So let me be the first to say,.....
its like "Airwolf" then?
http://en.wikipedia.org/wiki/Airwolf
US whirlycraft firm Sikorsky, having successfully flown its revolutionary (cough) X2 triplex sprint-chopper to an impressive 250 knots, says that it will now look to put the same technology into a prototype armed scouting craft aimed at the US Army. However, the company seems keen not to spend too much more of its own cash on …
Sure, it'd be great to double the speed of an armed scout, but it's really only worth it if the crew can actually perform the scouting role at that high speed, and can react to threats it runs into. So until we know more about that, it's hard to say what the actual combat value of this might be...
You forget that the world of Avatar has significantly denser air, with large amounts of foliage.
Ducted fans were used to protect rotors from the environment, and the small size of the rotors is balanced out by the density of the atmosphere. Not quite feasible in reality yet.
I saw footage of a small test craft similar to the c&c style with ducted jets, but it had major problems with stability and more importantly noise. Damn thing howled like a banshee, I can't imagine how loud a full scale prototype would be, which kind of defeats both civilian and military applications.
The XH-59 was Sikorsky's effort at the 19602-1970s gunship program. The winner was Lockheed's XH-56 Cheyenne, which had only one engine and not four. The Cheyenne did have a vibration problem, which was fixed (albeit after one helicopter disintegrated in midair and killed a test pilot.)
The problem with the Cheyenne was that the Army changed its mind. They originally wanted a high-speed escort for troop carriers; they decided that the carriers shouldn't be going to hot LZs, and that what was really needed was a low-speed high-maneuverability tank-killer. That's how we got the AH-64 Apache.
Of course, now we're in a situation where what we need is a high-speed escort for troop carriers...
Er, the XH-59 (Sikorsky S-69) wasn't even ordered until 1971, two years after Cheyenne was cancelled. And it was a pure research aircraft, nothing to do with any armed helicopter requirement. This was Sikorsky's first go at the Advancing Blade Concept, which is being used in the X2.
Sikorsky offered a totally different aircraft for the AAFSS competition that Cheeyenne won. The S-66 (Sikorsky's number, it never got a military designation) had an odd swiveling tail rotor but was otherwise very much like the Cheyenne, including relying on a single engine and a single main rotor.