Thanks Lee. I was thinking it had to be more complex than that.
As a general rule of thumb, can any two functions be combined to accomplish a task?
For example:
(setq pt3 (list (car pt2)(+ (cadr pt2) land) 0.0))
which makes the landing.
In order to make that landing always horizontal, I could just add the polar funtion to it?
I've seen quite a few lisp that you have written, and quite impressive. They have good structure to them. Is there a certain structure to go about writing them?