That's not a supersonic propeller, that's a propeller with supersonic tip speeds. A supersonic propeller is a propeller that can work in a supersonic airstream.

That's not a supersonic propeller, that's a propeller with supersonic tip speeds. A supersonic propeller is a propeller that can work in a supersonic airstream. The XF-84H had a top theoretical speed of Mach 0.9, though in testing it was evaluated to be more like Mach 0.83, and even that's disputed, with another estimate being Mach 0.7. It never achieved these speeds. The only plane to fly with a propeller at supersonic speeds was the XF-88B, though that was actually a jet aircraft that just had a propeller on the front for testing purposes - the vast majority of the thrust was still coming from the jet engines.