Since this video is all about learning, please reply to this comment if you have any insights on centrifugal force - including what we got right and/or wrong! 🧐
I think the wobble comes from the initial launch. The water in the cup ramps up to the speed and so the water is evenly pushed to the sides, but when throwing the disc, you are testing Newton's law of "an object at rest will stay at rest." The sand and the water are at rest, you yank the disc, and the water/sand push towards the back of the disc. Not sure how the rest of the flight works and if the centrifugal force pushes the sand/water out, but the wobble comes from the launch for sure.
Also I think the volume of water was insufficient to see a whole lot of difference, you need something denser like Mercury (Not suggesting this) to make a major change. either way you need heft with a low viscosity of gels are likely not a good answer.
I believe the disc with the hollow rim (the one you assumed to be very understable) demonstrated similar stability to its filled rim counterpart because even though the overall weight is less, the weight is more centralized to the disc body which gave it a lower inertia. This means the disc can spin quicker about it's axis. Think about a figure skater when they spin with their arms tucked in. They spin faster. Now with spinning objects such as a disc the faster they spin the more stability they will have. So to sum up, you reduced the weight, which tends to make the disc more understable, but also decreased it's inertia which increased the disc revolutions per second, which tends to make the disc more stable. Resulting in a net result of similar flight characteristics to it's original design.
I am inclined to believe that the sand was wobbling because at the launch of the disc-regardless of how you attempt to spread out the sand before-the sand gets pushed to one side of the disc from the sheer force you exert onto the disc through your pull. Then the sand attempts to level out evenly but struggles to do so perfectly because it is not a fluid(liquid or gas)-but acts similarly to one. TLDR: The sand would level out more and become more and more balanced, given that it had a longer flight time, whilst the water doesn’t need much time since it is not only a fluid but also had a high viscosity(ability to move around quickly). Love the videos; you’re making an amazing impact on growing the sport sustainably!!
The hollow disc being more overstable is exactly the opposite of what MVP does with their overmolds. The closer to the center of the disc the weight distribution, the faster a disc will lose its rotational speed and gyroscopic stability, causing it to fade faster. If you took the same disc, filled it with metal, and somehow threw it as fast as a hollow one, it would keep its rotational speed for a very long time. This in practice is used for things like a flywheel in a car. The reason you're not really seeing results with things like water or sand is in part the empty space will allow it to move around, which as you discovered becomes really complex when you add in the fact that the disc is flying while spinning. If you were able to have the disc at 100% capacity, it would keep the rotational forces more consistent and keep the disc spinning longer, but in theory also increases the initial energy needed upon release to get the disc spinning at the same rate. MVP has pretty much been working on this kind of technology since they started and it's the reason they have overmolds in the first place, it pushes the rotational inertia further away from the center of the disc.
There is one more variable in disc throwing and it is the fact that arm can only apply so much rotational energy to a disc which ofcourse isn't probably the same across different moment of inertia on varying discs it's still limited which results on lighter especially with lighter rim disc gettimg far more spin than a heavier disc. How fast it loses it I have no idea but the disc tends to keep the rotation going quite well usually comparing the airspeed slowing.
The phrase "pushes the rotational inertia further away from the center of the disc" should be changed to "increases the rotational inertia." Rotational inertia is a scalar quantity, so it doesn't have a "position" and doesn't move. A nitpick, but conceptually it matters.
THIS is the kind of science we need happening in disc golf. We know some scientific principles that make us lean towards this design being a poor idea, but we can learn so much by experiments like this. Keep it coming Jesse!
Rotational precession and the shape of the rim will have a bigger impact on the stability verses just the weight. The weight will impact how fast you can throw it, but like Tyrus said below the change of how far the weight is from the center will impact the rotational momentum to maintain high spin rate.
You need to get an engineer like Destin at Smarter Everyday to work with you on testing. He'll be able to explain why the discs fly the way they do, not just speculation, And could give you some better ideas for flight efficiency.
I've wanted to make a fluid filled rim disc since 2006, very happy to see you this. I was thinking of using mercury as the fluid and having it 100% filled, no air.
I want you and ezra alderhold to collaborate so bad. He is one of the hardest throwers and could make these discs fly to the absolute maximum potential. Pleaseeeee!!!!!
So, understability and overstability is measure by how the wind is distributed when going over/under the rim of the disc. The closer the top is to being flat and the rim being closer to the top of the disc the more overstable it will be, hence discs like the Tilt looking flat. The recent video by Latitude 64 explains this really well. You aren't changing the shape the disc at all by making it hollow, you're changing the weight. Changing the weight of a disc does two things: 1) makes it easier to throw higher speeds and 2) makes it so wind can push it around easier. Making the disc lighter so you can throw it faster will make it more flip up a little more than a max weight disc, but not as much as throwing a disc designed to be understable. Danny Lindahl from Dynamic Discs has a video about this.
Don't let the water-filled disc freeze! Regarding the stability of the hollow disc, it is known that weight is not directly related to stability. Take the blizzard-type discs: there are plenty of videos demonstrating that the lighter weight does not equate to understability. Stability is directly related to shape and spin. More spin results in more stability, not more overstability, but more stability in the neutral sense. If a disc has a lightweight rim compared to one of the exact same shape but heavier, you can get more spin on it. It will lose the spin faster though, because there is less angular momentum. Conversely, the heavier rim will yield less spin for the same power throw, but will maintain that spin longer. This is precisely the dynamic that MVP's Gyro technology plays with.
I mostly agree, but I'm quite certain that the spin does not slow down significantly during a flight (just look at a fidget spinner or a table top spinner where almost all resistance is through friction in the ball bearings and against the table). It is not the spin that makes a disc more stable, but the angular momentum, which is (simplified) the weight times the spin, so a heavier disc spinning slowly could have the same angular momentum as a light disc spinning fast. Do you have any tests showing that people actually get less spin on heavier discs? Of course this will be the case to some extent, but this is also down to human physiology and such, so it's possible most people get almost the same amount of spinn on both light and heavy discs (within reason). I don't feel that the weight of the disc is limiting my ability to put spin on a disc, but it would be interesting to see if this is actually the case.
Awesome video. Just really fun! Interesting application. Would be neat to host someone that could talk about the physics. I imagine most of this has been tried, but with all the money flowing into the sport, I guess there is a possibility that disc tech could take another leap. You are doing good things. Keep it up!
If you want to increase your rate of spin I would make a few models of the prototype that are solid on one section of the rim and 20-30% infill on the rest, I would try three designs, 15 degrees of arc, 30 and 60. this will be like the Aerobie epic but fit the technical standards and not be like a 15 speed. Your printer will have to work with slicer setting to get this to work out it not really straight forward and might be easier on an SLA printer over an FDM.
This is what I was thinking too. Experiment with imbalance and possibly try and use imbalance mitigation techniques (glass beads in motorcycle tires for example).
I could be completely off but my first thought was that you could get some way to spin the disc before it’s thrown. That would cause the sand/water to become evenly distributed using centrifugal force and then when you throw it I would think that distribution would stick through the whole flight. Maybe not but if it did that would be awesome lol
That was a great video. Way to push the limits of the pdga :p I wonder if the lighter disc is more stable because it doesn't have enough spin force to flip it because there isn't enough weight on the rim? Just like when you throw an under stable disc with low speed/spin it can be stable. (I know nothing of the science but figured it was worth a stab). Also way to represent the Kerr jar club.
If 3D printed parts struggle to hold water, no way they are going to hold helium. I reckon It also wouldn't have been that big a difference from the air one anyway, since the difference in weight would be negligible.
I’m sure there’s other people saying this but about lightweight discs: in general, when manufacturers, make something lighter, they have less dense plastic in the same mold. So it lowers the parting line height and makes the disc less stable. But it’s not simply because of the lighter weight, it’s because of a changed mold. The 3D printed disc makes the same exact mold at just a lighter weight. But it has the same shape and should fly the same
Most lightweight discs do fly less stable. But there is some Prodigy where the lightweight stuff is more overstable than max weight because that’s how the plastic cooled. I have a very overstable 139g P Model S
Interesting concepts. In order to adjust for the shift in sand and water due to inertia, you could try evenly distributed cells filled with water or sand.
Lateral thinking ahead, congratulations! The idea of a fluid inside the rim could change moment of inertia of the disc during the flight like a motorbike variator could work if: - Difference between inner and outer diameter of internal chamber is big. - Fluid is dense enough ( mercury=16,6 g/ml vs water=1g/ml ) - Disc is always horizontal and, without rotation, liquid stays close to the center. - Centrifugal forces pushes liquid to the outer part of the inner chamber during flight. I guess that those are too many conditions… The other line of investigation could be: if inner chamber walls were smooth enough so that de disc turns at higher rpm than the fluid ( mercury again ), disc would have a lower moment of inertia with the same total weight. I guess that it wouldn’t be good because it would loose its rotation faster.
maybe a non-newtonian fluid that becomes liquid when force is applied? also, some baffles/honeycomb in the hollow part could be useful to further slow the liquid from reaching the rim and then delay its return to the center when the disc slows.
I would like to see one with vegetable oil and one with bb’s. Try 3 of each with varying amounts inside to see which is better or maybe not. Fun video, thanks for sharing!
A few ideas to throw out there. 1) When the disc spins and the water fills the outside of the hollow portion due to centrifugal/centripital forces, there isn't much difference between the water and a solid infill. It is mostly just the density of the water that is the difference. The forces on the water are the same as the forces on a solid except that the solid doesn't move. 2) The fact that the water moves means it creates friction. That friction will in fact slow the disc spin which I think we wouldn't want.
yup. I think all it does is add some wobble. The rotation momentum should still stay consistent even though the spin rate slows. but not helpful either way. Water is less dense than disc plastic so I wasn't sure how it was supposed to help
MVP uses different plastic on the edge what if making the disc heavy on the edge can add distance. So in the hallow part add a heavy solid substance moving the weight to the edges.
My theory on why the hallow disc is still overstable has to do with moment of inertia. The more weight distributed from the axis of rotation the higher the moment of inertia, in our case our disk has a lower moment of inertia because the weight is more distributed towards the axis of rotation. The lower the moment of inertia means less resistance to a change in motion. From here we can suggest that it's easier to stop the disc from spinning hence it fades sooner.
I am quite certain of that the rotation of a disc slows only slows down an insignificant amount during a flight since there is very little air resistance acting on the rotation (as opposed to the forwards flight, where there obviously is significant air resistance). Just imagine a fidget spinner or a table top spinner where the vast majority of resistance is due to friction in the ball bearings or against the table. Here's a video of a spinner with only airresistance: th-cam.com/video/hu1jEWLZVug/w-d-xo.html which seems to be able to spin a lot longer than the duration of a disc flight. Instead I think fading happens when a disc slows down in its forwards flight and starts to fall. So a lighter disc might still fade sooner, since it will slow down through the air sooner. There is also a second effect in that a lighter disc will have less inertia from the angular momentum and thus once it starts to fade it will fall over quicker. However this second effect will also make understable discs turn quicker since there is also less inertia to resist the turn. So this explains why some people have witnessed lighter discs as more understable. Basically a discs over/understable characteristics are inherent to their shape, but light discs will accentuate any turn/fade and make these characteristics more extreme and noticeable.
The higher the center of mass the more overstable I think. If you hollowed out below the top of the disc you just shift the center of mass up. You can see on rims of overstable vs under stable discs how they are angled
Awesome video! Your content just keeps getting better and better. I've been really curious to see how an oblong disc would fly. My guess is that it would be extremely overstable . I assume that because it's oblong one edge will be moving faster than the other edge similar to how a boomerang flies. I hope you try it out! 🤙🏽
My theory on why the hollow wing is overstable is because it moves the center of gravity higher. Since the center of gravity is higher, this creates a larger moment of inertia in the vertical direction. This moment of inertia opposes the torque created by the different in lift between the left and right side of the disc, caused by spin. Since the lift difference is the same, you have the same torque but less resistance to that torque, which means more change in angle (turn) of the disc
I can flip a Innova base plastic Leopard to a roller with no problem. The MVP signal, though technically a flipper disc, takes me considerable more effort to flip to a roller.
Since I saw the Løft-disc with the rounded grip, I've wondered if it would be even more aerodynamic if the underside of the disc was flat and the grip was just carved as a ring. Making the center hollow might make it possible to keep most of the weight in the rim.
The hollow rim disc flew almost as stable as the prototype because while it is lighter the weight is even everywhere verses a lighter disc with most of the weight on the rim. To test it out I would make another disc that weighs the same as the hollow disc but without being hollow.
Just because the disc is super light doesn’t necessarily mean it’s going to be understable/flippy. It’s most likely stable bc of the shape of the disc.
As you are filling the disc with water… I couldn’t help but think about how a more dense liquid in comparison to water would react. Although very improbable and possibly unsafe something like Bromide or Mercury would be very intriguing to test out!
More weight at the outside edges makes Gyro disc harder to spin up but hold the spin longer. Making the high speed turn fase of flight last longer. So making the outside edge of the disc lighter would basically do the opposite.
Okay now take a super understable mold like an avenger SS and give it a hollow rim. I need to know if it’s stable 👀 then I need to see a hollow rim tilt 👀
it is possible that because the hallow discs moment of inertia is so low that the friction with the air took a lot of spin off and mad it fly more overstable. it is also possible that beacuse 3d printing plastic is so stiff that it didnt allow for flight plate expansion which usually makes a disc glide but also lowers the ratio of disc below the parting line
For the hollow rim, try evenly spaced hollow segments that you'd individually fill with water/sand etc. Would help with the balance issue. Though a ton more work Maybe some thicker gels and other substances like BBs? Bonus points if you name it " The BattleRattle"
Interesting...I was thinking about printing some discs and comparing different infills instead of just being hollow. On the centrifugal force side...some interesting comments I see in the comments section. But I'm a little surprised no one brought up, what I learned when I was still a physics major, that centrifugal force isn't really a force. Technically it is centripetal acceleration.
@@scottconner4100 It's surprising how many places get this wrong that are science related sites. Wikipedia screws this up even further by calling Centripetal Acceleration as Centripetal Force. For those of you wondering what Scott I are talking about...a "force" can only move in 1 direction by definition. When you change direction it becomes a change in force with is an acceleration. Since going around an arc is constantly changing the direction of force it now becomes an acceleration.
In the day I experimented with trying to take all the weight from the center to maximize rim weight. My approach was to literally cut the rim off of a disc and replacing the flight plate with plastic wrap. Results were inconclusive but might be an idea to pursue to the maximum extent
@@martymodus7205 not exactly, the flight plate was removed and then replaced with very light weight plastic film, so almost all of the weight was on the rim.
Soft edge on the inside of the rim is something I am curious about. This might make it a bit strange to throw, but I always wanted to know if it would make a difference in distance, my thought is that is would displace air with less interference, but I have no idea
Love your videos ! I don't have any physics that I can add, but I really dig the shirt you have on, midway through the video. The one with the 3 baskets. I went to your website in hopes you are selling them. Any help would be great. Would love to have one.
To counteract all of the sand/water being bunched on one side of the disc you could make separate "chambers" in the rim. For example, a disc with hollow rim would have just the one chamber, but if you put up some walls making 4 or so different chambers then you'd have better distribution
10 or so years ago, one (or all?) of the trilogy brands had a line called Fluid, with a liquid filled rim. I played with a fellow that used one, but cannot recall unique flight characteristics.
A 'dead blow' hammer is partially filled with grains of something like sand to kill the inertia of the object trying to make the hammer bounce backwards, which puts all the inertia of the hammer into whatever is being struck. Would partially filling the rim of a disc with sand or water do more to kill the spinning inertia than help it?
Yeah the water will slow the disc spin as the water slowly accelerates from stationary to matching the disc speed. But the rotational MOMENTUM should not be affected. so there should be minimal affect on the flight apart from the wobble
What about removable flight plates? You could make a locking clasp system and then change the rims depending on need. Then you wouldn't need to replace a whole disc just because the rim is worn out. As an aside - what do you think about microplastics in the environment coming from disc wear? All that beating in of discs removes material which is going into the soil - just wanted to hear your thoughts on this.
The water filled rim reminded me of SIL-X juggling balls. They are partially filled with a liquid silicone to affect the center of gravity. I wonder what that would do in a hollow rimmed disc.
Since this video is all about learning, please reply to this comment if you have any insights on centrifugal force - including what we got right and/or wrong! 🧐
I think the wobble comes from the initial launch. The water in the cup ramps up to the speed and so the water is evenly pushed to the sides, but when throwing the disc, you are testing Newton's law of "an object at rest will stay at rest." The sand and the water are at rest, you yank the disc, and the water/sand push towards the back of the disc. Not sure how the rest of the flight works and if the centrifugal force pushes the sand/water out, but the wobble comes from the launch for sure.
what if u used a thicker liquid than water like a shampoo gel
Also I think the volume of water was insufficient to see a whole lot of difference, you need something denser like Mercury (Not suggesting this) to make a major change. either way you need heft with a low viscosity of gels are likely not a good answer.
I believe the disc with the hollow rim (the one you assumed to be very understable) demonstrated similar stability to its filled rim counterpart because even though the overall weight is less, the weight is more centralized to the disc body which gave it a lower inertia. This means the disc can spin quicker about it's axis. Think about a figure skater when they spin with their arms tucked in. They spin faster. Now with spinning objects such as a disc the faster they spin the more stability they will have. So to sum up, you reduced the weight, which tends to make the disc more understable, but also decreased it's inertia which increased the disc revolutions per second, which tends to make the disc more stable. Resulting in a net result of similar flight characteristics to it's original design.
I am inclined to believe that the sand was wobbling because at the launch of the disc-regardless of how you attempt to spread out the sand before-the sand gets pushed to one side of the disc from the sheer force you exert onto the disc through your pull. Then the sand attempts to level out evenly but struggles to do so perfectly because it is not a fluid(liquid or gas)-but acts similarly to one. TLDR: The sand would level out more and become more and more balanced, given that it had a longer flight time, whilst the water doesn’t need much time since it is not only a fluid but also had a high viscosity(ability to move around quickly). Love the videos; you’re making an amazing impact on growing the sport sustainably!!
The hollow disc being more overstable is exactly the opposite of what MVP does with their overmolds. The closer to the center of the disc the weight distribution, the faster a disc will lose its rotational speed and gyroscopic stability, causing it to fade faster. If you took the same disc, filled it with metal, and somehow threw it as fast as a hollow one, it would keep its rotational speed for a very long time. This in practice is used for things like a flywheel in a car. The reason you're not really seeing results with things like water or sand is in part the empty space will allow it to move around, which as you discovered becomes really complex when you add in the fact that the disc is flying while spinning. If you were able to have the disc at 100% capacity, it would keep the rotational forces more consistent and keep the disc spinning longer, but in theory also increases the initial energy needed upon release to get the disc spinning at the same rate. MVP has pretty much been working on this kind of technology since they started and it's the reason they have overmolds in the first place, it pushes the rotational inertia further away from the center of the disc.
This guy physics
There is one more variable in disc throwing and it is the fact that arm can only apply so much rotational energy to a disc which ofcourse isn't probably the same across different moment of inertia on varying discs it's still limited which results on lighter especially with lighter rim disc gettimg far more spin than a heavier disc. How fast it loses it I have no idea but the disc tends to keep the rotation going quite well usually comparing the airspeed slowing.
The phrase "pushes the rotational inertia further away from the center of the disc" should be changed to "increases the rotational inertia." Rotational inertia is a scalar quantity, so it doesn't have a "position" and doesn't move. A nitpick, but conceptually it matters.
@@HadronFlux Yeah! and maybe we should call it "Principle moment of inertia" while we are at it too. :)
Best discs made
THIS is the kind of science we need happening in disc golf. We know some scientific principles that make us lean towards this design being a poor idea, but we can learn so much by experiments like this. Keep it coming Jesse!
MVP?
Literally MVP.
4:27 "let's see how it plays out" was on point
And how far does the stock disc go?
That's so cool, that's definitely not what I was expecting one bit. It's awesome to see some new ideas getting tried regardless of the outcome.
Rotational precession and the shape of the rim will have a bigger impact on the stability verses just the weight. The weight will impact how fast you can throw it, but like Tyrus said below the change of how far the weight is from the center will impact the rotational momentum to maintain high spin rate.
You need to get an engineer like Destin at Smarter Everyday to work with you on testing. He'll be able to explain why the discs fly the way they do, not just speculation, And could give you some better ideas for flight efficiency.
The helium gag alone gave this a like. The testing and evaluating is just icing on the cake!
Watching the disc slowly float to the ceiling at the end had me dying.
(which was fake, btw. Helium doesn't provide enough lift per liter to offset the weight of the plastic)
Trash Panda! You are pushing the boundaries and it’s so fun watching and being on the journey with you! So amazing keep up the amazing work!
One of the best valuetainment I've seen in a growing niche! Hang in there and keep running it.
My first thought before watching is that this would sap power in the beginning of the flight, but I don't know anything so I'm stoked to watch!
I know there were discs back in the day that had irregularly shaped rims (aerobie epic), but I think that's an interesting idea to revisit.
I've wanted to make a fluid filled rim disc since 2006, very happy to see you this. I was thinking of using mercury as the fluid and having it 100% filled, no air.
This is awesome!!
That was so cool you're a mad scientist bro, wow!!!
Awesome variety of experiments! and knowledge, my favorite part of the video is the "helium" filled disc floating off in the background!!
Are you sure the helium stayed in the disc?? If water leaks out a gas definitely would.... super cool idea!
To get the affect of helium he could tried sucking the air out instead (vacuum) or just printed the disc with a few grams less plastic.
It doesn't really matter anyway. Helium gives about a gram of lift/liter. What fits in that rim would be completely negligible.
There's no way he got the He to stay in the disc. :-) He is used in all kinds of leak detectors.
Wow u sease to amaze me, at first I thought oh some guy that makes disc from trash now I'm like oh wow!
Loved the interesting video, keep doing stuff like this!
That was so funny! Seriously that was awesome
I want you and ezra alderhold to collaborate so bad. He is one of the hardest throwers and could make these discs fly to the absolute maximum potential. Pleaseeeee!!!!!
So, understability and overstability is measure by how the wind is distributed when going over/under the rim of the disc. The closer the top is to being flat and the rim being closer to the top of the disc the more overstable it will be, hence discs like the Tilt looking flat. The recent video by Latitude 64 explains this really well. You aren't changing the shape the disc at all by making it hollow, you're changing the weight. Changing the weight of a disc does two things: 1) makes it easier to throw higher speeds and 2) makes it so wind can push it around easier. Making the disc lighter so you can throw it faster will make it more flip up a little more than a max weight disc, but not as much as throwing a disc designed to be understable. Danny Lindahl from Dynamic Discs has a video about this.
Don't let the water-filled disc freeze!
Regarding the stability of the hollow disc, it is known that weight is not directly related to stability. Take the blizzard-type discs: there are plenty of videos demonstrating that the lighter weight does not equate to understability. Stability is directly related to shape and spin. More spin results in more stability, not more overstability, but more stability in the neutral sense. If a disc has a lightweight rim compared to one of the exact same shape but heavier, you can get more spin on it. It will lose the spin faster though, because there is less angular momentum. Conversely, the heavier rim will yield less spin for the same power throw, but will maintain that spin longer. This is precisely the dynamic that MVP's Gyro technology plays with.
I mostly agree, but I'm quite certain that the spin does not slow down significantly during a flight (just look at a fidget spinner or a table top spinner where almost all resistance is through friction in the ball bearings and against the table).
It is not the spin that makes a disc more stable, but the angular momentum, which is (simplified) the weight times the spin, so a heavier disc spinning slowly could have the same angular momentum as a light disc spinning fast. Do you have any tests showing that people actually get less spin on heavier discs? Of course this will be the case to some extent, but this is also down to human physiology and such, so it's possible most people get almost the same amount of spinn on both light and heavy discs (within reason). I don't feel that the weight of the disc is limiting my ability to put spin on a disc, but it would be interesting to see if this is actually the case.
Awesome video. Just really fun! Interesting application. Would be neat to host someone that could talk about the physics. I imagine most of this has been tried, but with all the money flowing into the sport, I guess there is a possibility that disc tech could take another leap. You are doing good things. Keep it up!
Your so close to being groundbreaking here, I love watching you create this stuff
You Madman, I Love It!!
Thought of this when reading about Die Glocke the other day. Sweet science.
Sweet! Idk if it would be PDGA legal, but super interesting.
this was really cool
Yo, this is crazzy!!!
Great video!
Need a disc with ball bearings in evenly spaced slots around the rim of the disc. This would allow the spin to force them outward.
If you want to increase your rate of spin I would make a few models of the prototype that are solid on one section of the rim and 20-30% infill on the rest, I would try three designs, 15 degrees of arc, 30 and 60. this will be like the Aerobie epic but fit the technical standards and not be like a 15 speed. Your printer will have to work with slicer setting to get this to work out it not really straight forward and might be easier on an SLA printer over an FDM.
This is what I was thinking too. Experiment with imbalance and possibly try and use imbalance mitigation techniques (glass beads in motorcycle tires for example).
I could be completely off but my first thought was that you could get some way to spin the disc before it’s thrown. That would cause the sand/water to become evenly distributed using centrifugal force and then when you throw it I would think that distribution would stick through the whole flight. Maybe not but if it did that would be awesome lol
awesome sauce
This is when you should get involved with Mark Rober and "overengineer the crap out of it" :)
That was a great video. Way to push the limits of the pdga :p I wonder if the lighter disc is more stable because it doesn't have enough spin force to flip it because there isn't enough weight on the rim? Just like when you throw an under stable disc with low speed/spin it can be stable. (I know nothing of the science but figured it was worth a stab). Also way to represent the Kerr jar club.
So how exactly did the Helium filled disc fail? The volume is so low I'd have expected it to be nearly identical to the empty one.
If 3D printed parts struggle to hold water, no way they are going to hold helium.
I reckon It also wouldn't have been that big a difference from the air one anyway, since the difference in weight would be negligible.
I’m sure there’s other people saying this but about lightweight discs: in general, when manufacturers, make something lighter, they have less dense plastic in the same mold. So it lowers the parting line height and makes the disc less stable. But it’s not simply because of the lighter weight, it’s because of a changed mold.
The 3D printed disc makes the same exact mold at just a lighter weight. But it has the same shape and should fly the same
Most lightweight discs do fly less stable. But there is some Prodigy where the lightweight stuff is more overstable than max weight because that’s how the plastic cooled. I have a very overstable 139g P Model S
U shld get some skateboard ball bearings to put in there, or some magnets...like tesla blueprints! This shld def bring in some attention!
Interesting concepts. In order to adjust for the shift in sand and water due to inertia, you could try evenly distributed cells filled with water or sand.
Lateral thinking ahead, congratulations!
The idea of a fluid inside the rim could change moment of inertia of the disc during the flight like a motorbike variator could work if:
- Difference between inner and outer diameter of internal chamber is big.
- Fluid is dense enough ( mercury=16,6 g/ml vs water=1g/ml )
- Disc is always horizontal and, without rotation, liquid stays close to the center.
- Centrifugal forces pushes liquid to the outer part of the inner chamber during flight.
I guess that those are too many conditions…
The other line of investigation could be: if inner chamber walls were smooth enough so that de disc turns at higher rpm than the fluid ( mercury again ), disc would have a lower moment of inertia with the same total weight. I guess that it wouldn’t be good because it would loose its rotation faster.
maybe a non-newtonian fluid that becomes liquid when force is applied? also, some baffles/honeycomb in the hollow part could be useful to further slow the liquid from reaching the rim and then delay its return to the center when the disc slows.
I would like to see one with vegetable oil and one with bb’s. Try 3 of each with varying amounts inside to see which is better or maybe not. Fun video, thanks for sharing!
A few ideas to throw out there. 1) When the disc spins and the water fills the outside of the hollow portion due to centrifugal/centripital forces, there isn't much difference between the water and a solid infill. It is mostly just the density of the water that is the difference. The forces on the water are the same as the forces on a solid except that the solid doesn't move. 2) The fact that the water moves means it creates friction. That friction will in fact slow the disc spin which I think we wouldn't want.
yup.
I think all it does is add some wobble. The rotation momentum should still stay consistent even though the spin rate slows. but not helpful either way.
Water is less dense than disc plastic so I wasn't sure how it was supposed to help
Every idea is a good idea all the way up to the point of failure.
Fun stuff! what about filling it with a foam like TaylorMade does with its "Speedfoam" in their Irons? Love the curiosity and innovation! Keep it up.
I think it would be cool if a bunch of sand stuck to one side of the disc, it would be like those Epicyclic discs that were off center
You had me at water-filled disc... 1m 15 seconds in....
i have thought of this for a year and a half. It needs to be viscous and it need to have chambers that control its distribution during spin...
MVP uses different plastic on the edge what if making the disc heavy on the edge can add distance. So in the hallow part add a heavy solid substance moving the weight to the edges.
Why didn't you show the helium disc fly? What did it do to "not work"?
I’d like to know as well.
It floated off into the atmosphere like a balloon
My theory on why the hallow disc is still overstable has to do with moment of inertia. The more weight distributed from the axis of rotation the higher the moment of inertia, in our case our disk has a lower moment of inertia because the weight is more distributed towards the axis of rotation. The lower the moment of inertia means less resistance to a change in motion. From here we can suggest that it's easier to stop the disc from spinning hence it fades sooner.
Do you think imbalance forces could overpower mass moment of inertia forces though?
I am quite certain of that the rotation of a disc slows only slows down an insignificant amount during a flight since there is very little air resistance acting on the rotation (as opposed to the forwards flight, where there obviously is significant air resistance). Just imagine a fidget spinner or a table top spinner where the vast majority of resistance is due to friction in the ball bearings or against the table. Here's a video of a spinner with only airresistance: th-cam.com/video/hu1jEWLZVug/w-d-xo.html which seems to be able to spin a lot longer than the duration of a disc flight.
Instead I think fading happens when a disc slows down in its forwards flight and starts to fall. So a lighter disc might still fade sooner, since it will slow down through the air sooner.
There is also a second effect in that a lighter disc will have less inertia from the angular momentum and thus once it starts to fade it will fall over quicker. However this second effect will also make understable discs turn quicker since there is also less inertia to resist the turn. So this explains why some people have witnessed lighter discs as more understable. Basically a discs over/understable characteristics are inherent to their shape, but light discs will accentuate any turn/fade and make these characteristics more extreme and noticeable.
The higher the center of mass the more overstable I think. If you hollowed out below the top of the disc you just shift the center of mass up. You can see on rims of overstable vs under stable discs how they are angled
Awesome video! Your content just keeps getting better and better. I've been really curious to see how an oblong disc would fly. My guess is that it would be extremely overstable . I assume that because it's oblong one edge will be moving faster than the other edge similar to how a boomerang flies. I hope you try it out! 🤙🏽
Question I'm dying to know. How much further did the water filled disc go for you?
You could make the outside in soft plastic, then fill it with a firmer plastic.
Great video, how did you get helium in the inner rim? It seems like that would be impossible.
Love the video! One day I want to be a Trash Panda sponsored player hahaha
I would love to know what the water disc does forehand/flick
My theory on why the hollow wing is overstable is because it moves the center of gravity higher. Since the center of gravity is higher, this creates a larger moment of inertia in the vertical direction. This moment of inertia opposes the torque created by the different in lift between the left and right side of the disc, caused by spin. Since the lift difference is the same, you have the same torque but less resistance to that torque, which means more change in angle (turn) of the disc
The water innthe rim keeps the disc from spinning as fast.. fast spin is what gets a disc to flip... hence the water adds stability
I can flip a Innova base plastic Leopard to a roller with no problem. The MVP signal, though technically a flipper disc, takes me considerable more effort to flip to a roller.
Since I saw the Løft-disc with the rounded grip, I've wondered if it would be even more aerodynamic if the underside of the disc was flat and the grip was just carved as a ring. Making the center hollow might make it possible to keep most of the weight in the rim.
The hollow rim disc flew almost as stable as the prototype because while it is lighter the weight is even everywhere verses a lighter disc with most of the weight on the rim. To test it out I would make another disc that weighs the same as the hollow disc but without being hollow.
Have you tried acetone vaporing the discs to smooth them out and maybe seal it to avoid using flextape?
Use the centrifugal and make it light up leds
Try making a putter with a hollow rim next.
Did u try putting Anhyser on the light one
Just because the disc is super light doesn’t necessarily mean it’s going to be understable/flippy. It’s most likely stable bc of the shape of the disc.
Water or moonshine? LOL
You cant have any air bubbles in it at all or it will throw off the balance just like in the intermediate axis theorem maybe?
Can you make or recommend a putter that is less prone to rolling away from the basket?
Maybe try a roller with each sand. Water, and gas only half way filled each 🤯❤🥏
As you are filling the disc with water… I couldn’t help but think about how a more dense liquid in comparison to water would react. Although very improbable and possibly unsafe something like Bromide or Mercury would be very intriguing to test out!
More weight at the outside edges makes Gyro disc harder to spin up but hold the spin longer. Making the high speed turn fase of flight last longer. So making the outside edge of the disc lighter would basically do the opposite.
Okay now take a super understable mold like an avenger SS and give it a hollow rim. I need to know if it’s stable 👀 then I need to see a hollow rim tilt 👀
How flat is the top of the hollow only disc? That could play a part into why it is over stable.
it is possible that because the hallow discs moment of inertia is so low that the friction with the air took a lot of spin off and mad it fly more overstable. it is also possible that beacuse 3d printing plastic is so stiff that it didnt allow for flight plate expansion which usually makes a disc glide but also lowers the ratio of disc below the parting line
For the hollow rim, try evenly spaced hollow segments that you'd individually fill with water/sand etc. Would help with the balance issue. Though a ton more work
Maybe some thicker gels and other substances like BBs?
Bonus points if you name it " The BattleRattle"
Interesting...I was thinking about printing some discs and comparing different infills instead of just being hollow. On the centrifugal force side...some interesting comments I see in the comments section. But I'm a little surprised no one brought up, what I learned when I was still a physics major, that centrifugal force isn't really a force. Technically it is centripetal acceleration.
Thank you for pointing this out. It was driving me crazy watching the video and all he talks about is a false force that doesn't exist. Thank you!
@@scottconner4100 It's surprising how many places get this wrong that are science related sites. Wikipedia screws this up even further by calling Centripetal Acceleration as Centripetal Force. For those of you wondering what Scott I are talking about...a "force" can only move in 1 direction by definition. When you change direction it becomes a change in force with is an acceleration. Since going around an arc is constantly changing the direction of force it now becomes an acceleration.
All about aero, rim height makes it understable or not. Weight helps with carry, glide etc.
In the day I experimented with trying to take all the weight from the center to maximize rim weight. My approach was to literally cut the rim off of a disc and replacing the flight plate with plastic wrap. Results were inconclusive but might be an idea to pursue to the maximum extent
So, basically an Aerobie?
@@martymodus7205 not exactly, the flight plate was removed and then replaced with very light weight plastic film, so almost all of the weight was on the rim.
A water filled disc will resist snap. No spin, no precession. So little turn, little fade. It would probably make a great putter.
What did the helium disc do?!
Have you tried printing some in tpu?
Soft edge on the inside of the rim is something I am curious about. This might make it a bit strange to throw, but I always wanted to know if it would make a difference in distance, my thought is that is would displace air with less interference, but I have no idea
Love your videos ! I don't have any physics that I can add, but I really dig the shirt you have on, midway through the video. The one with the 3 baskets. I went to your website in hopes you are selling them. Any help would be great. Would love to have one.
This video is sweet.
This is curious. Especially involving liquid fluid dynamics, instead of just gasses involved with physical objects.
To counteract all of the sand/water being bunched on one side of the disc you could make separate "chambers" in the rim. For example, a disc with hollow rim would have just the one chamber, but if you put up some walls making 4 or so different chambers then you'd have better distribution
would be interesting to see ceramic balancing beads used inside the rim
10 or so years ago, one (or all?) of the trilogy brands had a line called Fluid, with a liquid filled rim. I played with a fellow that used one, but cannot recall unique flight characteristics.
Fluid was DD's name for Lat64 frost line plastic. It was not fluid filled, it was a solid plastic, but more flexible, similar to innova's gstar
@@awlogue Damn my memory!
Mercury is the correct fluid for this application.😁
A 'dead blow' hammer is partially filled with grains of something like sand to kill the inertia of the object trying to make the hammer bounce backwards, which puts all the inertia of the hammer into whatever is being struck. Would partially filling the rim of a disc with sand or water do more to kill the spinning inertia than help it?
Yeah the water will slow the disc spin as the water slowly accelerates from stationary to matching the disc speed.
But the rotational MOMENTUM should not be affected. so there should be minimal affect on the flight apart from the wobble
What about removable flight plates? You could make a locking clasp system and then change the rims depending on need. Then you wouldn't need to replace a whole disc just because the rim is worn out.
As an aside - what do you think about microplastics in the environment coming from disc wear? All that beating in of discs removes material which is going into the soil - just wanted to hear your thoughts on this.
Make the dome hollow and concentrate the mass at the center to see what happens. Same shape different weight distribution.
4:12 Me: Fill up balloon and watch it float to ceiling 🎈
Jesse: (inhales entire balloon contents) "TRUST ME!" 😂
Edit: floating discs for the win!
The water filled rim reminded me of SIL-X juggling balls. They are partially filled with a liquid silicone to affect the center of gravity. I wonder what that would do in a hollow rimmed disc.
My buddy and I are thinking of starting a disc brand, and we literally just talking about this idea yesterday...