optimize profiles is to optimize the normal force distribution to achieve the greatest area under that curve with the minimum peak deformation. Deformation has consequences namely dart incompatibilities (n.b. people have had catastrophic results and lockups when a super high crush SSS setup is accidentally fed a FVJ dart) and higher shock loads due to the dart tip. If we didn't need to worry about that, we could just keep cranking old cylindrical flywheels, which have that deformation and force curve I mentioned with the giant peak in the center, as tight as we need to get the total normal force and thus grip we want, but clearly that is not going to end well. If we want to minimize the max deformation at any point and apply a given normal force over a given contact area, then, the best case is a perfectly flat force (and deformation) curve. We need to be crushing the entire dart surface uniformly.
(Note that DrSnikkas seemed to have the very same logic with flywheels that are also quite high envelopment, though I haven't had access to loose uninstalled ones to measure and know what the groove radius actually is.)
Key element three is about envelopment. We want to contact as much of the dart surface as possible with the flywheels. Not because "contact area" is itself worth anything, but rather because once again, it reduces the deformation needed to achieve a given area under that force curve. Or, maximizes the area achievable given a minimum flywheel gap.
And here is where all this logic is going.
This is a model of a high-envelopment large format flywheel showing a preliminary groove profile. It is 42mm root diameter, 9.0mm groove radius, and 49.5mm OD, intended for a 51mm center distance cage.
The design principle is (somewhat erroneously?) describable as hydrostatic compression at the system centerline, i.e. the projectile is subjected to a uniform radial deformation. Instead of forcing a round dart through a rectangular or football-shaped hole, we force a round dart through a smaller round hole. Why a round hole? If you apply a uniform distributed load to the surface of a round dart and it elastically deforms under that load, it doesn't squash flat, it stays round. Seems obvious, doesn't it?
Here's a quick assembled cage render of another iteration of Hy-Con with suboptimal envelopment using some low-res meshes. You can see that generating circle appear out of the woodwork, broken only by the chamfers on the edges of the wheels to guide in darts and prevent the rims from being a pinchpoint.
This is another 9.0mm iteration BTW. I decided to initially back-off to 9.5mm root-to-root and corresponding 9.5mm groove radius in the real world prototype. We'll see what that does on the chrono and go from there. It has way more envelopment than anything that has ever existed before.
And this is the 3D printable, minimalist prototype cage and printable wheels (very distinct from the version that would be machined, other than the profile).
Meant for no blaster - its purpose is to verify that I am not an idiot, and that the geometry works, feeds, doesn't jam horribly, shoot sideways, reduce darts to a cloud of nanoparticles, generate a black hole, or anything else undesired. Then I will get to designing this into something bigger. Oh, do I have plans for this little number once it is nailed down and working.
So enough theorizing and renders, here are the very first parts I received today. Printed by dkdavid721. PLA since this won't see service. It is split down the center of the bore to avoid printing overhangs. Pieces will be Devconned together.
Note I have long been averse to printing in nerf and I am finally starting to turn around on that with recent demonstrations of its viability. Some combination of realizations about design for it, and improvement of the technology.
41.5mm root, 50mm OD, 9.5mm groove radius, 14mm thickness.
Comparison of OD to Hasbro HIR flywheel, and a SSS flywheel (Artifact V1 fullprofile serrated). These are big.
Okay, someone's gonna comment on that. Why is this a large format cage? Well, I am done w