Translations:KAVAN Beta 1400 Kit - Instruction manual/105/en

From KAVAN RC Wiki

Once the rudder leaves its exact vertical position, it also starts to behave as an elevator turned down, telling your model to dive. When in a banked turn, to maintain level flight, it is necessary to apply a little up elevator to counter the effect of the down-turned rudder. (Actually, the reason why your model descends in the bank is much more complex - the wing gives less lift in the bank as the vertical projection of the wing is the area that counts, and you also have to beat the inertia that tries to keep your model in the straight flight…) The elevator applied when your model is in a banked turn also works like a rudder - fortunately, it helps to maintain the turn.