2 grey with black chevron shaped crafts racing over Westminster, caI was in my backyard using a star app on my phone. As I was looking up I saw 2 grey with black chevron shaped crafts flying right next to each other at one point 1 wing overlapped other crafts wing. They were going really fast flying in a straight line south never changing direction. They seemed to be racing. There was no sound of there engines. I could hear a nearby helicopter but nothing from these 2. I have never seen anything like it. The only thing that I can come up with is two stealth bombers flying together.