North American P51D Mustang. 5 of these are featured in both books. The Mustang was among the best and most well-known fighters used by the Air Force during WW II. With excellent range and maneuverability, the P-51 operated mostly as a long-range escort fighter and as a ground attack fighter-bomber. The P-51D incorporated several improvements. The most obvious change was a new "bubble-top" canopy that greatly improved the pilot's vision and an increase from 4 to 6 .50-cal machine guns.