THE DISPERSION OF FINNED ROTATED ROCKETS

This chapter discusses the dispersion of a finned rocket that is rotated about its longitudinal axis during powered flights. The decisive factor leading to dispersion of finned rockets is the thrust malalignment moment M that arises from eccentricity of the thrust. The deliberate spinning of finned rockets about the axis of symmetry to improve dispersion is called “rotation,” and rockets with such rotation are called “rotated rockets”. The term spin-stabilized is confined to the case of un-finned rockets rotating at considerably greater angular velocities needed for gyroscopic stabilization. There are several methods by which finned rockets may be made to rotate during powered flights. They fall into three main groups: (1) the use of a device in the chamber to create a thrust moment about the axis of symmetry, (2) the fitting of slanted fins so that an aerodynamic axial moment M x arises that twists the rocket about its axis of symmetry, and (c) the use of a spiral guide in the launcher.