TABLE OF CONTENTS In this section the frequency-response database and associated frequency ranges are selected for incorporation in the identification cost function of Eq. (12.20). This leads to a frequency-response table that is then used to eliminate some of the control and response derivatives, thereby achieving an initial reduction in the complexity of the model structure.
In the case of the six-DOF model structure, there are n c = 4 inputs [Eqs. (13.28) or (13.29)] and n o = 9 outputs [Eq. (13.30)], yielding a total of 36 possible frequency response pairs T l, to be included in the identification cost function. (There are more if aerodynamic angles measurements ? and ? are also included.) We recall from Table 10.1 that one work flowpath is used to determine one column of the frequency-response (data) matrix 
. This is repeated for each primary control (four work flowpaths in total), corresponding to the n c = 4 columns of 
. Assuming that n w = 5 spectral windows are used, the total number of frequency responses that are calculated in creating the frequency-response database are 840 SISO frequency responses, 180 MISO (conditioned) frequency responses, and 36 composite window (final) frequency-response pairs comprising the n o n c data matrix 
. Thus a total of 1056 frequency responses are estimated to determine the flight data matrix 
. Keeping track of this large number frequency responses can be...
