PPRuNe Forums - View Single Post - Sikorsky S-76: Ask Nick Lappos
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Old 4th Dec 2006, 20:45
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NickLappos
 
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The forces on the tail cone on the ground are peanuts, it typically takes just 50 to 100 pounds of thrust to turn the S76, and the tail rotor can develop over 600 pounds. The tail cone's highest stress maneuver is the "yaw kick" maneuver, which is imposed on the design by FAA regulations. It is an assumed full throw of the pedals at Vne, and not a pretty picture. Do not even think about doing one!

Airframes are usually designed to extreme maneuver loads like that one, or crash loads that involve up to 20 G's. Therefore, taxi loads are just peanuts.

BTW the cracks some S76s have exerienced on the vertical pylon are due to long term tail rotor balance issues, because the loads are low but the frequency is high (about 50 Hz) so that many cycles build up over time.
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