"There's nothing like it out there," says Retired Commander Bill "Doc" Shoemaker, chief test pilot for Boom Supersonic, the startup aiming to make a passenger airliner for transoceanic flights at speeds (as you might guess from the name) faster than sound. Shoemaker, a former Navy aviator, fighter pilot, and aeronautics engineer, will have the daunting privilege of being the first to fly the company's proof of concept single-seater during tests next year....