How to make Damage Impulse based on Impact Velocity?

How can I change the variables of a Damage Type Class at runtime? I want to make the Damage Impulse value based on Impact Velocity. I tried casting to the class and making a blueprint of it and trying to access them there but nothing lets me get the variables. What is a way to do this?

Anyone? I mean I could make lots of Damage Type Classes in like velocity steps of 100 but that seems rather silly and there should be a better way? I need it for Apply Radial Damage btw.