Proportional Navigation on Nonstationary Targets

In a missile flying a proportional navigation course, the missile heading rate is made proportional to the indicated line of sight rate. While for stationary targets the resulting differential equations of motion can be readily integrated, this is no longer the case for moving targets. To obtain closed-form expressions convenient for the evaluation of trajectory parameters, the assumption is made in this paper that for moving targets, the angular rate of the closing velocity vector is made proportional to the line of sight rather than the actual heading rate.