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DATCOM or DIGDAT is a computer program that calculates the static stability, control and dynamic derivative characteristics of fixed-wing aircraft. In relation to FlightGear, it can be used for JSBSim FDMs.

Who made it

Digital Datcom (DIGDAT) or The Digital United Stated Air Force Stability and Control Data Compendium was made by the U.S. Airforce. It is based of the paper version of the same name, which has 3000 pages of aerodynamic equations collected since the 40'ties. The program was released to the public in 1996.

There exist also a missile version of the program.

How does it work

You input the geometry of your aircraft (or parts of it) and some key numbers. Datcom then computes aerodynamic data from your input. There are several ways to input some things. For example for a wing, you can enter a NACA code or you can input 2D coordinates of how the wing profile looks like.

Inputs can be in metric or imperial units as is preferred.

The Datcom+ version can even output directly to JSBSim. The maker of the Datcom+ is also offering a Pro version with bugfixes and extra features, like computing inertia. Notice however when outputting directly to JSBSim, that some unit conversion errors exist when inputing in metric. (like wing areas are a factor 3 off) This can be avoided by inputting a reference area to Datcom+.

Important notes

  • DATCOM input files (.dcm):
    • The maximum line length is 80 characters (or maybe 79?).
    • Do not put numbers in the first column.

External links