Is this interaction still bugged or has it been fixed? I am not getting a normal impulse other than 0,0,0 in ue4.9 for a custom event assigned to an actor hit event on a character class and it would be good to know if this is my fault or caused by this bug.
I know this is old but for completion… You would want to use the velocity vector (normalized) and the surface normal (inverted) to get the angle between them. The closer the angle is to zero, the more head-on the impact was. How to Find the Angle Between Two Vectors: Formula & Examples
I think you can also project the velocity onto the normal vector with the “vector project on to normal” node, this will give you the perpendicular velocity of the hit.
I too have this problem.