You can simply get a Rotate Vector node, set the yellow A pin of the node to (x = 1, y = 0, z = 0), then get the Get Control Rotation node and plug it into the node’s purplish-grey B pin, multiply the result with your desired value (btw you can just get a multiplication node, right click on one of it’s input pins and pick the float option to multiply all of the components of a vector instead of the way you did in your image) and plug the final result into the Launch Velocity pin of your Launch Character node.
Hope this helps! 