about 500 miles (about 800km-400km to go and 400km to return-it
Combat radius refers to the distance from an airbase that a warplane can reach, patrol there for a set amount of time and return to base with minimal fuel left, thus completing a combat mission.
For a given aircraft, its combat radius varies according to whether or not it carries external drop tanks, the level (altitude) of the combat mission, and the amount and weight of ordnance it is carrying:
Combat radius of Spitfire MK1 425 mi (680 km) on internal fuel (With a Merlin Engine)
So the actual miles travelled are 850 miles round trip plus the miles taken up in patrolling so the current four hex range for a bf109 and a mk1 Spitfire are spot on, if you were feeling generous you could even add a hex and make it 5 hexes.
The definition of Combat Radius is taken from wiki as are the Mk 1 internal fuel radius figures.


