In the present study, an analytical solution for nonlinear vibration problem of launch vehicle as a flexible beam
model carrying moving with constant velocity mass which is time function is proposed. The nonlinear third and
fifth order terms of partial differential equation with variable in time coefficients correspond to high amplitude
and mid-plane stretching beam and the right term of initial equation of the problem represents the concentrated
time-dependent moving mass effect. A hybrid asymptotic approach applied for an approximate analytical
solution problem at given boundary and initial conditions an given. The resulting (approximate) solution has a
form of a sum where each term consists of the product of two functions according to perturbation (on parameter
at nonlinear terms) and phase-integral-Galerkin technique (on singular parameter at higher derivative)
methods. The results of comparison of an approximate analytical solution and direct numerical integration of
initial equation have shown a good enough accuracy as for “small” as well for “large ” scalar parameters for
asymptotic expansion of the desired function