A slight correction.
It was actually May/1953, not August,
when the [prototype] YP-100 broke the sound-barrier in level-flight.
While the YP-100 was obviously not a production model of the F-100 Super Sabre, the differences between the
YP-100 and the F-100 Super Sabre [as far as the former is concerned] was basically the absence of armament.
Jacob
