ANALYTICAL DEVELOPMENT OF AN EQUIVALENT SYSTEM MISMATCH FUNCTION

A mismatch function is used to check the validity of a low-order equiv alent system model that has been derived from a high-order system repr esentation. If the difference between the low- and high-order models i s greater than allowed by the mismatch function, the flying qualities predictions obtained from parameters of the low equivalent system may not be representative of the ratings a pilot would give the actual air craft. A methodology is developed in this paper to derive equivalent s ystem mismatch functions analytically. The methodology is used to anal ytically determine a mismatch function for the longitudinal axis of a class IV fighter aircraft in the category A, nonterminal flight phase.