Orbit particle speed

Hey guys, maybe I'm just dumb but after looking into cascade and the unreal doc for hours ( and the unreal forums ), I don't see any way to change the speed of the particles with an Orbit node. There is nothing in the node to change the orbiting speed, and the initial velocity node doesn't seem to affect the orbit particles.

Am I missing something obvious ? Here it just seems that the particles are kinda slow when they spawn, and then they speed up until they die.