Why could early stealth aircraft not fly at supersonic speeds?

Early stealth aircraft were unable to achieve supersonic flight primarily because they lacked the necessary propulsion systems. To minimize their infrared signature and avoid detection, first-generation stealth aircraft were not equipped with large, heat-producing afterburner engines.1

Furthermore, the design requirements for stealth often conflicted with optimal aerodynamics. To reduce radar cross-sections, these aircraft utilized unconventional shapes—such as the flat, faceted surfaces of the F-117A or the complex curves of the B-2—which necessitated sophisticated artificial stabilization systems to maintain satisfactory flying characteristics. These design constraints, combined with the need to carry all weaponry internally, meant that early stealth platforms prioritized radar evasion over the high-speed performance typical of conventional supersonic fighters. It was not until the development of second-generation aircraft, such as the F-22 Raptor, that technology allowed for "supercruise," enabling supersonic speeds without the use of afterburners.1