Bifurcation sets in a problem on motion of a rigid body in fluid and in the generalization of this problem

In the paper, topology of energy surfaces is described and bifurcation sets is constructed for the classical Chaplygin problem and its generalization. We also describe bifurcations of Liouville tori and calculate the Fomenko invariant (for the classical case this result is obtained analytically and for the generalized case it is obtained with the help of computer modeling). Topological analysis shows that some topological characteristics (such as the form of the bifurcation set) change continuously and some of them (such as topology of energy surfaces) change drastically as $g \to 0$.