That calculator uses different methods, and the formulas and derivations were not available to me at the time this was created. The Multiplex calculator factors in wing area, but does not include servo deflection. Angular velocity and acceleration of the aircraft is zero. Air flow may be modelled using Bernoulli's equation for dynamic pressure. Control linkages have zero offset at hingeline and are perpendicular to horns at neutral.
Control mechanisms are frictionless and surfaces are mass-balanced.
The wing, stab, fuse, and control surfaces are thin, flat slabs. No aerodynamic counterbalances are used. The pushrods are significantly longer than the servo and control horns. Extreme control throws are probably not practical at high speeds. This model is best used for comparisons.