The Boeing Company

Mcdonnell Douglas Helicopter Company

Mostafa Toossi

Murugappan Meyyappa

A method and apparatus comprising an interface section and a vibration reduction structure associated with the interface section. The vibration reduction structure extends from a surface of the interface section. The interface section and the vibration reduction structure are configured to reduce vibrations at a number of frequencies that travel through the interface section and the vibration reduction structure.

Vibration reduction system using an extended washer

The present invention provides a desired design approach for retuning a rotorcraft airframe by utilizing resilient connections between major airframe components. In the preferred embodiment, the design employs resilient material, preferably elastomeric material, in the mounting system between the vertical tail and the tailboom of a helicopter as a method of providing dynamic detuning of the tailboom torsion/lateral mode. Other possibilities include similarly mounting the horizontal stabilator and the wing onto the airframe. Using elastomeric or similar devices to soft mount the vertical tail of a helicopter on the tailboom can efficiently and effectively alter the natural frequencies of the entire aircraft. By choosing the spring constant of this connection, the designer can place fuselage frequency at a desired value.

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Scottsdale, AZ, United States of America

Mostafa Toossi