you can use the rudder when landing with a crosswind...it's very effective to help control the plane right before touchdown. Especially if you want to fly in the wind... and everyone needs to learn how to handle the wind or you sit and watch others fly . Also you use it to make your turns look more coordinated. Aileron only turns can look really strange and non scale looking. Also if you want to fly any kind of 3d you will use it almost more than your ailerons. The best way to learn rudder control is to get a cheap 3d foamy plane.... those defiantly require more rudder than aileron to fly