That is an old one, the new ones have the same stealth rotors that the modern blackhawks have. It was extremely quite, just a slight low level rumble from the blades that if you are watching tv or something, you will not detect them; even at that height. A sight to behold because it was about 4 times bigger than a normal helicopter. Funny thing was, you could only see the lights and the body matched the night sky, if they ever shut off their lights, you probably wouldn't be able to tell where they are.