Wing loading The amount of weight an airplane can carry while flying is proportional to the size of its wings; the wing loading is the weight of the plane divided by the area of its main wing, in the units of kg/m 2 for the SI, and lb/ft 2 for the imperial system. During the 1920¶s the wing loading of the planes were limited by the poor design of the wings, the slow stalling speed (which were around 40-50m/h), the small lift coefficient (approximately 1), that led the wing loading to around values of 24-48kg/m 2. Later as they starting building airplanes with more powerful engines they could increase the stalling speed, thus the wing loading as it¶s related to the square stalling speed times the maximum wing lift coefficient. In the WWII there were many improvements made since the countries wanted to develop planes that were capable of carrying its military weapons and of course this stopped them reaching high stalling speed, although they manage to increase the maximum lift coefficient to values around 1.8, and still the modern aviation technology rounds that lift coefficients which is limited by the stalled angle of attack. The wing loading is a very important factor to consider in the design of an airplane because it affect directly to the: takeoff and landing speeds, the cruise speed and its effectiveness,the behavior during turbulences, and on the maneuverability of the turns. The velocity in which an aircraft can take-off is denoted by the lift force and the area of the wing, thus increasing the area of the wing will result in an increase of the lift force and areduction of the wing loading which helps the plane to take of at a lower speed. The same principle applies in the landing, lower speed in landing results in comfort for the passengers and more control to the pilot.Flaps also play an important role in the landing and take-off for plane, creating more drag to reduce the velocity and increasing the lint coefficient respectively. respectively. The effect of wing loading in the cruise is more controversial because on one hand a lower wing loading helps improve the performance of the aircraft because less thrust is needed to maintain a flight level, but on the other hand a big area of the wing produces more drag and these results in a lower cruise speed of flight.
When flying in turbulence, a low value for the wing loading results in rough ride since there is more area of the wing that interact with the different air densities, which can be overcome flying at higher altitudes. Fighter planes have the advantage here because they always try to reduce the area to avoid detection of radars, but this also punishes the amount of weapons they can carry. During turn maneuvers wing loading plays an important role, aircrafts with low wing loading values are more capable of doing tighter turns and maintaining them using less thrust. This may not be very important for commercial aircraft, but is indeed for fighter planes, although they overcome it with the high power engines. Some values for different planes are shown in the following table: Aircraft
