http://www.shephard.co.uk/news/rotorhub ... ings/6053/
i remember hearing when US Army pilots started training on the Mi-17s. can't remember where the article was though. one of my former crewmembers landed next to a few during his last deployment there.
it is mathematically impossible for either hummingbirds, or helicopters to fly. fortunately, neither are aware of this.