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A Robust Approach To Pre-Concept Design
Of UCAV Considering Survivability
Joongki Ahn, Suchang Lee, Jinsoo Kim
September 6, 2002
Abstract
In this paper, an aircraft pre-concept design methodology with the explicit survivability analysis is presented as a part of requirement analysis. Using the presented methodology, the robust goal requirement and performance levels can be found through the probabilistic analysis. The design procedure consists of three steps; screening, probabilistic sensitivity analysis, and multi-objective optimization. The whole procedure is organized under the multidisciplinary design optimization framework. In the screening step, the most influential variables are selected by design of experiment method to make an approximate model. The probabilistic sensitivity analysis step produces the most probable points satisfying customer’s requirement. The multi-objective optimization is incorporated into probabilistic analysis to find robust design points. To allocate the goal performance levels on flight velocity and maneuverability of generic unmanned combat air vehicle, the survivability of the vehicle against surface to air missile is considered quantitatively and explicitly. The design points, which are feasible to the goal requirements and satisfying the threshold requirements, can be obtained through the presented design procedure. Also, the presented methodology is found to be useful when establishing the goal requirement in pre-concept design phase.
Introduction
Pre-concept design is the very early work to establish the general concept and requirement. It provides mission need statement and operational requirements document. The documents usually consist of overall needs, concepts of operations, potential design solution, estimates of cost/schedule, analysis of alternatives, and assessment of effectiveness. The assessment of effectiveness is important technological products of the pre-concept design phase. It contains quantified measures of system effectiveness such as affordability, mission capability, operational safety, operational readiness, and survivability. Ref.[1,2,3] give an overview of effectiveness, mainly on survivability. The pre-concept design only develops reasonable design requirements to support technology readiness, cost, risk, and schedule estimates. There are two types of requirements, such as threshold requirement and goal requirement[4,5]. The threshold requirement is the minimum level of acceptable performance and the goal requirement is the maximum level of desired performance. If the design does not meet threshold level it is unacceptable and should be changed. On the other hand, if the design exceeds goal performance there is little benefits. So, reasonable performance should be allocated between threshold requirement and goalrequirement.
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