How did shock waves near Mach 1 limit the speed of propeller-driven aircraft?

Propeller-driven aircraft faced significant speed limitations as they approached the speed of sound due to the onset of compressibility effects. As an aircraft nears Mach 1, the air flowing over the curved surfaces of the wings and propeller blades accelerates, reaching the speed of sound even while the aircraft itself is still traveling at subsonic speeds.1

When this local airflow reaches the speed of sound, shock waves form on the airframe. These shock waves cause a dramatic increase in aerodynamic drag and a simultaneous reduction in lift. For propeller-driven aircraft, this phenomenon is particularly restrictive because the propeller tips often reach sonic speeds well before the rest of the aircraft, leading to severe efficiency losses, unsteady airflow, and dangerous buffeting that can result in a loss of control.12

While designers of early aircraft attempted to mitigate these effects by using thinner airfoil sections, the fundamental rise in drag in the transonic region made it extremely difficult for traditional propeller-driven designs to overcome the "sound barrier" compared to the high-thrust capabilities later provided by jet engines.12