From time to time while operating in Vietnam’s Mekong Delta area in 1968 we would get transported by Chinooks. The rumor at that time was that engineers had proven on paper that the Chinook was not capable of flight. The rumors were put to rest when we saw them sling load 105’s, huge rubber fuel bladders with jet fuel and cargo nets filled with all matter of materials needed for field operations. My only complaint about them was they have to be the noisiest most vibrating aircraft ever built. Of course back then no thought was given to ear protection and you couldn’t hear anything for several hours after a flight.