This year you have probably heard about ‘Deflate-Gate’ as it relates to under-inflated balls used by the New England Patriots during their game with the Indianapolis Colts. This post simply covers some of the physics that could have been involved, and covers how quickly and easily this could be done using the proper technology.
As I write this more information is released daily, so the information here may become dated. I believe it to be current as of Jan 27, 2015. At half time the footballs were checked during the AFC championship game between the Colts and Patriots. 11 of the 12 balls for the Patriots were found to be under-inflated by 2psi. The Colts balls were found to be within league specifications. If that’s true, what does it mean? It means that 2 hours and 15 minutes before the game the Colts and Patriots both turned in 12 balls to the officials for inspection. Those were found to be compliant. At half time, it appears that all 12 of the Colts’ balls were fine and that 11 of the 12 Patriots’ balls were 2psi low.
There are really only 2 possible explanations. The first is that the Patriots inflated their balls and delivered them at a warmer temperature than the Colts. However the temperature difference would likely have been noticed and felt by the referee checking them. Then as the Patriots’ balls cooled down they lost more pressure than those of the Colts: Possible, but doubtful.
The only other explanation then is that the balls were altered after inspection. Want to know how to quickly and accurately deflate a football/basketball/soccer ball? Purchase a gauge like the one shown to the right. It reads pressure and has an integrated pressure relief valve. As an engineer I wondered how quickly and accurate we could alter the pressure of a ball? We found that with the right technology (one easily affordable by a team with the net-worth of an NFL franchise) we could reduce the pressure of a ball in about 10 seconds and be moving onto the next ball.
So why do we have such a gauge? Well, in our business accuracy is important and so is consistency. We use this gauge to check the pressure of the basketballs and soccer balls during sport surface testing. It is an integral part of our testing and inspection program.
Added: 1-27-15: One more note: Ever wonder why that 12th ball might not be low? It could be that the kicker does not like the ball 2psi below league spec.