Recent content by Eric_T

It seems weird to me that the sign of the initial wobble angle should cause different flight. Wobble is measured by the angle of the disc relative to the disc’s local rotational axis. It only makes sense as a measure at the point of the release. As the disc rotates, or wobbles, it will move...

Thanks for adding to the discussion, Chris! It would be really cool to have 3D tracking of the throws, with something like a TechDisc in an open field. Benji, just to clarify one thing regarding the plots. You say the disc is moving right for a long time before hitting the apex, but it actually...

It's hard to tell from these video angles, and it's also downhill, but I think the trajectory is actually flatter than it seems towards the end, it doesn't really flare out. Here's another example from a distance competition, that seems to match my result: The apex of the flight is roughly at...

I haven't looked at the wobble part of the dynamics yet, but it's a really interesting question. The wobble definitely means that angular momentum is transferred between the axes, but not sure if you can say that you need to take momentum from the spin to damp the wobble. But the off-axis torque...

First of all, thanks for questioning my results, it helps to think about things from different perspectives, and maybe we can discover some new things. You have to be careful with that Lissaman paper, though, what they do there is look at what an idealized lift input would give. In the third...

I think I understand what you are suggesting, but I'm not sure I have seen that type of behavior in a throw. Do you have an example from disc golf coverage or something? I tried looking at some distance competations now, and the throws look very much like what I get from the simulator. One...

I did a few more simulations of this, and the results are pretty interesting. As you say, the disc will level out during the flight. Think of an air bounce throw, for instance, even with an extremely high nose angle the disc will eventually change its trajectory and start flying more straight...

Thanks for the input. It's an interesting theory with the nose angle, but I think what you say here is actually sufficient to explain the optimal trajectory. Like you say a wings-level approach would be optimal, so we need to try to approximate that. By having the disc at an anhyzer angle and...

Yes, it's about trying to spend as much time as possible in "glide-mode", letting the disc drift with high lift force throughout the flight. Here is one of the optimized throws I was talking about, throwing a nuke at 70 mph (with the usual caveats about uncertainties etc): This is thrown...

Thanks for creating a separate thread on this! I’d say that the benefit of a slightly negative nose angle is not only the lower drag (the difference in drag is not massive), but also the fact that you trade lift for more forward momentum, which translates to longer distance. Max distance has...

This is a very interesting question, and one I really want to study more in detail. Disc golf is really unique here, I think, in that the projectile we use wears over time and that this is a beneficial effect. I believe it's a combined effect of many separate factors. The idea that the PLH is...

Sure, @Nick481 explained it well. It's just the forces in Newton and Newton*meter (for the torque), but scaled with dynamic pressure and a representative area. This makes it possible to more easily compare results taken in different environments and also reduces the parameter space. Here, the...

Not sure I fully understand what you’re asking here. But in general I am a bit wary of using my intuition in complex problems like this, because it has turned out to be wrong so many times 😝 fluid dynamics is highly non-linear, which makes it difficult to reason about. The variables of the...

I ran the River/FD comparison through my simulation setup now. Or rather, the Innova Dark Rebel, which is more or less the old Discmania FD mold as far as I have understood. I thought this was interesting as the Dark Rebel is one of my favorite discs :) I believe the River I have is more on the...

Yes, I have data from -90 to 90 degrees. You see +4 in the graphs I posted. The drag increases exponentially with the angle, and increases by roughly 50 % from 0 to 4 degrees.