The Science Behind Stunt Flying

The Science Behind Stunt Flying

To fully appreciate the magic happening overhead during an air show routine, it’s important to realize that stunt flying is not magic at all, but a science.

The maneuvers the pilots are executing are the result of years of rehearsal, training, and careful aircraft design. But how does that happen? Smartphone videos usually aren’t enough to fully indicate what’s happening in the sky, not to mention the cockpit. But a bit of knowledge can contribute a great deal to understanding and enjoying the show unfolding overhead, whether from a single pilot or a well trained team or troupe. Here’s a look at the science behind stunt flying.

Beyond Straight and Level

It didn’t take long after basic human flight began that aerobatics followed soon after. It should come as no surprise that the Wright Brothers, bicycle builders by trade, distinguished  themselves as among the first aerobatic pilots, wowing spectators and fellow engineers with the ability to bank and turn the Wright Flyer using ailerons. While this doesn’t sound very exciting, or even like a stunt, to us—airliners do it every single day, on just about every single flight—it was a game changer in aviation even as the world was still grasping the importance of aviation itself.

Ailerons (“aileron” is “little wing” in French—and that’s just what it is) are now considered expected parts of a modern airplane. Even the most basic training aircraft boasts ailerons. The ubiquity of them in the 21^st century, however, masks what an important innovation they were in the early history of aviation and in aerobatic flying. By closely studying the action of birds on the wing at the North Carolina coast and applying their knowledge of how a bicycle banks, the Wright Brothers were able to design flaps that operated in opposition to one another to guide the direction of the airplane.

Ailerons are horizontal “baby wings” or flaps mounted on the outer part of the wings of an aircraft. They are “the wings of the wing.” When the pilot needs to bank the aircraft, he or she doesn’t make a perpendicular turn as we might while walking. The physics of airplanes don’t work quite so quickly.

The pilot uses the ailerons to initiate a rolling action. If he or she raises the left aileron, the right one goes down. Raising the left aileron lowers the right one. This imbalance of airflow means that the airplane will begin to bank. Disrupting the airflow over the fuselage and control surfaces of the aircraft results in controllable motion. What first seemed a source of entertainment was actually a quantum leap development in airplane design, not long after the first powered flight had taken place.

Loops

Spins, vertical flying, rolls, and large loops quickly became part of touring air shows once the public became used to the incredibly reality of human flight. Pilots from the United States, Russia, and Europe, particularly France, offered exhibitions for fees not only at air meets, but local fairs and festivals.

A member of the Russian military, Pyotr Nesterov, was the first to successfully perform a loop in 1913. Unlike the tighter loops which jet airplanes, particularly military ones, can perform today with thrust vectoring, these traditional loops were much wider due to the airplane’s need to build up enough speed to push the craft over the upper arc of the loop.

But it took an American, Lincoln Beachley, to refine the maneuver into a business. He asked aviation designer Glenn Curtiss to configure an airplane specifically maximized for loops. By the time he was done with it, Curtis was charging $500 per loop at air shows.

What enabled the astounding payday? Allowing gravity to work. Modern loops are performed much the way they were in early aviation. What’s known as an “inside loop” begins with level flight. Pilots direct the airplane in order to build speed, usually about 20 knots faster than usual cruise speed. The pilot then pulls the stick back, relaxing it at the top of the loop to avoid stalling. Gravity then begins to bring the airplane back down out of the loop. The pilot then returns to the stick in order to level the wings. “Normal” flight then resumes.

During the procedure, the pilot experiences G-forces. The frame of the airplane must be sturdy enough to withstand this, but light enough to leave the ground and maintain maneuverability. Concentrating on these factors enables many aerobatic maneuvers. Stunt flying pioneers like Beachey were able to provide further refinement with such arrangements as placing the cockpit behind the motor rather than towards the front of the airplane. Doing so allowed him or her to become more accustomed and in harmony with the whole of the craft.

Thrust Vectoring

In the 20^th century, many new air show maneuvers were born of a technology designed to allow jets the ability to take off and land vertically or without much of a taxi. Instead, it became useful for superiority and maneuverability in dogfighting. Vectored thrust, or thrust vectoring, is what enables the astounding feats of modern fighter aircraft. It contributes to what’s known as “supermaneuverability.” It is made possible by turbofans which generate massive amounts of thrust.

Without thrust vectoring and the increased speed of jet engines, the following stunt flying favorites would not be possible:

• Pugachev’s Cobra (the jet pulls up to an extremely high angle of attack, past vertical, then returns to level flight)
• The Herbst Maneuver (Pugachev’s Cobra with a roll, so that when the nose returns to horizontal, the jet is headed in a different direction from where it began)
• The Tailslide (slow flight, or performing Pugachev’s Cobra and staying in the position for longer)
• The Kulbit (Pugachev’s Cobra which ends in a backflip)

Thrust vectoring (also known as TVC) is also used in missiles, as well as rockets designed for human spaceflight. It controls pitch in ways which is much more dynamic than in conventional airplanes. While some of the stunt flying maneuvers seen in airshows aren’t tremendously useful in combat, they do make for spectacular social media moments.