How do i make....

[The_Great_Moo]

How do i make a real convinceing simulation of like a helicopter, like that drifts and handels somewhat lifelike? And biggest of all i got this thing im working with like you can move it up and down with keys,but how do i stop it from going through the ground? i tried using the flight simulator that came with it, the ground detection but i dont know how to set the varibles or somthing cause i cant get it to work. Thanks