50 calibre heavy machine guns with a maximum load of 1,880 rounds of ammunition for all six guns: three fixed guns housed within each wing on either side of the fuselage. The P-51D and P-51K were equipped with a basic armament of six wing-mounted air-cooled disintegrating link belt-fed Browning M2. A fighter pilot’s success is measured not only by how well he flies, but how he shoots. Although its ability to carry bombs and rockets is of great importance, a fighter is primarily a flying gun platform – a means of taking its firepower into the air to destroy enemy aircraft and targets of opportunity on the ground. The main objective of a pursuit airplane, as the designation implies, is to pursue and destroy. Under moisture freezing conditions, or at any time that temperatures and conditions indicate the possibility of carburettor ice, flight should be with the carburettor air control in the ‘Unrammed Filtered Air’ position. This screen will ice over under icing conditions and suction created in the induction system will open emergency doors, located aft of the icing screen, and allow warm air from the engine compartment to enter the carburettor. A hairpin-type icing screen is located in the rear duct section. With the cockpit control in this position, the ram air door is closed and the filter air door opened. However, under moisture freezing conditions, operation should be with unrammed filtered air. The air induction system provides a selection of two kinds of carburettor air: cold ram air and cold-filtered unrammed air. The following information has been gleaned from the North American P-51 Mustang Pilot Training Manual. This aerodynamic modification was implemented on the P-51D and P-51K production lines and the dorsal fin and rudder modification kits were sent to all of the P-51 fighter groups throughout all theatres of war. The NACA-Ames modifications essentially eliminated horizontal tail failures in manoeuvring flight. The dorsal fin eliminated rudder-force reversals in sideslips and had a favourable effect on structural loads. The addition of a dorsal fin, rudder trailing-edge bulges and a rudder anti-boost tab ratio of 1:2 gave it the best overall flight behaviour. This P-51B was tested with nine modifications in thirteen flight conditions in sequence so that the relative merit of each could be evaluated. The modification(s) were to be simple in order to facilitate alterations to aircraft on the production lines and in service. The USAAF AMC requested that NACA-Ames improve the directional characteristics of the P-51 to reduce sideslip excursions in rolling manoeuvres while retaining existing rudder force change with airspeed.

It was decided that in a high-speed rolling pullout, adverse aileron yaw could generate sufficient sideslip to inadvertently cause a snap roll and thus impose large enough stresses to cause horizontal tail failure. These failures had occurred at a time when earlier NACA-Ames flight tests revealed that the Mustang had unsatisfactory directional characteristics, including a reversal of rudder force at large angles of sideslip. Even though manoeuvring and handling characteristics were very good, the horizontal stabilisers of several P-51Bs and P-51Cs had failed structurally during slow aileron rolls. One factory-fresh production P-51B-1-NA (43-12490) was flown to Naval Air Station Moffett Field in Sunnyvale, California, from Mines Field near the NAA production facility in Inglewood, California, and it was placed into the NACA-Ames wind tunnel for aerodynamic testing. To cure the worst of these, in mid-1944, NACA-Ames was asked by the USAAF Air Materiel Command to investigate a rather serious handling problem with the Mustang. Nevertheless, it did suffer from a few aerodynamic flaws that showed up during combat. The P-51 Mustang became a legitimate force to be contended with after it was wedded to the Packard-built Rolls-Royce V-1650 Merlin engine. The P-51D was manufactured at both the Inglewood, California, and Dallas, Texas, facilities while the P-51K was manufactured exclusively in Dallas, Texas. These versions of the Mustang are identical with the exception of their propellers, slight differences in their cockpit canopy shaping and their production factories with a few other minor exceptions. Since the P-51D and P-51K were the definitive versions of the Mustang employed in both the Second World War and the Korean War, this part will focus on them.

P51 cockpit gauges