Which experimental aircraft broke Mach 3 but disintegrated due to frictional heating?

The X-2 is recognized for breaking the Mach 3 barrier, achieving a speed of approximately Mach 3.2 during its testing. One of the significant challenges it faced was the extreme temperatures resulting from frictional heating at such high speeds. This heating caused structural integrity issues that ultimately led to the aircraft's disintegration during its test flights.

The engineering and material limitations of the time made it difficult to manage the heat generated by the air friction at supersonic speeds, which was a critical aspect of flight testing at those velocities. In contrast, while the X-15 also achieved impressive speeds and altitudes, it was not the aircraft that specifically disintegrated due to frictional heating, as it utilized different materials and design considerations that allowed it to withstand extreme conditions. The X-29 and F-104 Starfighter, while notable aircraft, did not achieve speeds in the Mach 3 range nor did they suffer from the same heating issues leading to disintegration.