Hello Everyone, I am by no means a physics expert, I have a basic/intermediate knowledge at best. I am a graduate-level computer science researcher working on building computer simulations of quad-rotor helicopters. For simplicity, assume that the helicopters move only with their rotors (i.e. no thrusters or jets), and all external forces (like air, etc) can be neglected. They are also flown indoors and at low altitudes. The helicopters weight 0.4kg and require about 3.9N of upward force to hover. The question: I know that as a helicopter hovers it has no net force acting on it (i.e. the force with which the rotors are pushing upward is equal to the gravity pulling down)... that also means that it has no acceleration. But, does it have velocity? Pitching the helicopter as it hovers will cause it to start moving, meaning that the downward (i.e. z axis) component of the velocity is non-zero... right? The problem I am having is relating the force required to hover and the upward velocity that must be provided to generate enough force to allow for hovering (I know that one cannot convert between force and velocity). Is there an equation or concept that will allow me to express the upward force required to hover as some sort of velocity measurement?