Board Thread:General Nerf discussion/@comment-27306930-20190923064918/@comment-27306930-20190928043537

Okay boys, tonight we're talking about Crush and Glass-Ceiling. This is a flywheel blaster thing, so if you're a springer guy you can skip this post.

Let's start with Glass Ceiling. You can take a stock flywheel blaster and put better batteries and faster more powerful motors in it to make the darts shoot out faster. The current fave is the Stryfe, but this applies to all flywheelers. The stock dart velocity is about 70 FPS. But with the right combination of batteries and motors, you can crank that all the way up to 130 FPS. But then something weird happens. The faster the flywheels spin, the darts actually start to slow down. And when the flywheels go really fast, the maximum dart speed levels out at about 135 FPS. But why ???

It's what the NIC calls the Glass-Ceiling Effect. And anyone who's watched a high octane dragster can kinda figure out what's going on. At some point, the flywheels are going so fast they can't get any traction on the dart. They just spin-out on the surface of the dart, and generate a lot of heat, noise, and dart dust. For the first few fractions of a second, the darts are just inching through the cage as the flywheels spin-out trying to grab them. By the time the flywheels have a good grip, there's only a few millimeters of foam left to accelerate the dart to max speed. As a result, the darts actually exit the barrel slower.

As you increase the speed of the flywheels, you can temporarily compensate for the loss of FPS through brute force. But at some point around 40,000 RPMs, it doesn't matter any more. The lack of traction just gets worse and worse, and your darts start getting really burnt. Around that point, the darts rarely exceed 135 FPS.

And that's where "crush" comes into play. To compensate for the lack of traction/friction, the flywheels simply squeeze the darts harder. The motor spindles in stock flywheel cages are spaced 43 millimeters apart, which leaves a gap of about 12 millimeters between the rims of the flywheels for the dart to fit through.

High-Crush flywheel cages have less spacing between motor spindles resulting in less space between the flywheels. This crushes the darts more and provides additional friction that accelerates the darts more effectively. Common crush values are typically 42.5mm, 42mm, and 41.5mm. As the crush becomes smaller and smaller, the power necessary to push the darts through the gap increases. Eventually you need 3S LiPos and 12v neodymium motors to force the darts through the tiny flywheel gap.

RPMs, TIT, torque, crush, voltage, current. It's all a complicated balancing act. But hey, that's what super-stock is all about, right ? If you want to play with the big boys, you better know your stuff 😎