Aerodynamics and Propulsion Principles Coursework - 2

Aerodynamics and Propulsion Principles - Coursework Example An example of using this technique is Bell X – I which is the first airplane to break the sound barrier. The achievement of this amazing feat, considered impossible until then, is attributed largely to its ‘super thin wings’ (Bell X-I). The supercritical airfoils differ from the conventional airfoils such that they have comparatively flat at the top. Their unique design limits the rise of drag forces even after the critical Mach number is reached. Such airfoils have successfully been utilized in TACT aircraft program run by NASA Dryden Flight Research Center (Cury). The figure shows the above-mentioned control surfaces and the functions they perform. All the control surfaces work on the principle of creating drag for the incoming wind thereby changing the direction of the wind. Due to this change in velocity, a momentum change occurs which causes a force to act on the control surface and the desired movement of the aircraft is achieved this way. The ailerons tilt the aircraft around the longitudinal axis. They are always installed in pairs. The opposite motion of the two ailerons creates a couple which acts on the longitudinal axis to cause the desired motion. Anderson defines static stability in these words â€Å"If the forces and moments on a body caused by a disturbance tend initially to return the body towards its equilibrium position, the body is statically stable†. Hence a statically stable plane will be that aircraft which can maintain a continuous balanced flight with a constant angle of attack. In case of a wind gust causing the angle of attack to increase, the resultant center of pressure (the point where resultant lift force acts) will shift forwards from the center of gravity of the aircraft and a resultant moment will act that will restore the initial position of the aircraft.