We have obtained the exact expressions for the deflection of the two types of flat elastic thrustless trusses under uniform nodal loads depending on truss size and number of panels. Used vector method set the configuration of the truss and the matrix form of the method of cutting nodes to determine forces in the rods of the truss. The dependence of the deflection on the number of panels, the geometric dimensions and the load was found in an analytical form by induction using a special package for the computer algebra system Maple, intended for the preparation and solution of linear recurrence equations, which satisfy the coefficients of the solution. The solution obtained for different stiffness of the belts and rods of the lattice truss. The curves comparison of deflections and some asymptotic properties of the solutions, showing the fundamentally different nature of the change in deflection with increase in the number of panels.