In the 18MZ model menu go to "program mixes" and activate a mix then set your flaps to master and elevator to slave.You can have the mix activated by your flap switch. There is a graph showing you what is happening,you can also add delay to slow down the elevator mix input.I would have a play around with your mix functions until you get the hang of it.The Futaba manual although very detailed is not always easy to understand best to have a play dry first.Phil.