Yeah, 8S. Managed to shoehorn one of these into the back. You'd probably only get one fight out of it, but 8S batteries are big, and space was a concern. On 8S and 2:1 the disc speed is ~12,000rpm, and on that 150mm diameter disc tooth speed is ~215mph. That plus the wedge underneath means big hits every time. Disc weight is about 1.2kg. Weight-wise, I made a calculation error and factored in the weapon ESC twice, so realistically weight is about 12.8kg. And that's with basically the same shape as HWII, but half the thickness (all the way around) with 10mm HDPE instead of the stainless. Baseplate is also stainless, 3mm, which is 0.5mm thicker than the stainless base on HWII I believe. Put magnets in and it'd make for one heavy hitter! Drive-wise, this is the one being used, and if anyone else wants to use them I can upload the model to the workshop. On 5:1 top speed is as Matt said, 21mph. I reckon gearing down a little more for a bit more control and torque is a good idea, maybe just to 6:1. So yeah, should be a total brick with a hard hitting weapon and decent rambot drive as a plan B. What's not to love ?