Helicopter CH 53 - a whispering giant

Risky stationary flights above ground. High flying abilities at the Braunschweig airport Germany. A Sikorsky CH 53 is hovering for minutes very close above ground. Unusual manoeuvres for crew and scientists.  The team of the DLR facility in Göttingen, Germany, is a very special crew. They all are experts in aerodynamical behaviour of helicopters. Right here on the Braunschweig airfield they are studying the noise of the giant transport helicopter of the Bundeswehr. How can it be absolutely calm? The rotor blades are responsible for the noise. For the first time the scientists have been able to show the swirls of the rotor tips, which are responsible for the noise.