Mach tuck
From Wikipedia, the free encyclopedia
Mach tuck is an aerodynamic effect, whereby the nose of an aircraft tends to pitch downwards as the airflow around the wing reaches speeds close to mach one.
At low mach numbers the wing creates a bow wave similar to a ship in the water. The aerodynamic center is the point along the chord where the resultant lift acts. An easier way to think of it is like a CG, but for lift instead of weight. It is the center of lift, aerodynamic center, or center of pressure.
However when the critical mach number is reached the aerodynamics of the wing changes drastically. As the airflow over the top surface of the wing gets closer to mach 1, air begins to compress. The wing no longer makes a bow wave as the air cannot flow around the wing. The air is then compressing on the leading edge. At this point the aerodynamic center moves aft. The resulting moment aroung the CG causes the nose to drop. The resulting moment around the CG is defined as the moment created by the center of pressure balanced by the downward lift force of the tail. This balance is upset as the center of pressure moves aft.
