If there's one common trait shared by most helicopters, it's that they're light. And that's because it takes far less energy to lift something that's lighter, so the most efficient designs are often ...
A US Army UH-60 Black Hawk (left) and an AH-64D Apache helicopter at Camp Marmal, Afghanistan, at the foot of the Hindu Kush mountains, in 2012. In February, the US Army leadership inexplicably ...
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