Not to worry, this idea will go nowhere in the US. Open rotor engine airliners were already tried in the US in the 1990’s, and the airlines said no thanks. Same reason the Q400 and the Saab 2000 went nowhere, American airline passengers will not ride on anything with a prop. And voters will not tolerate an airplane that sounds different than a jet whether or not it is any louder or it makes noise limits. Ask any airport that has banned the Piaggio Avanti turboprop(Santa Monica, Ocean Reef).