Carry That Weight
Weight, or acceleration caused by gravity, is the most familiar of the four forces of flight, because it’s something we encounter each day. In straight and level flight, weight gradually decreases as fuel is burned during flight. Other than that, weight is a constant, at least whenever the airplane is flying straight and not climbing.
But during turning flight, the centrifugal force created during the turn adds to the weight of the plane. In very steep turns, the centrifugal force can double the apparent weight of an airplane. Of course, no mass has been added to the plane, but the centrifugal force caused by the turn makes everything feel heavier.
Manufacturers limit the maximum weight that a plane can weigh at takeoff because of the strength that must be built into the plane’s structure to withstand the punishment of turbulence and harsh handling of controls by pilots.
What a Drag
Lift is a marvel, but it’s not free. For every ounce of lift created by an airplane’s wings and other control surfaces, we pay a price in drag, a force that works to slow the plane down. It is because of drag that we have to equip airplanes with engines to produce thrust (which we’ll get to in a minute). There are two primary forms of drag:parasite drag and induced drag.