Climbs

An airplane climbs when its engine or engines produce more power (thrust) than is required to maintain level flight at a particular weight and angle of attack. Airplanes do not climb because the wings generate more lift.

This point may seem confusing, but it makes sense if you remember that whenever an airplane is in steady-state flight—for example, a climb at a constant airspeed and rate—lift equals weight. If lift exceeded weight during a climb, an airplane would accelerate upward.

A Steady Pull

During a steady-state climb, the component of lift acting vertically toward the ground is actually slightly less than weight, because when the airplane is in a climb attitude, some of the lift vector is directed rearward, not upward. So a climb is caused by the thrust vector pulling the airplane up at an angle. Imagine someone tugging a sled up a hill, and you'll get the general idea.

More Power

If power determines rate of climb, then it's apparent that the throttle, not the control yoke, is the primary "up-down" control in an airplane. Pulling back on the yoke to increase an airplane's pitch attitude usually does start a climb. But an increase in induced drag quickly counteracts the boost in lift, and the airplane, having gained a little altitude, settles into level flight at a lower airspeed or into a slow, constant-rate climb.

To establish and maintain a steady rate of climb, excess thrust must be available, and you must add power.

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