## Aircraft parameter definition utility MODBUILD

The Matlab script MODBUILD is used to build a datafile with parameters for the aircraft model. Although the current version of MODBUILD is only valid for the DHC-2 'Beaver' model (the Simulink Beaver model or one of its subsystem equivalents), the part that determines the inertia coefficienst is more generic in nature (see the comment lines in the MODBUILD.M source code for more details).

MODBUILD needs to be used only if the aircraft model parameters are to be changed. This includes changes in mass and inertia properties, since these are considered to be constant during the short time-intervals over which the aircraft responses are considered. MODBUILD lets you save the parameters to a datafile (by default: AIRCRAFT.DAT), which can be loaded for future sessions, using the DATLOAD utility. It is not necessary to run MODBUILD more than once for the same set of model parameters if the results are saved.

Changing the model parameters with the current version of MODBUILD can be done only by editing the source-file of the program! In practice, MODBUILD won't have to be applied very often, so this is not really as inconvenient as it may seem. Moreover, it is straightforward to add some kind of user-interface if required. Currently, MODBUILD functions as a simple batch-file. The user is informed about the construction of the datafile by means of '`echo on`' and '`echo off`' commands.

Change the aircraft-dependent parts of the program if you want to implement model-parameters for different types of aircraft. It is also possible to change the mass, geometry, and moments and products of inertia, but be careful not to change the generic inertia coefficient equations.