"Radiating" Cut through a curved surface - Help ? :-)

Hello everyone,

You've helped me a lot through this project of mine (school related), yet theres someting im rather stuck at for some time and i'm realy frustrated that I couldnt figure it out by myself.

I got this helmet model, and i want to cut its curved surface in a "radiation" cut, meaning the cut is perpendicular to the surface - as shows in the image marked in red.

Isnt there a way to sketch on a plane, split it on the helmet surface and cut it somehow?

The helmet file is also attached.

I would very much appreciate your help

Have a good day!

Sharon

SolidworksSketching