Question

Example 1 The figure shows a turbo-prop aeroplane. The mass of the plane is 7000 kg and its C of G is located the major axis, 1 metre forward of the main under-carriage. The moment of aua of the plane about its C of G, and in the plane of pitching, is 35000 kgm². a) given that the main under-carriage stiffness is 350 kN/m, determine the stiffness of the nose-wheel assembly such that: i) the lowest natural frequency in the vertical plane will be greater the 0.75 Hz; {Verify the answer by re-substitution.} ii) the two modes of vibration will be un-coupled. { i) 37.5 kN/m; ii) 87.5 kN/m } b) Given that the nose-wheel assembly stiffness is 37.5 kN/m, and the plane is travelling along the runway at 100 km/hr, determine the minimum wavelength of runway vertical deviation to produce resonance. { 22.5 m }

          Example 1
The figure shows a turbo-prop aeroplane. The mass of the plane is 7000 kg and its
C of G is located the major axis, 1 metre forward of the main under-carriage.
The moment of aua of the plane about its C of G, and in the plane of pitching, is
35000 kgm².
a) given that the main under-carriage stiffness is 350 kN/m, determine the stiffness
of the nose-wheel assembly such that:
i) the lowest natural frequency in the vertical plane will be greater the 0.75 Hz;
{Verify the answer by re-substitution.}
ii) the two modes of vibration will be un-coupled.
{ i) 37.5 kN/m; ii) 87.5 kN/m }
b) Given that the nose-wheel assembly stiffness is 37.5 kN/m, and the plane is
travelling along the runway at 100 km/hr, determine the minimum wavelength of
runway vertical deviation to produce resonance.
{ 22.5 m }

Example 1
The figure shows a turbo-prop aeroplane. The mass of the plane is 7000 kg and its
C of G is located the major axis, 1 metre forward of the main under-carriage.
The moment of aua of the plane about its C of G, and in the plane of pitching, is
35000 kgm².
a) given that the main under-carriage stiffness is 350 kN/m, determine the stiffness
of the nose-wheel assembly such that:
i) the lowest natural frequency in the vertical plane will be greater the 0.75 Hz;
Verify the answer by re-substitution.
ii) the two modes of vibration will be un-coupled.
i) 37.5 kN/m; ii) 87.5 kN/m
b) Given that the nose-wheel assembly stiffness is 37.5 kN/m, and the plane is
travelling along the runway at 100 km/hr, determine the minimum wavelength of
runway vertical deviation to produce resonance.
22.5 m

Added by Regina D.

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