To address the problem of insufficient guidance accuracy and limited damage effectiveness of traditional warheads when engaging highly maneuverable, high-altitude, and high-speed fighter aircraft, a D-shaped warhead with directional damage characteristics was adopted. By systematically optimizing damage parameter and energy transfer path, an efficient damage system tailored for high-speed fighter targets was constructed. A penetration model of a 120° D-shaped warhead against the composite skin of fighter aircraft was developed based on the Autodyn simulation platform. Considering seven common conditions, the case yielding the highest fragment lethality was selected to evaluate the optimal interception angle for damaging the cockpit canopy. The results indicate that during dynamic detonation, fragment dispersion velocity increases with a directional tilt. The penetration effect on the cockpit canopy is maximized when the relative fragment velocity is perpendicular to the aircraft's velocity (interception angle of 45.96°). The derived formulas for initial fragment velocity and interception angle demonstrate universal applicability. This research provides a theoretical basis for rapidly calculating the optimal interception angle between D-shaped warheads and fighter targets.