Have you ever seen a bird land? As it spreads its wings increasing its drag, slowing the bird down to a swift stop.
There are four main things you must know if you want to fly.
Thrust, Drag, Gravity, and Lift
Thrust, the opposing force of drag, is created by the power of the object, either the jet of an airplane or the figure eight motion of a bird flapping its wings. If the thrust of the object is greater than the drag, the object will accelerate and if the drag of the object is greater than the thrust the object, the object will slow down.
Drag is the force exerted on an object that moves through some type of fluid, either air, water, or even maple syrup. Drag increases if the surface area of the object increases, if the object increases speed, and if the viscosity of the fluid is higher.Like the example I gave before, when a bird prepares to land it widens it wings making them larger, increasing its draft, slowing the bird until it gently lands on the ground.
Gravity, affecting everything in universe, play a key role in flight. Gravity pulls the object toward the earth, causing the object to create more energy to stay in flight.
Lift is the force that opposes the weight of the object being pulled down by earths gravity and perpendicular to the drag of the object. Lift is caused by the enlargement of the bottom part of a bird’s or plane’s wings. Lift becomes higher if the object mover faster, if the bottom area of the wing is enlarged, and if the fluid is thicker (having more viscosity).
As you see a bird land you can see how it turns its wings perpendicular to the ground, turning them in to air brakes. (Airplanes function the same way)