In the second and third powered Flyers, the brothers strived to perfect their invention. By 1905, they solved the remaining aerodynamic problems and could bank, turn, circle and perform figure eights, all with ease and safety, while staying in the air for over 30 minutes at a time. This Wright Flyer III was the world's first fully practical powered airplane. Two of the forces, lift and thrust, help an airplane go up and stay up in the air. The other two forces, gravity and drag, work against an airplane from getting up or staying up.
Gravity pulls a plane down and works against lift which pulls it up.
Drag slows a plane down and works against thrust, which moves it forward. Lift occurs when air passes over and under a wing. Because of the wing's shape the air pressure over the top of the wing is less than the pressure underneath the wing. The stronger air pressure under the wing lifts it up. Thrust is made by a propeller, a jet engine, or a rocket motor.