I had read earlier on this forum that the coaxial rotor concept would not work. But the Sikorsky x2 helicopter actually got to fly at the end of August (check out CNN or Gizmodo for details).
It's nice when the forum members are wrong about a concept.
Not so impressive when you consider the Russians have had a coaxial rotor helicopter in service since 1995.http://en.wikipedia.org/wiki/Ka-50
27th September 2008 - 02:03 PM
Older than that, the US navy had an anti-submarine drone with coaxial rotors back in the 60s, the name escapes me at the moment. Not to mention that Sikorsky already has a co-axial helicopter in service with Nasa, the US Army, and the US Navy (I believe it's the S-69, but I'm not sure).
Also, the Kamov-50 is not the first chopper in the series. Many of its predecessors (One that I remember is the Ka-25) flew back in the 60s.