How to reduce the amount of air in a football without letting any air out

Ron Gronkowski

Guest post by Alec Rawls

Just fill the ball with warm humid indoor air, then when it temperature-equalizes with the 25°F cooler outdoor air on your AFC Championship playing field some of the water vapor in the ball will condense into water, leaving less air in the ball, solving the great mystery: how did the footballs used by the Championship winning New England Patriots show 12.5 psi of inflation pressure in the official pre-game check but only 10.5 psi when checked at halftime?

There is also a decrease in pressure due to the cooling of the molecules that remain gaseous. Those air molecules are not zipping around as fast as they were so they exert less outward pressure on the ball. But according to the ideal gas law, if there were no reduction in the number of gas molecules in the balls it would have taken a large drop in temperature, about 40°F, to cause the observed drop in air pressure. So says Boston College professor Martin Schmaltz:

In order for a ball to register a 10.5 PSI in a 50 degree environment [the temperature on the field at halftime] but register a 12.5 PSI in the testing environment, the ball would have to have been inflated, stored, and/or tested in a 91 degree environment.

I verify Schmaltz’s calculations at the end of this post, and while I’m no expert in the field, I get the same answer he does.

It wouldn’t be hard to deliver balls to the pre-game pressure check with 91° air inside. Just inflate them in a 100° sauna shortly before testing, but the Patriots are adamant that they do not know why the air pressure in their balls was low at halftime and if they had inflated their game balls in a sauna they would certainly know it.

The Carnegie Mellon experiment

An experiment performed by a team at Carnegie Mellon provides empirical support for the Patriots’ claim to have done nothing unusual. The Carnegie experimentalists inflated a batch of footballs to 12.5 psi at a room temperature of 75°F, then let the balls equalize to a new ambient temperature of 50°F, resulting in an average pressure drop of 1.8 psi. (They also wet the leather balls to simulate the rainy conditions of the game, surmising that this might allow stretching that would reduce air pressure in the ball, but this seems likely to be a minor factor.) The Carnegie experiment is video-documented here:

So how to account for the difference between the Carnegie findings and the ideal gas law, which predicts that a much larger decrease in temperature would be needed to create the observed pressure drop? Barring experimental error, it seems that the difference would have to be explained by condensation. Gas was removed from the ball, not via an inflation needle but by conversion to liquid water. What do our blog-reading experts say? Is this the likely explanation?

The Carnegie group was not monitoring humidity (at least in the short video above), but if this is the explanation for their greater-than-ideal pressure drop then it could easily have happened to the Patriots the same way without anyone intentionally manipulating the inflation temperature or humidity.  Still…

It must be common knowledge around the league that indoor inflation yields a softer game ball

The fact that the Colts’ balls did not show a similar pressure drop suggests that teams do know how to make these manipulations. Just as Patriots’ quarterback Tom Brady prefers to throw a less inflated ball, other quarterbacks

are known to prefer harder footballs.

If Colts quarterback Andrew Luck prefers a harder ball then all the Colts had to do is fill their balls pre-game with cool outdoor air. Ambient outdoor temperatures actually rose from pre-game to halftime so the temperature effect would have made their balls firmer. Also, moisture beyond what the cooler air could hold would never have made its way into the ball in the first place so wouldn’t there be any pressure-reducing condensation inside the ball either.

Players and equipment managers would surely have noticed over the decades how the conditions in which balls are inflated to regulation pressures affect ball firmness on the field. The basics are hard to miss. In cold conditions, inflate outdoors to get a firm ball, indoors to get a softer ball.

The existing pressure-test regimen, intentionally or not, leaves this room for teams to manipulate ball pressure to suit their preferences. The rule just says that air cannot be put into or removed from the ball after the pre-game pressure check. It does not regulate the conditions in which the balls are inflated going into the pre-game pressure check.

“Belichick rules”

If Coach Belichick had exploited this loophole to the max by inflating balls in the sauna then there would be a legitimate question whether this rule-bending constitutes cheating and there is plenty of history, both recent and ancient, to indicate that Belichick is eager to wring every advantage out of a loophole that he can. Where others may see exploiting loopholes as cheating, Belichick sees it as part of the game.

By the time he is done the NFL rule-book will contain at least a few “Belichick rules,” closing the loopholes he has so nicely pointed out, most recently by confusing the Baltimore Ravens about which Patriots players were eligible to receive passes. “It’s not something that anybody has ever done before,” complained Ravens coach John Harbaugh, “I’m sure the league is going to look at it and make some adjustments.”

Belichicks’ reward (besides a trip to the AFC Championship): he is now tied with Tom Landry for the most post-season coaching wins in league history, to which I say GO PATRIOTS! (That’s what you call “full disclosure.”)

But the full explanation in the present case seems to be that the Patriots filled their game balls with indoor air. If that is manipulation at all it must be utterly commonplace and well within the rules.

The biggest loser: Bill Nye, the phony-science guy

While real scientists keep acknowledging that the move from inside to outside can cause a substantial drop in football psi, Nye went on national television to proclaim that air must have been taken out of the balls with a needle. So that’s good anyway. Half the Northeast now knows that Bill Nye is an idiot.

Addendum: Gas law calculations

I was looking up how to calculate the expected pressure drop in a ball for a given temperature drop when I came across the claim from Boston College physicist Martin Schmaltz that, following the ideal gas law, temperature inside the balls would have had to be 91°F during the pre-game pressure check to account for the 2 psi drop in air pressure by halftime. In the exercise below I come up with a similar answer but I have no background in this stuff and am just following readily available information so don’t take my explication on authority (and please do note any inaccuracies in the comments).

When the number of gas molecules in a container is fixed (no gas escaping out through the bladder and no gas converting to liquid via condensation) then the ideal gas law simplifies to the general gas law, also called the combined gas law. Like the ideal law, the general law is said to be close to accurate so long as extreme pressures or temperatures are not involved. Mathematically, the general law just says that gas temperature, volume and pressure all vary in direct proportion to each other:

(P1V1)/T1 = (P2V2)/T2, where P1 is pressure at time 1, V1 is volume at time 1, and T1 is temperature at time 1.

In plain language, for the gas pressure in the Patriots’ footballs to drop by 7% the general gas law says that the temperature of the air in the balls must drop by 7% or the volume inside the ball must increase by 7% or there must be a combination of percentage changes in temperature and volume that add to 7.

The problem can be simplified further by assuming (as Professor Schmaltz does) that the volume of the space inside the football remains constant. (This won’t be fully accurate. When pressure in a ball drops the volume inside the ball will drop a small amount. This shrinking of the ball will make pressures higher in the low pressure state than they would be if the ball didn’t shrink so the constant-volume estimate of the temperature change required to account for the observed pressure drop will be a bit on the low side, unless the Carnegie experimentalists are correct and there is an offsetting increase in volume when the balls get wet.)

With fixed volume the general gas law becomes:  P1/T1 =  P2/T2

All of these numbers are known except for T1, the temperature of the air in the ball when it was first tested 2 hours before game-time. The known numbers just have to be converted from relative to absolute form.

First, the inflation pressures measurements are in pounds per square inch above atmospheric pressure, thus to get the full pressure inside a ball it is necessary to add atmospheric pressure (about 14.7 psi) to the measured psi.

Also, the gas law is based on degrees above absolute zero, which for Fahrenheit-sized degrees are “degrees Rankine,” which are Fahrenheit + 460. Solving for T1 in degrees Rankine:

T1 = (P1 x T2)/P2 = ((12.5 + 14.7) (50 + 460))/(10.5 + 14.7) = (27.2 x 510)/25.2 = 550.5°R = 90.5°F

Which rounds up to Professor Schmaltz’s 91°F.

Calculations for the Carnegie-Mellon experiment

In the Carnegie-Mellon experiment the expected post-equalization ball pressure, calculated just using the general gas law (where no gas is lost to condensation), is:

P2 = (P1 x T2)/T1 = [(12.5 + 14.7) x (50 + 460)]/(75 +460) = 25.9 psi

Subtract atmospheric pressure (14.7 psi) to get an expected pressure test reading of 11.2 psi, vs. actual experimental readings of 10.7 psi. The suggestion here is that the additional pressure drop found in the Carnegie experiment is a result of water vapor condensation.

If the Carnegie experimentalists were careful they would have compensated for the pressure drop that comes from energizing their pressure tester but game officials (who measured halftime pressure as 10.5 psi) might well not have taken this source of pressure loss into account. If they had the then the difference between their measured pressure drop of 2 psi and Carnegie’s measured drop of 1.8 psi might disappear.

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254 thoughts on “How to reduce the amount of air in a football without letting any air out

  1. <rant on>
    Oh give me a break. It doesn’t take CMU students (I’m CMU BSEE ’72) to do the experiment, some vo-tech students in eastern Mass did that.
    It doesn’t take Neil DeGrass Tyson to do the math (he flubbed it any way), it’s just high school physics. I’d even forgotten that direct proportion between temperature and pressure was named Guy-Lussac’s law. No need to invoke PV = nRT, just P = constant × T.
    Invoking condensation is interesting, but not necessary.
    And I’m tired of the @$&$ subject…..
    </rant off>

    • Ric. I know what you mean about being tired of the subject. I don’t like any kind of games. The great thing about it was it did expose Bill Nye. Anthony did a good job of that many months ago with the heat lamp experiment but not near as many people saw it. I thought the whole affair did enlighten many people to the wrong notion that things in physics can be boiled down to simple ideas. I was glad to see that an accounting of the air loss each time a pressure measurement is made. I have been surprised that no mention has been made of possible errors of the measuring devices and the reading of the devices. Also the temperature of the balls could have been raised signicantly by hand rubbing to roughen the surface.

      • “The great thing about it was it did expose Bill Nye.”
        And to prove that he is all about perception, lacks knowledge/education in real(atmospheric) science, objectivity and ethics/honesty, this gifted performer made a fraudulent video to prove he is right about the ideal gas law science that he is blatantly wrong about.
        http://www.avclub.com/article/bill-nye-also-investigates-science-deflate-gate-214608
        Then, he used it to pitch/appeal to people to get behind his other fraudulent “climate change” atmospheric science.
        The video is consistent with his knowledge about another gas, CO2. Clearly it’s greatly benefiting life on this planet………..while he uses his position as a celebrity and perceived scientific expert to state and promote complete scientific falsehoods about its effect on weather and climate.
        For the record: I’ve been an operational meteorologist for 33 years and Bill Nye’s communicated understanding of the atmosphere makes him either delusional or he represents the diabolical side of human beings that will use their powerful position to intentionally lie in order to influence as many people as possible to advance their fraudulent, personal agenda.

      • It only comes up when someone complains to the referees – I think the Ravens got grumpy and said something which the Colts picked up on and made a complaint about it. It may result in a change to the way the ball inflation is measured which may make the game marginally fairer (but if each team uses their “own” balls on offence, I am not sure where fairness is an issue here), but it is hardly a scandal.
        Personally, I think this is just anti-Patriot grumbling by the chattering classes who don’t like to see anyone win too much. The Yankees get the same attention, as do Manchester United in the English Premier League. The draft system in football works against long-term domination, but with an organization like the Patriots they will always be there or thereabouts come play-off time.
        P.S. In the interests of full disclosure I am a long-suffering Redskins fan – please have sympathy.

    • Simple physics and actual testing reveals the real scandal.
      Recent news reports reveal that the balls used by the Patriots were not under inflated by 2 psi but only by about 1 psi. The only ball with a 2 psi drop was the one handled by the Colts!![1]
      Repeating the calculations above using a 1 psi loss results in an initial temperature of 69F and not 91F. A locker-room temperature of 69F seems well within normal range. No additional pressure loss due to humid air is necessary.
      Additionally, the written report by HeadSmart™Labs on their ACTUAL testing of 12 footballs indicated an average pressure loss of 1.1 psi due to the inside/outside temperature differential alone and another pressure loss of 0.7 psi due to the wetting of the balls.[2] Natural conditions alone explains “deflategate.”
      The real scandal was the premature conviction and unbridled persecution of the Patriots by the media. This particular scandal continues as the media by-and-large ignores the exonerating testing done by HeadSmart Labs and does not conduct the most basic due-diligence investigations.
      [1]http://profootballtalk.nbcsports.com/2015/01/25/nfl-bears-plenty-of-blame-for-deflategate/
      [2]https://uploads.strikinglycdn.com/files/131228/d8f159cc-99db-47be-b8d1-1828d64dde17/HeadSmartLabs_The_Science_Behind_DeflateGate.pdf

      • “The real scandal was the premature conviction of the Patriots by the media. This particular scandal continues as the media by-and-large ignores the exonerating testing done by HeadSmart Labs and does not conduct the most basic due-diligence investigations”
        This is nearly the same thing with global warming.

      • When you start a compressor and it runs for a while, it will contain hot, moist air due to adiabatic compression– mystery solved. If we know our quarterback prefers softer balls, we wait to inflate them until just before we have to get them checked. We turn on the compressor, wait for it to come up, inflate the balls, then take them to the refs. Two hours later, they are a bit softer— just like our quarterback prefers. No rules broken.

    • Also, when you check the pressure and it is 12.5 psi and then you pull the needle out, a bit of air escapes. Then if the refs. check it, a bit more escapes. Then you take it out to cooler temperatures. So you do lose a bit of air each time you check the pressure. Also, I’m sure tiny amounts escape when a 250 running back falls on the ball and then 1,000 pounds from 3 other players pile on. Those valves can flex and move a bit and you may have small amounts of air escape during a game.

      • All the checks prior to the ref checking are irrelevant, because if your checks cause it to fall below the regulated PSI before the refs check it, it would be illegal.

    • The obvious thing to do here is let the quarter backs inflate (or deflate or abrade it or spit on it or whatever) the ball to whatever condition makes them happy. It’s impossible to police every little detail when the rules were modified in 2006:
      Two of the biggest stars in the league, New England quarterback Tom Brady and Indianapolis quarterback Peyton Manning, formed an alliance to change a rule that had pestered them for a while. Instead of having the home team supply footballs to the opposing offense, which was the existing method, the quarterbacks proposed visiting teams bring their own sets already worked in to their liking to be used on offense.
      Jeff Fisher, the Tennessee Titans coach and co-chairman of the competition committee, said there wasn’t any resistance to the rule, so it was easily passed.
      “The thing is, every quarterback likes it a little bit different,” Brady said. “Some like them blown up a little bit more, some like them a little more thin, some like them a little more new, some like them really broken in.”
      http://articles.sun-sentinel.com/2006-11-28/sports/0611270475_1_new-football-new-england-quarterback-competition-committee

    • Yes, it is a tiring subject an not a very exciting one at that.

      I didn’t really check but has anybody noticed that the amount of air isn’t reduced,?. The air pressure is reduced.

      • Which is why Bill Nye isn’t a technician or scientist, but a reporter.
        I really have to wonder why so much time and effort has been devoted to this issue, but then, not being a sports fanatic, I wonder why anyone would spend ANY time, money, or effort on it.

  2. Since a later report I read indicated the balls were closer to 11.5, this appears to be nothing more than ball inflated in a warm locker room deflating normally when cooled 20ish F. And since there is nothing in the rulebook making this illegal, there is really nothing more to see here. And Bill Nye is a moron.

    • Yes, him too. I wrote him off back when people were still making new episodes of The Magic School Bus.
      I bet Don Herbert (Mr. Wizard) inspired more people to become serious scientists than Bill Nye ever will. Hmm, I wouldn’t be surprised if Bill Nye inspired Michael Mann to become a climate scientist.

      • THANKS Ric for mentioning Don Herbert! As “Mr. Wizard” on his wonderful.TV show (that I still remember was sponsored by The Cereal Instirute) he inspired me as a kid to do electrical experiments and eventualily become an Electrical Engineer and then a System Engineer.
        I loved the “Big Bang Theory” episode a few years ago where Bill Nye, the “Science Guy”, was lampooned by “Professor Proton” (played to perfection by Bob Newhart).
        Ira

      • Don Herbert did not make me want to become a working scientist, but he did instill in me a love of science, which I retain today at age 71. I do not see Bill Nye as filling his shoes and the fact that there are positions in science and technology waiting to be filled is proof of that I think.

    • Oh there is plenty to see here, even if not technically breaking any rule. You may choose to ignore the seedier side to this whole episode. It does not mean other people will do the same.

      • Nothing seedy about it. It’s reading the rules and being extremely clever about your interpretation. The racing world is FULL of stories doing exactly this. If the NFL wants to tie this loose end up, they will add a temperature spec to the psi range. 13 psi +/- .5 at 70F. Done.

      • If intentional but not technically breaking any rules makes Bill Belichick a genius. The whole incident can be completely avoided in the future is the refs are simply in control of the game balls at all times.

  3. > P2 = (P1 x T2)/T1 = [(12.5 + 14.7) x (50 + 460)]/(75 +460) = 25.9 psi
    You’re making the assumption that the 2.0 psi underinflation was made to three places of accuracy. I checked amazon.com a few days ago and now all I see are ads for sports pressure gauges, most of which are real crap. Including those from Wilson, the manufacturer for the NFL balls.
    How was the Patriot’s gauge calibrated? How was the refs? Do the gauges use something decent like a bourdon tube ( http://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Manometer_inside.jpg/200px-Manometer_inside.jpg ) or are they the pencil-style throwaway tire pressure gauges? Does the needle have a peg that stops it before zero so you can’t tell it’s miscalibrated?
    Oh, let’s just leave rant on….. 🙂

  4. I read on a blog where the sports fans have argued DeflateGate to death. There are four from the Boston area who have acted as defense counsel. I don’t think this will ever be solved; an argument for the ages. For sports fans.
    Even I, enumerate I, could discern trouble with some of the statistics presented by plaintiff’s counsel.
    ===============

    • Well this will never be tried in a court of law, but instead in the court of public opinion which usually decides based on emotion and ignorance and rarely gets anything right including electing competent leaders.
      There is circumstantial evidence and Belichek’s past history for Goodell, but it is doubtful a smoking gun emerges unless a staff member comes forward and incriminates Belicek or Brady. In which case that person will never work for an NFL team again.
      Goodell will look for an out on this mess in the same way Belichick looks for loopholes in the rule-book, but will only partially succeed with the Patriots, Goodell, and the NFL looking worse for the wear.

  5. The sauna theory is also my explanation for what happened, and why Belichick, Kraft & company can unequivocally say they did nothing illegal and followed all the rules. You know, like cutting in front of people in a check-out line is not illegal but in poor taste and could start a fight or a scandal as in Belichick’s case.
    Belichick may be the only coach who in a addition to a full compliment of assistant coaches employs a team of lawyers to find out how to skirt, via technicalities, the spirit of rules in the rule book. Whether this is cheating or not depends on how you feel this approach is beneficial to the players and spirit of the game of football.
    As far as Bill Nye, I am not even sure if he knows how to add using a calculator anymore.

    • He very much reminds me of that moron wizard professor Lockhart from that one Harry Potter movie who’s best trick was telling everyone how wonderful he was.

    • Being intelligent enough to use technicalities in the rule book to your advantage simply exposes badly written rules and lends to the brilliance of coaches like Belichick. This is not remotely cheating.

  6. And here I thought Rankin was a family of singers from Cape Breton.
    I would prefer seeing metric calculations, Kelvin, Neutrons and Vulcan’s.
    These kinds of problems were solved long ago for hockey pucks in the Canadian sport known as hockey.

      • The pressure could have been different inside the locker room (or wherever the balls are initially tested) than it was on the field.

    • Yes, slp, barometric pressure changes during the game could have an effect, but it would be very, very small. The fastest barometric pressure might change in a few hours would be a few tenths of an inch of Mercury (Hg). A change of 1.0 Hg is equivalent to about 0.5 psi, so a change of 0.2 Hg would change the pressure by 0.1 psi. That is much less than what might be caused by a temperature change of 25 F, or even expansion due to wetting the balls. Ira

  7. I know that my car tyre (Sorry, Yanks – tire.) pump can get very hot from compressing air. If they ran the inflator for a while then inflated the match balls the air inside could be well above ambient, leading to a large pressure drop as they cooled.

    • And that air, upon leaving the accumulator tank on the air compressor, would experience a temperature drop on expansion.
      I thought about that. It’s a non-starter.

    • I haven’t seen anything about what the balls started at. I’d guess they were slightly underinflated, and only a little was added. OTOH, if they deflated the balls and then filled them with helium (or would argon be better?), then things get really confused because you’d have to account for the pressure in the supply tank and heat gain from the tubing warming the expanded gas.

  8. Gaia has weighed in with the Obama Effect, three feet of frigid obfuscation.
    You see, she hasn’t access to the press, so goes about it her own way.
    ==============================

  9. Hmm. Where does ‘playing the game’ stop and ‘gaming the game’ begin; it’s a very fine line.

  10. If Coach Belichick had exploited this loophole to the max by inflating balls in the sauna then there would be a legitimate question whether this rule-bending constitutes cheating and there is plenty of history, both recent and ancient, to indicate that Belichick is eager to wring every advantage out of a loophole that he can. Where others may see exploiting loopholes as cheating, Belichick sees it as part of the game.

    If it’s not against the specific rules and there is no general rule that “the equipment must be prepared without consideration for any home advantage” then… good on him if he did do it. Clever.
    It sounds like just an accident though. Disappointingly.
    More interestingly, if this is covered by rules than the calibration and maintenance regimes for the ball inflation pumps need to be regulated. At least the referee’s checking devices do.
    Is this why American Football needs so many stoppages? To allow for legal challenge?

    • Is this why American Football needs so many stoppages?
      No. The frequent ‘stoppages’ are provided for those who do not understand the game well, as an intermission of sorts, while they re-read the rules and cogitate on the implications.

      • I was recently reminded of this cricket video, and I am posting it for the sake of all those Americans who do not yet understand the worlds second* most popular sport. I think it will make everything perfectly clear.

        Warning: Australian Language.
        *Association Football is the most popular.

      • I cant watch it either. Grew up on Hockey and Rugby. More action. I especially loved Aussie Rules Football, when they had it on the sports channel back in the 80s here in Canada.

  11. “Half the Northeast now knows that Bill Nye is an idiot.”
    The other half of the Northeast now knows that Bill Nye is an idiot. Half of them knew it already.

  12. It’s an interesting thought. Still, I think the league also checks the footballs for gross weight, – meaning if this scenario is indeed the case, would you see a difference in weight?
    I chalk this one up as a process problem for the league which is easily solveable. Either the league inflates all footballs a certain way and therefore all footballs are subject to the same variables or each football is checked for proper inflation immediately before it’s put in play.
    OR…. it’s a bunch of hooey and applesauce (to borrow a Dave Dameshek line) over absolutely nothing and we can move on with our lives.

    • The weight wouldn’t change as the same amount of mass is in the ball.
      The idea is that the mass changes phases; from water vapour to liquid…
      and so reduces the volume taken up by the water…
      and so reduces the internal pressure.
      But all the mass is still there.

      • A wet ball would weigh more. That water is absorbed on the outside.
        Some of the reporters know so little science that they were reporting it was the actual weight of the ball that changed by two pounds. That really had me tearing out my hair. Imagine playing with a twelve and a half pound football! (They’d get back to the running-game in a hurry,)
        It’s sad to say, but I’ve seen reporters display the same lack of even the most fundamental science-education, when they report about arctic sea ice.
        It is a little like the old Art Linkletter show, “Kids Say The Darndest Things”, except, instead of children, it is reporters doing the talking.

      • “The ball shall be made up of an inflated (12 1/2 to 13 1/2 pounds) urethane bladder enclosed in a pebble grained, leather case (natural tan color) without corrugations of any kind.”
        I suppose one could argue that the bladder itself has to weigh 13+-.5 pounds. Now that would be a game changer!

  13. So, the Patriots filled 11 balls in the sauna to use on normal downs and one in the morning cold to use on kicking plays. No, no skirting of the rules at all – it is all within the letter of the law. It is however in the coach’s usual MO – gain any advantage you can.

    • That’s the MO of every coach on the planet for every team in every sport from the Olympics to Pop Warner, (excepting maybe chess..)
      I believe you are wrong about the kicking ball used for kick-offs. I think those are supplied by the NFL officials. Punting is another matter, too hard and the punter will have a more difficult time catching it, (but so will whoever on the opposing team is catching it). Too soft and it isn’t going to go very far but less chance of the punter fumbling it which is really a much worse thing than a shorter punt.
      Again – if each team is allowed to simply use whatever they wish then it would be fair.

    • Kicking balls are seperated from game balls and marked as kicking balls; not sure the difference though. (Why does AC/DC always play in my head when i read about this rediculous story).
      Inconsistant tools make for a bad carpenter. If they wanted softer throwing balls, then they have practiced this move and practiced with similarly underinflated balls.

      • The difference, is that kicking balls are shipped directly from Wilson, to the referee. My understanding is that The teams are given something like 45 minutes to break them in before the game under direct supervision. No buffing or any of that stuff – just what the kicker can kind of do.

  14. Decent post Alec. Avoiding the moisture issue is the reason race teams (and some tire shops) use nitrogen for tire inflating. The bigger molecule thing is really not significant and it is moisture and it’s ability to swing tire pressure that the race teams wish to avoid.

    • Pressurized Nitrogen (2 x 14 molecular weight) in 4x tires at 42-45 psig is lighter weight than compressed air at the same pressure. Water vapor pressure inside the tires? Well, even industrial N2 is always 100% dry. Fuel mileage testing isn’t done cheaply, but it IS taken very, very seriously. And
      Not a lot of weight I grant. But the federal demands (er, extortion) reward every 1/2 pound removed from the car … One reason so few cars now have a full-sized spare, and why run-flat tires are encouraged by the car manufacturers. Less weight, less volume outside the interior. And, if the tires are filled with nitrogen, the consumer has to return to the $dealer$ to get the tires refilled with $nitrogen$ …
      Does it really matter? No.
      Besides, after the car model is tested and certrified by the federal bureacrats, it will NEVER be tested again for fuel mileage, and 80% of consumers are going to (1) refill the tires with air if (2) they refill at all and then (3) they will let the tire pressure go doqn to 20-25 psig, then refill. Maybe.

      • So to solve this the NFL just needs to adopt run flat footballs. Now what to do with all the stuff my wife keeps in the van?

    • Well, except from what I’ve heard, the ones used on kicking plays are not the ones provided by each team. Meaning none of the 12 Patriot balls would be used on kicking plays.
      If so, wonder why all 12 balls were not the same pressure?

      • There is a rumored reason for the 12th ball being different, but I’d rather not junk up the thread…especially since most of the actual circumstances are just rumor at this point.

    • Maybe this whole sideshow was orchestrated by an industrial gas manufacturer’s marketing division eager to sell more cylinders of nitrogen (or small membrane N2 generators) to inflated ball sports (football, basketball, soccer, volley ball…) teams.

    • You dont actually need to gop to the extent of using nitrogen, compressed air is just fine as long
      as your compressor has drier stage. Such compressors are readily available being used for recharging compressed air for scuba gear as well as industrial spray paint systems whereentrained liquids are a very bad thing.

  15. I’m surprised nobody has questioned the accuracy of the pressure gauges used by the referees. What’s the margin of error on readings? Has anybody done a test, or does it depend on model output? If the measurements are analyzed, is there a trend? Are the football bladders defective and have minute leaks? C’mon, what kind of skeptics are we if we don’t question the data, or lack of it? — /sarc

    • Yeah, by imposing a pressure limit rule the NFL put themselves into the awkward position of potentially being challenged to certify that their gauge(s) are traceable to the National Bureau of Weights and Measures. So it’s another reason to axe the pressure rule altogether. Let each QB use whatever they wish when in possession. (As I understand it, the NFL still maintains control of the footballs used for kickoff so at least those would not be subject to the whim of either team.)

    • Maybe there was a manufacturing change to the valves that causes a leak. That kind of thing has happened in my former world.

      • The idea of the valve leak seems to of been pretty much ruled out by all of the balls holding their pressure through the second half.

  16. None of this “controversy” would have happened if the NFL had any brains and had maintained the old rules that had the officials in charge of the game footballs. On top of that, once they allowed teams to start using their own footballs during possession why even have pressure limits? If the QB on each team can set the pressure to whatever he wants then how cannot that be fair to both sides? That and there would be one less rule for everyone to be concerned with.
    “(They also wet the leather balls to simulate the rainy conditions of the game, surmising that this might allow stretching that would reduce air pressure in the ball, but this seems likely to be a minor factor.) “
    “Minor” is in the eye of the beholder – the Head Smart Labs report stated:
    The Lab also found that when the leather was wet, the ball dropped an additional 0.7 PSI.
    So they saw a 1.1psi change from a 25F deg change plus another 0.7 from wet leather so the wet leather contributed to 39% of the pressure drop, a portion I wouldn’t describe as “minor”. On top of that, the leather of the ball that was intercepted had been ‘worked’ in the course of being used which could only have caused it to stretch even more.
    https://uploads.strikinglycdn.com/files/131228/d8f159cc-99db-47be-b8d1-1828d64dde17/HeadSmartLabs_The_Science_Behind_DeflateGate.pdf?id=54

    • If the QB on each team can set the pressure to whatever he wants then how cannot that be fair to both sides?

      OK, assume the quarterbacks’ preferences cancel out. But a softer ball is harder to fumble, so the team using a softer ball gains a disproportionate advantage. The Patriots have an off-the-chart low-fumble record, a researcher has discovered. See http://www.google.com/url?q=http://www.nationalreview.com/corner/397045/does-deflate-gate-explain-pats-super-low-fumble-rate-jack-fowler&sa=U&ei=LgrJVKaSCI7XoASv4oCQAQ&ved=0CBQQFjAA&sig2=UWvApaG9lyJWd2NijUMaAQ&usg=AFQjCNFxGPMYgeSe1fsI7yUmNaQTAdMAhw
      Incidentally, since I think fumbles are a blot on the game, and encourage vicious tackling, I’d like to see the leagues–or at least the college leagues–allow a lower pressure limit.

      • I’m far from a natural sportsman (“unco” is the term that my brother used) but with a bit of practice and understanding of simple physics, I can stop a soccer ball dead that has been kicked over 20-30m using my foot. A good professional soccer player will trap one that has flown more than 50m. You do have worry about someone on over $1M a year needing an under-inflated ball to catch it (even with Neanderthal breathing down your neck).
        If anyone is wondering, let the ball hit your foot with full force then remove your foot before it rebounds (move your foot back a few inches using our whole lower body). If you concentrate, it seems like ages for the ball to rebound even if fully pumped up. Your timing doesn’t need to be good with a flatter ball but if I can get it right even most of the geeks here can do it with a pumped up ball.
        And the opposite with kicking. Just tap the ball hard but don’t over exert yourself so that you’re balanced and hitting the ball correctly. When you feel the pressure, use your torso to push your foot into the ball harder. The energy comes from the timing so that it s huge force over a short distance rather than a fast swinging foot. The latter is needed so that you start pushing when your foot is firmly embedded in the ball.

      • First, there is the practical matter of how much grip a human hand can apply to a ball. Soft is relative: a football at two PSI is clearly “flat”. A football at nine psi, is fairly solid. Eleven PSI is quite hard, and would not seem to fall into the descrtion of “soft”.. Anything above thirteen PSI is pretty difficult to distinguish with just hands.

    • Thanks for the pointer to HeadSmarts’ press release. I had only seen their video, which didn’t break out the effect of wetting the football. Very surprised to see it caused .7 psi of the observed 1.8 psi pressure drop. Don’t see how this can be from stretching of the leather when the drop in air pressure means there is less stretching force being applied. Leather really relaxes that much when wet? Maybe, I’m just surprised.
      Or it could be that the balls had not fully equalized to the 50 degree temperature and wetting them caused rapid equalization. It is also possible that the 50 degree room they used had low relative humidity, causing the water on the ball to evaporate, causing evaporative cooling, making for a lower effective temperature.
      This could have occurred on the field as well. Precipitation leaves dry air in the upper atmosphere. Not sure the effect on the ground. Would the wet balls have experienced evaporative cooling? Could be part of the story.

      • I would tend to agree – heat transfer from a gas to the ball and then out of the ball to the atmosphere is going to be relatively slow, adding water greatly accellerates this (even if the water doesn’t cool the ball, evaporation will)
        In all of these things the devil really is in the details. If nothing else, you should have the very clear sense that the NFL’s QC process is laughable if the intent is to maintain a 12.5-13.5 psig pressure in the balls during game conditions. A ball stored and tested in an indoor environment at 13.0 lbs is almost certain to be out of spec once it has equilibrated to outdoor game conditions. Even assuming that the gauge used is accurate to +/- 0.1 psig, which I rather doubt.

  17. Since compressors heat air as they work, it’s trivially easy to make them deliver hot air. Put it in a locker and run it for awhile, for example. Near the showers. Hot humid air in the balls. Check the pressure immediately before they cool off. Since the rule seems to state that the balls can only be inflated in the locker room, wouldn’t it be illegal to re-inflate them outside?
    And since hard or soft seems to be a QB preference, who really cares?
    Another chapter in the saga of men who run with balls…

  18. Oh come come Ric, Surely you know it’s because of CAGW. You see the Patriots balls are inflated here in the Northeast which suffers the additional CO2 in our atmospheric upper and middle layers thanks to all that mixing from those coal-fired power plants in Indiana, which suffers from less CO2. Therefore balls inflated in Indiana are filled under atmospheric conditions that has somewhat less CO2 and thus under inherently cooler conditions than those inflated in the CO2 polluted Northeast! Now of course as well we all know CAGW doesn’t predict that every day will be warmer than the next, there is some degree of natural variation in daily temperature. We are talking long term trends here (like a week). That’s why we renormalized the naming of the phenomena from CAGW to Climate Change. So therefore you can still get a colder day than the average day say when the ball was originally inflated and viola! Climate Change induced deflation! I’m ready for my honorary PhD or I’ll settle for a cushy job as an ESPN Science Advisor! In my next post I’ll point out why counting tree rings can be an important way to gauge the longevity of your Christmas tree! 🙂 (Yes I’m THAT Dave in NH. You know me well, Ric Deimos or Bust!) As always your friend, Dave in NH!

    • Hi Dave! (See http://wermenh.com/deimos.html – The Martian Festival is held each vernal equinox. More about the events on Deimos — after this.)
      Don’t give me any of this CAGW crap today. We were supposed to have the storm of the century (so far) yesterday and all I got was 8.5″ of fluff! All these claims of 20-30″? I sure haven’t seen it! (OTOH, I work in Nashua, so I will.) Look, I’m in a bad mood today, and seeing this Deflategate (10 yard penalty for overuse of -gate!) in WUWT is putting me in a worse mood and I’m gonna take it out on my co-workers!
      OTOH, I suppose the sports reporters are thrilled to have something novel to talk about before the Superbowl….

    • Nah. Elevation of the cities. The elevation of Indianapolis is increasing because of glacier rebound due to the melting of the ice fields differently over Boston and over central Indiana.
      Indianapolis’ ” mean elevation is 717 feet (219 m). Its highest point at 914 feet (279 m) above sea level is in the northwest corner 400 feet (120 m) south of the Boone County line and 400 feet (120 m) east of the Hendricks County line.” At 914 feet ASL, the differential pressure between Indianapolis balls (they inflated their footballs in a lower pressure atmosphere before flying to Boston two days before the game) and Boston’s footballs, inflated closer to sea level by a significant amount, means the measured differential pressure at sea level changed.

      You should see what happens when Boston plays in Denver!

    • Thanks Dave for that genuine frontier jibberish. I think you should be inline for a NBC,CBS or ABC nightly news anchor job.

    • Inflation Change is real and it’s happening now. And unless we reduce our Carbon emissions, by 2100 Football PSI will have dropped to 2.0004 PSI according to the models in the latest IPIC report, and our grandchildren will never know what a Hail Mary pass looks like.

  19. Occam’s Razor says the ball boy adjusted the pressure to where he was told. No need for complex explanations. Brady and Belichick should be incarcerated until Monday.

  20. Easy.
    The 12,5 psi pressure was calculated using an average of 68 models based on the physical properties of the constituent air.. The 10,5 psi was actual data

  21. Open questions for further review …
    1. Air temperature? When WAS it actually measured? Inside? OK – A humid warm atmosphere is easily created in a locker room shower area, if not an actual suana. But on the field? Down at the field itself? Or from the thermometer at the closest airport runway?
    And the outside air itself? If it was measured at the stadium, where was the “stadium” air temperature measured? When? How many times that morning and afternoon was it measured? How close to the field was the supposed air temperature measured? Was the air temperature measured up in the press room in the wind? (The field in a confined “bowl” exposed to the sunlight can be 10-20 degrees F hotter than outside the bowl in the wind. This “field effect” temperature is significant when heat stroke for the players, bands, cheerleaders, and others down in the bowl of an outdoor stadium in the late summer.)
    What SIDE of the field was the air temperature actually measured – WHEN it was measured each time?
    Solar heating between inflation and pressure measurement can vary as the sun moves across the sky between warmup start (1 hour before game whistle) to halftime (1-1/2 hours later given commercial timeouts and playoff fru-fru and commotions.) 2.5 hours in the sun (one team) but shaded on the near (south field) sideline?
    Or, shade one team’s football “trolley” .. Just a towel (or a WET TOWEL!) over the football trolley would cool the ball 10-20 degrees below atmosphere temperature, if the other team’s football trolley were in the sunshine for the same 2-1/2 hours with no towel and no evaporation losses.

  22. Come on folks. It’s simple IPCC physics.
    Assume a spherical football (football=globe). Man-made CO2 causes the globe to warm (‘global warming’).
    Normally, warming would cause expansion and make the pressure higher. But this is man-made warming, so we know it has halted (temporally) and this global warming is now hiding in the oceans.
    So the globe cools, due to man-made CO2, and the pressure drops by 2psi
    Q.E.D.
    /s

  23. saw something yesterday (cannot find not) saying colts balls also had a drop pretty close to the patriots balls but they had started at max pressure while pats started at min pressure.

  24. I think the balls should be filled with lead shot. American football is for people with attention spans of less than 5 seconds.

    • Just like NHL hockey and MLB, the TV networks take advantage of natural gaps in the game to insert inflated ‘timeouts’.
      Is FIFA next?

  25. The ideal gas law explains of course why the kicking ball was not underinflated…
    Face it, a softer ball is an advantage when it is cold and wet… just ask Jermaine Kearse of the Seahawks if the balls are hard to catch when they are wet, cold and fully inflated.
    They wee that way for a reason, the mechanism is interesting but irrelevant. The current direction of the ‘probe’ to blame some low level functionary is fascinating but not exculpatory.
    Brady and Belichick are responsible, they got caught.
    Next.

  26. I use an interactive psychrometric program on Trane’s commercial web site to analyze industrial wet cooling towers. Suppose the balls are filled with 75 F 50% RH air. The dew point would be 55 F. Specific volume would be 13.67 cu ft/lb.
    So if the balls cooled to/below 55F the water vapor would condense.
    At 25 F and 100% humidity inside the ball specific volume drops to 12.27 cu ft/lb, 90% of the original specific volume. P1/V1=P2/V1. I get 12.5 psig falling to 9.7 psig and 13.5 psig falling to 10.6 psig.
    So, yeah, it’s simply science.
    Just conducted operator training for a new CCPP and hammered them on about psig, psia, and vacuum especially since the site is a mile high and not at sea level.

  27. If the pressure gauges are as accurate as the thermometers contributing to our climate database, all we need to do is wait a couple of months so the readings can be homogenized and presto, no more deflategate.

  28. You’d be more convincing with some numbers, so Let’s do some math
    Going from 70F air to 45F (21C to 7C) air is a drop from 18.7 to 7.0 mmHg in water’s vapor pressure. That’s only a change of 0.226 psi.
    http://usacetechnicalletters.tpub.com/ETL-1110-2-253/ETL-1110-2-2530017im.jpg
    Starting with a 12.5 psi ball of saturated air at 70F and going to 45F.
    (14.7+12.5)*(505/530) -0.226-14.7 = 10.99 psi when cooled
    Now, There are several locations where it could easily be hotter, such as a croweded room or near a radiator, If the air started out staturated at 75F
    (14.7+12.5)*(505/535)-0.273-14.7 = 10.70 psi when cooled
    A quarter-psi is the most discrepancy you can expect due to measurement error even with a cheap gauge. However, 10.5 psi is hardly a suspicious difference. Any tiny stretching or leak could account for that difference.
    [But the premise was a starting temperature of at least, if not more than, 95 F. .mod]

    • Moderator, you don’t need a 95F starting temperature. You can get to the expected pressure from fairly normal indoor temperatures in a locker room.
      And I found a source saying that the temperature bottomed out at 41F in the game, so knock about 0.2 psi off my calcs above.

      • On the contrary, if they the balls in a locker room filled with sweaty men and hot showers, in which case the 100% humidity is practically guaranteed. Even before a game, the humidity is quite high due to warm ups and the sheer number of people moving about. Plus, it’s a logical setting to work the game balls and does not presume beforehand that there is ill will involved.
        Also, if they used a compressor without a dryer, water accumulation happens naturally in the air tank while compressing air, so cheap air compressors are constantly putting out saturated or even condensate-filled air.
        So assuming saturated is not only defensible, but it’s the most likely scenario.

  29. NFL footballs right out to the box are rigid. For years kickers have worked the balls on the side lines to soften them up so they have a little more flexibility allowing a longer kick. They are no longer allowed to do so, That is why “kicking” balls are used only once right out of the box. However, this is not the case for game balls. Quarterbacks are allowed to “work” the game balls making them less rigid and more flexible. Did these experiments allow for that?
    As an interesting note to all American football fans. Here is the reason for the “too many men in the huddle” rule. Back in the late 60’s Bud Grant was the head coach of the Minnesota Vikings. He would many times place 12-15 players in the huddle (for non Americans only 11 players are allowed to participate each play). As long as the extra players left the field prior to the play starting there was no infraction. And that’s what they would do. The extra players would run off the field, the quarterback would then immediately start the play leaving no time for the defense to figure out which players and formation to defend. Until they made the rule against this nobody thought Bud Grant was cheating, he was considered innovative.

    • In 1907, Glenn Scobey (Pop) Warner had returned to coach at the boarding school for Native Americans that he’d built into a football powerhouse beginning in 1899, largely through trick plays and deception. Over the years, he drew up end arounds, reverses, flea flickers and even one play that required deceptive jerseys. Warner had elasticized bands sewn into his players’ jerseys so that after taking the kickoff, they would huddle, hide the ball under a jersey and break in different directions, confounding the kicking team. Warner argued there was no prohibition against the play in the rules. The tricks were how the smaller, faster Native Americans could compete against players 30 or 40 pounds heavier.
      Read more: http://www.smithsonianmag.com/history/the-early-history-of-footballs-forward-pass-78015237/#VcXRDYDG4ZxfPgyU.99
      Was Pop Warner cheating?

      • In this context cheating is breaking a rule that has been agreed to or issued by a relevant authority. For those readers who ever played football outside a football league, did you ever measure the air pressure? Did you even own a gauge?

    • The same thing happened with the No Huddle offense. The offense team would start the play while the defense was making personnel substitutions, particularly on third and long, passing downs. The offense would snap the ball while the defense had more than eleven players on the field, resulting in a penalty and a free play for the offense.
      Defenses eventually adjusted to this tactic, and the NFL modified the rule so that if the offense made player changes, they had to wait until the defense completed their substitutions before snapping the ball.
      In a similar vein: In one of the Browns game this season the offense had two quarterbacks in the huddle (but still only 11 men on the field). Johnny Manziel pretended like he wasn’t supposed to be in the game and started walking off the field while coaches were screaming at him to get to the sidelines. The Browns snapped the ball and threw it to wide open Manziel for a touchdown, which was called back because of a penalty.

  30. Alex Rawls says: “When the number of gas molecules in a container is fixed…”
    ======
    A minor point, but if n in PV=nRT is fixed then the “amount of air in a football” is fixed.

    • Yes and no, n is the moles of gas in the container (football in this case). If water vapor condensed then the value of n went down because there is less gas in the football.

  31. Anyone who’s used a compressor extensively knows that compressors will build up a large amount of moisture if they’re not drained daily. Failure to drain this water will result in very humid air being pumped.

    • Also if the air was coming directly from a compressor it would certainly be warmer than ambient since compression raises the temperature.
      Ergo: if you want a soft ball start up the compressor and fill the ball immediately. If you want a hard ball, run the compressor well in advance (preferably in a dry environment), and let the air cool in the storage tank before filling the ball.

    • However, when you let saturated air from a 60 or 80 PSI compressor tank down to 12 PSI, the relative humidity goes down. A lot.
      If I wasn’t lazy, I could calculate the RH after taking that big pressure drop, but it’s going to be well below saturated.
      I think the ideal gas law alone explains this. It had to be excessively hot air to begin with.

  32. “Going from 70F air to 45F …” At 50% RH the dew point is 50F so at 45F the RH inside the ball would become 100%. Specific volume would go from 13.52 cu ft/lb to12.85 cu ft/lb, 95%, beginning 13.50 psia, ending 26.80 psia or 12.10 psig.
    Vapor pressure is irrelevant. It’s why warm air holds more water vapor than cold, but so what.

  33. “So that’s good anyway. Half the Northeast now knows that Bill Nye is an idiot.”
    Thanks for the much needed chuckle.

  34. Like many others, I did the calculations and ran the tests myself — using a Wilson “NFL” football, digital temperature gauge (0.05 psi resolution) and refrigerator in my house.
    I checked equipment for consistent measurement. I pumped up the ball. I allowed ball to stabilize at room temperature (roughly 68F) for about 9 hours — psi fell off due to air being warmer when first pumped (due to compression — heck the pump even felt warm).
    In my case, between pumping and stability, pressure fell approximately 0.4psi. I took the new lower pressure as the basis for the refrigerator cooling part of the experiment.
    Put in refrigerator (about 30 degrees cooler) for 1 hour (may take a bit longer for ball to stabilize — but, game balls do not necessarily stabilize).
    Merely measuring the air pressure removed 0.05 psi from the ball (due to air moving into the measurement device) — 10 measurements removes almost 0.5 psi. I took that into account.
    My ideal gas law calculations resulted in roughly 1.5psi for 30F temperature change (starting at roughly 70F). The ball in the fridge dropped 1.6psi during the hour. An hour later (2hrs total), it had dropped 1.65psi. All in the “ballpark”.
    So, the roughly 2 psi (+-??) reported for the “game day balls” (which may have been subjected to different conditions) seems reasonable.
    That was a simple, one pass experiment with cheap equipment. Multiple runs could refine the numbers — but, the reported numbers themselves are only rough figures — given the sources of measurement error, differing conditions, and possible reporting errors.

  35. I guess Bill Nye forgot the saying about folks wondering if he was an idiot—he opened his moth and removed all doubt.

  36. So funny how everyone falls over themselves in order to correct the many statements made… Brilliant!

  37. The solution to this is for NFL Officials to inflate each ball before the game with pure, dry CO2. When filled with the magic gas, the balls would be self-warming and offset any gas shrinkage due to temperature drops on the field.

    • Hmmm… Maybe you’re on to something! Maybe Brady had the footballs filled with helium? Everyone knows how helium seeps through just about anything, (picture those shrunken helium filled latex balloons laying on the floor the morning after the birthday party).

  38. Please, all the information we have is provided by reporters from anonymous sources. There’s absolutely no chance for mischief is there? No siree Bob! The first report claimed that the player who intercepted the ball noticed it was deflated and gave the ball to the equipment coach to check it out. Nope, he just wanted to keep the ball as a souvenier because he’d intercepted Tom Brady in a championship game. The rest of the subsequent reports have all been anonymous too. (For you furriners, Brady is considered one of the top quarterbacks to ever play the game, if not the greatest.)
    Compare and contrast science reporters and CAGW.

  39. If 11 of the 12 balls “prepared” for the Patriots were done in a fashion different from that of the 12 balls “prepared” for the opposing team in every single Patriot home game, it doesn’t matter the methodology.
    Rumor has it the refs knew in advance allegations of under inflated footballs for one team (and not the other) and, if true, would mean the Patriots were attempting to violate rules. If people who use science daily are interested in creating a scientific lesson, I’m all for it. It can be a teachable moment. Using that to speculate on whether cheating went on or not, using that same science, is a slippery slope. It would imply you can legally skirt the rules, in effect tricking the refs by presenting balls for inspection that have not been treated in the same manner – whether that’s inflating in a different environment or what have you. Measuring balls to make certain of their pressure is and should be a simple engineering event, and not a time to determine skullduggery.

    • Each team supplies it’s own balls. So the Patriots didn’t “prepare” the Colts balls, they take care of that themselves.

      • My misinterpretation of events, then. The ballboys would travel _with_ the team? That has to be a good gig. I missed my calling.

  40. Folks, folks, folks. . .
    A couple of overlooked items. . .
    First of all, the PV = nRT equation is for an ideal gas in a rigid container. . . .a football is not an rigid container. It’s a elastic container with non-linear characteristic. Now it might be possible to regard it as a rigid container over the range of pressure that is being discussed. . .but I’m not sure about that.
    Second. . . the ball manufacturer has stated that the footballs are inflated at the factory. . .and shipped inflated. In other words to wind up with 100% saturated air in the Patriots footballs at 91 degrees would require them to first deflate the balls. . .and then refill them with the completely saturated air, which would constitute tampering. Or. . . .they could inject just a couple of ccs of water into the football, which would result in complete water saturation of the air in the football, and then put them in the Sauna for a bit. Again. . . .that would constitute tampering. . . .under no circumstances could that be regarded as “normal ball preparation”. . . .
    Third. . . no one has mentioned that one of the Patriots coaches, the defensive coordinator, is an expert on things like this. . . having a degree in Aeronautical Engineering from RPI.

  41. how are the NFL footballs inflated? If the air is compressed immediately before inflating the ball (like with a manual bicycle pump), the temperature of the air inside the ball will be much higher initially. But if it’s inflated from an air tank that was pressurized hours ago to, say, 50 psi and was then allowed to cool, the air in the ball could be considerably colder than room temperature.

  42. Maybe Bill Nye can give us the scientific explanation of how the pressure in the balls used by the Patriots caused the Colts to only score 7 points.

  43. Perhaps they froze the balls and then inflated them. Regardless, we simply do not know enough details of the bizarre NFL rules and inspections to know IF there is simply a scientific explanation. This doesn’t even rank up there with wiping snot on a baseball. Time to move on.

  44. One possibility that could contribute to the measured under-inflation is that the leather actually stretched under the applied internal pressure. After all, the footballs were brand new prior to inflating. If this is so, as the “brand new” leather stretches, the enclosed volume of air will increase, thus producing a “too low” pressure reading at a later time.
    Some materials (e.g., polymers, leather) exhibit visco-elastic mechanical properties (i.e., time dependent properties). This means , over time, the leather will stretch at an ever decreasing rate under the applied internal pressure. In addition to just the leather stretching, one should also expect the football’s lacing to also “give” a little bit.
    So, summing up, the lower temperatures plus the possibility of the brand new leather stretching could explain much of the pressure drop.
    Of course, the Patriots could have just plain cheated.
    Oh well, it was not a close game anyway.

  45. Since the Patriots have stated that the ball pressure makes no noticeable difference in ball handling, the solution to the whole mess is easy. Just require the Patriots to play the superbowl with balls inflated to the same overpressure as the underpressure they used against the Colts. Shouldn’t cause them any problems at all.

    • The Pats only scored 17 points with the under-inflated balls during the first half. They went on to score 28 points after they switched to properly inflated balls, so it clearly worked against them.

    • http://www.wsj.com/articles/patriots-always-keep-a-tight-grip-on-the-ball-1422054846
      By MICHAEL SALFINO
      Updated Jan. 24, 2015 9:13 a.m. ET
      One of the many questions surrounding “Deflategate”—the controversy that has engulfed the New England Patriots—concerns what advantage an NFL team would gain from using a deflated football. Numerous players have said a softer ball is easier to grip, and a ball that’s easier to grip is harder to drop
      New England coach Bill Belichick and quarterback Tom Brady both denied ever purposely using footballs that were inflated below the NFL minimum. But on the basis of the allegations, the Count looked at the fumble rate of the Patriots compared with the rest of the league.
      New England has had an uncanny ability to hold on to the football for quite some time. According to data compiled by Warren Sharp of Sharp Football Analysis, the Patriots fumble far less than any other team that plays outdoors, where the elements can make the football harder to handle. Beginning in the 2010 season, Patriots players have fumbled (whether lost or recovered) once every 73 touches from scrimmage, which is 52% better than the league average. The next best team is the Ravens, who have fumbled once every 55 touches.
      Additionally, according to Stats, LLC, the six players who have played extensively for the Patriots and other teams in this span all fumbled far less frequently wearing the New England uniform. Including recovered fumbles, Danny Amendola, BenJarvus Green-Ellis, Danny Woodhead, Wes Welker, Brandon LaFell and LeGarrette Blount have lost the ball eight times in 1,482 touches for the Patriots since 2010, or once every 185.3 times. For their other teams, they fumbled 22 times in 1,701 touches (once every 77.3).
      The Patriots didn’t return a request for comment.

    • I should add, if Patriots fumble fewer times (and they do) because of whatever… more power to ’em. There are an average of 2.3 fumbles per game, and if Patriots lead the league in the “1’s”, they are doing the NFL a favor by eliminating the spectacle of very large men doing a strange dance over downed opponents who have just turned over the football. All teams should be allowed to play with footballs deflated to their chosen psi!

  46. Numbers- we still don’t have no dag-gum numbers! 😉 What WAS the initial PSI? What WAS the final PSI? Was any pressure released when testing? How much? What was the ambient temp of the balls before going out to the field? Does Gronking have any effect on PSI? How much?
    What was the starting PSI of the Colts’ footballs? What was their tested PSI?
    And can someone tell the difference between 13.5, 12.5 and 11.5 PSI by handling the ball?
    And what about chain of custody of the footballs? Also seeing that the Pats scored most of their points when using the Colts’ footballs I hear that Tom has contacted Andrew to find out what they do to their footballs… 🙂

    • 12.5 psi before game, temperature unknown,
      10.5 psi during game, temperature ~41F
      The Colt’s ball tested around 12 psi at halftime.
      If you feel closely, yes, you can tell. The refs removed several balls from play for being too soft over the course of the game.
      The teams have their own sets of footballs that they use during their offense. They are kept by the team. Kickoff and field goal footballs are used once and only once fresh out of the box.

      • The 10.5 has been changed. The latest has the test pressure at 1 psi less than 12.5. And no. you cannot tell between 12.5 and 11.5.

  47. It sounds to me like Coach Belichick use to follow NASCAR as a kid, or he got early training from ’em. ‘S t r e t c h i n g’ the rules is endemic there.

  48. Someone get Al Gore to declare that the football pressure science is settled! Then we can determine who are football inflators and who are inflator deniers as soon as possible.

  49. The fact that empirical (Carnegie Mellon) and basic physics (Ideal gas law) aren’t fully insync and that factors such as, humidity, ambient temp changes let alone, changes in barometric pressure, and thermal expansion/contraction of the material… If this simple problem has trouble being solved why would anyone think we got a good understanding of the climate?

  50. You’ve all got it wrong, the balls were never under inflated.
    It’s clear that the NFL hired NCDC to perform the pressure test procedure on the Pats balls.
    We know their post measurement algorithm always adjusts 11 out of 12 raw data (locker room) measurements upwards, unfortunately for them the Mann applying the adjustments used them upside down…

  51. Before reading this article, I had taken this website to be reputable. The facts are that all 24 footballs were filled with air pressure indoors and were again measured for air pressure indoors, at half time. The results were that 11 of the Patriots’ balls were found to be 2 to 3 psi bellow the minimum of 12.5 psig. One of the Patriots’ balls was not below specification and none of the 12 Colts’ balls were below specification. Just how could that have happened? Could the video of the Patriots’ locker room attendant taking all 24 balls into a bathroom just before game time, explain something? He was in there for 90 seconds and a New York reporter just posted a video today showing he could deflate 12 balls to the discovered values within 40 seconds.

    • Oh, I thought you were going to criticize WUWT for turning into a sports talk site.
      You say “The results were that 11 of the Patriots’ balls were found to be 2 to 3 psi bellow the minimum of 12.5 psig.” Check out http://www.msn.com/en-us/sports/nfl/report-10-of-patriots-balls-only-one-pound-under-inflated/ar-AA8BCNy which leads to http://profootballtalk.nbcsports.com/2015/01/25/nfl-bears-plenty-of-blame-for-deflategate/ which says:

      But what has the NFL really found? As one league source has explained it to PFT, the football intercepted by Colts linebacker D’Qwell Jackson was roughly two pounds under the 12.5 PSI minimum. The other 10 balls that reportedly were two pounds under may have been, as the source explained it, closer to one pound below 12.5 PSI.
      The NFL has yet to share specific information regarding the PSI measurements of the balls that were confiscated and measured at halftime. Which has allowed the perception of cheating to linger, fueled by the confirmation from Friday that the NFL found underinflated balls, but that the NFL still doesn’t know how they came to be that way.

      I’m sure the NFL will make things clear in their report, likely to be released on Feb 20, two days before the Daytona 500.

    • “The facts are that all 24 footballs were filled with air pressure indoors and were again measured for air pressure indoors, at half time.”
      I have not heard any official word about the conditions under which the balls had their pressure measured either before the game or during halftime. If the balls were measured under the same conditions both times, it also needs to made clear to what extent the balls were allowed to come to equilibration with the environment (were the balls that had been used in the game permitted to warm back up before measurement, or was the air inside still cold). I also haven’t heard official word that the Colts’ balls were measured at halftime, but I assume that the officials would have done so out of due diligence.
      “The results were that 11 of the Patriots’ balls were found to be 2 to 3 psi bellow the minimum of 12.5 psig”
      An anonymous source stated via ESPN that 11 of 12 balls were found to be below the limit by as much as 2 PSI. Later reports (again anonymous) said that most of them were more like 1 PSI below the limit. Assuming these sources know what they are talking about and can be trusted, your statement is a gross exaggeration. Let’s wait for the official report on the pressure here.
      “One of the Patriots’ balls was not below specification and none of the 12 Colts’ balls were below specification.”
      The Colts have said that their balls are inflated to the max before the game, which means they could lose pressure and still be within the specs. The one Patriots ball could have stayed in the bag the entire half (and thus not gotten wet, which allows the leather to stretch), or it might have started out fuller, or it might have been blow the limit too (again, we have no official word on the pressures of any of the balls, just anonymous sources), or some combination of these possibilities.
      “Could the video of the Patriots’ locker room attendant taking all 24 balls into a bathroom just before game time, explain something?”
      It could explain that he thought it wise to empty his bladder before he became occupied with the came.
      “He was in there for 90 seconds and a New York reporter just posted a video today showing he could deflate 12 balls to the discovered values within 40 seconds.”
      I’m not going to post a video of it, but I can assume you that I can urinate, flush, and wash my hands within the allotted 90 seconds.
      Really, let’s just wait for the official report before we start jumping to conclusions and attacking guys with weak bladders. If anyone in the Patriots’ organization was involved in willfully violating the rules, the league should come down hard on them, even if the advantage gained was miniscule or nonexistent. If it’s merely a result of the official pressure being taken 2 hours before the game, what reason is there to get all fired up?

  52. The term “boyscout” is synonymous with the words honest and forthright. So a rule follower can be called a “boyscout”
    Many fathers sign up their sons to join the organization called Boyscouts of America so that they can learn many practical lessons about nature and survival.
    One of the most popular activities in Boyscouts is called the Pinewood Derby. In this derby the scout builds a pinewood racing car and competes with other scouts by racing the cars down a wooden track. The raw materials for each car are exactly the same. The rules are simple total weight has a limit. The question is “At what point in modification, weight placement, axle polishing, axle manipulation, graphite friction reduction does the Boyscout become a Cheater?” Understanding the physics of weight placement gives the scout the largest advantage and the best chances to win. Most of us would not consider a scout that learns and understands the physics and then applies it to his pinewood racer a cheat. Instead we would applaud them and other scouts would copy him as they too learned these lessons.
    So why are we not applauding the New England Patriots for their understanding of the gas laws that gives QB Tom Brady the ever so slight advantage?

    • As usual, in a Pinewood derby some Dad’s get crazy. I saw one Dad put my little brother’s car at the top of the track, and press down so hard the axle’s bent. The little car had won the first race, but only wobbled halfway down the ramp during the next race.
      Repeat after me: “It is only a game. It is only a game. It is only a game.”

  53. The chart of vapor pressure of water versus temperature
    http://www.pumpworld.com/vapor-pressure-chart.htm
    indicates that at 90° F wet air would exert about 0.7 psi of pressure due to just the water vapor, but if cooled to 50° F the condensation would reduce that to less than 0.2 psi (about 0.18) – a ‘loss’ of over 0.5 psi just from condensation.

  54. Anecdotally, this was obvious to me as a child. Footballs and basketballs kept in the house always felt inflated. Those kept in the garage “swelled” in the summer and “shrank” in the winter.
    The duration of time it took wasn’t something I ever studied or cared about.

  55. I may have missed a comment that covered this already, but another thing to consider is the temperature of the air leaving the pump. Due to the restriction of the tiny holes in the inflation needle the actual pressure in the pump (depending on how fast you pump) will be well in excess of the final pressure in the ball with the air expanding across the needle holes. There is almost no temperature drop for air in this type expansion, The temperature of the compressed air in the pump could easily be120°F.

    • http://www.popsci.com/science/article/2010-03/how-start-fire-just-compressed-air
      “You’ve probably seen contestants on Survivor trying to make fire by rubbing sticks together or concentrating sunlight with their eyeglasses. But among preindustrial fire-starting methods, it’s hard to beat the portable convenience of fire pistons, used in Southeast Asia since prehistoric times.
      “Almost all gases heat up when compressed. The harder and the faster the compression, the hotter the gas gets, hot enough even to ignite cotton wool or other flammable materials. Diesel engines work the same way: They have no spark plugs; instead the fuel/air mixture is ignited by compression as the cylinder closes up.”

  56. I have found the answer to the question/issue. I seem to recall during the game a cam shot of the Gillette sky box. Therein lay the problem. Or solution as the case may be. Who other than the ever affable john’ f’n kohn-heinz-kerry was situated. The obvious lack of correct pressure was due to the overinflated ego that was present in close proximity to someones balls.

  57. Nice scientific exercise. it doesn’t explain the reports of the balls magically reinflating to 12.5 psi after half time. I seem to remember that Luck went 12 for 33 passing and Blount rushed for 148 yards (71 more than the Colts) and scored 3 TD’s (2 more than the Colts).

    • No magic. The NFL has said they only used balls with the regulation pressure, and reports say that the underinflated balls were inflated to regulation by officials at that half-time. Brady did not seem to notice at all.

      • No magic. The NFL has said they only used balls with the regulation pressure in the second half, and reports say that the underinflated balls were inflated to regulation by officials at that half-time. Brady did not seem to notice at all.

      • So the score is 17-7 at the half. Then NE scores 4 tds in the second half with properly inflated balls? No scandal that I could see. New England did better with the properly inflated balls.

    • Maybe the Colts overinflated their game footballs and got lucky when conditions put them back within spec.

      • Each team’s balls had to be within specs when inspected. While I don’t doubt the science, I’m from Missouri and I know the smell of manure when I hear it. Both teams should have been equally affected by the same game conditions. Or perhaps the Colts kept their footballs in a warmer?
        The fact of the matter is, the footballs were inflated to Tom Brady’s liking. Believe me, if the quarterback doesn’t like the condition of the football at game time, we’re going to hear about it.

    • That is already answered – knowing this problem and preferring a harder ball they inflated the ball in cold air or slightly over inflate it, knowing (it would be easy to experiment at different temperatures) roughly how much they would need to be inflated to fall within the rules when tested.

  58. Compressing air causes the temperature of the air to rise significantly. This is why a lot of vehicles use intercoolers after the supercharger or turbocharger in order to reduce the air temp prior to combustion.

    • The most obvious cause for different result conditions is different starting conditions. P is only one, V is pretty much fixed…so T would be different. Any balls which lost T, would HAVE to lose P. If they didn’t lose P, then they didn’t change T.

  59. The rules are the rules. If they don’t specify the temperature at which the ball must be inflated, then any team that doesn’t take advantage of it is a fool. It’s not cheating. If other teams have a problem with it, lobby the league to tighten the rules. But that would be discriminatory against quarterbacks that prefer a softer ball.
    Also, if this is a violation of the “spirit of the rules”, then I would also want to see a new rule to stop coaches that try to “ice” the field goal kicker by calling time-out at the last second before the opposing team hikes the ball for a game-winning field-goal attempt. THAT is “gaming the game” if I’ve ever seen it, and I HATE HATE HATE it when a coach pulls this crap. But not only do the referees permit it, there’s usually one standing right there beside the coach to blow the whistle on the coach’s command.
    Then again, if every coach played within the “spirit of the rules”, then they would decline penalties they knew were wrongly called against the other team, and if a penalty was not called on his own team when it should have been, he would do something on the next play to make up for it. And in a potential replay situation, they wouldn’t line up so quickly for the next play, so the referees (and the opposing coach) would have a chance to call for a replay. And every receiver who got credited for a completion when he knew he dropped it would own up to it. Hell, for that matter, they wouldn’t burn as much time as they could off the clock between plays when leading late in the game, or even choose running plays over passing plays in that same situation.
    These and many other tactics are examples of “gaming the game”. They are all perfectly legal, but are not in accord with the “spirit of the rules”. And they all have far more effect on the outcome than 2 pounds of pressure in a football.

  60. There is evidence that the Patriots have possibly using deflated balls since the 2007 rule change that allows the offense to provide their own footballs. This is shown in fumble statistics. Players who have played for other teams see their “touch to fumble” ratio rise dramatically when the join the Patriots. Also, once they leave the Patriots, it drops back to normal. A softer football is easier to hold onto and results in fewer turnovers. If a team can greatly reduce the number of turnovers across an entire season’s worth of games, they will end up higher in the standings.
    http://www.sharpfootballanalysis.com/blog/2015/new-england-patriots-fumble-more-often-when-playing-for-other-teams

    • Glad you got this indisputable evidence for us. It has allowed me to look through the stats and figure out who else was cheating. Hmm, in Adrian Peterson’s first 3 years in the league, he averaged a fumble every 49.9 touches, yet since then he’s gone 114.9 touches per fumble. Clearly this can’t be due to change in coaching focus, but must instead be due to the indisputable fact that he started using deflated footballs in 2010.

  61. The tires of large commercial airliners are filled with nitrogen not air. One reason for this is that the water vapour in air will freeze out at altitudes. The ice inside the tire will unbalance the wheel and lower the tire pressure. This will cause difficulty on landing and may cause the tire to burst.
    Thus the issue of loss of pressure caused by water condensation is recognized in the airline industry and prevention of this is the reason the for the regulation requiring the use of dry nitrogen

    • I bought a new set of tires last week for my Camry. They filled them with nitrogen without my asking them, so I assume this is going to become the norm. Does this prevent water vapor?

      • Sorry, what were we talking about? Inflation holding pretty steady… not enough for Janet to start yellin’ ; – )

  62. Of course, _everybody_ knows the Patriots deserve to lose all games in perpetuity, since the refs handed them that snow-bowl game against the Raiders a few years back.
    The rest is just details.
    Interesting points from Dr. Roy about the source of the compressed air, though.

  63. If you’ve ever pumped up a bicycle tire with those tiny cylindrical pumps that come with the bike you should know that the air “exhaled” by the pump can be quite hot. I’ve had pumps hot enough to be difficult to hold. Granted that the pressure in the football is less than a bike tire but the temperature of the air out of the pump is a function of how hard you compress it inside the pump. If it can’t escape rapidly into the football it can attain considerable pressure.
    If the football was inflated with a compressor the same physics applies. If the compressor was run recently the temperature of the air in the tank will be higher than the ambient temperature in the room. They don’t have cooling fins on those compressors for nothing. The smaller the compressor (a little portable just for inflating footballs vs a big shop compressor with a tank the size of a refrigerator for instance) the more likely the air will be hotter than the room air.
    It is, of course, possible that they used a big compressor that had enough pressure from being topped off days ago and the compressor never had to run and the air in the big tank was the same as room temperature. But I think it’s more likely that the team carries a small compressor just for this job and it has to be pressurized each time. And that means the ball was inflated with air that was hotter than room temperature.

  64. Don’t forget that compression of air increases the temperature, so the air actually inflating the ball is warmer than ambient. I have not done the calculation, but this would increase the effect. However I think you are right that the main difference is condensation.

    • Agree that the most important aspect of this silly debate is that by going on the record as a denier of one of the most basic laws of thermodynamics, Bill Nye has destroyed any credibility he may have had with other than conspiracy theorists.
      In addition to whatever else they did, the Patriots have thus made a great contribution to humanity.

  65. Once upon a time long years ago I was tasked with designing a relief valve for racing cars to be put in a secret location on the inside of the wheel. It was to relieve at 33 psi and reseal at 28 psi. Now normally racing tires heat up a good bit when running and this contributes to lack of grip and wear which is a disadvantage. This is why the NASCAR boys change all 4 tires every time they have a caution. They often put the same tires back on later in the race. This little valve was, of course, blatantly against the rules. The driver using this little device was quite successful for a good long time. Then he got caught. They had a huge wreck with many cars involved and the race track completely blocked so the red flag came out. Our guy was in second at the time so he was in a good position. When a race is stopped like that all the cars are lined up in their running order and no one is allowed to touch them until the race is restarted. After sitting stopped for about 45 minutes the tires cooled off and our guys tires were flat. Big OOPS. Gotcha! Black Flag, penalties, suspension, and fines. But it was good while it lasted then we were at the mercy of PV=NRT.

  66. Really, who cares if the balls were off by 2psi, and technically in violation of the rule? Well, you should if it can be proven that an advantage can be had by doing this. Whether or not Tom likes the feel is inconsequential, and in my opinion a red herring. Rather, see if there is any correlation to important statistics on game performance and see if the Patriots have been significantly improved since the rule went into effect, which was 2007.
    Well, in that regard, take a look at fumbles by each team in the league and you will see that the Patriots have significantly improved their ball handling skills as compared to the rest of the league, and it all started in 2007. Fumbles have a much larger impact on game outcomes, and the Patriot performance demonstrates a dramatic shift in performance since the rule was adopted. Somehow, the way Tom liked the feel of the ball doesn’t play much of a rule in that.

  67. Let’s not forget the cheating done by the NFL guru, the BIg Tuna, Bill Parcells. As the coach of the New York Giants and on a particularly windy day at Giants Stadium, he had the stadium service crew open the huge bay door at the end of the stadium allowing a howling wind to enter the stadium from that direction, but only when the opposing team was headed that way. When his Giants were headed that way, the bay door was closed. Most people, except the opposing team and their fans though it was clever. But then Bill Parells could do no wrong in peoples eyes.

    • Very funny, but most football fans are Americans, who won’t get it because they wouldn’t know that “Die Fledermaus” (“The Bat”) is an operetta written by Johann Strauss Jr.

  68. Your equation T1 = P1 X T2/ P2, is the same as P2 = T2 x P1 / T1, and at extremely cold temperatures, say -200 F, P2 = (-200 +460) * (12.5 + 14.7) / (50 + 460) = 13.9 = 14.7 – 0.8 psi? So at -200 F the pressure in the ball is negative??? How can it be negative when there is a higher concentration of air inside the ball than outside the ball? If the temperature inside the ball is the same as the air outside the ball, there will always be some positive pressure measured on the ball, until you get to 0 Rankine. So since the ball will be at zero pressure at 0 Rankine, shouldn’t your equation leave out the 14.7 psi from your calculations? Sure 12.5 is a gauge pressure above atmospheric pressure, but that gauge pressure is what will vary linearly with the ideal gas law isn’t it? Assuming atmospheric pressure remains constant. On Venus atmospheric pressure is 1337 psi, if I had a 12.5 psi gauge pressure football on Venus, then according to your equation with atmospheric pressure included, a 20 F(or R) temperature drop from 50 F would result in a pressure of P2 = (30 +460) * ( 12.5 +1337) / (50 +460) = 1297 psi , or 1337 – 30 psi, so the ball would be reading a negative pressure of 30 psi with a 20 F temperature drop?? Even though there is a higher concentration of air inside the ball than outside the ball?
    The pressure / temperature change calculation has to be done against gauge pressure, so the pressure is always positive in the ball until you get to 0 R. Which means a ball at 50 F that had a for a 2 psi temperature drop started at a temperature of T1 = 12.5 * ( 50 + 460 ) / 10.5 = 607 R = 147 F.

    • Pressure inside the ball relative to outside pressure can certainly go negative as temperatures continue to fall. Just remember the assumption that the ball stays the same size, as if it were a rigid container. As the air outside continues to drop in temperature it becomes very dense while the air in the ball remains of the same density. When the density outside exceeds the density inside then the outside air will be pushing to get in.

  69. Above I posted the results of my calculation and actual football-inflation experiment.
    To summarize: Like many others, I both calculated and measured experimentally using an actual football that a ball inflated at 70F would lose just over 1.5psi when cooled to 40F (under the conditions of my experiment). Cooling started after temperature and pressure had stabilized. The first cool football measurement was 1hour after the ball was placed in 40F temperature air.
    In the original post, I forgot to add:
    When the ball returned to room temperature, its pressure was restored exactly (less the 0.05 psi per measurement).
    I also did not mention that my temperatures were taken with a digital thermometer with 0.1F resolution.
    Thus, it partly depends on when the NFL measured the air pressure, how many times they checked it, and what measurement device they used. At room temperature, the balls should be at the former room temperature pressure (minus any loss due to measurements).
    My data does not “clear” the Patriots of wrongdoing. It merely roughly confirms their finding regarding football pressure loss as the temperature drops. And, there are other physical considerations besides temperature that might alter football pressure measurably — as noted in other posts.

  70. Yeah except humidity isn’t air. It’s moisture IN air. Condensation only collects that moisture together. The amount of air stays the same.

    • Humidity is water vapor, which is a gas, and is a component of air. When water vapor condenses to liquid water it is no longer a gas and the amount of air is lessened.

  71. At least one ref handles the ball after each play. Why did the Colt player notice this and not the refs? Or were they not impressed? If each side provides 12 balls, why not mix all 24 at 5 minutes before kickoff and then distribute 12 to a side for use in the game?

  72. Okay, I haven’t read the entire thread, above, but I searched it for some keywords. I didn’t find any mention of exactly how they inflate the balls or one obvious ploy: Have the QB or his stand-in SQUEEZE the ball while it’s being inflated at outdoor temperature. When he says ‘NUFF, stop the pump and store the ball in a warm room. They’ll test ok before the game and gradually return to the desired pressure over about 15 minutes.
    Also, condensation of water vapor within the ball could produce an unstable ball, since more water collect on one side of the ball when thrown.

  73. Funny seems like every time I mention temperature is not equal to energy and therefore humidity and pressure are needed with temperature other wise the measurements can’t really be compared I get jumped and everyone says I don’t understand the ideal gas law. Perhaps someone would like to explain to me how this is different than the earths atmosphere? Wouldn’t a high humidity air mass lose moisture as it passed a desert and vice versa changing the temperature but not the energy?

    • There’s more mixing in an air parcel passing a desert than between a football and atmosphere, for one.
      I don’t understand what you mean with “Wouldn’t a high humidity air mass lose moisture.” Conservation of mass argues that moisture either falls out as precipitation or is diluted if the surrounding air is drier due to mixing. The former releases latent heat, the latter doesn’t.

      • How about absorbed by the arid ground and plants? We all know energy is never “lost”. The question is how much does the temperature change simply due items such as the latent release of heat as you describe. Currently everyone assumes it is balanced over the globe and sums to zero. What if it doesn’t?

  74. This isn’t a science issue, it’s a rules issue
    Basketball, soccer, and even baseball (pitchers’ quirks notwithstanding) leave the suitability of a given ball up to the officiating crew, and even baseball doesn’t generally use two dozen actual game balls to complete a single game. In order to maintain its credibility, look for the NFL to eventually move to using footballs prepared and approved by the officiating crew ONLY (rather than from either team) in every playoff game at least, if not in all games during the season.
    Why does an NFL game need a dozen balls per team, anyway? 2 or 3 per quarter on a bad weather day seems like plenty to me (to allow for towel drying between uses, etc.). And why wouldn’t it be fair for both teams to use the same set of officially approved footballs in the first place?
    [Note: this commenter is not the erstwhile WUWT Smokey. ~mod.]

  75. If all balls were inflated by a pump witha defective pressure gauge, that would explain thing, too. I’ve yet to read if anyone thought to test all the pump gauges…

    • It would be an interesting defective gage to only identify the Patriot’s footballs as being deflated. . . and reporting a normal pressure for all the Colt’s footballs.

      • The Patriots prepared their footballs, the Colt’s prepared their footballs. It’s more likely they used their own pumps and gauges than shared. The Pats like their footballs at a low pressure, the Colts like them high. Cool them down outside and I have no trouble with the ref’s gauge identifying only the Pats footballs as too low.

  76. On the condesation issue, pulling out my trusty steam tables…
    At saturation, 100Fsteam has a pressure of 0.9503 psig.
    at 80Fthe pressure is 0.5073 psig
    at 50Fthe pressure is 0.17803 psig
    Partial pressure of moisture in air displaces the equivalent pressure of O2/N2, so a ball filled at 80F and 100% relative humidity would drop a little over 0.3 psi from condensation in addition to the pressure change of the non-condensables (no issue with that calculation) if it cooled to 50F. You could goose it a little more with warmer air, but the refs would probably notice the warmth of the ball at some point and (presumably) object.
    If you assume room air at 72F and 50% relative humidity you get to roughly saturated conditions at 50F, so virtually no condensation.
    In the end, humidity could contribute to a pressure drop, but wouldn’t be expected to unless the team is actively working to fill the ball with humid air.

  77. Nicholas- It wasn’t the Colt player that detected the “soft” ball, it was the Colt equipment manager that he handed the ball to after an interception (and the Colts had been tipped about Pats use of “soft” balls by Ravens.
    Jorge- The spin of an NFL forward pass would spread out any condensation inside the ball through centrifugal force, perhaps even evening out the natural imbalance of a hand sewn ball.
    Smokey- A nine inning major league game uses far more than a couple of dozen balls. Even a single long inning with some foul-offs, pitches in the dirt, and a home run or two could go through a couple of dozen.

  78. I was born and raised in New England. The most interesting aspect of this case, to me, is the proclivity of fans to rabidly defend anything their team does, right or wrong. Belichick is a known cheater, yet the Patriots fans all stick by him and go to great lengths to try to rationalize his team’s unethical behavior. One of the many reasons why today’s NFL makes me puke.

    • How is Belichick a “known” cheater? Deflate-gate has now been determined to be only about 1 pound, which is explained by temperature fluctuation. In Spy-gate all he did was film during a game – the same thing 80,000 other people could have been doing as well. I would hardly call that cheating. I am also sure that all the other teams bend rules every bit as much as Pats, but are not called out because they lose. This leads me to say that the only thing all of this cheating hub-bub has actually proven is “Sour Grapes.”

      • Charlie, exactly it is all just cry babies who don’t like to see their team lose to the Patriots and I’m a Giants fan so I have nothing in this. The more I learn about Belichick the more impressed I am about his intelligence.

  79. This has been a “rule following” problem in the past. Going forward there is such an easy remedy to this issue, unless the NFL and the Media and the Masses simply enjoy all the hub-bub (similar to the reason narcotics are kept illegal). The NFL already lets each team provide their own balls, so, very simply, just let each team provide their own desired air pressure in the balls, then everybody is happy, with no policing of pressure required. Is that too easy or does everyone just want to force others to follow more petty rules.

  80. How the balls were inflated is as important as where. Let’s say that, being the NFL, they have a compressor for the balls. Let’s further assume that the compressor leaks ‘just a little’, like most compressors do. When you compress air, you heat it by adiabatic compression. You also concentrate moisture, but I’m not as inclined to buy into that one. Anyway, compressors are noisy, so people are inclined to unplug a leaking compressor. When you plug it back in, it will contain hot air when it finishes running. Mystery solved. No violation of the rules involved. Further, it is not even necessary for the Patriots to intentionally do this, although I’m guessing such knowledge as this is common in the NFL.

  81. Rule 2 The Ball
    Section 1
    BALL DIMENSIONS
    The Ball must be a “Wilson,” hand selected, bearing the signature of the Commissioner of the League, Roger Goodell. The ball shall be made up of an inflated (12 1/2 to 13 1/2 pounds) urethane bladder enclosed in a pebble grained, leather case (natural tan color) without corrugations of any kind. It shall have the form of a prolate spheroid and the size and weight
    shall be: long axis, 11 to 11 1/4 inches; long circumference, 28 to 28 1/2 inches; short circumference, 21 to 21 1/4 inches; weight, 14 to 15 ounces.
    The Referee shall be the sole judge as to whether all balls offered for play comply with these specifications. A pump is to be furnished by the home club, and the balls shall remain under the supervision of the Referee until they are delivered to the ball attendant just prior to the start of the game.
    Section 2
    BALL SUPPLY
    Each team will make 12 primary balls available for testing by the Referee two hours and 15 minutes prior to the starting time of the game to meet League requirements. The home team will also make 12 backup balls available for testing in all stadiums. In addition, the visitors, at their discretion, may bring 12 backup balls to be tested by the Referee for games held in outdoor stadiums. For all games, eight new footballs, sealed in a special box and shipped by the manufacturer to the Referee, will be opened in the officials’ locker room two hours and 15 minutes prior to the starting time of the game.
    These balls are to be specially marked by the Referee and used exclusively for the kicking game.
    In the event a home team ball does not conform to specifications, or its supply is exhausted, the Referee shall secure a proper ball from the visitors and, failing that, use the best available ball. Any such circumstances must be reported to the Commissioner.
    In case of rain or a wet, muddy, or slippery field, a playable ball shall be used at the request of the offensive team’s center. The Game Clock shall not stop for such action (unless undue delay occurs). Note: It is the responsibility of the home team to furnish playable balls at all times by attendants from either side of the playing field
    Although the rule is explicit about the pressure requirement when the balls are submitted for Referee’s inspection, it doesn’t appear to speak to maintaining that standard throughout the game. If the Patriot’s cannot be shown to have deliberately interfered with the balls’ inflation after they were inspected there is no violation of the rule.
    If they wanted to be really clever they could pick a pure single element gas that has a more dramatic temperature response curve than atmospheric air and use that to inflate their balls as the rule, somewhat clumsily, defines the inflation pressure it doesn’t seem to address what the inflating gas must be.
    Unfortunately football is becoming virtually unwatchable due to the burgeoning growth of ever more arcane rules and penalties. What the game needs is a dramatic reduction in rules, not another large addition

  82. Interesting analysis. So the balls could have been inflated with heated air prior to the ref’s inspection. Yikes!
    The most damning evidence , however, that there was something amiss comes from the study of fumbles after the football rule was instituted. NE Patriots had a simply phenomenal decrease in fumbles following the imposition of the rule. Coincidence?

  83. “If the Patriot’s cannot be shown to have deliberately interfered with the balls’ inflation after they were inspected there is no violation of the rule.”
    Exactly, that is the brilliance in this.

  84. Maybe they should’ve surgically detached the pig first, or told it to hold it’s breath for the
    duration of the game.
    My ol man once went to an “American Football” game, I asked him what he thought,
    he said the people inside the stadium were marginally dumber than those outside,
    and the hot dogs were cold and tasted like they were made in a factory or something.

  85. Regarding the pressure drop due to condensation: wouldn’t you have to take into account the latent heating of the air associated with the condensation? This would increase the internal temperature of the ball and perhaps offset some of the pressure drop due to the loss of water vapor.

  86. Leather stretches when wet.
    The best way to break-in a new pair of hunting boots is to soak them a day or so in a tub of water. Then wear 2 pair of thick cotton socks at a time and wear until the boots until dry. You’ll need to change the socks often. When done your boots are ready for those 15 mile treks over rough mountainous terrain for the life of the soles. My Danners last about 3 soles. A day or so of wet feet sure beats blisters.

  87. Seahawks player fined for grabbing his balls!
    Officials measure and hold everyone’s balls!
    Super Bowl 50 is all about BALLS!
    Watch the half time show for more!

  88. What if we assume there was a nefarious intention to have an undetected under inflated game ball… most people are assuming that the balls would have had regular air in them… of course nobody wants to get caught doing this… and yes… someone above suggested helium… which makes me think… The valve and membrane of the football are not made to contain helium gas… so suppose a ball was partially filled with ten to twenty percent total ball volume of helium gas… then the ball was filled to 12.5 pounds overall pressure with regular air on top of the helium… maybe would the helium will leak out in the time after the balls are checked by game officials but before the game is played leaving an under inflated football without anyone having to let any of the air out… no need to use a sauna or anything exotic… perhaps just just party store helium… then after the game if anyone checks the air for consistency the regular air will be all that is left in the ball because the helium will have leaked out.

  89. This is fairly chewing out of the media for falling all over each other for this story.
    http://tanyarayfox.weebly.com/blog/how-the-nfl-made-a-fool-of-you-with-deflategate
    Small excerpt:
    You bought it hook, line and sinker because you’re under the delusion that your team is all clear eyes-full hearts and has somehow been victimized by this. It is one thing to buy into a perfectly timed PR stunt. It’s another thing entirely to fall into the ignorant space between conspiracy and reality that enables you to continuously denounce the NFL and its most successful franchise as cheaters and liars, yet still voraciously consume their product that they’ve pitted you against.

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