# Everything About Disc Golf Aerodynamics - Smarter Every Day 313

## Метаданные

- **Канал:** SmarterEveryDay
- **YouTube:** https://www.youtube.com/watch?v=-0JKHuzJ67A

## Содержание

### [0:00](https://www.youtube.com/watch?v=-0JKHuzJ67A) Segment 1 (00:00 - 05:00)

Hey, it's me, Destin. Welcome back to Smarter Every Day. This is my favorite disk golf course in the entire world, and I have a physics question for you today. Let's go figure it out. Every time you throw a disk golf disk, it curves. Every time there's a curve, it curves. Do you see that curve? Even a short throw like this. Let's see if I can hit this. Okay, it was subtle, but that disk curved on the way to the basket. Today, we're going understand why. It's a thing I've been wanting to figure out for a long time, but it's very, very complicated. And we're going to explore this three ways. The first thing we're going to do is we're going to go talk to some professionals in Finland. The Disk Golf World Championships happened in Finland for the first time, we're going to go meet these pros and ask them what's going on with this curvy thing, okay? The second thing we're going to do is we're going to meet some tech guys that integrated some technology into a disk, and it helps us understand the vocabulary and the dynamics and kinematics of how the throw happens. And once we understand all that, we're going to go meet the professor. Dr. Johnny Potts, did his PhD dissertation on the aerodynamics of disk flight, and he's going to put it all together for us. So if you watch this video, you and I are going to learn together the aerodynamics of a disk in flight and why that curve happens. This is going to be awesome. Let's go get Smarter Every Day. Now, in the last video, when we talked about disk golf, we talked to Brad and Chad. These guys own a company called MVP Disk Sports. They manufacture disk golf disks right here in America, which is really fun. So we went and learned how they do this with robotics, and it's an amazing thing. But we also learned about how they care about the geometry and the balance of these disks and all this stuff. It's amazing, right? So MVP has sponsored this video. I want to be very clear about that. Usually, when a company sponsors a video like this, there's a code or a URL or something, go buy this thing. Brad and Chad did not want that for this video. They just want people to love disk golf. And the thought is, because they're nerds, if you nerd out with the physics of throwing a disk, you're going to enjoy disk golf as well, and the whole community is going to rise. And I thought that was really cool. So big thanks to MVP for sponsoring this video. So to start our journey of understanding of disk golf physics, let's go to Finland. Now, when I got off the plane, I was greeted by an old friend, Jussi from Kamerastore, who later tagged me up with Juho from Kamerastore. These are buddies of mine from Finland from a previous episode, if you've seen that. The reason we're in Finland is for the first time ever, the professional disc golf association world championships is being held outside of the United States. It's being held in Finland. Finns absolutely love Disk Golf. So the day before competition, I went to the course and I met up with two of MVP's sponsored athletes. The first is Simon Lazotte, an absolute legend in the world of disk golf. And the second one was Eagle McMahon, who has an incredibly strong drive right now. He's on top of his game. These are two guys that were practicing the course, the day before, and they let me jump in with them. [S] This is the most treacherous hole in the hole course, actually, too. [D] Is it really? [S] It's the infamous Island hole. You got to lay one up between the stakes and then shoot over across the out-of-bounds to a little island that is pretty small. If you miss it, you have to keep re-throwing and get penalty strokes for each shot that misses. This first one is all about just putting yourself in position. Try to throw a big right to left swing to the fairway down there. [D] Sweet. [S] Little too wide, but that's going to be okay. Yeah, right there. Not bad. [D] Okay. You're doing the same, Eagle? [E] Yeah, I'm going out to the right just trying to get it just past that gravel path. [D] Got it. [S] That's better. [D] Got you. All right, so you set up over here. [S] Exactly. Everything inside these wide stakes is considered inbound, and the fairway goes all the way up to here. If you wanted to, you could lay up another shot to there to make the island shot shorter. Now you're just faced with a decision to make. If you want to go for it and try to stick it on that little half circle island green, anything outside of the hay or long over the path is out of bounds. [D] If you go OB, then you come back to this spot? [S] Well, I get to advance to the OB line, and then I have to try again from there until I say [D] -Dang. [S] This hole, obviously, is wide open, so wind comes into play more than in other holes. This one's all about angle control and distance control.

### [5:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=300s) Segment 2 (05:00 - 10:00)

Roll. I'm going to throw it pretty high and try to spike it down into the green so it doesn't skip or anything or roll. It just sticks right there. That's a bit too high, too left. Sit. So you made it? No, that's out of bounds by a foot. Are you serious? Yeah. I would basically have to. [D] I'm going to come watch Eagle. [S] Sit. Good shot. [D] Holy cow, dude. [S] That's perfect. [D] What the heck, man? [E] That's what you'd want in the tournament. [D] What the heck, dude? [S] That's an easy birdie right there for him. I'll get a double bogey. Everyone who that plays disk golf loves a specific course. Normally, they're home course. So what you're about to see is a total freak out moment for me because my favorite course is Sparkman Park in Hartzell, Alabama. It's great. So just watch this exchange. And if you play disk golf and you have an affection for a certain course, you're going to know what I'm feeling here. [S] Have you ever played disk golf? [D] Have I Yeah. Oh, you don't know about Hartzell, Alabama, dude. [S] I don't. [D] Sparkman Park, you've never heard of Sparkman Park in Hartzell, AL? No, it's internationally known. I can't believe you guys are [E] I played it. I played a tournament out there. [D] Did you really? [E] Yeah. [D] In Hartzell? [E] Yeah, I won the Monster in 2020. My girlfriend's from Huntsville. [D] Shut up, man. No way. [E] Yeah, I've spent plenty of time in Huntsville. [D] Dude. [E] Bronze Springs. [D] Bronze Springs, Huntsville, and then Hartzell is the... [E] Yeah. [D] Oh, you know-Oh, yeah. So it's the two put together. [E] Yeah. That's the monster. I haven't played this typical course at Hartzell. I've just played the tournament layout down there. [D] Gosh, man. Simon, I know you're new to disk golf, but you don't know how big of a deal that is. I'm joking, man. I know. [S] No, it's great. If someone played my home course, I got excited. [D] That's great. Simon, Eagle. I apologize for epic levels of cringe. I apologize to myself because I'm not going to forget that. And also, I do owe you an apology. I took the wrong micro SD cards on this trip, so the audio is pretty rough. I apologize for that in the video. Anyway, sorry for the cringe. Here we go. [S] That's ideal. I'll come back left, a little skip. That's going to be right about 10 meters. [D] So it went left, then right, then left. [S] Yeah, this is a bit under stable. That's when it has a tendency on a right-hand back-hand throw to turn to the right. But naturally, with clockwise spin, every disk wants to fall left when it slows down. So we're going to assume something called a right-hand back-hand throw when we're looking at the physics. This is my right-hand. It's the dominant hand I use to throw a disk. So a right-hand and back-hand throw is like this. And when you do that, if you were to look from the top down, a bird's-eye view, you would see that the disk is rotating. For flying that way, the disk is rotating clockwise. If you were to throw it with your left hand, back hand, the disk would be rotating counterclockwise when viewed from the top. So everything we're going to do, we're going to assume a right-handed back hand throw because that allows us to talk about the physics. Everything works. For left hand, it's just backwards. Okay, let's go learn. [E] What you just saw Simon do, he threw a back hand shot, which has a clockwise spin, and the disk is going to go out and naturally want to fade to the left. To throw a forehand, you're going to put a counterclockwise spin, and it's going to want to fade to the right. So the best players in our sport are very proficient in both forehand and backhand because you're able to shape different shots depending on what the fairway needs. Playing into the hillside generally is a little bit better coming in on a forehand angle, so that counterclockwise spin is going to help it stick better in the hill. [D] Meaning it's going to die when it hits because of the rotation. [E] It's going to die when it hits, exactly. [S] Perfect shot. Nice. [E] Now I'm going to try throwing a backhand with a putter, which a putter is a slower disk that won't go as far, but it has more drag in the air, so it's going to want to fall quicker and sit softer. [S] Perfectly played. [E] I like that.

### [10:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=600s) Segment 3 (10:00 - 15:00)

[D] You just shot a putter, 459 feet? [E] It helps because you have elevation on your side. [S] He has a top three fastest arms in the world. [D] Does he really? [S] I'd say so. [D] You just threw a putter, 450 feet? [E] I mean, that's what 18 years of playing gets you. [D] How old are you? You're like 19. [E] I'm 27. [D] That's crazy. [E] Yeah, I started playing when I was nine years old. So what we're going to do now is we're going to learn the vocabulary that they use. And the interesting thing about these words is they were born out of this utilitarian need to have a word for the thing that happens when you do this with the disks. So what we're going to do is we're going to go talk to them, ask questions, and we're going to learn the vocabulary of professional disk golf players. So what I want to know, Simon, is how you think about the angle that you throw at and the power and the spin and all that. Right now, if we were going for that cone that's way down there that I can barely even see, and you wanted to lay it up right in that. I know that as you throw a disk, it goes, and at some point it turns, and it turns a different way. How does all that work? [S] All right. As professionals, we try to figure out what is the most repeatable way to get to our target. There's something that we call a one angle shot, is where the disk actually only flies on one angle. The most natural angle for a back-end throw is this right to left diving hyzer, what we call it, where a disk goes up and then falls down to the left. The most repeatable thing is to throw a hyzer with an over stable disk because the room for error is very big because you can be slightly off angle and miss your shot a bit, but the result will be almost the exact same. [D] What does over stable mean? [S] over stable is the disc's tendency to basically dive to the ground depending on which way it's spinning. For a backhand throw for right-handed, it's spinning clockwise, which means it wants to fall left. For a forehand, it's counterclockwise and it wants to fall right. [D] Over stable, if I throw, it falls towards my belly button. [S] Correct. [D] Okay. [S] Basically, just with reading the wind direction and from experience how your disk flies. You basically visualize a line where you want the disk to go, and then you just throw it up on the one angle on the hyzer, and it should just consistently dive to the same spot. [D] Can you show me what that looks like? [S] Yeah, absolutely. Very easy. I'm just going to show you three examples. First, I'm what I would throw in a tournament as my most consistent shot, which is, like I said, a backhand hyzer shot where I will aim about 30 feet right of the cone, maybe 40 feet, throw the disk about 40 feet high, and have it dive left. [D] What angle are you going to throw the disk at this way? You're having to think about this angle, this way, and this angle, right? Yeah. I've been doing this my entire life, so I really don't try to think about it. [S] I just do it. [D] Okay, just do it. I'm going to watch. [S] I pick a spot in the sky, and then you want to line up your run up and your body to that spot, and then just match the angle with your hand and arm. [D] You're going to try to have it die on the line with the cone? Correct. Okay. Here we go. [D] Very high. [S] Yeah, a bit higher than I wanted, but you can see it's diving right on the cone. [D] Dude, you almost hit the cone. cone, dude. What I just learned is that if you're trying to get on a line right here, you want to hit over here and have it bounce over. So you're planning all that. [S] Correct. [D] Okay. [S] Yeah, I'm going to show you a different shot now. This is actually a putter, which is as straight as a disk can fly. Just the way the profile works, it doesn't have much tendency to dive in either direction. So this is more like a frisby. I'm going to try to throw just right straight at it in a straight line. We call it the easiest shot in disk golf, even though that's just a joke. It's the hardest shot in disk golf. Throw it dead straight. Technically, this should just go dead straight. You can see very little fade left at the end, but compared to the driver, basically just wants to go straight and dive down [D] Why did the putter stay so much straighter compared to the driver? [S] That is a great question. [D] You just know it does. [S] That's just what it does. [D] Okay, show me more. [S] Now I'm going to do the exact opposite of what I did. This would be a very technical throw, which this is a very under stable putter. The reason I know it's under stable is because you can see this nose of the disk is all the way bent down. Then the parting line between the two molds, which is the bottom and the top, meets very low on the profile. [D] That makes it under stable? [S] This makes this disk really want to go left to right. [D] Under stable means it goes behind you. If I'm throwing, it doesn't go where my belly button goes, it goes back. That's under stable. [S] Under stable means the disk has a tendency to turn over, and if it turns If it's too

### [15:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=900s) Segment 4 (15:00 - 20:00)

much, it'll actually hit the ground and start rolling. [D] You're going to throw the same shot and we're going to watch it fade left. [S] Correct. [S] I'm going to aim about 30 feet left of the cone, and the disk will naturally just drift left to right. Okay. [D] Wow. [S] A little short, but the line was good. [D] That's a good shot. Okay, so that's under stable and over stable. [S] Yes, correct. [D] That's amazing. [S] The second one was we consider stable. Stable means straight, over stable means right to left, under stable, left to right. [D] So the first throw was over stable. [S] Yes. [D] The second throw was And the third throw was under stable. [S] Correct. [D] Dude, I played disk golf as an amateur for a really, really long time, and I know that was simple for you. That was very good. [S] I'm glad. Okay, now, right-hand, backhand, we have over stable, we have stable, and we have under stable. Now, let's go to the next level deeper with Eagle, who's going to teach us a couple of more words. Eagle. I just learned about under stable, and over stable. [E] Okay. [D] I guess I should say it backwards. Over stable, under stable. What I want to know is how does… There's two angles that you throw. Which one is… There's a word for this. What's this and what's this? [E] This is a hyzer. [D] Okay, that's a hyzer. [E] This is flat. [D] Flat. [E] And this is an anhyzer. [D] So hyzer is like, if I'm throwing it, I want to fall into the ground. [E] Yes, exactly. A good way to picture it is think of a hula hoop around you. If you want to throw a hyzer shot, you're going to tip forward. The front of the hula hoop is going to go down and the back up. [D] So hula hoop, hyzer. So hula hoop hits the ground on a hyzer. [E] Yes, exactly. So you lean forward. And then on an anhyzer, you're going to be leaning slightly back. So that front part of the hula hoop is going to go up, and the back part is going to go down. I'll use these two stabilizers, which [D] Are they the same disk? [E] They're virtually the same disk, so you'll be able to see how they function. [D] Okay, so what are you trying to do now? [E] Let's throw a hyzer first. With this disk, I'm going to throw it out to the right on a hyzer. Since this is already a fairly over stable disk, it's going to want to fall to the ground and hyzer pretty quickly. [D] Okay. Got it. [E] Okay. Now I'm going to throw the stabilizer on a slight anhyzer. And with this being a slightly more over stable disk, it's going to want to gradually fight back to a hyzer. [D] So we're going to get an S out of this? [E] Potentially. [D] Okay. [E] Potentially. It depends how you want me to throw it. I could throw it a little bit. It depends on how much anhyzer I put on the disk. [D] Give me an S. So you're going to use anhyzer and over stability to create an S in the throw? [E] Yes. [D] Okay. Yeah. Show me that. [E] I'll show you the best of my ability. So you saw a little bit of that S curve. [D] Yeah, it did. Interesting. [E] It's easier to throw an S-curve with a more over stable disk because you're able to, what we call, force over on the disk. And with an over stable disk, as it gets through its flight, it's going to you're going to gradually start panning out and then fighting back into a hyzer with the natural stability of the disk. [D] Why would you do that? Why would you want to do that? [E] Because it depends where you're at on the course. Think of hundreds of trees in front of you the fairway, you have to start it out left and bring the shot from left to right and get as close to the basket as you can. There becomes a whole lot of creativity where you see the basket, you're like, Okay, how I'm going to get there? Am I going to throw a hyzer that's going to gradually flip up with an under stable disk and push forward? Or am I going to want to take a flex shot where I force an over stable disk on an anhyzer that's going to gradually pan out and fade. A lot of it depends on the ground. Is it going to skip? Is it on a hill? Is there water in front or behind the basket? So a lot of it comes down to is tactful decision making in the moment where you're at. And we play practice rounds at these courses, but it's really hard to be hard to know exactly where we're going to be until we're in that position

### [20:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=1200s) Segment 5 (20:00 - 25:00)

[D] And you got to do it. [E] Yeah. Okay. Already with the tendency of certain disks to be stable or under stable, and then combine that with the ability to throw hyzer or anhyzer, you now have the ability to morph how that disk will fly down the fairway. So we're getting a lot of tools in our toolbox that we can use at any point on a disk golf course, right? We're going to talk to Simon and the Eagle again, but we're about to meet a new player on MVP's team, Jeremy Koling, known throughout the sport as Big Germ. He's got a really strong forearm, and he's a great communicator about the sport. Show me how a forehand works. [J] All right. Well, so everything that I ever did as far as athletics, if I was throwing something, was using this motion. So when I found the sport of disk golf, I didn't know what this was. So I developed my entire game early on around just learning how to do this. You're bringing the disk back, and then you're using your wrist and your elbow coming through your hips to create this fulcrum, and you're going, wham, and you're trying to put basically as much spin as you can. My forehand, my spin rate stays pretty consistent, whether I'm throwing a short shot or a long shot. The thing that really is changing is how much pressure am I putting in with my legs when I'm planting, and how fast my elbow comes through my hip. [D] Yeah, I guess that's right, because all of the force has to come from the ground. [J] Starts from the ground, it goes all the way up from there. [D] Really? [J] Did they teach you the X-step? [D] No. What's the X-step? [J] The X-step is something that we teach people playing disk golf. When you learn the mechanics of the throw itself, you're usually teaching people early on the mechanics just from a standstill. But once they get the basics of the throw down, and you want to teach someone how to throw a little bit farther, you teach them the X-step, which is getting your body from this forward position where you can see your target, to getting your body into this perpendicular position where your back foot crosses over your front foot, and simultaneously, before this foot even lands, you're moving this foot forward into a plant position, and now your body and your hips are turned to your target so you're able to reach back, use your legs to push into the throw, and that's how you get your entire body from your ankles to your knees, your hips, your shoulders, your elbow, everything into the throw, as opposed to just your arm and your upper body throwing the disk. [D] It's all coming from that back leg. [J] It's all starting from the ground up. [D] But you're getting velocity by doing the X-step. [J] You're not only getting velocity, you're getting speed, but you're also getting this twisting, propelling, almost like you're squeezing or you're twisting this rubber band, and then you let loose in this rubber band on coils, and it creates all this power. [D] Can you show me? [J] Sure. We have a relatively short soccer field here, so I'll just grab a putter and give you an idea here. We'll try to go to somewhere near that cone, and I'll go in slow motion. So that's the idea of the step is that I want to keep my body in a straight line. If I start going out here and back here, then I'm losing whatever I was trying to get into that throw. [D] Oh, momentum. So you're trying to get linear momentum. [J] We try to go from slow to fast. [D] Okay. [J] Right? So we get our stable base. I got the cone lined up. Now, I'm going to move a little bit to the left because if I want to throw to that cone, I'm going to have to aim a little bit right of the cone because the disk is naturally, for a right-hand, back-hand throw, going to fade towards the left. [D] Because it's over stable. [J] Because all disk have a little overstability in them. It's just the amount of the overstability varies from disk to disk. Sometimes, if a disk is really under stable, and if I do want it to go left, I can make it go left by putting more down angle on it. But for this shot, I want to basically aim towards that right cone that you see in the background, and the disk will just naturally finish to the left. Okay. All right, so we'll do our run up here. [D] Wow. Yeah, and so you were far more linear than I do. I just play for fun, but I'm all over the place. [J] So that's just going to slow you down. And anytime you have all these moving parts, you want to eliminate the unnecessary, right? anything that can just add extra steps that doesn't actually serve you. So I try to keep things as simple as possible. And if we're talking about beforehand, I take all the fundamental ideas of the right-hand, backhand X-step, and I just flip it. I reverse it. Right, left. Then I'll bring this right foot semi-behind the left foot. But before it hits the ground, my left foot is getting into my plant position, and the benefits of the forehand really kick in right here. Because what we're doing with the forehand, instead of the backhand, where we're reaching away from the target, if I'm throwing this direction, my head has to be over here

### [25:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=1500s) Segment 6 (25:00 - 30:00)

and then I re-address. With the forehand, I can keep my head locked in on the target the entire time, so my head doesn't have to actually swivel at all. [D] Which one can you throw farther, forehand or backhand? [J] You can throw the backhand a lot farther. With more contact points on the disk like you have here with the back hand, you get the four finger pads on the disk. The way that you're pulling through here and finishing your follow through almost back in the same place, you get like 360 degrees of rotation. With the forehand, you're not even reaching straight all the way. You're reaching back about here. I would say about, if this is 90 degrees, you're looking at about 110 degrees here, and you're following through forward and you're releasing here. So 110 degrees of rotation versus 360, you could understand the forehand doesn't quite get you there. All right, let's throw it. [D] Oh, wow. And he just brought it in. Right in front of it, man. That's cool. Dude, okay. Thank you very much for teaching me about a forehand. [J] Of course. My pleasure. [D] Yeah. So the physicality of disk golf is interesting because there's a human to physical object interface, and there's a certain intelligence or experience associated with that, right? Remember, these are some of the best athletes in the world at this sport. What you're about to see blew my mind. Their ability to understand what this disk can do just by feel is off the charts. [J] If I have a disk that I want to know definitively exactly how it's going to fly, I would give it to Eagle first. He could hold a disk behind his back with any brand ever made, and he's going to tell you, if he doesn't get it right in the first guess, he's going to second guess. And that's impressive because there's tens of thousands of different [D] He understands what the disks are? [J] And he could tell you what plastic is. [D] Are you serious? [J] This guy is a savant, for sure. [E] To a certain degree. [D] Eagle, turn around. We got to... Okay, put something in his hand. Oh, this is no. Is this real? [J] If you do an MVP disk, this is going to be easy. This is no problem for him. [D] He's going to know what that is. [J] Oh, for sure, without question. Give him three 3 or 4 seconds. [E] That's a detour. [D] What? Are you serious? [J] What color is it? [E] It's orange. [J] If you get this one, I'd be impressed with this one. [E] I'm between two disks. [J] Alright say them. [E] Excite or Teleport? [J] It's a teleport. [D] What? That's nuts, dude. [E] Trail. [D] Shut up, dude. [J] We can grab a disk and we can feel right from the get-go, whether it's going to be something that we like or something that we haven't had a history of liking disks that feel like this. Maybe they're a little bit soft on the shoulder, which is where the disk starts to rise from the outer edge to the dome. So this is a disk that actually Eagle gave to me when I joined MVP earlier this year. This is a 14. 5 speed, which means it's a really fast distance driver. I knew as soon as I got this disk in the mail that I was going to fall in love with it because right here [D] Because Eagle gave it to you. [J] Well, A, it was a gift from Eagle, and I knew that he wasn't going to steer me wrong. But B, because right here, this is the shoulder area we're talking about. It's the area that's right above the bottom of the rim, the rim edge, right? Right here, when our thumb goes in that area there, whether the disk if the dome sags down or if the dome continues to rise on a very consistent plane and it creates a nice dome, I know that this is going to have a lot of loft, it's speed and over stability, which is something that a player with a lot of arm speed would need to get the most their flight with the driver. This is something that immediately I grab this disk, I do this little thing here, which all disk golfers do. We pop the dome down, we feel how much [D] Do you really? [J] Oh, yeah, absolutely. [S] Yeah, I mean, feel is a huge thing in disk golf, and especially for the pro players. The second we touch a disk, we know if we're going to end up using it or not. Love it first touch is probably a thing. I mean, I would totally agree here. You hear that? That's good. We call it the heartbeat of a disk. If it has that as a distance driver, it just means it'll go with those extra 50 feet that we need. [D] Because it's strong? [J] Because this dome and the way it shapes up right here and it goes perfectly like a... [D] The profile? [S] The profile is just this perfect shape where if you push down and you get this popping sound, for some reason, that means the disk just wants to keep flying and adds glide, and it just doesn't want to get to the ground as fast as a flat disk, for example, would. [D] One question I think most people have is what effect spin have? If I'm throwing a... This is a driver, right? If I'm throwing this and I'm spinning it really hard versus if I don't spin it a lot, when you guys threw up there in the practice, I heard your fingers pop as you let go. I've never heard that before. [S] We call it snap. [D] That's called the snap? [S] Yes. [D] Teach me about spin. Well, from the way I understand it, the faster something spins, the more stable it flies.

### [30:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=1800s) Segment 7 (30:00 - 35:00)

I'm not talking about over stable, which means a whole different thing in disk golf. But something that flies with the most spin will basically have, I think, the most lift and fly the most consistently on whatever angle you release it. [D] So it's gyroscopically stable? [S] Correct. [D] So you've got the aerodynamics, but you also have a gyroscope thing going on. Is that right? [S] Yes, but I'm not exactly sure if... Do you think any disk golfer adjusts their spin rate on a throw, or is that something we don't really tap into? [J] I think that's something that we do unconsciously or subconsciously. [D] Eagle's thinking things. [J] Unconsciously. We're definitely conscious when we're doing it. [E] For example, there's a bunch of different grips that you can use. So there's what we call a power grip, where you're putting four fingers underneath the rim, and that's ripping out of your hand with a higher spin rate. For a put, a lot of people will fan their fingers out, and that's going to produce less friction on the disk, creating less spin. In a way, for me, for example, when I'm throwing a distance shot, I'm using a four-finger power grip. But then as I dial back, when I'm throwing a put, my hand opens up, so I'm producing less friction out of my hand, moderating the spin rate of the disk. [D] So you're adjusting the spin rate just with how you hold the disk. [E] Exactly. It's not really a conscious thing, though. [D] Okay. [J] Something that you will get to see if you ever watch slow-mo flight is a lot of times people, when they throw their shots, especially forehand, something you see a lot on forehand, is that when the disk comes out of the grip, the disk is what we call fluttering. And the more spin a person throws the disk with, the faster the disk will stabilize in its flight, and then the disk can do what it's intent is to do. It'll fly more like what Simon is saying, the intent of the stability of the disk will be more true. Now that we understand how the professionals think about the disk, it's really cool to see it in action in actual competition. The opening ceremony for Worlds was fascinating. 288 athletes from 47 countries. This is a huge thing. It's hard to believe that this is not an Olympic sport yet. I got to believe one day it will be. Temper of Finland really put on a show for this opening ceremony. The next day, they got started with competition, and it was really cool just to feel the energy of the spectators and the athletes themselves. It was awesome. Representing Germany Simon Nizard. After talking to the athletes, I had a newfound appreciation for what I was seeing. Knowing that Simon had to throw it right in between these trees, I had a good feel for what he was thinking and how he was going to throw. Watch this one from Eagle. This is incredible. He's doing the X step, right? And then he's reaching back and he's transferring all the force from the ground to the disk. It almost sounds It feels painful when he releases. If you zoom in on the waveform, you can hear there are two distinct things happening. I have no idea what it is, but he is imparting a tremendous amount of translation power and spin to that disk. Listen to that. I started following the top card for the women. These are the best players in the world, and I got to see them in real-time make a decision using all this information we've learned. It was fascinating. So I got my hands on this yellow media vest, which allowed me to go just inside the rope and get closer to the action so I could see exactly what was going on. And I spoke to an official who was explaining to me that they were about to make a very complex decision on hole 11. So when they throw here, they're all going between these trees. Yeah, usually the sweet spot is here, that's tree or good players throw in this basket. That's the sweet spot. The They're just going to either shoot it straight through the trees here. And if you remember, Simon said that's the hardest throw in disk golf. This is what that would look like from the backside, or they can curve it around these trees here and try to avoid that water hazard. And again, this is what that looks like from the backside. So they had to decide if they were going to use hyzer, over stable, understable. What were they going to do? And it's just a fascinating thing to watch it play out. Okay, so the first person looks like they use some type of hyzer throw to go around the trees and over the water. And that, to me, feels pretty risky because if you hit a tree, you're right in the drink there. The second player was Silva, one of the newest players on MVP's team. She's from Finland. She went straight. It wasn't arcing very much. It was a straight shot. I don't really know how she did that. She goes low.

### [35:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=2100s) Segment 8 (35:00 - 40:00)

The third player decided to use the hyzer technique again, and the power was there, but unfortunately, the curve cut a little too soon. The last player is Cadence Berg. She's from Alabama, so I was really excited to watch her. She chose the left path. She came this way with it. It's stressful. It's very stressful. It was so fun running around the course and just watching these impressive athletes that were just so smart in terms of their understanding of what the disk would do with their physical intelligence about it. It was amazing. I was also blown away by how international the event was. Not only were these athletes from all over the world, the fans were world. They had come to Finland, and they were rooting for different players from different countries. It was amazing... Frisbee golf. Your family's from Mexico, you're from America, and you follow a finish disk golfer. Why? She's one of the best. She crushes. You see her go long on this one-off the tee? Yeah. It was amazing. She's been going aggressive this whole round. It's been not paying off for her because she's got this incredible shoes, but she's amazing to watch. She's a reining champion. Here we are on hole 16 in Tampara, again. We're watching the ladies try to negotiate over to that hay bale Island. I'm watching with my new Mexican friends, and it's just really cool to see what these players do in this situation. She's trying to make it past this island. This was the first day, so there weren't as many people as the final days, but there were already thousands of people on the course, and some of them had paid extra money to sit closer to the tee box when they throw. It was a very interesting system, and I got to move around with the crowds and understand how the whole thing worked. It was fascinating. The crowd wranglers look like a very stressful job. We are going the same way as the players, so let's give them some room. Also the media. Those trees might be slippery, so be careful. Wait, wait, wait, wait, wait. This is so funny. People are pushing and stuff. What's your name? Atin. Do you have to be mean? I don't say that I want to be mean, but I have to. You're going to have to because the crowd's excited. The Finns took this event incredibly seriously. It was on the National Streaming Service. The whole country was talking about it. And so that morning, we're eating pastries at a bakery. We're just watching the whole event. It's really, really interesting. So when we got there, You Ho and I were coordinating where we should be by watching that stream. And then I realized there's a camera crew making this happen. I bet they're interesting. So the camera guys are running all over the course trying to get there. I'm going to watch you. Yeah. What's your name? Maxence. Maxence? Yeah. I'm Destin. Nice to meet you. Are you broadcasting? Yeah. Really? Yeah. Okay. Let's go behind the basket. Behind the basket? I don't know what to do. You have a computer on your back. It's not a computer, it's a live view. A live view? A live view, yeah. And so that's transmitting back to the center hub? Exactly. So obviously, I had to go find the hub. Are you a disk golf network? Yeah. I'm Destin. I'm Media Operations Manager. And your name is? I'm Blaine. This is what they're wearing on their back? [B] Yes, exactly. And then we have DTAP batteries to make it charge. But then inside here, it's all the brains. [D] Those are cell phone SIM cards? [B] Just a bunch of SIM cards in there. And then, yeah, cell phone towers. So we don't actually see what's switching live. In my ear right now is we have a control call, and he's directing the call to all of our camera guys right now. [D] And they know their number. [B] they know that each one has... Each camera has their own number. So number three is on Simon right now. Correct. Are you able to show me what number five is doing? Because I saw him earlier.

### [40:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=2400s) Segment 9 (40:00 - 45:00)

Number five. What about camera one? He was with... So one, two, three is with the lead card. Yeah. And then four and five are both chase card. Seven is actually the drone. Six and eight are with just whoever shooting high right now. That's incredible. And we can split those guys up if we wanted to. And you have people in America and other countries switching this at their house? Yeah. In the States? Yeah. It's all in the cloud. Wow. And staying up as late as possible. It's incredibly legit, but incredibly lean. [S] Yeah, we're breaking a lot of broadcast rules. [D] In what way? [S] The fact that we're using completely just bonded cellular transmission is a lot of people view it as very risky because when you think about it, when you look at a main golf broadcast, they're running fiber or they're doing point-to-point RF for cameras transmission stuff. It's all gone to a truck on site. And then from there, they can broadcast it out to the world. For us, we're relying on cell phone networks that we really have no control of. [D] So you're like, We're doing it live. I thought the TV thing was worth it. I know that was a side tangent there, but it's time for us to move to the next step in our understanding of how to throw disk golf disk, right? It's time to go talk to some engineering nerds. Now, I wanted to stay for the rest of the event, but Youhou had some friends that captured some footage of how amazing that became. But we're going to move on to the tech geeks, okay? So the pros, they had a physical understanding of how the disk works, but they couldn't really articulate that from a numerical perspective. It's time to learn the numbers. So there's some Americans that made this thing, and they met me in Finland at this place down the road. I just wanted to document that Youhou drives like a madman. [Y] I'm just a normal fan. Now, Youhoe drove me there, and I, of course, like to pretend that all [D] Finnish people drive to death metal all the time. We went to a place called Disk King. That's what it translates to. This is a second-hand disk golf disk store, and they do fulfillment. They mail these things all over the world, and they've got this really big business. But as a part of their business, they have a simulator in the back room, and that simulator is made by Americans. These Americans that made this simulator technology went over to Finland to see worlds, but they agreed to meet me at the simulator so we can talk about the numbers associated with the physics of throwing a disk. Hey, I'm Destin. Michael. Great to meet you. We e-mailed. John? Yeah. Okay, cool. I want to know about your technology because I went and learned about how disk golf disks are released and stuff like that. I learned words like hyzer, Anhyzer. I think that's right. No, hyzer. Gosh. [M] You did it the first time. Yeah. Hyzer and then Anhyzer. Okay, cool. I learned those terms. But there's other things that I'm interested in, like release angle, like angle of attack up or down, and spin rate. I think those are interesting. And is that the thing on the disk there? [M] Yeah. So This is what's going to measure all that for us. This is a tech disk. It's a normal golf disk, but with a suite of sensors installed on board. This is what we build in Kansas City. This is what measures your throw and all the metrics you're talking about. [D] Is this an IMU, an inertional measurement device or inertional measurement unit? [M] Yeah, we have a lot of accelerometers and gyroscopes on here, and that raw data gets sent up to the cloud to get processed into a motion that we can understand. [J] This is the main IMU thing that you're asking about. [D] What? It's like... Okay. Can you Oh, wow. Okay, so what on Earth? Okay, that's cool. That's very cool. [J] It's always tracking the orientation of the disk. Then there's a suite of accelerometers that when you throw it, can go up. So some of the pros can throw over 200 Gs at that hit point. [D] We geeked out over the physics together, and turns out we had read some of the same research. And the seminal paper on this, we talked about on the phone, right? And that's Potz, right? Potts, yeah. Dr. Potts in England. [M] Yeah, some of the best experimental data that's been done out there. [D] So they showed me how it worked, and it felt like a game. There's this disk, and it has instrumentation on it. And when you throw it, it interacts with the virtual the world. But what's really cool about it is it gives you the data of the throw you just made, like the actual numbers. Oh, wait, we're at a different level now. Okay, hold on. So you can get speed. [M] It's on kilometers an hour. I can't throw 77 miles an hour. [D] That's good. Does it know that you did a backhand hyzer? It knew that. [J] It does. We told the app that we're throwing right-handed. So we're going to label it as a backhand hyzer. [D] So it knows from the data, backhand hyzer, it knows the speed, it knows the spin

### [45:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=2700s) Segment 10 (45:00 - 50:00)

the wobble, the hyzer, the nose angle, and the launch angle. Oh. They let me try it out. And just playing this for one hole led to a revelation for me for understanding why a disk does what it does. So I'm about to get to play hole 16, you said? [J] Hole 16? [D] Okay. [J] The beast. [D] Yeah, the beast. This is the beast in Nokia, hole 16. And this is the one where you have to hit the island, and that first throw really matters. The cool thing about playing this particular hole, virtually, hole 16, is that I actually got to film how the professionals approach the hole. Remember, they have to go over the out-of-bounds area and land in the island? Well, here we have four different people throwing from a fixed camera view, and you can see that each player takes a little different approach to get to the basket. Fascinating. Am I at the tee box right now? You are on the tee It works. Okay, so I'm just trying to get out onto the fairway there. I'm just going to do that. So I'm not going to throw crazy. I went left. [M] It's probably going to go left. [D] left? [M] Yeah. [D] Oh, dude, I'm really bad at this. They make it- That's fine. I think we're having a good time. They make it look so easy. Okay, so now I'm here. So I can rotate. Yeah, rotate me. No, there's [J] We're going to point you this way. [D] Let's play the fairway. Okay. I've got a green dot here, so I'm ready? [J] You're ready. Yep. [D] Okay. Throwing. All right. Again, left. My launch nose angle was 11, which is way too much. I learned from those guys, if you have a high launch angle, that it's like putting the brakes on. I You threw too high. Is that what happened? [J] You threw too high, and your nose was even higher. You threw it up in the air, and you put the brakes on. [D] Really? So my launch angle was 4. 7, and my nose was 11. 3. Those are two different things. [J] And so nose is traditionally called angle of attack. [D] Yes. [J] And so nose is relative to launch. So you can throw up and still throw the zero nose. [D] So I threw up at 4. 7 degrees. [J] Traveling this way? [D] But I threw it like that. [J] Yes. You can imagine when it's traveling this way. [D] I just made it a parachute. Okay, this is a cool data. [J] So what we say is launch is relative to the ground. [D] Yes. [J] Relative to the horizon, and nose is relative to launch. Now, let's do the opposite of that. We'll throw up in the air with a positive launch and get that nose down so you can travel. [D] Okay, let's do it. [J] If we replay that, it should slow down right there. You're going to see a positive launch angle. [D] The nose was down. Frame that. The nose, yeah. [J] Yeah. What I like to do is draw a line for that launch angle. Starts here, launch angle goes here, or the launch trajectory, we'll say, is here. [D] Yeah. [J] You see that disk is not lined up with that. It's actually below it. [D] Yeah. [J] That nose, trajectory is here, but the disk is oriented this way, so it's nose down. [D] What you're saying is the aerodynamics of disk off disk is a complicated thing. [J] It's a complicated thing. [M] But in the best way possible. [D] Why? [M] Because it's so much fun. [D] I see. [J] It's so interesting. Yeah, you can go forever and not feel like you know everything. But we did try to make it as simple as possible, boiling all that down to six metrics so you can work on getting better yourself, even if you don't fully understand all the aerodynamics of it. [D] What are the six metrics? [J] The six metrics are speed, spin, wobble, and then the angles, hyzer angle, launch angle, and nose angle. [D] Okay. So it's not... Yeah. Speed, spin, wobble, hyzer angle, launch angle, nose angle. [J] Right. [D] Is that it? [J] Yeah, that's it. [D] That's awesome. Okay, so I need to go talk to Dr. Potts. [J] Awesome. Okay. You remember at the beginning of this video, I told you we were going to meet a professor, Dr. Johnny Potts. Well, it's time for us to get an airplane and fly from Helsinki, Finland, to Manchester, England, to Sheffield, Holland University. This is Dr. Potts' PhD dissertation or thesis, I think they call it in the UK, Disk-wing aerodynamics. This thing is literally the book on disk flight, or at least the best book that I have found. An interesting thing about Dr. Potts' thesis here is he doesn't talk a lot about a spinning disk. He talks disk flying without spin.

### [50:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=3000s) Segment 11 (50:00 - 55:00)

Dr. Potts and I have had a lot of phone conversations prior to the meeting outside the bus stop you're about to see here. And we've discussed the various physics having to do with disk flight. I'm very excited to finally meet this academic legend of flying disk aerodynamics. Good to meet you. Destin. The first thing we did is Dr. Potts walked me into the amazing aerospace research facilities they have there at Sheffield Holland University. We walked in and we got to see some of the wind tunnels and some of the incredible lab space they have there. It's awesome. We're going to use these things to try to figure out some specific physics of disk golf flight. In fact, Chad from MVP Disks, Chad made some aluminum disks that we shipped over, and Dr. Potts and I are going to rig this thing up, even with a spinning rig for a future video that we're hoping to work on. But for now, we're just going to pick Dr. Potts' brain and try to understand a little bit more about disk golf flight. Early in flight, it's flying really fast. High spin rate, high speed. But at the end of the flight, when it starts dying, it starts doing this. Yeah. [P] That's because drag, the resistance to motion. So as the disk flies through the air, you have a drag force, which is slowing it down over the entire flight. As they release, as you quite rightly say, it's very fast in the spin rate. Spin rate probably doesn't change too much, actually, from the start to the end. But the actual resistance to motion as the disk flies forward slows it down, and then the vertical velocity increases towards the end, which is why you see it. Then as the vertical velocity increases, the disk slows down, and then there's not as much force in terms of lift to support its weight. Then it starts to come back to the ground. As it does that, the angle of attack then increases towards the end of the flight. That's where you see the almost a hovering effect as it comes to the ground sometimes for a disk like this. [D] Yeah, exactly. One thing that they said happens in flight a lot is a lot of times when you throw a disk, if you're the basket and I'm throwing towards you, and just assume this is spinning, as it's coming at you, it'll come over this way, and then towards the end, it'll die. Yeah, that's right. The turn and the fade. [P] Yeah, and we can look at some graphs to talk about that later of why that happens. [D] You know why it happens. [P] Oh, yeah. Because you get a trim condition, what's called in aerospace. As the disk is launched, it comes from a low angle of attack to a high angle of attack. We pass through this trim condition, which is zero pitching moment. Initially, we have negative pitching moment, which means the disk from a right-hand, back hand throw, it comes up like this and then starts to drift right. Then as it goes through the trim condition, it stays in that orientation, it won't move. Then as it goes to a positive pitching moment, then it starts to then roll back and get this S-shaped flight path. And that's why they were talking about this, and that's why it happens. And I can show you a graph. It's just the basic pitching moment graph that you've probably seen in the papers that we've published. Yeah, but that's why. Dr. Potts, clearly extremely smart. So the purpose of this video, we're trying to understand why does a disk curve. So the chart that Dr. Potts is showing me here on the screen is this one right here, Figure 5. 4 0. 13. It's like a subgraph on his PhD here. This curve is the key to understanding why disks curve when they fly. It's fascinating. But in order to explain this curve, pitching moment coefficient as a function of angle of attack, we're just going to experience it. So the thing that we did first is Dr. Potts took me to a wind tunnel where we had a half scale model set up, and we could pitch this disk at different angles of attack. And we had a little smoke streamer that we put right on the front of this thing. And as we vary the angle of attack, you could see how the airflow separates over the backside of the disk. There we go. Slow, slowly, slowly. [P] You have to follow the leading edge. [D] That was cool. That was very cool. Can you do that one? [P] Yeah. [D] One more time? [P] Zero, 10, 20, 30, 40, 50, 60. So this little wind tunnel demonstration, it wasn't an experiment, it was a demonstration, can tell us a lot of things, okay? So as you first throw the disk, right? Really, really fast. So it's going to fly super level and straight, right? But towards the end of the flight where it starts running out of gas, it's going to start falling to Earth like this, right? And if you think about it, that means the angle of attack of the air

### [55:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=3300s) Segment 12 (55:00 - 60:00)

is going to change to something down here. What's the last foot of the throw, right? It falls right to Earth and it goes straight down, right? So the air is actually coming from here. So we have this whole sweep of aerodynamic possibilities. But what's interesting about that is if you look at the flow over the back of the disk, at the beginning, the flow is attached to the disk. But towards the end, you end up getting this really weird bubble off the back of the disk where you get flow separation. So we have a different pressure situation along the back of the disk, and it varies throughout the flight of the disk. That's important. So if I'm launching this direction, going that way, the center of mass is right here in the center, right? [P] Yeah, correct. [D] Where is the center of pressure on a disk? [P] can move. It moves through the center, essentially. It moves from across that center location. That's why it pitches nose and then nose down. [D] Does the center of pressure start in the back because you're going high speed? Then as it slows down, does the center of pressure move forward? [P] It starts slightly further back, you're right, as you get a slightly negative angle of attack, and then it moves further forward. So you get a pitching moment, which actually makes it roll right from a right-hand back and throw. And then as the pitching moment moves forward, then it comes It's all right. Does that have to do with gyroscopic procession? [P] That's right. Yeah. Okay. I said two fancy pants things there, right? The first one was center of pressure, and the second was gyroscopic procession. Potts knows what I'm talking about. I kinda know So I'm going to just briefly break that down right now. So let's say we've got the disk, right? I've got a wet erase marker here, and we've got the center of gravity right here on the disk. Okay, that's the center of the disk. It's pretty easy circles. You always know it's right in the middle. Where is the center of pressure? What Well, if you ask an aerodynamicist, they're going to laugh at you because it's one of the hardest things to figure out from my perspective. I'm going to grab something off the shelf. I've never used in a video, but I think it's really cool. If you were to ask an aerodynamicist, please calculate the center of pressure on this T-38 aircraft, they're going to laugh at you because it's a hard thing to do, because you have to take into account things like body drag, like literally the friction of the air on the skin of the aircraft. How much surface area do you have at different points along the aircraft? In fact, this particular aircraft, it's made so that it's a... I forget the name of the theory. The cross-sectional area of this aircraft, they try to keep it the same. You'll notice right here, the fuselage goes in a little bit. It's got hips when the wings go out. There's a whole lot that goes into calculating the center of pressure. And the reason you would want to do that is It's because this is a tank-fired K. E. Rod. This is what's fired out of a main battle tank. It's awesome. I think it's a Russian one, but the way it works is if I try to balance this thing, I can say, Okay, the center of gravity is about right there. These fins What are the purpose of the fins? It's to pull the center of pressure behind the center of gravity. Because as I fire this thing at really, really fast, I want to have what's called a riding moment that aligns it. So if you think about it, if I fly through the air like this, there's going to be more dragged down here, and it's going to pull it around the center of mass, right? Well, that's interesting because our center of pressure is behind the center of gravity, which means this is aerodynamically stable. What would happen if I tried to fire it like this? Well, it would automatically ride itself because there's a riding moment. It's a very interesting thing. That's why arrows have fletchings or feathers. I always had a hard time understanding what center pressure actually was. But look at this. If I were to take, in this case, a wing, and I were to average out the pressures all around that wing, they would equate to one force going through one spot. In that little spot right there, that is the center of pressure. Okay, let's go back to the disk. Okay, so we've got our center of gravity of the disk here, right? Okay. So as we fly this thing in the wind tunnel, like we said earlier, we start in all that wind, the air is going over the top, and we have an attached flow to the back of this thing. So if you think about it, if we think about it like the aircraft, and we have all the body drag and the fins and all this, that means everything comes into play. This little groove on the bottom side of the disk, that comes into play. This little nose, the leading edge, that affects drag. The surface finish of the disk. All these things affect where the center of pressure is. But if I'm flying towards you, that's my cross-sectional area. What happens when I tilt it up? It changes. So suddenly my center of pressure changes, right?

### [1:00:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=3600s) Segment 13 (60:00 - 65:00)

And on top of that, we've got that flow separation off the top. So what Potz just said is he said there's like a line from the front to the back through this disk, right? And he said that our center of pressure starts off somewhere in the back. And that makes sense because we're flying level, right? But as we start to tilt up, we get that bubble right here. We have drag stuff going on the front, even. And so our center of pressure is going to move forward, okay? But you got to remember, this thing is spinning. So we've got a center of pressure that's moving forward, and that's creating lift in different places, and we're spinning. So that's going to factor into a gyroscopic procession. I've always used the term center of pressure, but there's some other terms there, center of lift or whatever. But anyway, the point is the center of pressure is moving, and so now it's time to go to the garage and look at gyroscopic procession, which is where the big setup is to understand that. Okay, Let's go to the garage where I have this really awesome setup. In fact, I did this on the last episode of Smarter Every Day, episode 312, we talked about gyroscopic procession because I wanted this thing to be its own video because of how cool this is. I have a big model of a disk here, right? It's suspended from these wires, from the ceiling. I've got these cameras set up that I've already turned on. So this camera is looking 90 degrees to the flight line. This is looking along the flight line. You'll notice I've got the flight line illustrated here by a blue tape arrow on the floor. Imagine that we are throwing this disk in that direction. We're going to do a right-hand, back-hand throw. And the purpose of this is just to demonstrate gyroscopic procession. And in the last video, I did this really interesting model, at least interesting to me, of these pool balls on a stick. And once we started rotating this thing and we hit it with a pool ball, you see the gyroscopic procession take place, or at least something like it. So gyroscopic procession basically shows you that if you have a spinning object and you push on it, the displacement happens 90 degrees after the place where you pushed on it. And I'm going to show you that now. So let's just get a baseline here for thinking about it. And I highly recommend looking at that other video if you want to understand this better. So we have this disk, and I'm just going to push down right here. And you'll look at it from that camera right there. And you'll notice that when I push down, because I'm imparting a torque about the center of mass, it ends up tilting just like you would expect, right? I'm pushing straight down and I get a torque over there pitching that thing up. What happens when we spin it up? Okay. So again, looking at it from this side, I'm pushing down here. It tilts up like that. Okay, so now let's spin this thing up. What did I do with my drill? Here it is. So now I'm We're going to impart a spin to the bottom of this, and then we're going to push down in the same place, and we're going to see what happens. Let's get this thing going. This is a little paint stirrer in a 3D printed connector that I made. Let's spin this up now. Okay, that might be the fastest I've ever gotten. This is pretty great. Okay, so now I'm going to do the same thing, only I'm going to push down with air. And from this camera, remember, it tilted up. Look what it does this time. It's going to tilt 90 degrees after. You see that? Oh, I need some oil on my bearing. Does that help? Come on. That doesn't help. All right. Okay, so what happened there is when I pushed down on this edge with the air, it actually pushed down about 90 degrees after, which is really weird. In the previous episode, we showed that if you put a force into a rotating mass system, then that force turns into what seems like a displacement 90 degrees after the place where you input the force. We showed that with pool balls and the sticks, and it was really interesting, and that works for my brain. But this same thing works with a rotating disk. I highly recommend checking out the earlier episode to understand what's going on. But I want to I'm going to talk about what that does for us in terms of disk golf. I'm going to stop this thing so we can just talk about it here. I'm going to put you up right here, okay? We'll have a little conversation. Man, it's pretty wobbly, isn't it? All right, so we'll slow this down. Okay, so we're flying in that direction now. So Potts was talking about the fact that we have this longitudinal line running from tip to the tail, so to speak, of the disk.

### [1:05:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=3900s) Segment 14 (65:00 - 70:00)

And so I'm going to actually draw a line on the disk, and we're going to move things along that line and talk about it. Okay, so if we think about the disk flying and we think about what we saw in that wind tunnel, we had air providing lift on the disk, right? So it's like a weird airfoil. And so it's going to be lifting. It's not going to be right in the middle. It's going to be somewhere back here. Dr. Potts said it's going to start a little bit further back. And if we think about this thing, lift is lift. It's actually pulling up on the disk. And so that's what lift would look like on a stationary disk. But this is not a stationary disk. This is a rotating disk. Therefore, gyroscopic procession is a thing. So it's almost like that lift vector creates this displacement vector that's actually over there to the side, like that. So when we first start off, that lift is going to And you start to try to displace the thing like this. Isn't that interesting? Now, Dr. Potts said that center of lift or the aerodynamic center is going to move forward throughout the flight. Now, think about this. If that's true, then that means that displacement vector is going to move as well. See, this is basically what we're referring to as the pitching moment. A moment is another fancy way of saying torque. And so the distance from the center and the force, those two things combine to give you the pitching moment. So because lift force is going from the back of the disk to the front of the disk, it's almost like that displacement effort is going from the left of the disk to the right of the disk, which is fascinating. Let's look at that graph that Dr. Potts had in his dissertation, and let's look at the wind tunnel experiment, and let's just look at what's happening. As the angle of attack changes, that pitching moment moves with the angle of attack. It goes from negative to the neutral point or the trim condition back to positive. Let's go talk to Dr. Potts and try to understand what that means. Okay, we want to see the whole flight of a disk, what's happening along the whole way. So we're going to throw a right-hand, back hand. How does it work? Don't worry about the cameras over there. [P] I'm just going to draw the flight path of a typical flight initially. It goes reasonably straight and we get that turnover, and then it drifts right, and then we get that hard turnover back the other way. I'm going to draw the pitching moment which drives it, which is what we were looking at before, which is something like that. This is the pitching moment coefficient against angle of attack. Then we're going to relate what happens in the flight, primarily because this roll is driven by the pitching moment, which is this curve. [D] The pitching moment is a function I've got lift that's moving along this axis from here to here, right? But it's acting out of phase. [P] Yeah, because of... Just to recall that the roll is as a result of the pitching moment, which is happening because of gyroscopic procession. [D] Got it. I'll do this. We've got a disk here, and we have the center of gravity, the center of mass, It's right here in the center. Does that work? [P] Yeah. [D] Then could you maybe just talk about the center of buoyancy? Not center of buoyancy, I'm thinking most Center of pressure. [P] Center of pressure, yeah. Related to in there. If you've got the center, so the disk is traveling in this direction, so the flow rate is here like this, so the flow coming that way. We've got a direction of travel, a double, triple, triple line, so that's direction of travel. We were talking earlier about the center of pressure, which starts, we call it, say, after or behind the center of mass, which is then what drives the pitching moment. You have lift which acts at the center of pressure. [D] If I had a disk right here, and so I'm basically pulling out of the board behind the center of mass. I'm pulling at that location. [P] Yeah, so the lift force is acting perhaps out of the board. Right. [D] But because of gyroscopic procession, that doesn't happen. It goes over here, right? [P] Yeah, correct. So it... [D] Do you have another color? [P] It lifts. It lifts the wing on the left-hand side. The actual motion. To talk in lift is incorrect, but the actual motion, the motion as a result of the moment lift force is actually at 90

### [1:10:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=4200s) Segment 15 (70:00 - 75:00)

degrees in the roll plane. [D] All right, so let's just pretend it acts here. Does that work? [P] Yeah. Okay. That lift force translates around 90 degrees, and then the motion as a result of that is to be this turnover, which is happening here. [D] Got it. This is at the beginning of the flight. Lift is acting behind the center of gravity. [P] Dropping the nose. [D] Dropping the nose, or trying to drop the nose. [P] Trying to not drop the nose, yeah. [D] But because the It's a gyroscopic perception, it happens over here, and that's when it starts rolling anhyzer. [P] Yeah. [D] Okay. [P] That's right. [P] Then you get to maybe this point here. Let's say in the middle of the flight, On the pitching moment curve, you're actually at this point, which I called trim condition, which is the correct name in aerospace, which is basically where the lift now has moved. It's now at the center. I'm just going to draw it to the right, so I don't… Yeah, just because… But it's at the central point. Therefore, you don't have any moment at all. The orientation of the disk at this point would just maintain whatever it was. [D] I see. [P] Yeah, at this point on the Pitching Moment Curve. [D] I see. [P] Then as you go into the positive Pitching Moment, then it starts to drive the roll rate in the opposite sense. You've got center of pressure here now. Sorry, lifting center of pressure moves. [D] All the way forward of the center of mass. [P] Probably not too far, but just a certain distance. I've probably drawn it too far. Then that translates for a right-hand back-end throw, of course, all this we're talking about, it translates around 90 degrees to drive the rotation in the opposite sense to the way it was before. Then the curve, you think, into this phase. [D] I see. Yeah, as soon as it moves forward of this, that's when... Yeah, I see. I got you. [P] Then it starts rolling left rather than right. You got the initial turnover for the negative part of the curve here. Then for the positive part of the curve, you're then rolling left. It's that which gives you the classic disk flight trajectory, viewed from above. [D] If I pick a disk out of the bag, can I expect it to do this every time? [P] It depends on the speed of release, and that would depend on whether you're an elite or an amateur player. If we, for instance, suggest that is a perfect S-curve for an elite player, then they may be using a disk which is set up for them, or they've chosen the specific disk to be able to turn over just the right amount so that they get that distance that they're after. Whereas a more amateur player, if I draw it blue next to it, or maybe we should start from the same point. It may not turn over as much, so it may go maybe here or something. It may then turn hard left straight away because it didn't quite reach this trim condition. [D] Okay. [P] Or maybe it goes into this beyond the trim condition much faster, I think probably This is the way to talk about it. Then they go over here. Not only are they getting less distance compared to the elite player, but they're also not managing to turn it over so that they're tracking it more towards where they perhaps want to be for the same disk. They would probably then, if they change their disk out to get more distance, they probably to track more the elite player trajectory in terms of the flight path, then they could get a disk which turns over a little bit more. And then let's say it tracks over here, but they still can't quite get the distance of an elite player because they don't have the speed. But then they perhaps could get a bit more distance. [D] Have you seen the... [P] That makes sense? [D] Yeah. Have you seen the MVP flight feather concept? Have you seen that? So earlier when I was touring the MVP disk golf factory, Brad and Chad had a poster in their office that had something on it called the flight feather. I now understand what they were talking about. [B] So the left and right motion is a good example. We have different lines that have different power levels. If you're throwing it with lower power, you're going to have it go straight and then hook to left a little bit. As you increase that initial speed, you're going to see a turn phase. When you throw at high speed with a disk that wants to turn under stable, it'll drift to the right, right-hand, back hand. and as it slows down throughout its

### [1:15:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=4500s) Segment 16 (75:00 - 80:00)

flight, it'll begin to fade out left. All right, here we are. Hole 18. Can we do it? We can because now we understand the turn and the fade. We understand that as it rotates. We have gyroscopic procession, and the center of lift moves along the longitudinal axis, giving us that turn and fade. Except that's not all. I've learned in my whole life, if I think I understand something, there's a bonus level right over there, and we got to go check it out and think about it. Let's go to the bonus hole. Okay, this is extremely complex, and I've been thinking about it for an inordinate amount of time. I want to just say all the caveats in the little outlier conditions because we simplified everything, but I want to just get all of these ideas down. So if you don't track this, what I'm about to say, just hang with me because I think you can. I think you can get this. Why does a disk curve? That's what we're trying to answer. So Brad and Chad arrived at the flight feather by just observing what happens when people throw disks, right? Dr. Potts arrived at the flight feather using physics and his understanding of this mental model. One thing I think is interesting, though, is there's so much more going on than what meets the eye, just a spinning disk and the spinning airfoil. Because if you think about it, everything we looked at here depended on this disk flying forward. And you see, I've got some arrows on the ground here for wind coming at the disk. Well, if you think about it, If this disk is flying and we're spinning it, we're right-hand, back-hand, we're spinning it. So it's moving forward into the wind and it's spinning, right? So what that means is one side of the disk is spinning forward like this, right? So you have the radius and the rotational velocity. And on this side, you have the same thing. You have the radius and the rotational velocity. So this side is going forward and backwards. But we have the wind that we have add in as well. So if you think about it on this side, if you have the velocity of the wind plus the forward velocity of the disk, it's like that side is going faster. But on this side, if you have the velocity of the wind and the retreating velocity of the disk, it's like this side is going slower. So we have an asymmetric wind velocity on the disk, which means if you have asymmetric wind, you're going to have asymmetric lift. If it's flying faster on this side, so it's going to lift up more or try to lift up more. It's flying slower on that side, it's going to try to decrease. So what I think is you have what's called the advance ratio. This is something Dr. Potts wrote about in his paper. But what I think is so fascinating about this is originally on our model of lift, we had this longitudinal axis from the front all the way to the back of the disk, right? And we imagined that the lift vector went right through that, right? So We've got this longitudinal axis, and we imagined that the center of lift was along that longitudinal axis, and the lift displacement over this side was off to the side like that, right? But because of this asymmetric lift we're talking about, I think it's even more complicated than that. I don't think... I'm going to park those right there. I don't think that the lift is happening right on this axis. I think it's happening a little bit more on the advancing side. So it might be out We're like this, okay? But as it goes forward, it's rotating around. We might not come through the exact center of mass or center of gravity of the disk. We might actually come like this right here. But maybe as it slows down in rotation towards the end of the flight, maybe it comes over like that. Who knows what's happening? Maybe it's some fancy curve. Maybe it does go through the center. I don't know. But what I do know is there's more happening than what we initially thought about. Because it's rotating. It has to be different. Another thing to think about is disk golf players know this. If you have a brand new disk and you hit a tree like I do all the time, what happens? That edge on the disk right there gets what's called beat in. The edge of that disk starts to become dented, and what happens is you create turbulence over the top. Dr. Potts explained this to me. He said that once a disk becomes beat in, you get this turbulent layer of flow, which makes the flow want to stay attached to the disk longer. Because that attached flow stays attached longer, the center of lift is going to stay back, which makes it behave more under stable, which I think is fascinating. There's so much going on here. Dr. Potts and I even talked about the leading edge of the disk. If the parting line was higher, it was more over stable. If it was lower, it was more under stable. Dr. Potts and I talked about that as well. And it has to do with the attachment of the center lift and also the front

### [1:20:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=4800s) Segment 17 (80:00 - 85:00)

edge and how it drives the air up or down. And now I also have to say this. Back in the day, the early pioneers of disk golf did not consult aerospace engineers, the kinds There's a lot of people that would use slide rules like this. And the reason I know that is because when you have an aircraft, as we discussed earlier, when the center of pressure is behind the center of mass, you get a riding moment. And so it is a stable aircraft, right? But if that center of pressure ever moves forward of the center of mass, you get that moment to work against you, and you are more unstable. So the stability of the aircraft has to do with where the center of pressure is in relation to the center of mass. Okay, so when we start looking at disk, let's think about it. So there's one type of disk, when the parting line is lower, the air will flow over the top, which means the center of pressure stays behind the center of mass longer. You have a more stable disk. Conversely, when you have a disk with a higher parting line, that air gets driven down, and among other things that come into play, the center of pressure gets pulled forward of the center of mass. So if you think about our riding moment working against us in an unstable aircraft, which of these two is more unstable? Yeah, that one right there is the more unstable aircraft between the two disk, which is odd because that is referred to as an over stable disk in the community. What does this even mean? It doesn't make sense. Over here, when you have the center of pressure behind the center of mass, what do people call that? An under stable disk. It does not make sense to an aerodynamicist. But does it make sense to an amateur who might be picking up a disk for the first time? Well, which of these two make more sense to give an amateur? I heard from the pros. If you want a person to enjoy disk golf for the first time, you give them a more under stable disk. Why does that make sense? Because in modern aircraft, if it's an under stable aircraft, we have to incorporate fly by wire technology to even be able to fly the thing. A more under stable disk is not what you would inherently think needs to go to a newbie. So this is what I propose. I think these words are exactly wrong, not only from an aerodynamics perspective, but from a let's go play this golf perspective. Because if you think about it, you want something that makes sense. And if you've ever tried to explain these terms to somebody playing with you, you know it's hard. So that leaves us with the question, what should these words be? And I talked to Dr. Potts about it. He and I were batting around the word roll, because if you think about it, when you throw a disk, it's going to roll one way or the other. So we talked about maybe under roll, because it rolls under the direction you throw it, or over roll, But you still have the issue with over and under, which one is which. In golf, you have a hook and a slice, and that makes sense, but we don't really have those terms in disk golf. So when they were coming up with these in the late '70s and '80s, it was clear that these terms were established in the '90s because we have literature that says that, this is exactly wrong. However, in the modern day, we have the ability to change this. And I know this because disk golf is rooted heavily in the aerospace community. You've got Oak Grove out at Jet Propulsion Lab in California, Bronze Springs near Marshall Space Flight Center. These were some of the first courses to exist. So the roots for technical accuracy go deep in the disk golf community. So I think it's just time to revisit these terms, and it needs to be something that's agreed upon by everyone because this is a sport for everyone. Okay, I said the thing. So you can't just straight up design a disk that looks like a certain way and like, Oh, it's going to behave this way. At some point, it makes sense just to make a disk and throw it. [P] Exactly. It's really complex. And that's how golf disk have evolved. They've evolved because it started with whatever they had initially, and then they slowly curved the upper surface and they've, in terms of driver disk, I guess I'm talking now, and they've elongated the rim and they've reduced the cavity and they've just seen what effects that has. Then they've sent it out to all their players within their sponsorship team or whatever, and they get them to throw, Do you like it? How does this... And then they analyze what he actually does on the fairway. So they really are very much changing the designs that they've got currently and tweaking them. And then they're giving them to the players and then trying to learn what the effect that has to then see how they translate that back into knowledge

### [1:25:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=5100s) Segment 18 (85:00 - 90:00)

to then progress golf design, disk golf design forward. [D] So the fact that disk golf disk technology is evolving and progressing is happening now. Listen to what Brad and Chad had to say in response to one of my questions. [B] That turn and fade is a key too. [D] But there's two things when I throw a disk. I've got the forward velocity, and I have the rotational velocity. [B] If we can maximize that rotational momentum, that will reduce that turn and fade. If you think about it, that turn and fade is wasted energy that could be straightened out to travel farther. If you're spending all that time in the air, turning and fading, All that drag during that long path is shortening your potential distance. If you can increase that MOI, you are essentially pulling out that S-curve, so to speak, and making that travel farther. That's really the [C] And also just the predictability. In disk golf, you want accuracy, not just distance, but accuracy. So that turn and fade is a little bit of instability in that flight. But if you increase that moment of inertia or that gyroscopic stability, it's more predictable in its turn and fade phase, a little bit more consistent and reliable. [D] Okay. Technically, this video is sponsored by MVP, so it's an ad, to even mention them. But I don't want this part to feel like an ad. I want this to feel like a scientific inquiry because that's where I'm at with it. So I chose to say yes to MVP when they reached out to Smarter Every Day years ago because they said, Hey, we want you to talk about disk golf because we love disk golf. And I was like, I like disk golf. I'm not a pro like these people we interviewed in this video, but I love it. It's really fun. And I like science and aerodynamics. So it was like our Venn diagrams were perfect. So what I'm about to tell you is interesting. And I make no claims. I'm just telling you I'm going to investigate this further, and there will be opportunities in the future for you to investigate this further. So this is a disk golf driver made by MVP Disk Sports. This is a custom Simon Lozat driver. You'll notice there's a black rim along the outside. This is an overmold. This is MVP's differentiator. They claim that By putting more mass on the outside, they are increasing the moment of inertia, which gives you more angular momentum, which makes the disk not want to turn and fade as much. You just heard Brad and Chad talk about that. Well, we've been talking about this for years, them and I. We've been talking about it offline. And one of the things I mentioned is, Hey, you guys really should look into these devices to measure the moment of inertia. They were doing it already. So I worked with them to find a device to measure disk golf disk moment of inertia around this axis. And here's a clip of them testing a new device. Basically, it shakes the disk and it can measure the rotational inertia, more or less, and you can get the moment of inertia. It's really fascinating. I think it would be awesome that they're already laser engraving the mass on the disk. If you remember in the production video, we got to see them put a disk in the laser machine and use a laser to engrave the amount of grams on the disk. I think it would also be cool to put the number of the moment of inertia on the disk, which brings me to their new prototype. Mvp has a prototype disk. You'll notice that the outer rim is much smaller than the drivers. So the outside of this disk is impregnated with copper powder so that it's heavier, but the inside has what they're calling micro bubble technology in the plastic, so it's lighter. So you're taking the mass from the inside of the disk and you're pushing it out to the outside. So you're increasing the moment of inertia while maintaining, hopefully, the same mass. I think this is fascinating. What I can tell you is that in my front yard tests, this disk flies further and straighter. I'm not an expert, but what I can tell you is it's a very interesting disk to throw, and it's very similar in a normal driver, only it doesn't roll and turn and fade as much. It's fascinating. In summary, when you throw a disk golf disk there is a three-dimensional saddle that you have to ride and find. And you do that by how you hold the disk, how you throw the disk. But there's this fine turn and fade, and there's this perfect saddle point that if you're a good player, you can find it. And I hope this video helped you understand where it is and what you can do to change it. For me, I learned that I have to get my arm up and then the nose actually down when I'm throwing for distance at the beginning. No clue that was a thing, but I learned that. It's fascinating. So I hope you incorporate some of the stuff you learned in this video to improve your disk golf game or just your love of the sport. And you get to appreciate when you see a disk flying and you get to know, oh, that's what's happening.

### [1:30:00](https://www.youtube.com/watch?v=-0JKHuzJ67A&t=5400s) Segment 19 (90:00 - 92:00)

The pitching moments in the back, which is driving it right. And then it moves forward, and then it's going back to the left. Just knowing that is a beautiful thing, and I'm excited about it. So I hope you enjoyed this video. I want to say thanks to MVP Disk Sports for sponsoring Dr. Potts and everybody else in this video for teaching me so much. I hope you will stick around for an upcoming video when we actually test some of this stuff with engineering tools that I am not willing to reveal yet. But I'm excited for an upcoming video where we're going to learn even more about how disk golf disks fly and maybe test some of these prototypes and understand if this gyro technology is the future of disk golf technology. I think it might be, and I think it's fascinating to learn. I also think there's other things you can do to improve these disk, and I've been thinking about that as well. Anyway, I absolutely love this. It's fascinating to me. I would be doing this stuff even if YouTube wasn't a thing. I hope that comes through in the videos. I certainly feel that. But thank you to everybody that supports Smarter Every Day on Patreon at Patreon. com/smartereveryday. It's a huge deal. And thank you to you for watching. This was a long video, and I hope you enjoyed it. Anyway, that's it. I'm Destin. Stay tuned for video three. You're getting Smarter Every Day. Have a good one. Bye. They just crane operated a bathroom over a car and look at the back of the crane. It's so cool. Couldn't make it. You couldn't make it? What? Let's go get Smarter Every Day. Was it? What was that?

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*Источник: https://ekstraktznaniy.ru/video/20960*