Staff writers
Who better to explain the aerodynamics of the football than NASA? The very success of every space mission depends on a deep understanding of how objects move through, air, other gases and liquids.
Miniscule alterations in the basic shape of an object will change flow patterns and that has big ramifications for making aircraft more efficient or getting a spacecraft to Mars the fastest way possible.
But as Super Bowl 50 got underway in Levi’s Stadium in Santa Clara, California, the space agency turned its thoughts to football.
“Sports provide a great opportunity to introduce the next generation of researchers to our field of aerodynamics by showing them something they can relate to,” said Rabi Mehta, chief of the Experimental Aero-Physics Branch at Ames Research Centre.
Aerodynamics plays a significant role in all ball sports. Science determines the best way to throw a football, how to make a baseball curve, a cricket ball swing and a golf ball take flight as the dimples in its surface creates turbulence which cuts down drag.
And while the science can be complex, the visuals from the Ames test facilities can be simple and mesmerising.
The researchers at Ames use small wind tunnels and water channels for quick tests of how fluids at known speeds flow over a stationary test item.
Smoke, lasers or brightly coloured dyes make the usually invisible aerodynamics around the items brilliantly visible.
They put a range of sports balls in to see what happened.
“What we are looking for in the smoke patterns is at what speed the smoke patterns suddenly change,” said Mehta.
“There is a thin layer of air that forms near the ball’s surface called the ‘boundary layer’, and it is the state and behaviour of that layer that is critical to the performance of the ball.
“The materials used, the ball’s surface roughness and its distribution determines its aerodynamics.”
Elongated footballs, as used in today’s Super Bowl 50, are shaped like wings, much more aerodynamic than a round ball.
In addition, a quarterback spins the ball when he throws it so that a tight spiral with high rotation rate helps stabilise the ball and to lower drag.
Kicking is also subject to aerodynamics, with the punter aiming at getting the ball to spin along it horizontal axis.
Mehta says that he has taught the science of sports balls to athletes often, using the visual tools of his lab to illustrate aerodynamics concepts.
“The understanding on their faces is remarkable, and that, I find very gratifying.”
