Did Wells' scientists do empirical tests? -- and why that matters so much

[teamplay]

Busy week so forgive me for not reading the Wells report for the answer. Just read about 10 posts/articles about the ball pressure data. One critical questions goes unanswered.

Ideal Gas Law calculations are based on the assumption that the volume inside a football is the SAME when temperature and humidity change. BUT we know the balls got wet that night, AND we know that leather expands when wet (earlier empirical tests demonstrated this). Wet the balls and the volume increases and the PSI drops, even if the T stays the same.

If you want to know what would happen to footballs when the T drops AND they get wet, you can't rely on the Ideal Gas Law. YOU MUST DO EMPIRICAL TESTS.

Was this done??? I'm dying to know. Thanks.

 

[Bobsyouruncle]

They did empirical tests but they sprayed the ball with water and toweled it off. It's not necessarily a great test since rain water can be much colder, and there may be other factors we haven't considered that happen during a game. Better than nothing I suppose.

 

[Ice_Ice_Brady]

They did their simulations using Madden 2011 and a meat thermometer.

 

[Marko]

And I would imagine atmospheric pressure would be a variable as well.

 

[Froob]

They did their simulations using Madden 2011 and a meat thermometer.

Watch EA add ball pressure as a brand new feature. They're due for a new feature, only comes every five years and then is removed the following year and reintroduced seven years later as a new feature.

 

[mikey m]

What I'm waiting for is to see if/how the psi rule will change. It's obviously common knowledge now that during cold weather games, footballs have been and will continue dropping below what was decided to be the acceptable range 70 years ago

 

[BelichickFan]

Not exactly :

For these and subsequent experiments a “wet” football was one in which a hand held spray bottle was used to spray a football with water every 15 minutes during the period simulating the first half of game play. The spray bottle with its contents was kept at the same environmental conditions as the footballs undergoing spraying. Each time the footballs were sprayed they were toweled off.

 

[AQPE]

There is a rubber bladder inside the leather skin of the ball. The presumption is that the only way air gets in and out of the ball is through the valve, and that in the relatively short time between pressure measurements it is unlikely that any air would escape out the valve without human interference. The issue with the wetting of the leather is not that it would change the volume of air inside the bladder, but rather that the wetness would cause the temperature of the air in the bladder, and correspondingly the pressure of the air inside the bladder, to go down even more than it would if the leather skin stayed dry. In engineering terms, the heat transfer of wet leather is higher than the heat transfer of dry leather.

 

[RobertWeathers]

They did their simulations using Madden 2011 and a meat thermometer.

I thought it was a rectal one?

 

[upstater1]

Busy week so forgive me for not reading the Wells report for the answer. Just read about 10 posts/articles about the ball pressure data. One critical questions goes unanswered.

Ideal Gas Law calculations are based on the assumption that the volume inside a football is the SAME when temperature and humidity change. BUT we know the balls got wet that night, AND we know that leather expands when wet (earlier empirical tests demonstrated this). Wet the balls and the volume increases and the PSI drops, even if the T stays the same.

If you want to know what would happen to footballs when the T drops AND they get wet, you can't rely on the Ideal Gas Law. YOU MUST DO EMPIRICAL TESTS.

Was this done??? I'm dying to know. Thanks.

They did fine.

See my other thread on gauges. The scientists actually concluded that there is no discrepancy between the Patriots and Colts balls if you use the gauge that ref Walt Anderson used.

 

[Marko]

They did fine.

See my other thread on gauges. The scientists actually concluded that there is no discrepancy between the Patriots and Colts balls if you use the gauge that ref Walt Anderson used.

Again. Why I say Wells saw that house in the Hamptons slipping away if he concluded the investigation in a week

 

[hwc]

The firm hired by Wells did empirical tests that initially showed nothing out of the ordinary with the Pats balls. So they started adding stuff to get the results they wanted.

1) They ran a test with four balls to show that they regained their pressure within 3 or 4 minutes after being brought in from the first half. Under this dubious finding, the Pats balls still would have been perfectly legal if measured within the first two minutes, but barely low if measured at 4 minutes. Nobody can remember how long it took to begin measuring them, but Wells assumed it must have been at least 4 minutes....

2) For a wet ball simulation, they spritzed one ball with a household hand held spray bottle once every 15 minutes and wiped it off. I can't imagine this got the ball as wet as a football used in a rain game.

3) Their tests showed that if the balls had been checked with the gauge that Walt Anderson told Wells he used, then they would have been legal. So Wells concluded that Anderson used the other gauge. The two gauges varied by .4 PSI.

4) Instead of comparing the pregame inflation with the halftime measurement using the same gauge (they measured the balls at halftime with both gauges so they had two sets of measurements), they converted everything to some mythical Master Gauge pressure that allowed them to prove that the Pats balls were .2 to .4 PSI less than predicted.

 

[JJC]

http://www.google.com/patents/US6422960

Patent: Self contained sport ball inflation mechanism
US 6422960 B1

 

[Marko]

So if the Pats were ,2 to .4 below that was unacceptable but having a gauge differ by .4 is ok

 

[juny]

The firm hired by Wells did empirical tests that initially showed nothing out of the ordinary with the Pats balls. So they started adding stuff to get the results they wanted.

1) They ran a test with four balls to show that they regained their pressure within 3 or 4 minutes after being brought in from the first half. Under this dubious finding, the Pats balls still would have been perfectly legal if measured within the first two minutes, but barely low if measured at 4 minutes. Nobody can remember how long it took to begin measuring them, but Wells assumed it must have been at least 4 minutes....

2) For a wet ball simulation, they spritzed one ball with a household hand held spray bottle once every 15 minutes and wiped it off. I can't imagine this got the ball as wet as a football used in a rain game.

3) Their tests showed that if the balls had been checked with the gauge that Walt Anderson told Wells he used, then they would have been legal. So Wells concluded that Anderson used the other gauge. The two gauges varied by .4 PSI.

4) Instead of comparing the pregame inflation with the halftime measurement using the same gauge (they measured the balls at halftime with both gauges so they had two sets of measurements), they converted everything to some mythical Master Gauge pressure that allowed them to prove that the Pats balls were .2 to .4 PSI less than predicted.

I think their calculation in #4 is ok as they calibrated the game day gauges with a known source, the so called master gauge. I do believe that they did not fully account for #2 the rain factor which could have very well accounted for that fraction of a psi they are up in arms about.

Seriously, one gauge would have cleared teh Pats, the gauge the ref thought he used. The other gauge produces an error of .2-.4 psi which is lower than the psi differential between the two game day gauges. Why is this point not getting enough attention?

 

[hwc]

I think their calculation in #4 is ok as they calibrated the game day gauges with a known source, the so called master gauge. I do believe that they did not fully account for #2 the rain factor which could have very well accounted for that fraction of a psi they are up in arms about.

Yes, but neither the pre-game measurement (if it was done) nor either set of half time measurements was done with a Master Gauge. Why not just run the graphs with the known halftime measurements (unadjusted) and 12.4 pregame assuming either gauge? In other words, compare apples to apples or oranges to oranges. The fact that they muddied the graphs by adjusting the measured PSIs tells me they needed more fudge.

 

[hwc]

Seriously, one gauge would have cleared teh Pats, the gauge the ref thought he used. The other gauge produces an error of .2-.4 psi which is lower than the psi differential between the two game day gauges. Why is this point not getting enough attention?

That pretty much sums it up.

And, if they really took into account the wetness of the footballs on a day that had seen torrential rain pregame and steady rain throughout the game, there would be no issue at all.

At the end of the day, we are right where most of us started many months ago. They don't know the inflation pressure of any of the balls pregame.

 

[juny]

Yes, but neither the pre-game measurement (if it was done) nor either set of half time measurements was done with a Master Gauge. Why not just run the graphs with the known halftime measurements (unadjusted) and 12.4 pregame assuming either gauge? In other words, compare apples to apples or oranges to oranges. The fact that they muddied the graphs by adjusting the measured PSIs tells me they needed more fudge.

Good points but I'm not the right type of engineer for this to know for sure. I'm hoping more articles like the fox sports article discussing the rain factor would come out critiquing the exponent report.

 

[Tony Cahncuhd]

Headsmart Labs did a more thorough empirical test simulating the effect of a cold rain and found that wetness added another 0.75 psi to the pressure loss, for a total reduction of about 1.82 psi on average.

http://www.headsmartlabs.com/

 

[PatsFanInVa]

The spray bottle with its contents was kept at the same environmental conditions as the footballs undergoing spraying.

Excuse me?

So two assumptions:

1) they are using the only rain in the world that does not fall from higher in the atmosphere. Adiabatic rate and all that (this would be the wet adiabatic rate [usually cited at 3 degrees F/1000 feet] in the case of rain). Clearly they're cheating, or nobody in this firm is familiar with aviation. If pilots made the assumptions these guys used we'd all be in trouble. So where in the atmosphere was the rain falling from?

2) It cannot be too difficult to find out the height from which the rain was falling; I guarantee you, it was not forming at ground level. Here's a general ranking of the heights at which you find various clouds... which is, by the way, where rain comes from.
http://www.waterencyclopedia.com/Po-Re/Precipitation-and-Clouds-Formation-of.html

• High clouds (cloud base above 7 kilometers or 23,000 feet). Usually consisting of ice crystals, these include cirrus, cirrostratus, and cirrocumulus.

• Middle clouds (2 to 7 kilometers or 6,500 to 23,000 feet). Consisting of liquid droplets, these include altocumulus and altostratus.

• Low clouds (below 2 kilometers or 6,500 feet). Consisting of liquid droplets, these include stratus, stratocumulus, and nimbostratus.

• Clouds of vertical development (cloud base generally is in the low cloud range, but the tops may reach great heights). These include cumulus clouds and the towering cumulonimbus.

Read more: http://www.waterencyclopedia.com/Po-Re/Precipitation-and-Clouds-Formation-of.html#ixzz3ZyKbutLd

Before accounting for the warming of the rain as it falls, we're looking at 19.5 degree difference if the rain came from low clouds. But of course, rain does warm as it passes through warmer air. The question is what were the weather conditions January 18 from 6:50 to halftime, roughly. Did the temperature drop during that period? What was the ceiling? was it a broken ceiling? At what height were the clouds the rain was coming from etc.? You want to know these things so that you don't do what Exponent did, and spritz the balls with the wrong temperature water.

However on page 30, we find this:

Weather Data. We, together with Exponent, analyzed weather data collected at Gillette Stadium on the day of the AFC Championship Game.

Exponent uses a cheat of unspecified magnitude in assuming rain to be ground-temperature, despite their access to weather data.