Arduino Drone (improve stability)

Idahowalker:
Perfect, good luck with that.

You might want to look into what a Optical Flow sensor or a TOF can do for you in relation to stability of a drone.

I searched for those terms and i am prety confused...
Is TOF like ultrasonic sensor? Optical Flow sensor seems to stabilizes the drone very well but i couldn't find any to buy except one brand that is really expensive. Can you suggest me any ?

Thanks a lot for the info!