flights of 8 or less planes. These are the prime blocks for determining initial detection, combat rounds, etc.
Once 'flights' are deemed to be participating in combat, the combat is then between the individual planes within those flight.
The same core air-to-air mechanics as in Witp exist in AE. But for AE, we added a whole extra dimension with altitude bands,
altitude advantage, speed differences, time to target, out of position, etc.
The max rounds is the number of times a flight from the CAP can engage a flight from the Escort - combat between flights.
The following is a trimmed down how:
A random flight from each side (CAP or Escort) is checked to see if they detect each other, are not delayed, etc.
If one doesn't pass the check, then a new random flight is selected.
Flights can engage multiple times until all planes in the flight are destroyed, out of fuel or ammo, drop out, etc.
It is also possible that some flights wont get to engage due to time-to-intercept, being out of position,etc
A round is counted when the flights engage each other, or a delayed CAP arrives.
This is repeated up to the determined 'max rounds' which is described below.
Compare this to WITP, where every Escort flight was engaged by every CAP flight in the hex in one massive bloody air combat.
It finished when there were no more Escort flights, or all CAP had been allowed to engaged.
As we approach the fighter combat between the large number of flights/planes, the 'max rounds' that was sufficient for smaller battles is being over-taxed. Not every flight (whether in CAP or Escort) is getting a chance to participate. Thus my desire to increase this 'max rounds' based on larger than expected number of CAP flights. I say CAP flights since having 5 CAP flights against 30 Escort flights shouldn't take longer than 30 CAP flights against 5 Escort flights.
My original estimate of the max rounds was based on the CAP flights being able to fight 15 times during a 30 minute period. This was then adjusted by time to target (less than 30 minutes would shorten the engagement time). Plus of course the old random factor.