MSC.FlightLoads and Dynamics Version 1 creates aerodynamic models and produces results that are compatible with the Doublet-Lattice and ZONA51 aerodynamics that are provided in MSC.Nastran. The Doublet Lattice method (DLM) is applicable to subsonic flows while ZONA51 can be considered its supersonic counterpart. These methods are of a of class "Panel Methods" that represent lifting surfaces by flat panels that are nominally parallel to the flow. The Doublet Lattice method has the additional ability to represent bodies as variable radius cylinders, also aligned with the airflow. Other "Panel Methods" can be more general and represent the surfaces as discrete curved surfaces in 3-space.

This Appendix provides a brief description and theoretical discussion of these methods and then offers some guidelines for their use. Much of this development is taken from the MSC.Nastran User’s Guide for Aeroelastic Analysis (Ref. 12) with corrections and supplementary material provided for this document.

MSC.Nastran aerodynamic analysis, like structural analysis, is based upon a finite element approach. The finite aerodynamic elements are strips or boxes on which there are aerodynamic forces. The aerodynamic elements, even for complex vehicles, must be in regular arrays. In particular, the aerodynamic elements for the lattice methods are arrays of trapezoidal boxes with sides that are parallel to the airflow. These can be described simply by defining properties of the array (panel).

Aerodynamic forces are generated when the flow is disturbed by the flexible vehicle. Theory leads to a matrix that relates the forces acting upon the structure due to the deflections of the structure.

These deflections are the combination of rigid body motions of the vehicle and the structural deformations of the vehicle as it undergoes an applied loading during a maneuver. For the steady flow considered in FlightLoads Static Aeroelastic analysis, the relationship between the deflection and the forces is a function of the aerodynamic model (including any symmetry conditions) and the Mach number of the flow.