Birds in the Sky: Understanding the Physics of Flight

Posted by Stacey Venzel
bird flying

Airplanes were modeled after birds for a reason.

Experts in the sky, birds mastered the art of flying long before humans. And they did it with just their feathers and bones.

Every aspect of a bird, from head to toe and inside out, evolved to aid in aerodynamics. Avians master four major concepts of flight in order to flap their wings overhead: weight, lift, thrust, and drag.

birds flying


For starters, hollow bones make birds literally light as a feather. The heavier something is the more energy it takes to maintain in flight. But nothing is weightless, and so gravity is still working against lightweight birds in the sky.


Lift counters gravity, but must be generated strong enough to combat weight. This is where wing flapping comes in, forcing wind to glide over the interlocking barbules of a feather.

Birds can decrease the amount of lift exerted by reshaping their wings into a downward V, called a negative dihedral. When both wings are pointed upward in a V, this is referred to as a positive dihedral. A negative dihedral will allow a bird to return to the ground.

Thermal lift is effectively called soaring. Birds take advantage of these pockets of warm air based on the principle that heat rises.

flying birds


Forward motion--think long jumping--is called thrust. Birds accomplish this by pushing their wings not upward, but backward. Thrust fights drag, the force working against it to bring something in flight back down to earth.


Everything in motion meets with friction, even in the air. Drag is the result of friction. The aerodynamic streamline shape of a bird and plane decreases the amount of drag.

While the physics of flight can get much more complicated, these are the basic tenets of how an animal defies gravity and friction.

Feathers, too, aren't just pretty to look at. They serve a purpose from flight to mating to camouflage and insulation.

Did you learn something new about birds? What other avian questions can we answer? Tell us in the comments below!

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Birds in the Sky: Understanding the Physics of Flight