In the course of helping an acquaintance do research for a book, I listened to hours of interviews with an 80 year old aerodynamics specialist who worked for Bo

In the course of helping an acquaintance do research for a book, I listened to hours of interviews with an 80 year old aerodynamics specialist who worked for Boeing for decades. It was fascinating stuff. One of his specialties was the design of the inlets for jet engines and, through the conversation, I learned that the inlet is the entire aerodynamic approach to the actual engine intake, starting before the air even encounters any of the structure of the aircraft. Turns out that certain designs cause turbulence out in front of the aircraft and all of that path to the intake must be taken into account. He referred to the SR-71 inlet design and called the potentially catastrophic disruption of the air an "inlet unstart."