The dynamics of the aerodynamic forming of fibers is studied. The forces are calculated as functions of the fiber-forming path for different final fiber velocities. It is shown that there is a substantial difference between classic and aerodynamic forming in regard to the behavior of the rheological and aerodynamic forces along the path. The extrema of the functions of these forces are determined as a function of the difference between the velocity of the fiber and the velocity of the air leaving the ejector. It is found that the final velocity of the fiber depends linearly on average air velocity in the ejector. This dependence makes it possible to control the radius of the fiber as it is being formed.