Nonstationary random pulses representation of ground roughness for taxiing aircraft

This paper presents a general method of describing both nonstationary and stationary roughness experienced by an aircraft taxiing on ground. The generalized roughness spectrum is shown to be in agreement with previously published results. It also reduces to the similar form of the one-runway-one-speed case presently employed by the aircraft industry. These procedures, however, assume that the input spectra of either the velocity components of atmospheric turbulence or the runway roughness are stationary instead of nonstationary as is actually the case. Recently, studies were made on nonstationary flight vehicle gust response and rotor blade vibrations. However, since no attempt was made to treat the taxiing problem accordingly, this work was undertaken.