Missile Datcom AIM Overview

A module in the Computational Aircraft Prototype Syntheses (CAPS) has been developed to interact with Missile Datcom.

Details on the use of units are outlined in AIM Units.

An outline of the AIM's inputs, outputs and attributes are provided in AIM Inputs, AIM Outputs and AIM Attributes, respectively.

Geometry Requirements and Assumptions

The Missile DATCOM coordinate system assumption (X – downstream, Y – out the right wing, Z – up) needs to be followed.

Airfoils in ESP

Within OpenCSM there are a number of airfoil generation UDPs (User Defined Primitives). These include NACA 4 series, a more general NACA 4/5/6 series generator, Sobieczky's PARSEC parameterization and Kulfan's CST parameterization. All of these UDPs generate EGADS FaceBodies where the Face's underlying Surface is planar and the bounds of the Face is a closed set of Edges whose underlying Curves contain the airfoil shape.

Important Airfoil Geometry Assumptions

There must be a Node that represents the Leading Edge point
For a sharp trailing edge, there must be a Nodes at the Trailing Edge
For a blunt trailing edge, the airfoil curve may be open, or closed by a single Edge connecting the upper/lower Nodes
For a FaceBody, the airfoil coordinates traverse counter-clockwise around the Face normal. The OpenCSM REORDER operation may be used to flip the Face normal.
For a WireBody, the airfoil coordinates traverse in the order of the loop

Note: Additional spurious Nodes on the upper and lower Edges of the airfoil are acceptable.

A NodeBody may be used for a sharp fin tip.

Missile DATCOM also supports the the specific HEX, ARC, USER, and NACA fin sets. The fin set and corresponding ESP airfoil section are listed in the table below.

missile DATCOM Airfoil	ESP Airfoil
HEX	misdathex
ARC	biconvex
USER	Any airfoil UDP
NACA	See FinSet SecNACA in AIM Inputs

The misdathex UDP has the same arguments as the missile DATCOM HEX airfoil, i.e. zupper, zlower, lmaxu, lmaxl, lflatu, and lflatl

Notes

DEXIT is calculated based on any inner loop found on the last FaceBody of the missile's body using the following: $D_{Exit} = \sqrt{A_{Loop}*4/\pi}$

ToDO

Add Base-Jet Plume Interaction Inputs
Add fin controls.

Code Distribution

DISTRIBUTION STATEMENT A. Approved for public release: distribution is unlimited. PA#: AFRL-2024-6115.