The two component neutron star model and the response of the neutron star under the influence of external white torque noise are reviewed. A new simulation technique is developed for estimating the crust core coupling time and the moment of inertia of the superfluid in the neutron star from the irregularly sampled data. The model is applied to Vela X-1, since this source has a long period P = 283 s and theoretical estimates of crust-core coupling time which are proportional to P lie in the observable region, tau = 1 - 30 d for Vela X-1. In the analysis, it is found that moment of inertia of the superfluid cannot exceed 85% of the total moment inertia of the star if the crust core coupling time is longer than 1 d (tau > 1 d). This is in agreement with the analysis of Boynton et al. (1984) on earlier data. This result indicates that either the core superfluid mixture is less than 85% of the total moment of inertia of the star or the crust core coupling time should be less than 1 d.