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What Makes Airplanes Fly?

By JETechnology Staff

It’s fascinating to think that it was only a little over a century ago — on December 17, 1903, to be exact — that Wilbur and Orville Wright first flew their heavier-than-air powered airplane at Kitty Hawk, North Carolina. Within a few short years, they patented their flying machine — U.S. patent 821,393 — and claimed their rightful place in aviation history.

Back then, it would have been next to impossible for the Wright brothers to fully conceive the impact their invention would have. In terms of the sheer amount of today’s commercial air traffic, the numbers are staggering — the National Air Traffic Controllers Association estimates that it tracks over 87,000 flights in American airspace each day.

How Do Planes Fly?

The simple question “How do planes fly?” still leaves many people scratching their head for a proper explanation of the dynamics of flight. It’s a question that has captured the minds of great thinkers for centuries. For instance, consider the drawings of Leonardo da Vinci’s flying machines, where we can see the clear influence winged animals had on his theories of flight.

What’s so important to understand about the physics of airplane flight is that everything that flies — from an Airbus A380-800 to a paper airplane — obeys the same laws of physics. And once you examine the forces that combine to give birds, prop planes, jets and even helicopters the ability to fly, you can comprehend how something that’s heavier than air can still take to the skies and fly with perfect control and reliability.

What Are Flight Dynamics?

There are four primary forces to consider when explaining flight dynamics — weight, thrust, drag and lift. Let’s first look at each force individually, then see how they combine to give an aircraft its ability to fly.

  • Weight: The force of gravity that brings you squarely back down to ground level after you jump up is due to weight. Every aircraft designer must consider this factor when attempting to fly. Too much weight, and it won’t get off the ground. Too little weight, and it won’t be controllable for the pilot.
  • Thrust: Typically, thrust is the forward-moving force — or momentum — produced by a plane’s engine. It's usually accomplished via either a propeller or a jet engine. While these are two vastly different forms of propulsion, their end results are the same — they move a plane forward. Note that thrust is a major reason that most unpowered gliders must first be towed by powered planes — so that upon release, they have sufficient forward speed.
  • Drag: A plane’s size and shape are responsible for displacing air as it moves. This force of resistance is known as drag. Imagine walking through waist-high water with your hands at your sides — you can feel drag as your body displaces water molecules while you move forward. If you cup your hands and close your fingers, you can even feel how drag is increased. Similarly, if you’ve ever watched the flaps on a plane’s wing extend during landing, you’re seeing proof of drag — those flaps help slow the plane’s forward momentum.
  • Lift: When an airplane’s forward motion overcomes its drag and air moves at speed over its wings, lower air pressure is created above the wings, resulting in lift. While helicopters don’t operate the same as fixed-wing aircraft, their rotary blades still tilt, which results in lift as well. The fact that most wings are designed to move air faster over the top of the wing is what helps create greater air pressure under them — which results in a pressure difference that moves the plane upward.

Has this brief explanation of what makes planes fly helped you appreciate the importance of a well-maintained fleet? For more information on what equipment ground personnel count on to keep today’s airplanes in top flying condition, contact us today.