In the twelfth day of public debate over whether or not a man or a group of men purposely released air from footballs, a CMU mechanical engineering graduate student traveled to Phoenix to join the discussion.
Thomas Healy said the deflated footballs the New England Patriots used during the first half of its defeat of the Indianapolis Colts in the AFC Championship game January 18 could be a result of atmospheric pressure and not foul play.
He is presenting his detailed experimental data to several organizations this weekend before Sunday’s Super Bowl.
Two hours before the AFC Championship game, the 12 Patriots' footballs to be used were inspected and approved to meet the regulation of 12.5 and 13.5 pounds per square inch.
An interception by the Colts’ D’Qwell Jackson prompted a halftime inspection, which determined the balls were under inflated.
The NFL does not keep a log of the psi of footballs, but multiple reports suggest 11 of 12 balls were between 1 and 2 psi under. The NFL confirmed January 23rd that the balls were under inflated and an investigation including more than 40 interviews continues.
In what the media has dubbed, “deflate-gate,” pre-Super Bowl stories are now filled with physics terminology.
The debate seems to be summed up as: did the Patriots tamper with the balls to make them easier to handle or did they lose air in the move from a warm locker room to a cold field?
Academic and research physicists first said the deflation must have stemmed from foul play based on their calculations using the Ideal Gas Law.
But Healy’s experiment found otherwise.
“When you run that equation it’s going to tell you based on temperature change, what pressure change you would see in the ball. But what it doesn’t account for is that the football also became damp,” he said.
Healy and his team inflated 12 NFL regulation footballs in their “hot room”, heated at 75 degrees to replicate the locker room the balls were checked in. The balls then sat in the “cold room” at 50 degrees for two hours, the time they were on the field before kickoff.
The team landed on 50 degrees after averaging temperatures in areas surrounding Gillette Stadium in Foxborough, Mass., where the game was played.
The 25-degree temperature change alone resulted in a 1.07-psi drop. Then the team added water, as it was raining during the game. The combination resulted in a 1.82 pressure decrease, around the same amount the NFL has reported the balls were under inflated at halftime.
So far, Healy said his team is the first to bring in the additional scenario of the rain, which they found also affects the footballs by three-quarters of a pound.
The former CMU punter started an independent lab, HeadSmart, this fall to study ways to better use helmets to prevent concussion.
Some of the lab testing looks at air pressure in football helmets and how they perform at inflation levels. His curiosity of “deflate-gate” led to the experimental study using the HeadSmart lab.
But Healy and his team continue to look at the question left; how were the Colts footballs not affected? He said it’s possible the Colts footballs had been on the field before they were checked by the referees.
“And so if they had been inflated to 13.5 PSI outside in the colder weather and then brought indoors and then brought back outdoors, you wouldn’t see that big pressure change that you would if the football was indoors the whole day and then brought outside,” he said.
Meaning the rain would have been the only real effect on the Colts’ footballs. However, NFL policy is that the officials inspect the footballs of both teams two hours before game time.
The HeadSmart team also found that the pumps heat up the air to a significant temperature and could affect the balls.
“If you take an electric pump, the kind you would plug into the wall, which is the type the NFL teams would use, after the pump runs for a little while, after it heats up for a couple of minutes, the temperature of the air coming out of the pump is actually around 130 degrees Fahrenheit,” he said.
But until Sunday, Healy and his team will be among many of the country’s great scientists debating footballs.
Corrections to this post were made Saturday, January 31st.