The reason why-- to setup a "differential"- that is -- when doing a right turn -- --the left DOWN aileron really did not go as far off c/l as the right UP aileron
so there no need to add rudder to get a nice- non skidding turn.
This problem was common on older designs -full size /models
Some were so bad that adding a little right turn input--simply caused a right bank and the plane skidded along merrily
If the operator has a good understanding of geometry -or a radio which can ad differential - the plane can be setup with ailerons trailing on c/l then any turn input adds more UP than DOWN

all this is NFG for a fully areobatic model but the 4* is not in this market --