Proportional Navigation Guidance 2D: Terminal Intercept

Proportional navigation (PN) is the terminal-guidance law behind almost every homing interceptor and every autonomous orbital-rendezvous final approach: instead of aiming at the target, the chaser steers to drive the rotation rate of the line of sight to zero, which geometrically forces a collision course. This simulator flies a real planar PN guidance loop — computing the closing velocity, the line-of-sight rotation rate and a g-limited commanded acceleration every frame — against a target that flies straight, weaves, or executes a sudden break-turn, plotted on a pannable, zoomable top-down engagement view with a live history strip of LOS rate, closing velocity and commanded acceleration. Tune the navigation constant N′ and the autopilot's g-limit and watch the chaser either null the LOS rate and intercept, or saturate its thrusters and miss.