THE GUNSIGHT VIEW
During its career, the P-38 was equipped with a variety of optical gunsights, including the Army/Navy N-3 in the P-38F through J-5 models. It was a simple reflector sight that projected a 30-mil circle around a center aiming dot or "pipper." From the P-38J-10 onward, a redesigned windscreen required a new sight and mount and that led to the Lynn Instrument Company's L-3.
All U.S. aerial sights were based on the mil system, in which one mil equals one foot at a 1,000-foot range. The 30-mil circle was useful for range estimation, as a typical single-engine fighter's wingspan was 30 to 35 feet, which filled the aiming reticle at a boresight range of 333 yards. Most Bf 109s spanned 33 feet; Zeros and Oscars spanned 36 to 37 feet. Bettys measured 82 feet; at 30 mil they ranged less than 100 yards. The IA sight, however, used a 50-mil ring with a larger pipper. After the L models had begun to carry launch rails, the L-3 also included stadia lines below the ring to compensate for rocket trajectory.