Original Date: 05/08/1995
Revision Date: 01/18/2007
Best Practice : Modular Six Degrees of Freedom Analysis Program
The Modular Six Degrees of Freedom (MODSDF) Analysis Program is a McDonnell Douglas Aerospace (MDA)- developed, continuous system analysis tool that provides high-fidelity simulations of the complete air vehicle. This highly modular software program is designed to be an integrated multidiscipline resource which uses a shared database. MODSDF provides engineers with efficient and validated models and methods which can be applied uniformly across MDA-St. Louis product lines to a wide variety of engineering tasks. It replaces a large number of single-purpose simulation programs and databases.
MODSDF capabilities include single and multirate model calling frequencies, analog and digital control system simulations, flat or rotating spherical earth equations of motion, MIL-SPEC turbulence and aircraft carrier airwake models, and open-loop analysis of control systems. Among other applications, MODSDF is used to analyze full six degrees-of-freedom aircraft carrier suitability and performance characteristics, flight control design evaluation, verification of manned simulator models, weapon separation characteristics and flight test program plans and clearances (Figure 2-4), and reproduction of flight anomalies for incident and accident investigation.
When used to analyze design and fatigue loads on the F/A-18 E/F, MODSDF provided the same tool and flight control system to all functional disciplines instead of the variety of uncoordinated special purpose tools and models previously used individually. This practice allowed MDA-St. Louis to check performance impact on the entire maneuver set rather than the isolated checks on only limited portions of the set. This resulted in a 50% to 90% reduction in the time required to identify critical points.
Other benefits of MODSDF include improved communication between disciplines and rapid assessment of synergistic effects, higher quality simulations due to uniform use of validated methods resulting in more highly integrated designs, a broader scope of analysis capability than single purpose simulation tools, and faster manned simulator checkout and verification.
Figure 2-4. Sample MODSDF Store Separation
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