How did the largest flying animal hover in the air?

The Quetzalcoatlus northropi was the largest flying animal that ever lived. The huge pterosaur existed during the Late Cretaceous period, around 66 million to 68 million years ago.

The mass of Q. northropi is believed to have been between 65 and 260 kilograms and its wingspan was estimated to have been over 10 meters. Using this information, Scott Lee developed a lesson plan to determine the physics of the pterosaur’s hovering flight.

“In terms of flight, the bigger it is, the more dramatic it is,” said Lee. “It’s just mind-boggling that such a large animal could fly.”

While animals in flight can be difficult to model due to fluid dynamics, modeling the physics of a hovering creature is much easier to understand.

“As an animal is hovering, gravity is trying to accelerate it down, so there must be an upward force of the same magnitude,” Lee said. “The way it generates that upward force is using its wings — it moves air downwards, giving the air a downward linear momentum. Conservation of linear momentum results in the upward force on the wings.”

From there, the students can determine the geometry of the wings, the amount of air it pushes down per stroke, and how often it must flap its wings to stay hovering.

The equations can also be applied to a range of flying animals, including another extinct creature, Meganeurites gracilipes, the world’s largest known flying insect.

The lesson plan is a part of Lee’s larger course called “Jurassic Physics,” which is aimed at non-scientists. While Lee is now retired, he plans to continue to publish lessons from his course to spread the joy of learning physics.

Source: “Hovering by flying animals: how often did Quetzalcoatlus northropi, the largest pterosaur, flap its wings?,” by Scott A. Lee, The Physics Teacher (2025). The article can be accessed at https://doi.org/10.1119/5.0223350 .