https://uk.news.yahoo.com/6-most-fas...9.html#VTXdJno
Declassified files.
The CIA developed a "quiet" helicopter in 1970
Long before the world learned of "stealth" helicopters like those used in the 2011 Osama Bin Laden raid, the CIA had developed a "quiet" helicopter all the way back in 1970.
The agency set to modify the OH-6 light observation helicopter for use in secret infiltration in hostile places.
Surprisingly, "the first test bird was up and flying in about 60 days, and it was fully operational in about six months."
In March 2008, Air & Space magazine wrote about one of the aircraft's missions to tap phones in North Vietnam.
The technology apparently hasn't arrived at NPAS
