On October 18th at about 10:30 PM while sitting on a balcony facing north I saw a large silent mostly transparent craft fly directly overhead. It had three visible circles, one on each point of the triangle, the edges rippled a little so you could just make out the edges of the craft but the rest of it appeared transparent. This was followed by a black helicopter that had a light and made noise. It returned on exactly the same path, north to south about 20 minutes later, but without a helicopter following.At first I thought it was a UFO but after seeing a MUFON program Hanger 1 I realized it was exactly the same as they showed and it is one of ours. It appeared to be about 30 feet across and flew relatively low - appearing the size of a softball in the sky relative to my position. It flew perfectly straight at a low altitude without any noise. I should have know it was one of ours because the cloaking was not perfect. The edges of the triangle rippled showing its shape and there were three large round lights slightly glowing - one on each end of the three points.I was very surprised it came back about 20 minutes later on the exact same trajectory, but without a helicopter following it.