The SJ-100 prototype aircraft b/n 97021, manufactured at the Yakovlev Production Center in Komsomolsk-on-Amur, has started runway runs and completed shimmy tests.
Shimmy is an intense oscillation that can be observed on the wheels of the nose landing gear strut when the airplane is moving on the ground at high speed. This phenomenon is caused by the action of lateral forces from the ground on the tire of the rolling wheel. Increasing amplitude of such oscillations can lead to loss of control due to increasing yaw or even to the destruction of the strut.
“Today, to combat this dangerous phenomenon, airplane landing gear is equipped with special dampers, and to make sure that the strut copes with the resulting shimmy effect, full-scale tests are conducted,” the UAC press service explained.
For shimmy tests, a special metal board is placed on the runway at an angle of 45 degrees to its axis. To fix the collision on the board, it is covered with paint or chalk. When the board is hit, the very transverse forces that can cause shimmy begin to act on the airplane’s landing gear. The forces and resulting vibrations are measured by sensors installed in the strut and throughout the airplane.
The tests have shown that the SJ-100 airplane is protected from the shimmy effect.
Earlier, UAC head Yuri Slyusar said in an interview with Rossiya 24 TV channel that the SJ-100 will make its first flight in September 2023.
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