Prototype for a long range bomber by Viktor Nikolayevich Belyayev whose designs often featured unconventional configurations. This design dates from the late 1940s but was cancelled in 1940 in favour of a more conventional aircraft. According to the limited information I have been able to find in English the aircraft flew well but was sensitive to changes in its centre of gravity (such as might occur when dropping bombs).
The spherical recess underneath the model is for mounting it on an 8mm BB.