Supersonic speed motion faster than the speed of sound in a brittle material. At the beginning of the 20th century, the term "supersonic" was used as an adjective to describe sound whose frequency is above the range of normal human hearing. The modern term for this meaning is "ultrasonic". The tip of a bullwhip is thought to be the first man-made object to break the sound barrier, resulting in the telltale "crack" (actually a small sonic boom). The wave motion traveling through the bullwhip is what makes it capable of achieving supersonic speeds. Most modern fighter aircraft are supersonic aircraft, but there
Center of gravity of an aircraft be able to be lowered, resulting in possible loss of control, or the rotor blades striking the tail boom. In fixed-wing aircraft, lateral balance is often much less critical than fore-aft balance, simply because most mass in the aircraft is located very close to its center. An exception is fuel, which may be loaded into the wings, but since fuel loads are usually symmetrical about the axis of the aircraft, lateral balance is not usually affected. The lateral center of gravity may become important if the fuel is not loaded evenly into tanks on both sides of the aircraft, or