On the convergence of unsteady generalized aerodynamic forces

Generalized aerodynamic forces computed from analyses based on distributed pressures and finite paneling procedures are examined for solution convergence The necessity for examining the convergence of calculated forces as a function of the number of assumed pressure terms or the number of panels is well demonstrated The lifting series method converges abruptly, whereas panel methods converge gradually and monotonically for the cases analyzed An increase in wave number with increasing frequency or Mach number may cause increased computational problems coupled with increased computer usage costs With the panel methods, increase in prediction accuracy is obtained with moderate computer costs by extrapolating through the force results of two different not so fine panelings