How do I animate acceleration?

I’m animating a game model of a minigun and I cannot figure out how to animate the barrel spinning up. I’ve made the spinning action then manipulated that action in the NLA editor to make it look like it’s spinning up but it’s not gradually spinning up and just changing speeds. Any suggestions?

Check out this scene in 3D and virtual reality on Sketchfab:

Minigun Minigun - Download Free 3D model by wburton95 (@wburton95) - Sketchfab

I’m not super familiar with the nla editor, but if you want to to accelerate into the rotating animation you’ll need to set a crossfade. I’m presuming the spinning action doesn’t have an acceleration.

Cool! Blender is full of all sorts of overlooked tricks. Thank you.