Abstract: Applying the general linear theory of shimmy, this paper analyzes the main wheel shimmy problem of a special type of the main landing gear equipped with an additional shimmy damper between the upper part and lower part of torque arms. The influence of various structural and operational parameters on shimmy is discussed, and the results show that the additional damper is necessary and effective for preventing shimmy. Meanwhile, a new version of this type of airceraft with four wheel bogie main landing gear is also investigated. It is concluded that in this case the additional damper can be omitted, since this landing gear itself is inherently stable as for shimmy. This approach aims to explain the practical advice adopted in an existing design. The results may also be referred for other aircraft design.

Key words: main wheel shimmy, additional damper, the stiffness of fuselage, the boundary of shimmy stability