According to my calculations:

An 80 inch prop turning 2,700 rpm has a tip speed of 942.5 ft/s.

An 86 inch prop turning 2,700 rpm has a tip speed of 1013.2 ft/s

Speed of sound at sea level standard day is 1,126 ft/s.

I am unable to reconcile my calculations with your statement. What did I miss?

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