PPRuNe Forums - View Single Post - Dynamics - N-per-rev Vertical Vibration
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Old 22nd Jan 2002, 02:15
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Dave Jackson
 
Join Date: Nov 2000
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Nick

Thanks for mentioning the BVI (blade vortex interference) and the fact that it is particularly noticeable on some helicopters when descending during an approach.

This enhances the concern regarding BVI in helicopters with twin rotors, such as the coaxial configuration, where the lower rotor never gets out from under the vortices of the upper rotor.

Your point B) is also noted.. .________

CTD

Prouty appears to confirm what you are saying. He mentions that the "Designers at Bell generally placed horizontal stabilizers forward on the tail boom so that they are in the wake during hover and never have an awkward transition going from outside the wake to inside it."
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