Ok so I tried adding force but it doesn’t work I don’t know why. But I also found a solution !
I use the set physic linear velocity which add a velocity to the object. Next you juste have to choose the force you want to apply every frame. This is fake gravity, so you have to set the simulate physics of your blueprint to true. I also set my world’s gravity (in the world’s setting) to 1 so I have no problem with that.
That’s maybe fake gravity but it looks not so bad 
If you need this is my object blueprint :
