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Science of the Long Bomb

Researcher studies spin of the 'Hail Mary' pass

FRIDAY, Sept. 7, 2001 (HealthDayNews) -- In 1975, Dallas Cowboys quarterback Roger Staubach threw a 50-yard bomb to receiver Drew Pearson, who caught it and stepped into the end zone for a winning touchdown in the last 24 seconds of a divisional title game against the heavily favored Minnesota Vikings.

When sportscasters asked Staubach how he did it, he said he offered up a Hail Mary and threw the ball. Thus, the "Hail Mary" play was born, and it's now football legend.

It was a heavenly moment in sports history that had an inadvertent result. It motivated William J. Rae, professor of mechanical and aerospace engineering at the State University of New York at Buffalo, to spend the next 26 years thinking about and studying what makes a football curve to one side when it is thrown in a long, arched forward pass.

Rae, who teaches the dynamics of aircraft flight, relies on the "Hail Mary" pass to keep his students from falling asleep while he explains the principal of gyroscopic torque. He starts the lesson with a videotape of another Staubach "Hail Mary" pass, this one in a game against the New York Giants, showing students frame by frame how the soaring ball curves gently but inexorably.

The aeronautical lesson boils down to this: An interaction occurs between the gyroscopic torque, which, thanks to gravity, is present on any spinning body, and the aerodynamic torque caused by wind rushing over the football, blowing harder on one end than the other.

The result is that one tends to cancel the other. "Nature wants to zero out the sum of those two effects," and that causes the football to head straight for the numbers on a well-positioned receiver's jersey, says Rae.

That would be the end of it, except that some quarterbacks are left-handed and some are right-handed, and therein lies the curve. To measure this effect and complete his research, last month Rae placed a football fitted with sensors into a wind tunnel. After measuring the passage carefully, Rae concluded what football fans might have suspected intuitively: When a right-hander throws the ball, it curves slightly to the right -- about two feet on a 50-yard pass. When a lefty throws, it moves the same distance in the opposite direction.

Staubach, a two-time Super-Bowl winner who now runs an international real estate company based in Dallas, laughs a little at the notion that science is spending much time on this. As a former engineering student at the U.S. Naval Academy before joining the National Football League, he had his share of physics lessons.

"The only formula that I was ever concerned about as a quarterback is force equals mass times acceleration," the Hall-of-Famer says. "That means the big, fast guys can hurt you more than the small ones."

Rae doesn't take himself too seriously, either. Although his research was funded in part by Wilson Sporting Goods, he's unsure what exactly it will mean to the sport of football. "Athletes seem to know these things instinctively," he says.

On the other hand, the research has given him an enormous advantage at home. "When I'm sitting in front of the TV on Sunday afternoon, and my wife asks me to do something else, I tell her, 'I'm not just watching football, I'm doing research.'"

What To Do

Football is on the minds of a lot of people now, especially since the 2001 professional season kicks off Sunday.

Go to the National Football League to find schedules, trivia, and lots of other information for this and seasons past. You also can see the Pro Football Hall of Fame's cyber-entry on Roger Staubach.

SOURCES: Interviews with William J. Rae, professor of mechanical and aerospace engineering, University at Buffalo, the State University of New York, and Roger Staubach, the Staubach Co., and former quarterback, Dallas Cowboys
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