Predicting the Tour de France and Soccer Ball Aerodynamics

every once in the night ok so what a weapon is a very low spec so what we’ve got sweatsuits colloquium they were honored a fair shot here from lynchburg college professor got his best websites degree at Vanderbilt University event master Indiana where he worked on photon dragon he’s been the visiting professor at Kenyon and Olin College and he caved the Lynchburg golf in Virginia in 2002 the chair 73 and press 0 Graham is an expert on the physics of sports and is the author of a great text book it’s called goldpetal physics that we use the ark uvm so it’s a pleasure that happen today cut from the tour de bronx and soccer ball aerodynamics and should before we start a small token of our appreciation I just let me put first day in Vermont very interesting place is everybody’s it’s nice and cold I love it’s a pretty nice view zagreb chocolatey grows so physics of sports is not perhaps in traditional research area that a lot of people going into physics to think about factors a big engineering community that probably worse than physics and do sports science the interest that I got in discourse physics was high school-age thinkin I’m going to be a professional baseball player and I mentioned to a few faculty members that I joke around i’m one of those few people that went to physics because something else was too hard i know i’m getting a curveball to be a little more challenging than diagonalizing of matrix inequalities okay so I always had an interest in sports and then once I got to a signal over armies college with very few faculty members i found that not everybody wants to do the kind of things I was doing you in my grandma school days they were running things in sports they were athletes playing sports and Romanian physics and this dish just kind of started snowballing it’s just been a lot of crime I got involved in torrance modeling ten years ago and the soccer modeling took place and I have that time and just curious how many people follow the tour across yours oh and you all just sit together right so this is the soccer signs how many your world cup soccer a smattering of those eyes okay I love this let’s do so I’m going to try to split this talk into into two pieces just to give you a flavor the kind of research that I’m doing how many of you here on athletic teams were super not kind of melt what’s worth cyclin all barriers curious big results of what I asked poinciana last night right yeah that’s got an investable just just check and see just a lot of games go to the got a flavor blessings local here’s the idea that we had ten years ago the tour Franz website every year will show you the state profiles for all the stairs this is run three weeks in July there are 21 stages sometimes the first one is the stage 0 is the state line it’s a very short prologue a couple of time trials and it’s just beautiful scenery maybe start in Corsica belgium but most of this is plenty of friends and you get a profile like this and if you’ve ever watched the Tour de France I don’t think you’ll agree that the actual terrain looks like this this is just a very rough sketch that we get on the horizontal here we see distances in kilometer these are actually distances bite they’re not actually showing a horizontal projection and then you get these elevations here in meters with different mountains label here the altima’s is the very famous 21 air can climb up the mountain that they actually did twice this year to celebrate centennial of the sort of gloves and

these mountains are classified the unclassifiable the big climbs are these hd’s bridge might be better than mine I’m gonna try so the boars pedigree pronounced climbs with really bones to watch and get fans everywhere and we were trying to find some way of actually predicting Detroit bronze the head of time and simply could come up with the state winning times but this is all we’ve got and crashes happen huygens happen brings happen you also learned that they find ways of using the restroom perhaps while they’re still in the bike they do all kinds of things sickle fans are dressed up like clowns or super action heroes and writing along with flags and what is it challenging think the model now this is also a 2d profile to eat but the limited number of points we get here can actually be supplemented with some Google Earth websites and some other websites where you go in and follow the train so for example maybe we’d like to know what’s going on in here and the Tour de France website doesn’t give us any information about elevation here how slow this down to that box right there before you get to the top of that P so we would go to some other websites to fill in some of these gaps how many of you are in the intro physics quarter are taken did you ever wonder when the world are we ever going to use the inclined plane we said you know you’re giving us heights and distances let’s make it fly planes of all these things so we learn to solve the inclined plane because it’s 100 high school whatever you first met this so we see we’ve gotta wait on the cyclist or some resistive force here we become air resistance and rolling resistance the road is pushing the tires forward we model this is kind of a force that originates from the cyclist power output normal force from the road and physics one right just break these things into various components it really is just a one-dimensional problem we can set this thing up computer in two dimensions and have these things can make some nice pictures but it really is just a one-dimensional problem here and you can solve these second law equations from you oolitic Lee now this is a simplification I think anybody who’s going to get into modeling knows that this is not 21 hairpin turns and someone urinating on bicycle this is a challenging thing to model here so we thought we would give this a shot we look online at some get to the parameters of knowledge I think everyone’s probably seen these forces before so you know you’ve got the weight a normal force we model the bikers power it output divided by this beautiful so there’s a lower limit cuddle small here the retarding horses you’ve got a lot of drag force so what speeds can you cycle in your bicycles if I’m going on a flat for a while I can talk with me about 26 27 miles an hour yeah so think about that get upwards of 30 miles an hour stick your hand out the webinar universe there’s a hefty amount of errors is there you’re going slowly you’re fighting a lot of resistance with the grounds the rolling friction declamation of the tires you lose energy there so kind of this ancient ghulami model unfortunately we use to follow the rolling friction here and we’ve got these two drag board system forces here the dragon rolling resistance blocking the signal retarding force the bike route that’s power and push the Earthman interaction bicycle as well some numbers we just found the average cyclist mass the bicycle as a mass lower limit and seventy seven kilograms seemed to work for an average of all the elite cycles they’re meeting lots of research has been done on the tires rolling resistance air density of improvement to this in a little while we first did this we thought where we’re going to have to come up with some kind of drag in an area usually these things are measured together very hard to separate had a student trying to take a picture of himself up by two grid and try to actually we got his area but it’s hard anything elbows are moving out try to get every place we found some wind tunnel data and at the beginning we just

split this up into two regions if you’re going uphill you know if you’re ever real advice about do you tend to be more upright on the bike you’re really excited to get up a hill if you’re going downhill you’re really crouched if you’re sleeping the love and filled with in your face and your brother keep the air resistance down that so we reduced the air drag right now you know theta was our inclined plane or whatever so we made some modifications and post your we actually then used an exponential model for the atmosphere to give some more something more realistic to the air gets that either climbing mountains that are two kilometers above sea level so we want to include and we didn’t introduced a continuous model for this still consistent with what people were measuring in metals I was trying to think is there something out there that’s kind of constant over here and costs it every year and just kind of joins those two flat lines and having just taught magnetism I thought well let’s try to provide light and affection I don’t think it’s too terribly sophisticated whatever you pick for the Russian here is I make too much difference you just need something that’s kind of what size here what size here that you need to join these two but this gave us some parameters we could play with and it gave us four parameters here for the drag coefficient times the cross-sectional area the cyclist and i’ll come back to how we find even a moment with the power outlet lots of physiological spoil you lots of cyclists on bicycles with oxygen masks and scientists and lab coats commercials will sleep and they’re doing all kinds of experiments to see what kind of power outlet yeah now when you’re going downhill and you’re fighting a lighter is that you’re flying and you’re saying well it plus 30 miles an hour down yo putting more power into it is not going to help you that much you’re fighting a V squared in your drag so it’s not the models not too sensitive to this number this right here is enormous but it’s only a really tiny stretch where there’s a very steep incline and I’ll show you why these moment and then we try to find something more kind of this maze where we’re going to add most of the power and then another transition region again trying to stay consistent with what experiment earth tell us here well this past year we introduced a continuous model and I found that if we go out to just the third order polynomial any angle here we could get pretty good matching the 2012 result we tried many many different things here we tried higher order polynomials and by various functions we’re basically trying to come up with some idea of if we have a steep hill and you know a lot of power we have a very steep hill it’s went down you don’t have that much power at all trying to find something that matches the experimental data so for more for Ramage we have eight so we have an eight dimensional parameter space between sears what happens in 2012 we had 441 angles for the 21 stages so they ran for a wedding client planes in a row and we found that there were cut off their these gaps here there’s another one there if we wanted to give an interview no we found a gap here we’ve got a gap just right of any checkpoints it’s right there and this is where we were using these discrete models so we have six angle year most of them are at this kind of lower region here and it’s worked well for ten years you were predicting quite well I’ll show you in a moment that almost looks like you could make a third-order polynomial now we had to make some modifications because there are sub stages that are as long as other states so the prologues the team time from individual time kernels you’re allowed to do drafting and a tee time travel here watching you have the lead cyclists doing all the work and the buddies are back there taking it easy and then they’ll swap and now can’t do that on the individual time trials will get it back to Tony Martin here but the toileting is greater than a Maquis nice

teardrop shape of Homeland scared crowds forward these bikes almost have no handlebars you would recognize if you’ve never been it’s like this you close all the Scopes back here the shoes are basically attached to the I mean as much aerodynamic help as you can get here to make for a very fast right so we found over the years that we take our drag coefficient of x the area’s drag area perimeter we drop it by about twenty percent that seemed to work pretty well what people were binding and win titles were normally we didn’t have to make that modification so here’s what happens 2011 the first time i decided i would put this on a blog and i thought well i’m going to stick my neck out so instead of publishing it which is what i’ve been doing the past after the race was done trying to get people to believe yes these were actually just his prediction for this good before they started I started putting them online on my blog and we were getting some nice agreement here nice and a relative term here’s 2012 bradley wiggins who had a breed apart good year 2012 do so here’s the actual wedding result we’re always after the winter we’re not trying to predict one specific bicyclist here and we were off by 22 seconds which seven-minute raises five percent and the first time we did this we were only held one stage by ten percent we just kept getting better and better better I think maybe this one here nearly four hours that we were off seven seconds I was kind of yelling in my next day we were 18 seconds solved yeah we kind of thought well gosh we’d like to get better than 10-percent now we’ve done this as well it’s better than seven percent see how many we can get kind of under two percent or so the overall time we’ve always done really well we were off 16 and a half minutes 2012 just three add up these areas quadratures I think it’s around 29 / stars so closer to the percent you wait a little bit differently you got rest days in years intermedia mountain stages last pages so different types of stages they’re pure mountain stages of able to begin and the blog statistics go through the roof during this race and I’m not even going to be 29 to know why people getting and I’ve got contacted this year when the predictions were not put in into the eleventh hour people in Belgium and France and Germany and all over the world are coming are you going to put yeah benefit prediction one so we were ecstatic 2012 we thought what we’re going to use this as our blueprint for 2013 we make this transition the more continuous models well we’re going to spend a little time talking about the 2013 race because had some eyebrow raise the moment but what we did was we used 2012 because we know the answer we’re going to mine our eight dimensional parameter space we’re going to find those eight parameters even make 2012 a better predicted before and we reduce that overall went 3 2 percent of the quarter percent the largest error that was around 7.3 percent without about six percent so we were able to reduce these things incrementally if you stared at the picture along enough you can see a little reduction and this took several weeks doing this over here because you know we weren’t even sure what most women to let oldest form of the annuals yes and what’s the ribs are published then people like me just mind the office early I mean we’re just good at the hardest part about all this is just entering all these bloody all these different angles and then you know we look at the profile they don’t have that little park there so we go on mapping satellite pictures these get more data voice I mean Google Earth is really

helpful for this cool begad you get all this data and you know where this stuff is presented the cyclists are sitting in the audience watching you know the content words and the other hybrid stuff is big mouth thing to produce item in these pictures so here’s what happened now first day comes along in this kind of traditional flat stages about a five-hour prediction we have we got hundred percent we’re really happy lockets are going through the roof while they’re hitting it again they’re really nailing this thing around your four percent under weather said there’s a six-second difference then things started to happen in the second week and that’s what we’re going to talk about a little bit here in fact if you see a plus sign on that percent difference it means what you slow see a minus sign we were a little too fast Chris Froome another a victory here team um question on them yes you’ve got to rest is marked do you have anything in your model that says after a day of rest the cyclist will be able to X or wire well when we did this before the thing is we’re going from a red they arrest to a pure mountain stage both of these times so we’re not anticipating some drastic increase in power output but here I think we had a pure mountain yet a flat stage so no i mean the the only thing we’re assuming with the rest days are getting back up to the level that we think our models to model those days aren’t there then we would anticipate we’re just going to fast throughout the race but we got to the end here they were two and a half hours off this is you know I don’t look at a three percent error and think that’s good I mean I I look at two and a half hours and think well that’s something really happened here and it’s really the second week and I’ll talk about a couple of these stages and what happened the time trials we first got a hit at this time trial the Australian team had an average of 57 on his 50 kilometers an hour this is almost 36 miles an hour that’s Holland but on a blessing that’s really fast when I bicycle so we started to get curious by how fast these these cyclists were going here we can’t predict the weather we were way too fast on this they fought terrible weather honest 30 clobber Crossman’s and nice thing to follow this online i’ll show you the direction again almost exclusively head bent now were we too slow we might have been bricked so I mean I I take this with a grain of salt you know i’m not going to go to predict weather so turning mark i showed you a picture him winning that stage 11 time trial he and chris brim with right behind it they were 12 he wanted this 54.2 seven cars an hour that’s that’s almost 34 on our individuals there’s no team help here there’s no draft converting like that I look back and I I try to find comparable stages in the past he won a stage that was a comparable distance 2011 a little less than forty six dollars and we’re just seeing these speeds and just completely baffled by what is it going on we get down the year this is marcel hotel he beat every single flat stage every letter from 2012 except 11 he didn’t appear here a moment the other thing that’s goofy about this stage now his third tour phone lat stages every single cyclist who came in beat our prediction we’re always trying to predict the winner everyone come out 170 so cyclist beat our prediction this is 218 commoners their biking this day very long stage and credibly large speed another 173 clogger states 13 it’s flat

here this is more than 29 on our average mark cavendish would be every single flat stage from 22 feet of all he was the one who Patel cudahy previa /a the one here I like this 181 site was completed this day they all do this 191 kilometre stage he also not only did all of them beat us the person who finished last in this stage beat the winners average speed in every single media mountain stage from the previous year and you go up here two stages two and three their medium out the stages that average speed from the last place finisher the person who is the 180 first cyclist across the line that day had a better every student illiterate on the preview to the previous state student and again we we had Madison strategies like this before we had not just could not understand this one here just completely crazy number 41 a half minutes too slow I will come back to this here’s a picture of stage 15 now I was chomping at the bit at this stage I mean imagine this you’re on a bicycle for 221 kilometers you got a couple of these little category for three climbs you know not too bad for these professional cyclists 221 kilometers you’re on this bicycle you get to that point this stage 15 is 30 kilometers longer than the day’s stage you just ran in the previous day it is also longer than every other stage in that year’s race but two of them okay as being the other big one the lead cyclist or 47 kilometers an hour at this point completely baffling how that speed could be so large amy has this unclassifiable climbs to go so they had completely got to this point well in excess of everything that you’d ever seen historically for what people to do in Germany when kilometres and what’s the strategy oh wait we still have this uncategorised climb to do you’re straight up the mountain and all but one of our hundred eighty one cyclist beat is so whispering finished this is the winner pretty much sealed don’t worry a little less than 40 to water our average how much choices here’s another one where the weather this was actually painful to watch this time trial they were coming off these platforms hey lollee green swirling winds and we were too fast so I kind of write these offices publishing ahead of time but that’s just what happens with the weather i’m going to show you why i thought we would be a little fastest staying the night teams is a little famous for one particular reason to see this moment so they don’t run the same race every year just what makes it but illegal silk so much fun i had to go back to 2004 and stage 17 to compare to this past year stage 19 that i was talking about they have the same starting point almost the same elevation same ending point almost same elevation the same mountains here they got the same mountains here i think the only main difference was there was a little sprint area here was back a little bit further here the distance is exactly the same I mean you’re not going to find to tour across stage is more similar than these two right here really cost though from portugal as the one who went in this past year 46 of 170 cyclists that ran like this stage beat us about twenty-seven percent who do you think why this one he did that six hours 11 minutes and 52 seconds and costco came in under six hours now by this time in the race our eyebrows were in the back of their head I mean we’re just trying to do what is going that’s actually licensed winning

pose for 2004 stage 17 we were trying to figure out what was going on now so I had this idea when the Ray said first weeks okay separate these crazy speeds and then you start reading and before started last same question we’re asking and I would certainly never make a conjecture and probably during the private pouring without data and evidence I’m a scientist so I I will not make any claims at all why I bigamist so because you’re high because I don’t have any blood sample data analyst but I wasn’t though if you get back in history and you looked at the average speed for the winner of the past several toward process how would that person have fared this past year’s quarterfinals all the stars have been vacated all of lance armstrongs seven straight titles are gone Floyd Landis is God contador had to give his 2010 anglea this is how they would have finished a 1999 Armstrong would have come in 18 last year’s Bradley Wiggins would have been lumbering at thirty fifth place Cadel Evans from Australia would have been 42nd here’s Contador now I did put the distances on here through the fog reason only two of these are shorter than last year’s race last year’s race was thirty four hundred and four kilometers so you have these two here that were actually shorter so I would expect a longer race to have it is slightly lower average speed but you know 30 for 30 over three weeks three credit for we’re not talking about a huge difference here and still finishing well out of money here well out of the pictures in your physical yes are you taking their average speed and yep that’s very very very simple I’m not proud of waiting or do anything crazy like that I’m just saying hey this was the average vu one with that year where would that average speed of that you 2013 so just I don’t know noticed we’re the ones are but I don’t I honestly don’t know the answer this question I’ve been researching I’ve been talking to my colleagues in Europe I can’t find a major technological advance or training advance from from 2012-2013 you believe that kind of change in the speed now first every tour de france is different i mean the anointing and take this with a model of salt here but the point has the you know a lot of people a lot of publications who are writing stories at the time this past july that something looks a little out of whack here you got some ideas your scientist TI things you’ve heard anything new about the technologies but the colleagues I’ve got overseas who do cycling a little bit more fervently than I do so you segue to just average velocity sure the the old discrete model we used was just a slow we were just trying to find a way to make this thing a little more portable while you’re the next we didn’t have to look at all the gaps in the picture but yeah I mean we still noticed that our model was behind but I mean this has been working well for us for a decade and in this past year was a was a curiosity so make science fun we get a curiosity more reading so we got some publication than this we just this recent work has been accepted by the journal Science Engineering I am on the cover of my book the back that’s not those are my abs but the blog

here contains our predictions in July so every day the name of for each stage and run we do this I get a kick out of it is that I get and the country’s I get but I do want to segue into soccer here so second happened to talk i’ll tell you about someone we’ve been doing connected to it please if you’ve got questions about for tots i’m happy to take them in at ua that the introduces the soccer so why do people care well every four years the world plays a sport that those of us in the u.s. thing isn’t that big a deal and you don’t make me during the world’s population what I’ve lectured in England and I thought like one of these balls and I say go okay I’m not sure about a soccer 10 day I get blue soccer so you know there’s a language and a passion that a lot of us is Gabriel didn’t grow 2002 Korea Japan share the road come and Heidi daus is the maker of the ball they put up this 32 panels traditional 12 10 minutes ago but here where you got a pattern of the ball that if you’ve ever kicked the soccer ball you probably had as a kid talking like that are you still here the real change came in 2006 when Germany hosted the World Cup they used what was called the team guys ball and the team baseball was the first one that had thermally bonded panels we’re stitching better technology keeps the ball your dryer inside and they went from having 32 battles to just 14 and the players started to notice a difference in the aerodynamics and those of us studied a little bit about aerodynamics know if you start changing the surface character of an object passing through the air things can change well 2010 comes along and the job a lot of all was introduced for South Africa and it only had eight panels I mean you know we’re trying to get this perfect sphere ideal as few scenes as possible thermally bonded as well the approved bladder design because you kept going from something that had lots of places of roughness to something that kept getting smoother and smoother imagine hitting a golf ball without dimples imagine the days in the aristocracy when the golf was just admitted and they’re hitting these nice smooth balls bourgeoisie that gets broken use bowls or driving them farther wait what we can’t let that happen so what are you doing golfing el dimple level thing that these we make it as rough as you can and it goes far that’s have less drag on well they had to intentionally rough on the surface of this ball over this whole thing are these little bruise this thing up they could not have this ball being smooth it’s just a male it just changes there at a tedx completely so they artificially fitted big roundness it’s not due to stitching everything so in the next year look up I’m going and it’s down in Brazil and the brazuca ball is the name that I’d US has not revealed the pattern of all you don’t know how many patters our own roughness and stuff the sixth of December is the day when the final world cup world cup draw is announced usually that’s the day with the ball to do so I expected at that time getting a little all you know lots of calls in 2012 what’s going on the 22 juju John Moneyball wisest thing acting like that so I’m really anxious to see what this goal so let me just tell you that some work that I’ve done with a colleague University of Sheffield he’s got a wind tunnel as a small one they have to use a small prototype wall there are some larger wind tunnels where you use actual size balls colleague panties got a really nice window tired moment the problem is

there’s this pesky thing on gravity where if you hold something that you let go but it falls and you can’t put the ball in there with nothing holding it and you blow air over this thing into either blow away or a ball so you have to jam a big broad it and hold it there well the thing is you don’t play soccer or football with a big ROG up in the mall so I was trying to think how are we going to analyze a soccer ball via trajectory information get there both dishes kind of in its natural environment without having a rod so we made use of a kind of a homemade ball washing machine they’ve got these for counter rotating wheels so we can send this thing out no spin sending out the sides bed topspin max pay whatever we want an eagle is good there’s a camera set up here that we use is the high speed 2,000 frames per second camera we put the information at the launch here jealous my colleague took this picture they’ve got the ball coming out the axes that we set up we also noted where the range of all when it landed we’ve got a second camera set up back here to try to get the apex of the trajectory and this is what some of these pictures look like so from the launch we were able to give data like so whenever the apex given more points like that so we’ve got these two camera stones and we’re going to extract your enemy coefficients from so how do we do this fo mechanics towards your setup second law you got away to the ball here nearly a pound or four dudes so if the ball has a certain stem in this case it would have some backspin kind of kicked under the ball and it’s rotating way so there’s a force we call lift sometimes the shores good by various names there’s kind of fact people doing air aircraft flight dynamics but the idea is the air gets pushed around like so we’ll get pushed down a little bit more so it separates off the backings ball asymmetric it’s like you look at the back of the boat there’s a rudder there and you want to turn the boat you turn the rudder the water gets pushed one way and good old Newton’s third law says a little but it’s got to go the other way so if you can make the water separate asymmetrically one side or the other can make the kind of turn same idea here you push the air back not straight back that it off to the side and you get this lift force then of course you got this drag now the air just exerts a force on the ball it was me nerdy scientists to come along and want to break up these different components and given names something like that that you know the air is just because you’ve got a boy horse I but we set up this equation we can even have a little science bit as a component to the spin also out of this plane of the spin axis here we’ve been coming out of that direction to include all three different pieces of this full three-dimensional problem and here’s what we do we solve the second horses have to do this numerically but we don’t have coefficients to have a brand clothes on the lift coach put it so what I have to do is I have to do an optimization here have to try to find what coefficients are going to give me the solution that sits right on those data and that’s what I’m showing you here here’s camera one data here’s camera to data and the solid curve eaters of pure numerical solution and I optimize it so that i can get care one nice and bit right there nice and swears they can or tues data and I also look at the Reynolds number which is proportional to the speed of the ball to see if registered the domain where the drag coefficient might change and we happen to be make sure that this entire trajectory is that a reynolds number here the 2 times 2 divided i’ll show you yeah is your camera tracking the spin of the ball as it goes through like do you know this is a no-spin runner is that based on here ended up for this in and i can’t show this in I mean it’s taking plenty of frames per second allergy dollar franc is what we’re doing that we say yeah we can track the spin I’ll show

you the spinners only but what I do is I look at the range out that this particular ball went 21 and I can show you how sensitive it is to change a non spinning football live you changes drag coefficient from background which is going to land out here a little 26 metres or so all the way up to a half a teen boy premieres are all added right here well not only did we match the range exactly read into that our camera data also fits that was a little bit of a fudge because they all kind of go out there are our camera to data fits right on that curtain cbs12 now one problem i’ll show you the experimental versus computational under experimental squared has a minimum is rated zero ready to year i’ll show you the problem with this so the dots here are my colleagues data in a wind tunnel now he’s using a small ball it’s not a real soccer ball and it’s plastic and the places where the seams would be tend to be like corners so it tends to be a little bit rougher so the drag coefficient tends to be a little bit smaller than some rosy a sock in here then it gets actually bigger than a real ball because what happens after you get him a turbulent flow situation my colleague in japan for a 32 count of all his drag coefficient data is a function of Reynolds number which again it’s just like buying this inflections easier does the fun and there’s this characteristic drag crisis as we follow you actually go faster and this drag coefficient drops and the fun thing about a sport like soccer or baseball is the sports played where that great crisis is that’s what makes this so much fun well that range of rental numbers i showed you i only had one Reynolds number everyone drag coefficient I was assuming for that entire trajectory I wasn’t taking it to be velocity of pleasure so that whole range of Reynolds numbers could be here well have we matched the prototype little-scale minie balls or we actually the real ball kinda hard to tell so they don’t have a very large gym I said well let’s take the ball watcher turn it toward the diagonal try two shooters far as we can we don’t want to go too high into the rafters we try to get the fastest watch speed be good and we got the next set of data right down in here so i think we’re tracking the real ball more than we are the scale of all that result with the lift we use the first camera we don’t there’s an exponential degradation of the spin as you move along the path in a ball comes off of baseball bat 2,000 rpms by the time if someone catches it it’s under six months I mean if it was going that fast when you’re trying to catch it with roll out of your glove so there has to be some reduction it’s been just catch the ball but here it over this short very short time scale right that first camera I been able to track the spin we have this thing called the spins lameter this thin parameter measures the equatorial speed of the arse omega of all times it’s divided by its center mass p now wind tunnels can spin balls but it’s been a very fast and when tunnels are very limited to how far you can go up in the spin here and I’ll show you as data illustrates is better but we’re able to extract drag and lift from that first camera and we can do this for all kinds of different settings of our wheels so here is men’s model data wind tunnels only go up to about a spin for a bit over 13 so again you want to make spent forever big you’ve got to really spin the ball fast or you got to make the speed really slow while it’s spinning which is also tough and wins I’ll just have a light breeze it revolves not very angry so most wind tunnels are giving up to about point three why tell my colleague hey let’s do this outside the wind tunnel and we can get data out here spin parameters one or bigger in fact what I showed you here we didn’t I showed your four points here we get matched with hot all day over these two values here we’re also able to get values for the win top that’s the sea we did this with the team guys ball and

again the wind tunnels are going to stop about here we’ve got lots of data past the spin premier 23 that the wind tunnels are not getting so we’re anxious to they went it was to catch up to us a little bit here see if we’re getting on the same numbers here the last thing i want to show you here is some best experiments we did now it’s the end of my time there i’m thinking around like to study this boundary layer you know the air comes off of the surface the ball and really complicated ways and how are we going to study this i thought well we could inject smoke in the wind tunnel but he doesn’t have a very big wind tunnel i also gets a little bit messy and hard to do can do like the japanese do and get this really piling toxic thing they got to learn ass and love and stuff put on the ball and shoot it or watch it come off instead we just use some chalk so what I did was I would stand over here next to this like black curtain a handful and chalk and just flap out some dust my colleague would drop the ball under fire right into the dust cloud and then we have another student here Nick Emerson who was working our high-speed camera and just thought well let’s see what we get and you know we can make a nice cool sketch here my whole we got some beautiful pictures the great thing about this drag crisis is where the drag is eyes directly inside the separation this laminar region is large so the separation of that boundary layer happens at a large angle like this the faster you go the separation takes place back here little smaller so this is a ball moving little more 70 miles an hour this was almost 43 miles down and we are able to go in with all of these shots the media these are non spinning and measure these any goals and I had a great time of this because this is where we did our experiments is right in here where the direct pricing system and the angle that we’re going to measure is try to estimate where the separation happened at the top of the bottom suite with an angle fire here now relive this is what we got and there’s one mystery here had a student who built a little goomy ometer of cardboard with some little arrows here that we used to try to estimate jumped of all the same company model and godly exactly where your passions with video and here are the angles we plot drag coefficient versus speed on this axis i’m going to show you the angle of separation so up around in here for all these shots at these lower speeds separation angles are between about under Navy and agrees that one that I showed you the commitment fast was down here 95 or so degrees and then we saw this pattern we’re going to get past the drag prices and then this thing would drop and it would drop for our high-speed ones except for the fact that we have three data up here and this right now remains that I’ve been questioned and I presented this there are international it’s in 2012 it generates a lot of conversation but we’ve yet to resolve this power I don’t know really what was going on the balls were in different orientations for using panel walls so try to eliminate the seam orientations but every shot we fired around that speed how much separation angle greater than a little bit reward a little bit higher again that’s one of the great things about doing science and understanding these balls is critical because if you look at the job Lodi ball if you’re before the drag crisis that ball had more drag that a team baseball so the lower hit lowers to be balls that were hit by the players the goalies would notice coming at him a little slower once you got past the drag crisis that I’ve worked the jaw the line ball but below the so then it was hopping fast so the goalies had a lot of trouble adjusted to this so again i’ll add another shameless the publication’s of this you’re just looking for a general read physic today invited me to write a little quick

studies so for the world cup in 2010 that was bred most accessible but that’s the gist of those two pieces of sir some of the reporters must’ve asked the Tour de France officials and the team captains and such hey you guys are blowing last year’s times out of the water what’s what do you attribute we’re all tested but it’s a little harder than that because once you finish the stage with a given time I mean every stage is different so it’s not like you’re running you know the Hydra years and all of a sudden Ben Johnson I mean it’s not like there’s just huge gap between last year this year with exactly the same race but once you start going back and you look for similar stage as sometimes you got to go back 10 or 15 years finding the stage that looks very similar to what bretons current toward frauds and only with that little bit of digging you start speeds or anomalous now once they came in with average speed hi we started to read into that second week that some of the reporters are saying while these beats in kind of high and what’s going on here and of course you read the message boards and all these other conversation places everyone has the same time nobody none of the tour officials have said okay we’re good not that I’ve ever during that ten years of modeling how much how much does remodel change just for general technological advances better in a training zone we did increase the power slightly from one sub two or three year period to the next we started to notice trainings getting a little bit better athletes are getting better you know the cyclist technologies bicycle technologist I mean some of these bicycles that the Japanese put on the shipping it they’ll have pictures of these things advertised you can’t even see the bike I mean they’ll have an end on view of the bike you’re looking at this ad and someone like me on the other side of forties like where is the ball there ok then I said I mean it’s unbelievably thin credibly low drag bicycles but of course you still have a human being sitting on top of it I mean here here there’s only so much drag you’re going to be able to reduce just by making the bike two-dimensional but yeah I mean we have had to make a criminal changes here’s one year we kept noticing that we were fast and can we check the weather and from five or six seven straight stages they all bought admits and we actually found what we needed to it feels like a bit of a fudge because we have to do it after the fact tell us what the head with now we go back make a new prediction which is really a prediction did any the car apart any correlations of characteristics of the contestants pie plate things of this world just the basic biographical information you get on lying about the cyclist as you say height weight doesn’t seem to be that different the cyclists are fairly small I mean weight wise Kai there’s a little bit more variation that I’m either compact I mean they have to be able to stay on a bicep four or five hours and you know they’re burning seven eight nine thousand calories a day some of your stages it takes the training in preparation for this is enormous and you have to if you make up those calories some mountain you have to do a lot of eating and preparing the night before and the morning up all this just to be prepared for okay over the next five hours i’m going to lose yes have you compared here power input to you can find the power box or a lot oh yeah these are consistent with what we’re seeing a lot of people there they actually we’re now like a couple of cyclists has passed your war a device

that would try to guesstimate what their power out that’s it yeah they’ve got partners and bikes now get that record is every single entire day and some of them actually make it public and like that’s a good way to see people going to get faster but the numbers I mean the power numbers that people who are putting these things on by our consistent what we’re using Chris Froome are so you know I don’t know what this I mean I can go in my model very simply a blink of an eye and change the power to get whatever time I want to get and I can see what power out that would be needed the powerful this year well I mean to match the times we would have to crank these up a few percent well so the weather sometimes makes you slow have you the one thing that may change from you the years what direction she couldn’t have been the Vizier the weather out more than hinder so that they had more weed in Diwali I’ve tried to look back at past races and it’s a good question we have try to look at weather trends you go back 10 years or more each really multiplying really detailed this is what the wind was doing this day is in this direction just I need in this part of the stage they were battling a killer direction or whatever we’ve been taking better notes last couple of races your faces to notice what the wind direction is doing great unit stage means so much of that stuff changes to and winding around these different rows and talking earlier submit I mean you got fans crowding around these be logging sometimes they get shield as pointless as you know the flags that people are I so I just kind of course they in yeah yeah most of the time I guess by have about a consistent pattern where I would say oh this year all getting tail means some of their statement they were out so submissive but you seem to be into that is that way there’s a super duper that bow enhancement such nothing happened between 2012-2013 i am just completing my own earrings i mean either there’s some technological advancement in the way you can more efficiently transfer power disciples to bicycle something in the training that I just I literature and if it’s out there about by welcome hearing about of him so are some of the advances that occurred in my school they’ve gone to tires study but increase of their look at cars actually actually put bread on them for retraction actually suspension system so that’s a bit I know the the gear shifting is now more automatic than it used to be you haven’t like chronic relaxing they’re all they were doing that last year too so it has to be a change that happen in other the other thing I don’t understand what are they it’s the makeup of people change so long flexees there are flat so oh yeah i mean the marginal revenue is a huge part of our self really fast they don’t care sure and in you’re taking your chances

of you want to win all plastic it is all under consideration is just trying to find the ball like do they want more drag well like what what people when adi does makes the ball and a lot of the researchers that are the testing done along with the UK the i mean the idea is to create something that isn’t going to be that noticeably different from what the players are used to you don’t want to just roll this ball out from the game’s biggest stage and woke up and then all of a sudden everyone’s complaining you know I kick it around you don’t you don’t want something so dramatically different from what they’re used to mean you would still want the game to be played in the high level and you know their reaction times are going to be based on you know having played with the ball certain height and that was the problem with the Java Moneyball is that those low speed kicks just didn’t have the more drag and that the high-speed kicks had less drag so first in South every a half the games you play at sea level the other half bird and while all the nations had big influence influence on the final match stupid the goalies were noticing while this ball really fast and that’s you know because these people we were shooting 10 or 20 yards out and just really really getting hard I mean that was in a low drag region compared to previous policy views so I mean I don’t to my understanding is that they’re not trying to create something especially controversial they want to be able to have a sport played and elite level that the players are gonna like I I can’t imagine they’re sitting there these little dimples here then the goalies hypersensitive think would be unintended cause it was it that i’m a favor since these were suppose we could in your spousal play sure and you know the mini aerodynamics comes in of course during the shots and you know if your vanish team i mean you know that they’re just all about passing incredibly you watch that passing but I meet a lot of that 70 ball rolling on grass or kind of but even then you got longer always gotten more drag than your years to now I mean someone like means never played soccer going to organize teen everything like that more than just kickin Gloria I’m not going to notice the jersey in Java by law atty nice ball at that level those little subtle differences will be noticed and the player diddums its destroy any sport the elite the best of us are going to notice those differences how do like is it I think well the picture that I so if the ball is completely smooth this transition would happen out here if this was a golf ball the transition would happen earlier so the referee you have the ball would sooner that transition happened what happened with Java why is it started up here and then it transitioned down like this and get lower than the ball they use of the previous one of the ranges that always lovers level soccer players can actually shoot a soccer ball I don’t actually know though is that 0 to 40 relevant or today the some of the longest like this isn’t just go shooting I meet some of the goalies you keep the ball to third in the way down or say those things can be 60 70 miles an hour they’re really hard it falls put this up a mile high elevation cell every day no one thing about higher elevation and less air resistance just get less than you can throw the ball harder and course feel use don’t get quite the same drop curveball so I mean it’s got a little

bit of betrayed that I mean the other the speeds are variables is endemic select wind velocity I’m sure the oxygen density also makes a difference in temperature maxes why just publish a confidence or do now I mean the thing is it’s a really complicated problem and we’re simply trying to get our foot in the door how we model how to be predict the winner of the Tour de France given stage 13 so we were not privy to all the strategies they’re going to be employee we don’t know when the peloton is going to break up we don’t know whether you were going to leave the peloton and start chasing who’s going to try to start or leave we don’t know what crashes are going back there’s so many factors it’s such a complicated problem in the terrain and everything I mean this is a reasonable start and you’re still hanging these things to within a few percent so whether oh sure yeah I mean and then we thought about doing that like I say I suppose the fact I Hannah I knew our last questions effective wind this one right here each one kilometer per hour of a of a head wind grows our prediction between 7-8 nuts stage so we figured there was an average of a three kilometer and so we know what ahead but on average so we could certainly say it the men’s averaging between is 3 and 3 km/h expect the time Chris range I think we’re a little more trying to get back I mean it’s just part of the vellum it’s just part of the fun doing it a day to day okay I