text: The fastest World War II fighters were the first aircraft to experience Mach tuck.   Their wings were not designed to counter Mach tuck because research on supersonic airfoils was just beginning; areas of supersonic flow, together with shock waves and flow separation, were present on the wing. This condition was known at the time as compressibility burble and was known to exist on propeller tips at high aircraft speeds.
  The P-38 was one of the first 400 mph fighters, and it suffered more than the usual teething troubles. It had a thick, high-lift wing,  distinctive twin booms and a single, central nacelle containing the cockpit and armament.  It quickly accelerated to terminal velocity in a dive. The short stubby fuselage had a detrimental effect in reducing the critical Mach number of the 15% thick wing center section with high velocities over the canopy adding to those on the upper surface of the wing. Mach tuck occurred at speeds above Mach 0.65; the air flow over the wing center section became transonic, causing a loss of lift. The resultant change in downwash at the tail caused a nose-down pitching moment and the dive to steepen (Mach tuck). The aircraft was very stable in this condition making recovery from the dive very difficult.
  Dive recovery (auxiliary) flaps were added to the underside of the wing (P-38J-LO) to increase the wing lift and downwash at the tail to allow recovery from transonic dives.