Great demo! Precession is also useful for understanding why nose up (positive aoa) negatively impacts distance. Throwing nose up moves the center of pressure forward on any disc profile, causing a reduction (or loss) of high speed turn and a much quicker transition to fade causing the disc to fall short and left of it's max potential distance for a RHBH throw.
I'm into DG for about 2 years now and have watched _a lot_ of videos about it. This is the video I have been looking for all the time and never found. Thanks so much for the great and very visual explanations!
So many youtubers out there trying/pretending to explain turn and fade. This is the only video I've seen that answers the question for me. Will be paying attention to part lines more from now on (for fun). Thank you!
So freaking cool, my brain has been searching for this explanation for years. You've given us all a beautiful gift of understanding with this one Pete. I'm no expert, but I know Bernoulli's Principle of fluid dynamics is key in this.
Pete! I've done so many (less sophisticated and useful) explanations to myself and friends about the stability of discs, how wind affects them, etc. and this is INCREDIBLE. Best explanation I've ever seen! I will refer them to this video next time someone asks! I think Bill Nye would love to do a collab with you ;)
Thank you for the kind words! I suppose it would be an incredible honor to meet and discuss science with Bill Nye! I’d also love to have the opportunity to play a round, discuss, share and learn disc physics with Destin from the Smarter Everyday and his collaborator Matt from the podcast “No dumb questions”. That would be fun. Dreams right?
Great video and you make it very easy to understand the general concept of flight/stability. Its one thing to know about weights and stability as an average player but this is a clear summation of why that all matters. This will help a lot of people zero in on a disc that fits them rather than adapting their play to the discs in their bag.
Super well done video. The force vector visuals you added to the physical discs will be really helpful for people to see the interaction between the pitching moment and resultant precession. Was holding off on my disc physics video and started working on a different video idea because I knew you would explain this really well, and I made the right choice because I no longer need to make the disc physics video, haha!
That was very interesting. Me, going from very little knowledge on this, other than flight numbers and trial and error, to listening to this explanation, I was able to grasp the concept. Id like to see more of these breakdowns.
Best explanation that I've seen on what makes discs turn! That also helps explain, for me, why understable discs go further with less effort -- more lift! A Hades generates more lift than a Zeus which generates more lift than a Force 🤔
Remember though: when you throw a disc that has more lift and turn, it flys farther because you traded predictability and stability for under-stability and less predictability :) More lift = more drag - more turn More lift = more turn - less stability Less drag = less turn - more stability
Great explanations. All your points are spot on with awesome visual aids. One thing to add though, the shape of the wing can affect the center of lift (changing stability) a ton just like the parting line height can. A concave wing design will push the center of lift forward towards the nose making it more overstable. It pushes air down at the nose and this can cause resistance to turn even at high velocities. It also causes drag. It's an inefficient wing design because the angle between the flat bottom of the disc and the nose is too sharp and disrupts smooth airflow. Sharp angles are the opposite of aerodynamic. Convex wing designs like an IT or roadrunner do the opposite. They are rounded and smoothly connect the nose to the flat bottom allowing smooth airflow underneath the disc removing any lift generated at the nose (until the angle of attack increases but that's unavoidable at low speeds). This means at high speeds much more of the lift is created at the tail of the disc from airflow over the top of the disc. Some understable disc's nose sort of hang down towards the bottom of the disc to accomplish the same thing as a convex wing. I'm guessing this is to cut weight with higher speed discs with larger rims but I'm not sure.
Thank you for your comment! You make very good points. I did have a slide that I considered using with the nose angle tool that showed how air would be diverted and come together at the back of the disc…I decided to save it for later so as to to not “drag” the audience into the weeds to far in this one. I figured save it for another video on disc speed and drag.
Man I love these videos. I've been a hobbyist physics nerd since high school. Although I get a bit lost in the weeds attempting to do the logarithmic and cal based equations, I have always been able to gain a solid CONCEPTUAL understanding of various areas of physics if I'm given a good explanation, be it from a text or lecture. That is exactly what these disc physics vids you're doing have been for me - excellent conceptual explanations of what our beloved spinning plastic is experiencing in flight. Thank you and I look forward to any future vids you do. Cheers
This is so good. I spent a decent amount of time trying to figure this out but I was missing the fact that CG moves back during high speed so I never understood it. Thanks a ton Pete!
Very good explanation, and to add to the physics there is also lift acting from under the front of the wing the whole time and as it slows it is the most amount of lift and the lift from air going over the top is almost negligible. Thanks for making this!
great! with that explanation, you can extrapolate the effect of cross winds on a level disc - it causes the nose angle to change! which then affects turn and fade....layers upon layers.
You are correct!! That’s on of my next videos!! I’ve got a great visual to help visualize it that I learned from searching for thermals with my rc sailplanes.
Best explanation do far! As an engineer I have never been satisfied with the simplistic explabation of stability and left/right tendencies. From your explanation and definition of forces made, it is easy to see how the thrower (by causing spin and initial velocity) affects the flight path. For example, take a beginners hyzer and explain it, or a hyzer flip and why it works. Or an amateur throwing a speed 14 disc and why it will flip left. 😁 Also, alter the surrouning air and its properties - wind direction and altitude (density) and think on how the disc responds. Answers easily found in your explanation made! Bravo!
Thank you! I learned to play disc golf at high altitude.7000’. The difference in air density and learning the subsequent flight stability’s from there to 1000’ is a huge learning curve!
Finally the mystery is solved, I do believe. I've been frustrated in the search for an explanation for turn and fade of the flying disc until now. I still need to understand better why the lift position changes but for now I'll take your word for it.
So I assume that when a disc is in glide mode that the lift force aligns with the center of gravity. Any understanding of why air speed across the disc causes the lift position to shift?
@@David-ps2nb thanks for the comment! For simplicity sake, we could look at an air plane wing. The wing would be designed for optimal airspeed to lift ratio, in line with how the Weight of the disc is balanced over the wing. Typically near 30% of the wing chord. The faster you fly, the more the center of press pressure (lift) would move behind the center of balance, causing the aircraft to tip forward. If the aircraft were to slow down below the optimal airspeed, the center of pressure would move forward of the center of balance and the wing want to tip up and eventually would be in danger of stalling. What the airplane has that a disc does not, is a motor. This allows the management of speed and angle of attack to keep the wing in its optimal flight envelope. With a disc, we throw it, so based on the disc’s designed flight speed, if it’s thrown faster than its optimal L/D glide speed the lift pressure moves behind the center of balance, this is what causes “turn”. But because a disc doesn’t have a motor, and “drag” is constantly pulling on the disc in opposition to its forward velocity, the disc is constantly slowing down during its flight, because of this the center of lift pressure is dynamically moving from behind the center of balance towards the center, and then eventually in front of the center of balance toward the end of the flight. If the disc is thrown high enough, it like an airplane will stall. The higher the speed of a disc, the more narrow its optimal L/D glide portion of flight is. Thinking of a neutral midrange, it has a relatively wide L/D flight envelope, however it has a lot of drag due to its more blunt edge, so its distance is more limited.
I know I'm a bit late to the party, but does the amount of dome have anything to do with the turn/fade? I think most would agree, from personal experience, that flatter disc are more stable than their domey counterpart, but what would happen, for instance, if a tilt had dome? Or a mamba was flat? Does the dome solely affect the glide, which would slow the speed at which a disc would fade? Great video!!!
Thank you! (I copy and pasted my comment below from another question that was similar with a couple added thoughts) The flat versus Domey argument has always been a little comical to me, because some guys think the flat disc are more stable and the domey are under-stable, and other guys think that Domey are over stable, and the flat one stable. Domey discs tend to have more glide than flat discs. Where the parting line is dictates him much air is diverted over the top vs.the bottom. A mamba is virtually flat from the nose to the bottom of its lip, but has a high curve from the nose to the shoulder…more air is diverted over the top. from here weather the flight plate has a pop top or a flat top, it’d seem to be a lift to drag issue. It’s going to be flippy either way. For our two discs, Let’s assume both have identical parting lines. There are many components to understand it all, from lift, to drag, and even release angle. My personal observation is this: I think the varying opinions are a result of a grip issue. Some guys love to throw flat discs while others prefer domey, and those are the camps they tend to stay in. When a person who loves throwing flat discs, throws a domey disc, they tend to believe it’s more stable. When a person who loves domey discs throws a flat disc, they tend to believe it’s under-stable, and vis versa. Hold a flat disc in your hand, be exact at how it settles into your hand, like you are ready to throw in the power pocket position, notice how the edge of the disc closest to your chest looks. Now grab a domey disc of the same mold, Hold it in the same exact manner as described above. I believe that you will observe that the domey disc settles into the hand in such a way that the edge closest to the chest will be lower by up to a 1/4” or so. This result is because the domey disc is slightly taller leaving the rim and the thumb sets higher over the flight plate pushing the edge closer to your chest down slightly, so what feels “normal” is a slightly different angle between the two disc, and would leave the domey, disc on more of a hyzer angle out of the hand compared to the flat disc. Thats my observations and opinion after years of observing the two groups and various opinions. In flight we are always trading one preference in flight for another. Lift we trade for drag Speed we trade for control Stability we trade for glide Distance we trade for control Speed and stability we trade for glide. Wanting Speed and glide we must trade for in-stability.
Really good stuff! A question popped up during your parting line explanation. If we had two discs with the same flight plate molds and parting line, if we make the lower half of the rim divert the same amount of air but one is convex vs concave, won't we have pretty dissimilar high speed turn rates? I imagine this lower half shape determines air flow and where it might hit the bottom of the flight plate at different speeds. Strangely, this would be counter to your reasoning because the convex shape would seemingly push air flow to re-enter further back behind CG than a convex shape. Curious if there is another major component to disc stability than where the air is parted.
Thank you Eric for your insight. I don’t fully have that answer. Here is a thought exercise. Yes, when we divert the air below in this manner we do tend to have more over-stability. The concave shape of the bottom half of the rim, from the part line downward must create a low pressure behind the wedge edge of the disc on the nose side. I have a hypothesis and I’ll use an extreme example to explain for visualization. Take the disc called the “Tilt” for example, 90% of the air is diverted downward at an extreme angle 📐, the interesting thing about this disc is that it flies/ “glides” farther upside down than it does in traditional flight. Think of a pickup truck and the age old question, “ do we get better gas mileage with the tailgate up or down”? The answer is “tailgate up” because the tailgate traps a slow rolling a pocket of air behind the cab, which allows for the high speed airflow coming off the cab to smoothly pass over that pillow of air with less drag, whereas the tailgate down allows the air to drop downward into the bed, essentially pressing down on the tailgate and causing more drag behind the vehicle. The extreme angle of the tilts bottom rim, when flipped over and thrown upside down essentially diverts the air upward in such an extreme way that the airflow at high speed would essentially create a boundary layer of air similar to observed in the bed of the truck🛻. This boundary layer allows the airflow to pass more efficiently from front to back on the disc. Another thought is this which which I believe is a key component of understanding flight is: Drag. The most important part of understanding the speed of a wing/disc, is not how efficiently it cuts through the air at the front, but how efficiently it allows the air to come back together at the tail. Something like a putter moves, the same air out of the way at the front of the disc as a driver, but it does not allow the air at the back of the disk to come together in an efficient manner, and so it drags a bunch of air with it, which slows the disc down faster. Something high speed like a nuke, allows the air at the back of the disc to come together, smoothly and efficiently, with very little air being pulled or dragged behind the Disc. The angle of the bottom half of the rim being concave or convex, helps determine the way the air is diverted downward off the top of and at the back of the disc. I did have a little slide for this video showing airflow at the back of the disc that I considered using but didn’t want to get folks lost in the weeds. Maybe I’ll make a specific video on drag….understanding the basics of that is huge.
This was a super informative demo! Appreciate the video. If you're able or have the understanding, I'd love to hear what effects domey vs flat flight plates have on the flight of a disc.
Thank you! The flat versus Domey argument has always been a little comical to me, because some guys think the flat disc are more stable and the domey are under-stable, and other guys think that Domey are over stable, and the flat one stable. Domey discs tend to have more glide than flat discs. Let’s assume both have identical parting lines. There are many components to understand it all, from lift, to drag, and even release angle. My personal observation is this: I think the varying opinions at a result of a grip issue. Some guys love to throw flat discs while others prefer domey, and those are the camps they tend to stay in. When a person who loves throwing flat discs, throws a domey disc, they tend to believe it’s more stable. When a person who loves domey discs throws a flat disc, they tend to believe it’s under-stable. Hold a flat disc in your hand, be exact at how it settles into your hand, like you are ready to throw in the power pocket position, notice how the edge of the disc closest to your chest looks. Now grab a domey disc of the same mold, Hold it in the same exact manner as described above. I believe that you will observe that the domey disc settles into the hand in such a way that the edge closest to the chest will be lower by a 1/4” or so. This result is because the domey disc is slightly taller and the thumb sets higher over the flight plate pushing the edge closer to your chest down slightly, so what feels “normal” is a slightly different angle between the two disc, and would leave the domey, disc on more of a hyzer angle out of the hand compared to the flat disc. Thats my observations and opinion after years of observing the two groups and various opinions.
Pete - really just started watching your channel (it popped up on my channel feed), but this is a great first-principles analysis of disc flight. …and, explains what I’m seeing when I unleash my noodle arm. Now if I just had a Tech Disc to generate measurements… 😊
Great explanation. How does the difference in apparent air speed between the left side and right side affect lift, turn and fade? The air on the left side is moving across the disc faster than on the right, for a right hand back hand throw.
Thanks for the great question @edneely! From what I understand, based on the best scientific studies and data available thus far, there is no measurable difference From the left and right side feeling a difference in apparent airspeed as you were asking. My thoughts are: If you think about it they are wedge shaped edges on the left and right wingtips, but not within the lifting part of the wing, so it’s more of a slip stream near the edge. That’s my visual reference for understanding. But I honestly don’t have a full understanding of why at the moment other than Basically not enough difference to cause a Magnus effect either.
Thank you for your comment! I’m working on that particular video in my notes and head. Proof is better than opinion, however, I’ve got years of flying Rc sailplanes, along with looking at what the free flight and hand launch geniuses have learned from wing shaping for both high and low speed flight. This has made me a little biased in understanding flight physics. But flight is flight, I love learning and it’s all super fascinating to me, so when I tackle that subject for a video I plan to share what’s valuable and factual about both opinions.
That’s a wonderful question. It’s air airspeed and pressure issue. Let’s think of it this way. Imagine a boat moving slowly through the water. Now imagine its wake moving out alongside and behind it. The wake is small because the pressure of the boat against the water is small. Now let’s make the boat go fast. The boat now raises out of the water and rides higher because the pressure is greater and as a result the wake is greater also. If our boat goes fast enough the pressure will increase and the entire boat will skim across the surface because the center of pressure is well behind the center of the boat’s balance. Now let’s slow the boat back down. As the boat slows, the pressure below it decreases and the bow begins to pitch upwards because the center of pressure moves forward of the center of the boats balance. With our boat analogy we can see how the speed of an object within a fluid can change pressures, how that center of pressure can be forward or behind the objects depending on its speed. With a disc, the principle is basically the same. The faster a disc moves through the air, the greater the pressure, and the more that pressure slips behind the center of balance. When the disc slows, the center of pressure/lift decreases and moves ahead of our discs center of balance, and much like our boat, the nose pitches upwards increasing the angle of attack as the disc begins to fall. I hope that helps answer you question:)
@hundowasmynama COMPLETELY AGEE! It's up there. Huge Paul fan, always here about Pete, seen a little but haven't heard it explained so well. Thanks Pete! Subscribed!!!
I wouldn’t mind a video on glide. How do two discs with same speed have very different glide characteristics? I think it may have to do with the dome to some extent, but curious as to the exact way it happens. In particular, the Rask was designed to have low glide with a fast rim. They essentially molded a concave puck to the bottom, so I don’t know if reducing the volume underneath the dome may have an effect on glide? Would this be why a flat top disc doesn’t glide as much as a higher dome version of same mold?
Good questions! First let’s understand the disc flight number system is an approximation of what could be expected at that discs intended speed, and is subjective to each individuals throw on how it’s experienced. In aerodynamics we are always trading one thing for another.. Lift for drag, speed for control … If you want a faster disc, you will inherently be trading speed for control, If you want more glide you will inevitably be increasing drag. The dome of a disc can have an affect on its flight, some folks experience dome top discs as under-stable while others experience the same disc as over-stable, as well as flat top discs feeling both stable and under stable to different throwers. For a moment, let’s assume a dome top disc and a flat top disc of the same mold, color, run, and other parameters have the exact same parting line. Meaning they divert the same amount of air over and under. What I’ve observed in these kind of instances is this: when holding a dome topped disc, the disc will tend to set in the hand with a little more “hyzer” angle because of the way the top of the disc fits against the thumb and palm. While the flat top disc will tuck up into the palm a little more causing the disc to set a little flatter with a little less “droop” or angle. This is interesting to me because this situation sometimes means the difference of several degrees of angle when thrown normally.
Great video! I'm glad more people are talking about gyroscopic procession to explain turn and fade. Do you think another factor affecting turn/fade of the disc is that higher parting lines (more air diverted under the front edge of the disc) actually push the front edge of the disc upward? Gyro procession would divert this force 90 degrees in the direction of rotation to cause fade. Understable (lower parting line) discs would have more air pushing downward on the front edge of the disc.
Thank you for the comment! It’s a great question but for the purposes of this video I’d touched on the basics and we discussed basically the leading edge of the disc, however a major component to understanding, is that the leading edge of the disc is not the ONLY factor. Were it like a rudder on the front of a ship ONLY diverting the fluid on one end of the object causing an opposing reaction, then we could assume that the discs parting line causes upward force…(perhaps the disc call the “tilt” could be an extreme example) Ono part of this video I left out for simplicity sake, in order to not “drag” the viewer into the weeds too soon, (pun intended) is the visualization of what happenes at the back of the disc….the air diverted over and under at the leading edge of the disc, comes back together at the trailing edge of the disc. What happens here it’s the Drag force acting upon the disc. Air from the top and bottom come back together and the shape of the edge of the disc determines the shape of the downward flow of the lower pressure air moving over the top into the higher pressure air below, this is another component to understanding lift and amount of drag induced by that interaction. Main point is this: the upward force you describe of a high parting line has an opposite force at the rear of the disc to contend with.
It is a great explanation except when you’re a lefty, then you have to think about it just a little bit more OK so you guys are going forehand or backhand but if I’m a lefty that’s like your forehand so I have to sit there and think think think now it’s getting a lot of easier now been doing this a whilebut sometimes I get confused whether I should be putting Heizer or Anheuser on different discs
Sorry, I don’t speak lefty. Think everything is counter clockwise and the force put into the gyroscope takes effect 90 degrees away from the force in the direction of rotation:)
Thank you for your video! I have a couple og questions I hope you Can answer: Why dont you talk about the angle of attack when talking about the shape of a disc fx. An over stable disc instead of diverting the Air under or over the disc? And how come diverting Air over the disc creates more lift instead of underneath?
Thanks for your comment! Ok, for your first question, for simplicity sake and for introducing the basics in this video, I’m discussing and assuming an angle of attack of 0. This helps us visualize what is going on as the airfoil is interacting with the air at both the front and back of the disc. Common vernacular in disc golf for a high angle of attack would “nose up”. A good AOA would typically be 0 anyhow. The other thing I did not discuss which really weighs into the equation, is what happens at the trailing edge of the disc, which is twofold, drag (which determines disc speed), and the manner in which the airflow is finally diverted and brought back together. I suppose this is for a future video. For your second question we need to take a look at “Why does a wing generate lift”? Let’s think of a traditional wing, an airplane wing like a Cessna to start with. If we assume Bernoulli’s principle: as the wing passes through the air, it’s diverted above and below the airfoil. Air passing over the curved top of an airfoil must travel faster than air passing under the bottom which creates higher pressure and so the airfoil moves upwards from low to high. Next, a traditional wings balance point is typically set at 1/3 the chord of the wing. This is where its optimal Lift/Drag for its particular wing speed would balanced to fly efficiently and carry its load. If the airspeed for the wing would begin to exceed the optimum L/D, the drag would begin to pull the center of lift behind the balance point and cause the wing to begin to tip forward. If the wing were to be flown too fast, the aircraft would begin to move into a steep dive. On the opposite side of this understanding, if a wing begins to fly slower than the optimal L/D, the lift pressure would move in front of the CG; the wing would also be moving towards a higher AOA and if flown too slow it would eventually stall. With a disc, unlike a traditional aircraft wing, the leading edge of the disc/wing is exactly the same as the trailing edge and the center of balance is the center of the disc. With an over-stable disc like a Raptor, the air diverted over the top is near the same as below, and the wing shape doesn’t allow for the center of lift to move behind the center of balance. This means that its optimal L/D for its designed airspeed is at, or in front of, of the CG. We must understand also that a discs airspeed is dynamically changing and slowing down throughout its flight due to drag. Which means that the center of lift pressure is also dynamically moving or changing also. With a disc like a raptor, very few people can throw the disc fast enough to cause it to “turn”, meaning, throw it fast enough that the induced drag will cause the center of lift to move behind the center of balance. If we consider a Captain raptor, we will notice that more airflow is diverted below the part line than above, this means the disc was designed so the center of lift will typically always be in front of the center of balance or CG. Worthy of note and for understanding. With a disc like the tilt, the air at the front is all diverted downward. This force pushes up on the nose of the disc, the assumption would be a direct change to Angle of attack, however, this force is transferred 90degrees away in the direction of the discs spin due to gyroscopic precession and the effect is seen as instant fade and over-stability (similar to lift acting in front of CG but far more pronounced)
I feel like I'm learning a lot from your last few videos. I do have a question though, how does RPM affect this? Does a higher RPM cause the gyroscopic precession to happen at a larger than 90 degree angle so rather than lift producing as much turn or fade it ends up producing less because less of the force is directly causing the disc to tip left or right and more front and back?
Great question! As I understand it, the faster a disc spins the more it resists both turn and fade. My backhand is 60 mph with around 1200rpm’s. 1200 rpm’s is equivalent to 30 mph. My discs rpm’s are 50% of the discs airspeed. This is a very good ratio. Good Forehand throws tend to have a 30% rpm to speed ratio. This is why forehands, thrown at the same speed as backhand throws do not travel as far as backhand throws, and also have more movement from left to right. Spin narrows the flight of a disc to a straighter line because the faster it spins the more it’s able to resist the other forces it experiences in flight. Less spin means more turn and more fade. As far as I understand the physics of gyroscopic precession, the effect of force always takes effect 90 degrees away in the direction of rotation. It’s how they stabilize the space station with spinning flywheels and keep it oriented, so it’s quite a predictable rule in physics.
Great explanation! Buy WHY is the center of pressure (lift) start so far back??? My understanding of typical airfoils is it is usually around 1/3 back from the leading edge....the flow goes turbulent past that point so no lift....what's happening here? I need to think more. Maybe since the Reynolds numbers are so low my experience with normal airfoils is useless?
I’m not sure what you mean by “the flow goes turbulent past the point so no lift”? . I don’t think I stated that, but I’ll try to extrapolate what you may mean. On a traditional wing the balance point is typically 25-30% of the mean wing chord measured back from the leading edge, like you stated. A disc golf disc is balanced in the center of the circle of itself. Unlike a traditional wing which is balanced specifically to each wing and aircraft for stability in flight. A disc being balanced over its center gains its wing like ability to fly and stay balanced from its spin. The spin of a disc gives it gyroscopic stability, so all the forces it experiences during flight that are not on it spinning axis, will be transferred or observed 90degrees away in the direction of rotation. The shape of a putter is blunt, its slow because of its Drag, think a “Piper cub”. The putter’s leading edge is also the same shape as its trailing edge, Unlike a traditional wing. If we throw a disc faster than its “wing” is designed to fly, the center of pressure drifts behind the center of balance. If we over-speed a traditional wing say on the “Piper Cub” we compensate by adding elevator to keep it in balance. But because the disc is spinning, the lifting force that lifts on the tail of the disc, would tip the wing forward, like on the airplane, but instead is transferred 90degrees to the left (clockwise spin) because of gyroscopic procession, so the left wing then lifts. If we throw a disc slower than it’s designed to fly, it will like an airplane, Stall. The lifting force moves far ahead of it CG towards the front of the disc, this would lead to a stall like an airplane, but the because gyroscopic effect on the disc takes place 90 degrees away from the force, the right wing lifts causing the disc to dive left. A distance driver on the other hand is sharp rimmed, it’s fast, not because it “cuts” the air so efficiently at the leading edge, but because it’s trailing edge has very little drag…once again a discs leading edge is the same as their trailing edge, so its induced drag is much less than a putter. I assume that a putters Reynolds numbers would be much lower than drivers. I’ve never tried calculating Reynolds numbers, I am only aware of them in passing, as I fly rc DLG gliders and there is a lot of technical discussions about each wings high speed and low speed capabilities.
Thank you for responding! I've been trying to understand (in detail) how exactly a disc flies ever since being introduced to the sport a couple years ago. A friend threw his disc (first time I'd seen one fly) and it did the typical right then left flight path....and I was like "wait...what??? how does it do that????". With no control surfaces like an airplane, I was totally befuddled how the disc could roll right then roll left. It is really unique and fascinating. Actually read a bunch of research papers on the subject and every one of them left me thinking "wait a minute...you didn't account for this or didn't answer that". The papers that did flow and forces analysis without the disc spinning you know to toss out instantly ! Your video is the FIRST explanation I've seen that makes sense, thank you so much. Gyroscopic procession is a strange topic so using the prop you built is genius and I'm sure totally helped a lot of people understand it. It is something that is not intuitive for sure. Back to my original confusion......I'm just not sure I understand how the Cp (center of pressure) can move fore/aft significantly as velocity changes, I would just expect its magnitude to change not its location. For typical aircraft airfoils, AoA (angle of attack) changes certainly causes the magnitude to change, I'm not sure if the location moves fore/aft significantly or not. I'm also thinking the boundary layer is coming into effect, as one lateral side of the disc is experiencing DiscVelocity+SpinRotationVelocity while the opposite side is DiscVelocity-SpinRotationVelocity. Hope I'm making sense. I think this comes into play, the actual pressure field should be different on the left side of the disc vs the right side of the disc, due to the surface speed of the disc and boundary layers effects. It would be interesting to somehow keep a disc at a constant forward velocity while changing the RPM from 0 to a high number and see how the forces are affected. If the left/right pressure field is not symmetrical and the forces change with RPM, that would certainly induce a pitch up or pitch down moment, from our pal gyroscopic precession. I'm also curious what the actual flow looks like on the underside of the disc, but probably not contributing to the flight mechanics. No way it stays laminar, but the vortices may not be significant. Then again, the flow field could change with RPM and velocity so I'm not sure. In any event, wonderful video and I'm going to keep pondering the details. Sorry I typed so much....this is just really interesting stuff to me. This is a pretty complex subject so if we ever meet in person I'll buy you a Coke and we can sit down and talk, always love learning something new. I'm certainly no expert, always found a PhD in aerodynamics to assist in the complex questions...and a spinning disc is pretty complex. Just the fact that a given disc flies differently after getting "beat in" is crazy (and tells me boundary layer is having an effect!). Oh, and RC gliders are fantastic ! Used to fly them years ago. So much fun.
@@timhossfeld7260 airspeed change by itself doesn't move the CP... just magnitude, like you said. But remember that airspeed change always comes with AOA change (as the wing/disc slows down, AOA increases) and *that* moves the CP forward.
Most unexpected Sark sighting. Been watching since early MW2 days on Machinima. Man i'm getting old... Anyway, excellent and intuitive explanation of disc golf physics with great visual aids! :)
Neat video. Quite informative. I'd love it if you could explain how players are able to throw a disc which turns over late. I've done it a few times, but I'm unable to do it with any predictability. Based on my experience, discs turn over at high speed, but not low speed. I suspect it is some type of hyzer-flip, but I don't understand how players are able to get the disc to fly straight for a couple hundred feet (or more) and then turn over before panning out to flat.
Yes, part of it is hyzer flipping a disc (rhbh perspective) so that the late part of the turn is just past its level flight, and the second part has a lot to do with proper nose angle throughout that precession so when the disc “tips” to the right of level with the proper nose angle, most likely a neutral angle of attack or slightly nose down angle of attack it would appear to track to the right as it glides…(a nose up angle of attack at this point would cause it to slow down and fade more quickly). coupled that with it possibly having reaching its best lift over drag ratio (perhaps the lift acting over the center of balance at this point) would help hold the flight pattern for longer. To throw this shot with any consistency, one has to know the flight characteristics of that particular disc, how much it turns and when it typically “settles in”. It’s a bit of a touch and nose angle game from my experience. At least that’s my current hypothesis. :)
Also, I think Pete’s answer to the question about spin creating stability plays a role. If the disc highs high spin and stays stable longer, it will take longer for the spin to slow enough to be more affected by the lift, I think, which means the turn would come later than a disc with less spin. I believe drag would slow both the spin of the disc and the linear speed on the target line.
Great explanation of how profile and speed affect turn over and fade! Still missing something I think. Specifically, an explanation of how wear and tear affects same. I believe it is a Magnus effect. Perhaps is is somewhat less pronounced than what was explained here, and maybe that is why no one ever mentions it.
Thank you for your comment! I can’t throw everything into one video, that would be a long video!!. I will talk about wear and tear later in another discussion, but it has a bit to do with laminar flow becoming turbulent flow over the surface of the disc. And the magical thing that occurs at the back of the disc called….Drag! What I do know, based on the best scientific studies available to us currently and conversations I’ve had with fluid dynamics engineers, the Magnus effect has no measurable effects on the flight of the disc.
Hey Colin! Hope you are well my friend! In what other way do you mean the effect of spin? Spin creates a disc stability which when increased, helps the disc resist external forces. Spin narrows the flight envelope of a disc, allowing for less turn and fade. This resistance to forces that are not on its spinning axis is the reason for the disc having turn. The force of lift acts on the rear of the disc, but the effect of that force takes effect 90 degrees away in the direction of rotation causing the left side of the disc to lift. This phenomenon is due to spin. If you haven’t seen the two previous videos, please check them out. Later I plan to discuss how disc spin and OAT act in the wind, also the physics of Rollers….that’ll be a big spin discussion!
@@DiscgliderPete I am doing well thanks! I was wondering more about how spin factors in for late-flipping shots. My current understanding (which may be very wrong) is that the higher spin at release resists the turn initially, but later in the flight the disc flips when the spin has slowed enough that it can no longer resist the turn
I would love to see you do one explaining how more or less spin affects flight. My friends all think more spin means more turn but I try to tell them it means less turn AND less fade. More true gyroscopic stability.
Thanks for the comment! yes that is a common misconception, and one I used to think years ago. Here is a great experiment: take a fidget spinner, spin it slowly and then twist it around of axis. This will be easy. Now spin it super fast, then try to twist it off axis. It will now be hard. More spin = more resistance to any off axis toque, whether the disc is flying with air pressure lifting on it or being twisted in the hand.
This is awesome Pete! Begs me to ask how ‘speed’ or rim width effects gyroscopic precession and also the effect of rims that are flat vs curved more specifically are rim curves only producing tern at specific speeds.. more speed = more lines, exponentially larger amount of molecules on top of disc vs bottom
Great questions, If you have time to roll through the comments, I chat about something like that in several threads… lots of good stuff and great questions throughout this videos comment section this far!
I don't know if I will get lost in the, however. Your take is very good and well explained. But I believe and understand that for the flight carateristics, the "nose" of the disc makes a big dofferense. You didn't bring up the force generated by the wing hitting the nose. If the parting line is very low, more wind will hit the upper part of the disc wich you will see as turn. If the parting line is very high, or the bottom half of the nose is very agressive (or has a pead) the bottom will catch more air and generate a forse as stability.
The amount of lift a disc generates is a major factor in its stability. It’s not just that the air is getting diverted over or under the disc, that splitting of the air is only half of the story. The air, once diverted, must travel over and under the disc and come back together at the back or tail of the disc… this is another component of lift, but is also the location of drag….another video for later:)
@@DiscgliderPete I'm just playing. :). I love Paul and in my eyes he soars with the most majestic of gazelles.. lol, and since this stellar video was my first intro to you, I love you already as well. Very well done video. Loved all the physical visual aids that you can interact with in real time as opposed to graphics edited in after the fact.
Can you clarify what you mean by “wing height”? . If I assume you mean the leading edge of the disc being higher or lower as a triangle in relation to the rim, then yes, as stated in the video, a higher parting line is typically more stable than a lower parting line. A secondary part is the shape of the bottom part of the wing, being convex or concave and how it sheds the air below the disc, but that’s for another video.
@@DiscgliderPete Awesome! Yes I was wondering about that variable too (the bottom part of the wing being concave or convex). What do we call that? And yes, my understanding of "wing height" is, if you place the disc on a flat surface, it's the distance from tabletop to the parting line.
Greats video, very well explained ! I had no idea what actually occurs when a disc flies and always wanted to dig into that. I am wondering tho : doesn’t the drag force intervene ? I guess it depends on the disc maybe it is insignificant compared to the other forces, but I feel like it also plays a role ? And also how is it that the gyroscopic procession takes place at 90 degrees ? Is it always at this precise angle ? I also feel like it would vary with the disc profile. Open questions if anybody knows I’m just really curious :)
Great questions! The Gyroscopic precision phenomenon as I understand it is always at 90 degrees. It’s how they keep orientation of the space station, using heavy flywheels and using the torque against them to change position. So it’s a very precise and predictable rule in physics. Yes, drag is a huge component, I had another card to use with the visual aid in the video that showed the downward airflow and drag component behind the disc… however I decided for the purposes of this video to “drag” the viewer into the weeds this go round. Save it for another video
There are two theory’s. 1. As discs beat in the nose gets pushed down slightly. I think that’s a viable explanation for base plastic discs, but not necessarily for premium plastic discs. 2. As disc get dinged and scuffed, the air over the surface stops being laminar and becomes turbulent, eg. separated from the surface. This would tend to cause more lift and induce more drag as a result. I tend to believe this theory more, due to many experiences in model aviation.
Wings are designed for specific airspeeds. The best lift/drag ratio is most likely over the center of balance, when we throw a disc faster than its best L/D the center of lift pressure drifts or moves behind the center of balance due to the pressure in airspeed. As it slows down below its optimal L/D the lift force moves in front of the center of balance because the velocity of the disc is slower… thus the pressure is lower because air velocity over the surface is also slower. . Perhaps a topic for the next video
As far as I understand, in physics the 90* rule is always at play in gyroscopic precession, I don’t believe it drifts forward or backwards based on speed of spin. They use spinning weights to keep the space station oriented in orbit, so It’s an extremely predictable rule. Think of it like this, whether I throw a ball at 20 mph or 60 mph, it has momentum, that momentum carries it forward with a specific amount of kinetic energy, the faster it’s thrown, the more inertia it has and the higher its impact is when its momentum is interrupted. Its momentum its directional because it’s traveling in a “straight line” (though gravity causes a downward arc). When a disc is spinning it has inertia, that inertia can’t move in a straight line because it’s being held around its center axis, The higher the spin rate, the stronger its resistance to any off axis torque, or changes to its angular momentum. Its momentum is angular because it’s being held rotationally instead directionally.
Is it fair to say that Understable discs receive more downward force at the front rather than lift at the back? After all, isn't the wind that the disc is moving out of the way the primary force acting on it (besides gravity)?
No, I do not believe that would be an accurate statement. Just because air at the front of the wing of an under-stable disc diverts air upward does not mean that it pushes the nose down, because that’s not the whole story or only force acting on the disc. Air passing around the disc’s shape is a result of its velocity, Wings are fluid diverter’s. What happens at the trailing edge of a wing is what gives us the speed of a disc, in that all discs move or displace nearly the same amount of air out of their way, but it’s how much air they divert downward and “drag” along with them. Drag is what slows a disc down. If we do a little study on how to balance an airplane wing. The aircraft weight is typically balanced around 30% of the wing chord measured from the leading edge of the wing. The faster a wing flys, the farther back the center of lift moves behind the center of balance. This means the faster that an airplane flys, the more it will want to nose dive, this is counteracted by the opposition of the horizontal stabilizer/ elevator at the back of the aircraft. With Disc Golf Discs, the center of balance is the center of the disc, also the airfoil is the same in the front as it is in the back. A disc without spin will not fly because of this balance issue. It will just tumble, because there is a Dissymmetry in Lift and balance along with the angle of attack and lift pressures. Spin is what allows a distance to fly, because of gyroscopic procession, this is the magic behind the flight of a Disc. How much lift a disc generates is mostly dictated by the parting line and airspeed as discussed in the video. The lower the parting line in relation to the triangle shape of the rim, the more air will pass over the top of the disc, the more lift it will generate, the amount of lift compared to the airspeed will determine how far back the center of pressure of lift will move behind the balance point of the wing. When the center of pressure moves behind the center of balance, because of gyroscopic procession, the lift force’s effect will transfer 90* forwards in the direction of rotation. For the most part, Over-stable discs don’t allow the center of pressure to move behind the center of balance, this causes the center of pressure to remain from the center towards the front of the disc, this forces effect will transfer 90* in the direction of rotation and lift towards a discs natural fade. Discs flight is a very complex problem to work out. I’m basically discussing the simplified understanding of it. If we change the discs shape by .5-1mm its flight characteristics can change quite dramatically.
@@triptaylor2509 thanks for commenting and asking:) as simply put as possible, when speed decreases AOA (Angle of attack) increases. This is what leads to a stall on a traditional wing. The center of pressure moves towards the front as AOA increases. Speed changes the center of pressure (where lift is acting on the wing). I’ve taken what I’ve learned from building rc model gliders, and what I’ve gleaned from many lengthy discussions with fluid dynamics engineers to arrive at this current understanding. I’m always learning, revising, growing in understanding, and improving on articulating what I’m seeing to others. Here is a link to some of the bests study’s ever done on the subject for discs. Most everyone references this research. www.researchgate.net/profile/William-Crowther-6/publication/268559957_FrisbeeTM_Aerodynamics/links/552fb5af0cf27acb0de627b8/FrisbeeTM-Aerodynamics.pdf www.researchgate.net/profile/William-Crowther-6/publication/225330184_Simulation_of_a_spinstabilised_sports_disc/links/54dc61150cf28d3de65f9d3d/Simulation-of-a-spinstabilised-sports-disc.pdf
Great question! I think part of the answer lies in hyzer flipping a disc (rhbh perspective) so that the late part of the turn is just past its level flight, and the second part has a lot to do with proper nose angle throughout that precession so when the disc “tips” to the right of level with the proper nose angle, most likely a neutral angle of attack or slightly nose down angle of attack it would appear to track to the right as it glides…(a nose up angle of attack at this point would cause it to slow down and fade more quickly). coupled that with it possibly having reaching its best lift over drag ratio (perhaps the lift acting over the center of balance at this point) would help hold the flight pattern for longer. To throw this shot with any consistency, one has to know the flight characteristics of that particular disc, how much it turns and when it typically “settles in”. It’s a bit of a touch and nose angle game from my experience. Another component I think would be that a disc with high spin rate resists off axis torque more than a disc with a lower spin rate. So the high spin rate would tend to delay the turn till later in its flight down the fairway. As we can see, other than just throwing and enjoying it, nothing about understanding the complexities of what’s going on with the flight of a disc is casually simple. At least that’s my current hypothesis. :)
Спорт
Woah the match box demonstration of airflow was better than 90% of the graphics ive seen.
Thank you!
This is the holy grail of physics of flight. Please make this viral
Great demo! Precession is also useful for understanding why nose up (positive aoa) negatively impacts distance. Throwing nose up moves the center of pressure forward on any disc profile, causing a reduction (or loss) of high speed turn and a much quicker transition to fade causing the disc to fall short and left of it's max potential distance for a RHBH throw.
Yes sir! Well said! Thanks for a great comment, also my previous video had to do with demonstrating gyroscopic precession.
stability is part of it but i think the main reason nose up reduces distance is just plain old aerodynamics
@@ts4gv good ol drag.
I'm into DG for about 2 years now and have watched _a lot_ of videos about it. This is the video I have been looking for all the time and never found. Thanks so much for the great and very visual explanations!
Thank you!
Well done Pete! I haven't seen a video yet on an accurate description of what is causing turn and fade. Until now, thank you!
So many youtubers out there trying/pretending to explain turn and fade. This is the only video I've seen that answers the question for me. Will be paying attention to part lines more from now on (for fun). Thank you!
Thank you:)
I immediately shared this with my friends who play. I feel like I have such a better understanding of disc mechanics now, thank you so much for this
So freaking cool, my brain has been searching for this explanation for years. You've given us all a beautiful gift of understanding with this one Pete. I'm no expert, but I know Bernoulli's Principle of fluid dynamics is key in this.
Pete! I've done so many (less sophisticated and useful) explanations to myself and friends about the stability of discs, how wind affects them, etc. and this is INCREDIBLE. Best explanation I've ever seen! I will refer them to this video next time someone asks! I think Bill Nye would love to do a collab with you ;)
Thank you for the kind words! I suppose it would be an incredible honor to meet and discuss science with Bill Nye! I’d also love to have the opportunity to play a round, discuss, share and learn disc physics with Destin from the Smarter Everyday and his collaborator Matt from the podcast “No dumb questions”. That would be fun. Dreams right?
Very informative. Fun visual aids. Well done!
This is an excellent explanation Pete. Thanks for taking the time to put it together!
Looking at the other videos you uploaded, looks as if there is more of this. I'll check them out.
Wow great vid man! Very easy to understand
First time seeing one of your videos. This was an awesome explanation regarding the forces that affect disc flights. Thank you!
I never knew about centre of lift. Great job!
This was the first video able to explain to me the mechanics behind turn and fade. Thank you, great video!!!
Glad it was helpful!
Great video and you make it very easy to understand the general concept of flight/stability. Its one thing to know about weights and stability as an average player but this is a clear summation of why that all matters. This will help a lot of people zero in on a disc that fits them rather than adapting their play to the discs in their bag.
Super well done video. The force vector visuals you added to the physical discs will be really helpful for people to see the interaction between the pitching moment and resultant precession.
Was holding off on my disc physics video and started working on a different video idea because I knew you would explain this really well, and I made the right choice because I no longer need to make the disc physics video, haha!
That was very interesting. Me, going from very little knowledge on this, other than flight numbers and trial and error, to listening to this explanation, I was able to grasp the concept. Id like to see more of these breakdowns.
Thank you!
I'm gonna have to watch this a few times to fully ingest this. Great breakdown though, thank you
Glad it was helpful!
Very helpful explanation. Thank you!
You're welcome!
These videos you are making are great!!!! Please keep up this series!!!!
Thanks, will do!
Dude, you're crushing it with these!
Wow that was an awesome explanation and I also understand now, why my discs turn and fade in the other direction as lefty
As beginner; Thank you! Much appreciated knowledge
Awesome. I’m a visual learner. Thank u
Wonderful!
Bravo, sir. Well done!
This was super informative, man! Thank you!!
Glad you enjoyed it!
Honestly the first time I've felt like I understood the physics behind it-- great visual aids!
This is the explanation I have been looking for thanks!
Best explanation that I've seen on what makes discs turn!
That also helps explain, for me, why understable discs go further with less effort -- more lift! A Hades generates more lift than a Zeus which generates more lift than a Force 🤔
Remember though: when you throw a disc that has more lift and turn, it flys farther because you traded predictability and stability for under-stability and less predictability :)
More lift = more drag - more turn
More lift = more turn - less stability
Less drag = less turn - more stability
Hard thing to explain but I think I finally got it now! Ive read and tried to get it b4 but was just overwhelmed!
Awesom job visually explaining the physics of disc golf. 👏 Easy to follow and understand for dummies like me!😂 Well done sir!
Really great explanation
Very well explained.
great work on educating us Pete. thank you
Glad you enjoyed it
Congratulations on your video eventually going viral because this is great
That would be cool! Thank you for watching and the comment.
Great explanation
Wonderful use of tools and visual aids. Great video!
Great explanations. All your points are spot on with awesome visual aids. One thing to add though, the shape of the wing can affect the center of lift (changing stability) a ton just like the parting line height can. A concave wing design will push the center of lift forward towards the nose making it more overstable. It pushes air down at the nose and this can cause resistance to turn even at high velocities. It also causes drag. It's an inefficient wing design because the angle between the flat bottom of the disc and the nose is too sharp and disrupts smooth airflow. Sharp angles are the opposite of aerodynamic. Convex wing designs like an IT or roadrunner do the opposite. They are rounded and smoothly connect the nose to the flat bottom allowing smooth airflow underneath the disc removing any lift generated at the nose (until the angle of attack increases but that's unavoidable at low speeds). This means at high speeds much more of the lift is created at the tail of the disc from airflow over the top of the disc. Some understable disc's nose sort of hang down towards the bottom of the disc to accomplish the same thing as a convex wing. I'm guessing this is to cut weight with higher speed discs with larger rims but I'm not sure.
Thank you for your comment!
You make very good points.
I did have a slide that I considered using with the nose angle tool that showed how air would be diverted and come together at the back of the disc…I decided to save it for later so as to to not “drag” the audience into the weeds to far in this one. I figured save it for another video on disc speed and drag.
Man I love these videos. I've been a hobbyist physics nerd since high school. Although I get a bit lost in the weeds attempting to do the logarithmic and cal based equations, I have always been able to gain a solid CONCEPTUAL understanding of various areas of physics if I'm given a good explanation, be it from a text or lecture. That is exactly what these disc physics vids you're doing have been for me - excellent conceptual explanations of what our beloved spinning plastic is experiencing in flight. Thank you and I look forward to any future vids you do. Cheers
Thank you so much for the kind words. I’ve got a few others in the pipeline that I’m excited about!
Very cool explanation. I’ve never seen anyone explain that. Thanks!
Glad it was helpful!
This is so good. I spent a decent amount of time trying to figure this out but I was missing the fact that CG moves back during high speed so I never understood it. Thanks a ton Pete!
Thank you!
Quick note:
I believe it’s the center of lift that moves back. It moves behind the CG, which does not change.
@@DiscgliderPete Yeah. I'm a pilot, force of habit. The cg on a disc doesn't change. Thanks for the video!
Great explanation, thank you! I have wondered this a lot.
Glad it was helpful!
Thanks, Pete! I have always wanted to at least have some general understanding of the science behind the flights. You did a great job!
Thank you for the kind words, Glad you enjoyed it!
Very good explanation, and to add to the physics there is also lift acting from under the front of the wing the whole time and as it slows it is the most amount of lift and the lift from air going over the top is almost negligible. Thanks for making this!
I don’t understand what you mean in your explanation. Can you explain?
great! with that explanation, you can extrapolate the effect of cross winds on a level disc - it causes the nose angle to change! which then affects turn and fade....layers upon layers.
You are correct!! That’s on of my next videos!! I’ve got a great visual to help visualize it that I learned from searching for thermals with my rc sailplanes.
Best explanation do far!
As an engineer I have never been satisfied with the simplistic explabation of stability and left/right tendencies.
From your explanation and definition of forces made, it is easy to see how the thrower (by causing spin and initial velocity) affects the flight path.
For example, take a beginners hyzer and explain it, or a hyzer flip and why it works. Or an amateur throwing a speed 14 disc and why it will flip left. 😁
Also, alter the surrouning air and its properties - wind direction and altitude (density) and think on how the disc responds. Answers easily found in your explanation made! Bravo!
Thank you!
I learned to play disc golf at high altitude.7000’. The difference in air density and learning the subsequent flight stability’s from there to 1000’ is a huge learning curve!
Finally the mystery is solved, I do believe. I've been frustrated in the search for an explanation for turn and fade of the flying disc until now. I still need to understand better why the lift position changes but for now I'll take your word for it.
So I assume that when a disc is in glide mode that the lift force aligns with the center of gravity. Any understanding of why air speed across the disc causes the lift position to shift?
@@David-ps2nb thanks for the comment!
For simplicity sake, we could look at an air plane wing. The wing would be designed for optimal airspeed to lift ratio, in line with how the Weight of the disc is balanced over the wing. Typically near 30% of the wing chord.
The faster you fly, the more the center of press pressure (lift) would move behind the center of balance, causing the aircraft to tip forward. If the aircraft were to slow down below the optimal airspeed, the center of pressure would move forward of the center of balance and the wing want to tip up and eventually would be in danger of stalling. What the airplane has that a disc does not, is a motor. This allows the management of speed and angle of attack to keep the wing in its optimal flight envelope.
With a disc, we throw it, so based on the disc’s designed flight speed, if it’s thrown faster than its optimal L/D glide speed the lift pressure moves behind the center of balance, this is what causes “turn”. But because a disc doesn’t have a motor, and “drag” is constantly pulling on the disc in opposition to its forward velocity, the disc is constantly slowing down during its flight, because of this the center of lift pressure is dynamically moving from behind the center of balance towards the center, and then eventually in front of the center of balance toward the end of the flight. If the disc is thrown high enough, it like an airplane will stall.
The higher the speed of a disc, the more narrow its optimal L/D glide portion of flight is. Thinking of a neutral midrange, it has a relatively wide L/D flight envelope, however it has a lot of drag due to its more blunt edge, so its distance is more limited.
I know I'm a bit late to the party, but does the amount of dome have anything to do with the turn/fade? I think most would agree, from personal experience, that flatter disc are more stable than their domey counterpart, but what would happen, for instance, if a tilt had dome? Or a mamba was flat? Does the dome solely affect the glide, which would slow the speed at which a disc would fade? Great video!!!
Thank you!
(I copy and pasted my comment below from another question that was similar with a couple added thoughts)
The flat versus Domey argument has always been a little comical to me, because some guys think the flat disc are more stable and the domey are under-stable, and other guys think that Domey are over stable, and the flat one stable.
Domey discs tend to have more glide than flat discs. Where the parting line is dictates him much air is diverted over the top vs.the bottom. A mamba is virtually flat from the nose to the bottom of its lip, but has a high curve from the nose to the shoulder…more air is diverted over the top. from here weather the flight plate has a pop top or a flat top, it’d seem to be a lift to drag issue. It’s going to be flippy either way.
For our two discs, Let’s assume both have identical parting lines. There are many components to understand it all, from lift, to drag, and even release angle.
My personal observation is this:
I think the varying opinions are a result of a grip issue.
Some guys love to throw flat discs while others prefer domey, and those are the camps they tend to stay in. When a person who loves throwing flat discs, throws a domey disc, they tend to believe it’s more stable. When a person who loves domey discs throws a flat disc, they tend to believe it’s under-stable, and vis versa.
Hold a flat disc in your hand, be exact at how it settles into your hand, like you are ready to throw in the power pocket position, notice how the edge of the disc closest to your chest looks.
Now grab a domey disc of the same mold,
Hold it in the same exact manner as described above. I believe that you will observe that the domey disc settles into the hand in such a way that the edge closest to the chest will be lower by up to a 1/4” or so. This result is because the domey disc is slightly taller leaving the rim and the thumb sets higher over the flight plate pushing the edge closer to your chest down slightly, so what feels “normal” is a slightly different angle between the two disc, and would leave the domey, disc on more of a hyzer angle out of the hand compared to the flat disc.
Thats my observations and opinion after years of observing the two groups and various opinions.
In flight we are always trading one preference in flight for another.
Lift we trade for drag
Speed we trade for control
Stability we trade for glide
Distance we trade for control
Speed and stability we trade for glide.
Wanting Speed and glide we must trade for in-stability.
Great video it would be awesome if you did one on the shape of the bottom part of the wedge and how that effect the flight
Great suggestion! That’s a big one to tackle. Perhaps in the future….
well done explanation
As an engineer who took aerospace classes back in college I think this is a great non-technical explanation of what going on. Good stuff!
Thank you. That’s the goal:)
love this. thanks pete!
Really good stuff! A question popped up during your parting line explanation. If we had two discs with the same flight plate molds and parting line, if we make the lower half of the rim divert the same amount of air but one is convex vs concave, won't we have pretty dissimilar high speed turn rates? I imagine this lower half shape determines air flow and where it might hit the bottom of the flight plate at different speeds. Strangely, this would be counter to your reasoning because the convex shape would seemingly push air flow to re-enter further back behind CG than a convex shape. Curious if there is another major component to disc stability than where the air is parted.
Example Drawing drive.google.com/file/d/1zYpI2C_siFGTM_Vy13qpw-ilpv_pcBJh/view?usp=sharing
drive.google.com/file/d/1zYpI2C_siFGTM_Vy13qpw-ilpv_pcBJh/view?usp=sharing
Thank you Eric for your insight. I don’t fully have that answer. Here is a thought exercise.
Yes, when we divert the air below in this manner we do tend to have more over-stability. The concave shape of the bottom half of the rim, from the part line downward must create a low pressure behind the wedge edge of the disc on the nose side.
I have a hypothesis and I’ll use an extreme example to explain for visualization. Take the disc called the “Tilt” for example, 90% of the air is diverted downward at an extreme angle 📐, the interesting thing about this disc is that it flies/ “glides” farther upside down than it does in traditional flight. Think of a pickup truck and the age old question, “ do we get better gas mileage with the tailgate up or down”? The answer is “tailgate up” because the tailgate traps a slow rolling a pocket of air behind the cab, which allows for the high speed airflow coming off the cab to smoothly pass over that pillow of air with less drag, whereas the tailgate down allows the air to drop downward into the bed, essentially pressing down on the tailgate and causing more drag behind the vehicle.
The extreme angle of the tilts bottom rim, when flipped over and thrown upside down essentially diverts the air upward in such an extreme way that the airflow at high speed would essentially create a boundary layer of air similar to observed in the bed of the truck🛻. This boundary layer allows the airflow to pass more efficiently from front to back on the disc.
Another thought is this which which I believe is a key component of understanding flight is: Drag. The most important part of understanding the speed of a wing/disc, is not how efficiently it cuts through the air at the front, but how efficiently it allows the air to come back together at the tail. Something like a putter moves, the same air out of the way at the front of the disc as a driver, but it does not allow the air at the back of the disk to come together in an efficient manner, and so it drags a bunch of air with it, which slows the disc down faster. Something high speed like a nuke, allows the air at the back of the disc to come together, smoothly and efficiently, with very little air being pulled or dragged behind the Disc. The angle of the bottom half of the rim being concave or convex, helps determine the way the air is diverted downward off the top of and at the back of the disc. I did have a little slide for this video showing airflow at the back of the disc that I considered using but didn’t want to get folks lost in the weeds. Maybe I’ll make a specific video on drag….understanding the basics of that is huge.
Link to example drive.google.com/file/d/1zYpI2C_siFGTM_Vy13qpw-ilpv_pcBJh/view?usp=sharing
great explanation!
@@tylerharper819 thank you!
This was a super informative demo! Appreciate the video. If you're able or have the understanding, I'd love to hear what effects domey vs flat flight plates have on the flight of a disc.
Thank you!
The flat versus Domey argument has always been a little comical to me, because some guys think the flat disc are more stable and the domey are under-stable, and other guys think that Domey are over stable, and the flat one stable.
Domey discs tend to have more glide than flat discs. Let’s assume both have identical parting lines. There are many components to understand it all, from lift, to drag, and even release angle.
My personal observation is this:
I think the varying opinions at a result of a grip issue.
Some guys love to throw flat discs while others prefer domey, and those are the camps they tend to stay in. When a person who loves throwing flat discs, throws a domey disc, they tend to believe it’s more stable. When a person who loves domey discs throws a flat disc, they tend to believe it’s under-stable.
Hold a flat disc in your hand, be exact at how it settles into your hand, like you are ready to throw in the power pocket position, notice how the edge of the disc closest to your chest looks.
Now grab a domey disc of the same mold,
Hold it in the same exact manner as described above. I believe that you will observe that the domey disc settles into the hand in such a way that the edge closest to the chest will be lower by a 1/4” or so. This result is because the domey disc is slightly taller and the thumb sets higher over the flight plate pushing the edge closer to your chest down slightly, so what feels “normal” is a slightly different angle between the two disc, and would leave the domey, disc on more of a hyzer angle out of the hand compared to the flat disc.
Thats my observations and opinion after years of observing the two groups and various opinions.
Thanks for the content!
Greatest Disc Golf video's of all time: 1) The round of the Holy Shot. 2) This video.
Pete - really just started watching your channel (it popped up on my channel feed), but this is a great first-principles analysis of disc flight. …and, explains what I’m seeing when I unleash my noodle arm. Now if I just had a Tech Disc to generate measurements… 😊
Thank you!
Cool video, Pete
Thanks 👍
Great explanation. How does the difference in apparent air speed between the left side and right side affect lift, turn and fade? The air on the left side is moving across the disc faster than on the right, for a right hand back hand throw.
Thanks for the great question @edneely! From what I understand, based on the best scientific studies and data available thus far, there is no measurable difference From the left and right side feeling a difference in apparent airspeed as you were asking.
My thoughts are:
If you think about it they are wedge shaped edges on the left and right wingtips, but not within the lifting part of the wing, so it’s more of a slip stream near the edge. That’s my visual reference for understanding. But I honestly don’t have a full understanding of why at the moment other than Basically not enough difference to cause a Magnus effect either.
Very nice vid. I would kill to see you make a vid like this on dome vs flat and finally burry the debate about which of the two is more overstable.
Thank you for your comment!
I’m working on that particular video in my notes and head.
Proof is better than opinion, however, I’ve got years of flying Rc sailplanes, along with looking at what the free flight and hand launch geniuses have learned from wing shaping for both high and low speed flight. This has made me a little biased in understanding flight physics. But flight is flight, I love learning and it’s all super fascinating to me, so when I tackle that subject for a video I plan to share what’s valuable and factual about both opinions.
@@DiscgliderPete sounds awesome!
At 5:19, why does the center of lift move forward with slowe air speed?
That’s a wonderful question.
It’s air airspeed and pressure issue.
Let’s think of it this way. Imagine a boat moving slowly through the water. Now imagine its wake moving out alongside and behind it. The wake is small because the pressure of the boat against the water is small.
Now let’s make the boat go fast. The boat now raises out of the water and rides higher because the pressure is greater and as a result the wake is greater also. If our boat goes fast enough the pressure will increase and the entire boat will skim across the surface because the center of pressure is well behind the center of the boat’s balance.
Now let’s slow the boat back down.
As the boat slows, the pressure below it decreases and the bow begins to pitch upwards because the center of pressure moves forward of the center of the boats balance.
With our boat analogy we can see how the speed of an object within a fluid can change pressures, how that center of pressure can be forward or behind the objects depending on its speed.
With a disc, the principle is basically the same. The faster a disc moves through the air, the greater the pressure, and the more that pressure slips behind the center of balance.
When the disc slows, the center of pressure/lift decreases and moves ahead of our discs center of balance, and much like our boat, the nose pitches upwards increasing the angle of attack as the disc begins to fall.
I hope that helps answer you question:)
@hundowasmynama COMPLETELY AGEE! It's up there. Huge Paul fan, always here about Pete, seen a little but haven't heard it explained so well. Thanks Pete! Subscribed!!!
Thank you!
Awesome video Pete
Thanks 👍
I wouldn’t mind a video on glide. How do two discs with same speed have very different glide characteristics? I think it may have to do with the dome to some extent, but curious as to the exact way it happens. In particular, the Rask was designed to have low glide with a fast rim. They essentially molded a concave puck to the bottom, so I don’t know if reducing the volume underneath the dome may have an effect on glide? Would this be why a flat top disc doesn’t glide as much as a higher dome version of same mold?
Good questions!
First let’s understand the disc flight number system is an approximation of what could be expected at that discs intended speed, and is subjective to each individuals throw on how it’s experienced.
In aerodynamics we are always trading one thing for another..
Lift for drag, speed for control …
If you want a faster disc, you will inherently be trading speed for control,
If you want more glide you will inevitably be increasing drag.
The dome of a disc can have an affect on its flight, some folks experience dome top discs as under-stable while others experience the same disc as over-stable, as well as flat top discs feeling both stable and under stable to different throwers. For a moment, let’s assume a dome top disc and a flat top disc of the same mold, color, run, and other parameters have the exact same parting line. Meaning they divert the same amount of air over and under. What I’ve observed in these kind of instances is this: when holding a dome topped disc, the disc will tend to set in the hand with a little more “hyzer” angle because of the way the top of the disc fits against the thumb and palm. While the flat top disc will tuck up into the palm a little more causing the disc to set a little flatter with a little less “droop” or angle. This is interesting to me because this situation sometimes means the difference of several degrees of angle when thrown normally.
That makes sense and thank you for the explanation!
Amazing explanation. Subscribed!
Awesome, thank you!
Great video! I'm glad more people are talking about gyroscopic procession to explain turn and fade. Do you think another factor affecting turn/fade of the disc is that higher parting lines (more air diverted under the front edge of the disc) actually push the front edge of the disc upward? Gyro procession would divert this force 90 degrees in the direction of rotation to cause fade. Understable (lower parting line) discs would have more air pushing downward on the front edge of the disc.
Thank you for the comment! It’s a great question but for the purposes of this video I’d touched on the basics and we discussed basically the leading edge of the disc, however a major component to understanding, is that the leading edge of the disc is not the ONLY factor.
Were it like a rudder on the front of a ship ONLY diverting the fluid on one end of the object causing an opposing reaction, then we could assume that the discs parting line causes upward force…(perhaps the disc call the “tilt” could be an extreme example)
Ono part of this video I left out for simplicity sake, in order to not “drag” the viewer into the weeds too soon, (pun intended) is the visualization of what happenes at the back of the disc….the air diverted over and under at the leading edge of the disc, comes back together at the trailing edge of the disc.
What happens here it’s the Drag force acting upon the disc. Air from the top and bottom come back together and the shape of the edge of the disc determines the shape of the downward flow of the lower pressure air moving over the top into the higher pressure air below, this is another component to understanding lift and amount of drag induced by that interaction.
Main point is this: the upward force you describe of a high parting line has an opposite force at the rear of the disc to contend with.
It is a great explanation except when you’re a lefty, then you have to think about it just a little bit more OK so you guys are going forehand or backhand but if I’m a lefty that’s like your forehand so I have to sit there and think think think now it’s getting a lot of easier now been doing this a whilebut sometimes I get confused whether I should be putting Heizer or Anheuser on different discs
Sorry, I don’t speak lefty. Think everything is counter clockwise and the force put into the gyroscope takes effect 90 degrees away from the force in the direction of rotation:)
This was really really great. Thanks!
Glad you enjoyed it!
Great stuff!
What a freaking awesome video. I love the work you put into this. I hope you keep making awesome content like this!
Thank you so much!
Thanks for the explanation. Liked and subscribed 🎉
You may have been the 2k subscriber!!! Thank you
Would love a video explaining why discs become more understable as they beat in
Yes, that is a fascinating subject we will discuss In the future.
Great video! thanks!
You're welcome! Thanks for watching
Thank you for your video!
I have a couple og questions I hope you Can answer:
Why dont you talk about the angle of attack when talking about the shape of a disc fx. An over stable disc instead of diverting the Air under or over the disc?
And how come diverting Air over the disc creates more lift instead of underneath?
Thanks for your comment!
Ok, for your first question, for simplicity sake and for introducing the basics in this video, I’m discussing and assuming an angle of attack of 0. This helps us visualize what is going on as the airfoil is interacting with the air at both the front and back of the disc.
Common vernacular in disc golf for a high angle of attack would “nose up”. A good AOA would typically be 0 anyhow.
The other thing I did not discuss which really weighs into the equation, is what happens at the trailing edge of the disc, which is twofold, drag (which determines disc speed), and the manner in which the airflow is finally diverted and brought back together. I suppose this is for a future video.
For your second question we need to take a look at “Why does a wing generate lift”?
Let’s think of a traditional wing, an airplane wing like a Cessna to start with.
If we assume Bernoulli’s principle: as the wing passes through the air, it’s diverted above and below the airfoil. Air passing over the curved top of an airfoil must travel faster than air passing under the bottom which creates higher pressure and so the airfoil moves upwards from low to high.
Next, a traditional wings balance point is typically set at 1/3 the chord of the wing.
This is where its optimal Lift/Drag for its particular wing speed would balanced to fly efficiently and carry its load.
If the airspeed for the wing would begin to exceed the optimum L/D, the drag would begin to pull the center of lift behind the balance point and cause the wing to begin to tip forward. If the wing were to be flown too fast, the aircraft would begin to move into a steep dive. On the opposite side of this understanding, if a wing begins to fly slower than the optimal L/D, the lift pressure would move in front of the CG; the wing would also be moving towards a higher AOA and if flown too slow it would eventually stall.
With a disc, unlike a traditional aircraft wing, the leading edge of the disc/wing is exactly the same as the trailing edge and the center of balance is the center of the disc.
With an over-stable disc like a Raptor, the air diverted over the top is near the same as below, and the wing shape doesn’t allow for the center of lift to move behind the center of balance. This means that its optimal L/D for its designed airspeed is at, or in front of, of the CG.
We must understand also that a discs airspeed is dynamically changing and slowing down throughout its flight due to drag. Which means that the center of lift pressure is also dynamically moving or changing also.
With a disc like a raptor, very few people can throw the disc fast enough to cause it to “turn”, meaning, throw it fast enough that the induced drag will cause the center of lift to move behind the center of balance.
If we consider a Captain raptor, we will notice that more airflow is diverted below the part line than above, this means the disc was designed so the center of lift will typically always be in front of the center of balance or CG.
Worthy of note and for understanding.
With a disc like the tilt, the air at the front is all diverted downward. This force pushes up on the nose of the disc, the assumption would be a direct change to Angle of attack, however, this force is transferred 90degrees away in the direction of the discs spin due to gyroscopic precession and the effect is seen as instant fade and over-stability (similar to lift acting in front of CG but far more pronounced)
@@DiscgliderPete awesome! Thank you for taking the time to explain it in more detail🙏
@@madsbundgaard9014 hopefully that helped
@ it truely did!
I feel like I'm learning a lot from your last few videos. I do have a question though, how does RPM affect this? Does a higher RPM cause the gyroscopic precession to happen at a larger than 90 degree angle so rather than lift producing as much turn or fade it ends up producing less because less of the force is directly causing the disc to tip left or right and more front and back?
Great question!
As I understand it, the faster a disc spins the more it resists both turn and fade.
My backhand is 60 mph with around 1200rpm’s. 1200 rpm’s is equivalent to 30 mph.
My discs rpm’s are 50% of the discs airspeed. This is a very good ratio.
Good Forehand throws tend to have a 30% rpm to speed ratio. This is why forehands, thrown at the same speed as backhand throws do not travel as far as backhand throws, and also have more movement from left to right. Spin narrows the flight of a disc to a straighter line because the faster it spins the more it’s able to resist the other forces it experiences in flight. Less spin means more turn and more fade.
As far as I understand the physics of gyroscopic precession, the effect of force always takes effect 90 degrees away in the direction of rotation. It’s how they stabilize the space station with spinning flywheels and keep it oriented, so it’s quite a predictable rule in physics.
Good job!
Thank you!
Great explanation! Buy WHY is the center of pressure (lift) start so far back??? My understanding of typical airfoils is it is usually around 1/3 back from the leading edge....the flow goes turbulent past that point so no lift....what's happening here? I need to think more. Maybe since the Reynolds numbers are so low my experience with normal airfoils is useless?
I’m not sure what you mean by “the flow goes turbulent past the point so no lift”?
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I don’t think I stated that, but I’ll try to extrapolate what you may mean.
On a traditional wing the balance point is typically 25-30% of the mean wing chord measured back from the leading edge, like you stated.
A disc golf disc is balanced in the center of the circle of itself. Unlike a traditional wing which is balanced specifically to each wing and aircraft for stability in flight. A disc being balanced over its center gains its wing like ability to fly and stay balanced from its spin. The spin of a disc gives it gyroscopic stability, so all the forces it experiences during flight that are not on it spinning axis, will be transferred or observed 90degrees away in the direction of rotation.
The shape of a putter is blunt, its slow because of its Drag, think a “Piper cub”. The putter’s leading edge is also the same shape as its trailing edge, Unlike a traditional wing.
If we throw a disc faster than its “wing” is designed to fly, the center of pressure drifts behind the center of balance.
If we over-speed a traditional wing say on the “Piper Cub” we compensate by adding elevator to keep it in balance. But because the disc is spinning, the lifting force that lifts on the tail of the disc, would tip the wing forward, like on the airplane, but instead is transferred 90degrees to the left (clockwise spin) because of gyroscopic procession, so the left wing then lifts.
If we throw a disc slower than it’s designed to fly, it will like an airplane, Stall. The lifting force moves far ahead of it CG towards the front of the disc, this would lead to a stall like an airplane, but the because gyroscopic effect on the disc takes place 90 degrees away from the force, the right wing lifts causing the disc to dive left.
A distance driver on the other hand is sharp rimmed, it’s fast, not because it “cuts” the air so efficiently at the leading edge, but because it’s trailing edge has very little drag…once again a discs leading edge is the same as their trailing edge, so its induced drag is much less than a putter.
I assume that a putters Reynolds numbers would be much lower than drivers. I’ve never tried calculating Reynolds numbers, I am only aware of them in passing, as I fly rc DLG gliders and there is a lot of technical discussions about each wings high speed and low speed capabilities.
Thank you for responding! I've been trying to understand (in detail) how exactly a disc flies ever since being introduced to the sport a couple years ago. A friend threw his disc (first time I'd seen one fly) and it did the typical right then left flight path....and I was like "wait...what??? how does it do that????". With no control surfaces like an airplane, I was totally befuddled how the disc could roll right then roll left. It is really unique and fascinating. Actually read a bunch of research papers on the subject and every one of them left me thinking "wait a minute...you didn't account for this or didn't answer that". The papers that did flow and forces analysis without the disc spinning you know to toss out instantly !
Your video is the FIRST explanation I've seen that makes sense, thank you so much.
Gyroscopic procession is a strange topic so using the prop you built is genius and I'm sure totally helped a lot of people understand it. It is something that is not intuitive for sure.
Back to my original confusion......I'm just not sure I understand how the Cp (center of pressure) can move fore/aft significantly as velocity changes, I would just expect its magnitude to change not its location. For typical aircraft airfoils, AoA (angle of attack) changes certainly causes the magnitude to change, I'm not sure if the location moves fore/aft significantly or not.
I'm also thinking the boundary layer is coming into effect, as one lateral side of the disc is experiencing DiscVelocity+SpinRotationVelocity while the opposite side is DiscVelocity-SpinRotationVelocity. Hope I'm making sense. I think this comes into play, the actual pressure field should be different on the left side of the disc vs the right side of the disc, due to the surface speed of the disc and boundary layers effects. It would be interesting to somehow keep a disc at a constant forward velocity while changing the RPM from 0 to a high number and see how the forces are affected. If the left/right pressure field is not symmetrical and the forces change with RPM, that would certainly induce a pitch up or pitch down moment, from our pal gyroscopic precession.
I'm also curious what the actual flow looks like on the underside of the disc, but probably not contributing to the flight mechanics. No way it stays laminar, but the vortices may not be significant. Then again, the flow field could change with RPM and velocity so I'm not sure.
In any event, wonderful video and I'm going to keep pondering the details. Sorry I typed so much....this is just really interesting stuff to me. This is a pretty complex subject so if we ever meet in person I'll buy you a Coke and we can sit down and talk, always love learning something new. I'm certainly no expert, always found a PhD in aerodynamics to assist in the complex questions...and a spinning disc is pretty complex. Just the fact that a given disc flies differently after getting "beat in" is crazy (and tells me boundary layer is having an effect!).
Oh, and RC gliders are fantastic ! Used to fly them years ago. So much fun.
@@timhossfeld7260 airspeed change by itself doesn't move the CP... just magnitude, like you said. But remember that airspeed change always comes with AOA change (as the wing/disc slows down, AOA increases) and *that* moves the CP forward.
Cool vid.
Most unexpected Sark sighting. Been watching since early MW2 days on Machinima. Man i'm getting old... Anyway, excellent and intuitive explanation of disc golf physics with great visual aids! :)
Neat video. Quite informative. I'd love it if you could explain how players are able to throw a disc which turns over late. I've done it a few times, but I'm unable to do it with any predictability. Based on my experience, discs turn over at high speed, but not low speed. I suspect it is some type of hyzer-flip, but I don't understand how players are able to get the disc to fly straight for a couple hundred feet (or more) and then turn over before panning out to flat.
Yes, part of it is hyzer flipping a disc (rhbh perspective) so that the late part of the turn is just past its level flight, and the second part has a lot to do with proper nose angle throughout that precession so when the disc “tips” to the right of level with the proper nose angle, most likely a neutral angle of attack or slightly nose down angle of attack it would appear to track to the right as it glides…(a nose up angle of attack at this point would cause it to slow down and fade more quickly).
coupled that with it possibly having reaching its best lift over drag ratio (perhaps the lift acting over the center of balance at this point) would help hold the flight pattern for longer. To throw this shot with any consistency, one has to know the flight characteristics of that particular disc, how much it turns and when it typically “settles in”. It’s a bit of a touch and nose angle game from my experience.
At least that’s my current hypothesis. :)
Also, I think Pete’s answer to the question about spin creating stability plays a role. If the disc highs high spin and stays stable longer, it will take longer for the spin to slow enough to be more affected by the lift, I think, which means the turn would come later than a disc with less spin. I believe drag would slow both the spin of the disc and the linear speed on the target line.
Great explanation of how profile and speed affect turn over and fade! Still missing something I think. Specifically, an explanation of how wear and tear affects same. I believe it is a Magnus effect. Perhaps is is somewhat less pronounced than what was explained here, and maybe that is why no one ever mentions it.
Thank you for your comment! I can’t throw everything into one video, that would be a long video!!. I will talk about wear and tear later in another discussion, but it has a bit to do with laminar flow becoming turbulent flow over the surface of the disc. And the magical thing that occurs at the back of the disc called….Drag!
What I do know, based on the best scientific studies available to us currently and conversations I’ve had with fluid dynamics engineers, the Magnus effect has no measurable effects on the flight of the disc.
@@DiscgliderPeteKinda related to drag is the reduction in angular velocity due to friction. How does that effect the angle of attack?
Awesome video! The one thing I would like to see added to the explanation is the effect of spin
Hey Colin! Hope you are well my friend!
In what other way do you mean the effect of spin?
Spin creates a disc stability which when increased, helps the disc resist external forces. Spin narrows the flight envelope of a disc, allowing for less turn and fade. This resistance to forces that are not on its spinning axis is the reason for the disc having turn. The force of lift acts on the rear of the disc, but the effect of that force takes effect 90 degrees away in the direction of rotation causing the left side of the disc to lift. This phenomenon is due to spin.
If you haven’t seen the two previous videos, please check them out.
Later I plan to discuss how disc spin and OAT act in the wind, also the physics of Rollers….that’ll be a big spin discussion!
Could you potentially do a video that discusses how to create more spin or why some people are able to generate more spin than others?
@@DiscgliderPete I am doing well thanks! I was wondering more about how spin factors in for late-flipping shots. My current understanding (which may be very wrong) is that the higher spin at release resists the turn initially, but later in the flight the disc flips when the spin has slowed enough that it can no longer resist the turn
I would love to see you do one explaining how more or less spin affects flight. My friends all think more spin means more turn but I try to tell them it means less turn AND less fade. More true gyroscopic stability.
Thanks for the comment! yes that is a common misconception, and one I used to think years ago.
Here is a great experiment: take a fidget spinner, spin it slowly and then twist it around of axis. This will be easy. Now spin it super fast, then try to twist it off axis. It will now be hard. More spin = more resistance to any off axis toque, whether the disc is flying with air pressure lifting on it or being twisted in the hand.
This is awesome Pete! Begs me to ask how ‘speed’ or rim width effects gyroscopic precession and also the effect of rims that are flat vs curved more specifically are rim curves only producing tern at specific speeds.. more speed = more lines, exponentially larger amount of molecules on top of disc vs bottom
Great questions, If you have time to roll through the comments, I chat about something like that in several threads… lots of good stuff and great questions throughout this videos comment section this far!
I don't know if I will get lost in the, however.
Your take is very good and well explained.
But I believe and understand that for the flight carateristics, the "nose" of the disc makes a big dofferense. You didn't bring up the force generated by the wing hitting the nose. If the parting line is very low, more wind will hit the upper part of the disc wich you will see as turn. If the parting line is very high, or the bottom half of the nose is very agressive (or has a pead) the bottom will catch more air and generate a forse as stability.
The amount of lift a disc generates is a major factor in its stability. It’s not just that the air is getting diverted over or under the disc, that splitting of the air is only half of the story. The air, once diverted, must travel over and under the disc and come back together at the back or tail of the disc… this is another component of lift, but is also the location of drag….another video for later:)
Awesome!
Also.. is this guy related to the "gazelles are birds" guy? Lol
Also…don’t judge a book by his brothers t-shirt sales! Haha
But yes, he’s my younger brother:)
@@DiscgliderPete I'm just playing. :). I love Paul and in my eyes he soars with the most majestic of gazelles.. lol, and since this stellar video was my first intro to you, I love you already as well.
Very well done video. Loved all the physical visual aids that you can interact with in real time as opposed to graphics edited in after the fact.
Nice explain! Comment for the algorithm!
Boom!
Would you say that “wing height” is the major variable determining the stability of a disc?
Can you clarify what you mean by “wing height”?
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If I assume you mean the leading edge of the disc being higher or lower as a triangle in relation to the rim, then yes, as stated in the video, a higher parting line is typically more stable than a lower parting line.
A secondary part is the shape of the bottom part of the wing, being convex or concave and how it sheds the air below the disc, but that’s for another video.
@@DiscgliderPete Awesome! Yes I was wondering about that variable too (the bottom part of the wing being concave or convex). What do we call that?
And yes, my understanding of "wing height" is, if you place the disc on a flat surface, it's the distance from tabletop to the parting line.
Greats video, very well explained ! I had no idea what actually occurs when a disc flies and always wanted to dig into that. I am wondering tho : doesn’t the drag force intervene ? I guess it depends on the disc maybe it is insignificant compared to the other forces, but I feel like it also plays a role ?
And also how is it that the gyroscopic procession takes place at 90 degrees ? Is it always at this precise angle ? I also feel like it would vary with the disc profile.
Open questions if anybody knows I’m just really curious :)
Great questions!
The Gyroscopic precision phenomenon as I understand it is always at 90 degrees. It’s how they keep orientation of the space station, using heavy flywheels and using the torque against them to change position. So it’s a very precise and predictable rule in physics.
Yes, drag is a huge component, I had another card to use with the visual aid in the video that showed the downward airflow and drag component behind the disc… however I decided for the purposes of this video to “drag” the viewer into the weeds this go round. Save it for another video
@@DiscgliderPete Very interesting thanks !
Well done. I love me a good free body diagram.
I love this stuf!
Me too!
Can you explain why discs goes more understable when beating in? Most have something to do with leading more air over the disc when beated or?
There are two theory’s.
1. As discs beat in the nose gets pushed down slightly.
I think that’s a viable explanation for base plastic discs, but not necessarily for premium plastic discs.
2. As disc get dinged and scuffed, the air over the surface stops being laminar and becomes turbulent, eg. separated from the surface. This would tend to cause more lift and induce more drag as a result.
I tend to believe this theory more, due to many experiences in model aviation.
So why does the center of lift change depending on the speed of the flight?
Wings are designed for specific airspeeds.
The best lift/drag ratio is most likely over the center of balance, when we throw a disc faster than its best L/D the center of lift pressure drifts or moves behind the center of balance due to the pressure in airspeed. As it slows down below its optimal L/D the lift force moves in front of the center of balance because the velocity of the disc is slower… thus the pressure is lower because air velocity over the surface is also slower.
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Perhaps a topic for the next video
Thanks for the detailed reply!
@@DiscgliderPete
Cool!
Is the force of lift being applied 90 degrees to the center line always exactly 90 degrees? Is it an approximation that varies with spin rate?
As far as I understand, in physics the 90* rule is always at play in gyroscopic precession, I don’t believe it drifts forward or backwards based on speed of spin.
They use spinning weights to keep the space station oriented in orbit, so It’s an extremely predictable rule.
Think of it like this, whether I throw a ball at 20 mph or 60 mph, it has momentum, that momentum carries it forward with a specific amount of kinetic energy, the faster it’s thrown, the more inertia it has and the higher its impact is when its momentum is interrupted. Its momentum its directional because it’s traveling in a “straight line” (though gravity causes a downward arc).
When a disc is spinning it has inertia, that inertia can’t move in a straight line because it’s being held around its center axis, The higher the spin rate, the stronger its resistance to any off axis torque, or changes to its angular momentum.
Its momentum is angular because it’s being held rotationally instead directionally.
Is it fair to say that Understable discs receive more downward force at the front rather than lift at the back? After all, isn't the wind that the disc is moving out of the way the primary force acting on it (besides gravity)?
No, I do not believe that would be an accurate statement.
Just because air at the front of the wing of an under-stable disc diverts air upward does not mean that it pushes the nose down, because that’s not the whole story or only force acting on the disc. Air passing around the disc’s shape is a result of its velocity, Wings are fluid diverter’s. What happens at the trailing edge of a wing is what gives us the speed of a disc, in that all discs move or displace nearly the same amount of air out of their way, but it’s how much air they divert downward and “drag” along with them. Drag is what slows a disc down.
If we do a little study on how to balance an airplane wing. The aircraft weight is typically balanced around 30% of the wing chord measured from the leading edge of the wing.
The faster a wing flys, the farther back the center of lift moves behind the center of balance. This means the faster that an airplane flys, the more it will want to nose dive, this is counteracted by the opposition of the horizontal stabilizer/ elevator at the back of the aircraft.
With Disc Golf Discs, the center of balance is the center of the disc, also the airfoil is the same in the front as it is in the back.
A disc without spin will not fly because of this balance issue. It will just tumble, because there is a Dissymmetry in Lift and balance along with the angle of attack and lift pressures. Spin is what allows a distance to fly, because of gyroscopic procession, this is the magic behind the flight of a Disc. How much lift a disc generates is mostly dictated by the parting line and airspeed as discussed in the video. The lower the parting line in relation to the triangle shape of the rim, the more air will pass over the top of the disc, the more lift it will generate, the amount of lift compared to the airspeed will determine how far back the center of pressure of lift will move behind the balance point of the wing. When the center of pressure moves behind the center of balance, because of gyroscopic procession, the lift force’s effect will transfer 90* forwards in the direction of rotation.
For the most part, Over-stable discs don’t allow the center of pressure to move behind the center of balance, this causes the center of pressure to remain from the center towards the front of the disc, this forces effect will transfer 90* in the direction of rotation and lift towards a discs natural fade.
Discs flight is a very complex problem to work out. I’m basically discussing the simplified understanding of it. If we change the discs shape by .5-1mm its flight characteristics can change quite dramatically.
Love it!
So glad!
I want to do more research on the CP moving forward as the speed of the disk slows. Is there an official name for this phenomenon?
@@triptaylor2509 thanks for commenting and asking:)
as simply put as possible, when speed decreases AOA (Angle of attack) increases. This is what leads to a stall on a traditional wing. The center of pressure moves towards the front as AOA increases.
Speed changes the center of pressure (where lift is acting on the wing).
I’ve taken what I’ve learned from building rc model gliders, and what I’ve gleaned from many lengthy discussions with fluid dynamics engineers to arrive at this current understanding. I’m always learning, revising, growing in understanding, and improving on articulating what I’m seeing to others.
Here is a link to some of the bests study’s ever done on the subject for discs. Most everyone references this research.
www.researchgate.net/profile/William-Crowther-6/publication/268559957_FrisbeeTM_Aerodynamics/links/552fb5af0cf27acb0de627b8/FrisbeeTM-Aerodynamics.pdf
www.researchgate.net/profile/William-Crowther-6/publication/225330184_Simulation_of_a_spinstabilised_sports_disc/links/54dc61150cf28d3de65f9d3d/Simulation-of-a-spinstabilised-sports-disc.pdf
So then what is the cause for late turn? Mostly straigth flight at beginning and gentle turn from mid point onwards?
Great question!
I think part of the answer lies in hyzer flipping a disc (rhbh perspective) so that the late part of the turn is just past its level flight, and the second part has a lot to do with proper nose angle throughout that precession so when the disc “tips” to the right of level with the proper nose angle, most likely a neutral angle of attack or slightly nose down angle of attack it would appear to track to the right as it glides…(a nose up angle of attack at this point would cause it to slow down and fade more quickly).
coupled that with it possibly having reaching its best lift over drag ratio (perhaps the lift acting over the center of balance at this point) would help hold the flight pattern for longer. To throw this shot with any consistency, one has to know the flight characteristics of that particular disc, how much it turns and when it typically “settles in”. It’s a bit of a touch and nose angle game from my experience.
Another component I think would be that a disc with high spin rate resists off axis torque more than a disc with a lower spin rate. So the high spin rate would tend to delay the turn till later in its flight down the fairway.
As we can see, other than just throwing and enjoying it, nothing about understanding the complexities of what’s going on with the flight of a disc is casually simple.
At least that’s my current hypothesis. :)