hi again, and thankx for ur responds guys. and about the questions u asked:
no i'm not from the middle east even though that they r very good people , but i'm from libya and it's in north africa, and my project's only mission is to apply what i've learned in my past semsters, so i can have the high deploma in a peaceful way.
about the ultrasonic sensor ,no i'm not going to use it for controlling the airplane from the base.
coz i'm going to control the airplane movements by an RF transmitter "27MHz" which is going to be connected to the PC via an LPT..
if u r wondering about the function of the ultrasonic sensor! it's going to be making sure that the airplane altitude won't axceed 4 meters, and the reason why i chose the altitude rang that way, is bcoz i have an altrasonic sensor in that specific distance range!
so if i send "up command" to the airplane, first it will have to check that it's not flying in the 4 m range, if so it will not take the command ..
so the adjustments of the airplane movement will take place in the receiver part, if u want to see the circuit block diagram, it is as the following: