[en] In the usual forcespinning (FS) process, a meso-scale fluid jet is forced through an orifice of a rotating spinneret, where the ambient fluid is air. This leads to the formation of a jet with a curved centerline. In this study we make use of a phenomenological viscosity model, which, in particular, takes into account both extension thinning and thickening of the polymeric jet, to investigate the properties of polymeric fiber jets during FS process. We consider the governing modeling systems for such rotating jets and calculate numerically the expressions for the nonlinear steady solutions for the jet quantities such as radius, speed, stretching rate, strain rate and trajectory versus arc length. We determine these quantities for different values of the parameters that represent effects due to rotation, viscosity and relaxation times for shear and extension. We also carry out experimental investigation for several types of polymeric fluid jets during FS process that provide general agreement with the present theoretical results. (paper)