Using Optimization as a Tool in Fuel System Conceptual Design

Choosing between concepts is often the most critical part of the design process. Different concepts have different advantages and disadvantages. The concept that is the best choice is most often dependent on the top level requirements. Sometimes there may also be a trade off between concept choice and the top requirements. In aircraft (a/c) fuel system design it has often proved difficult to find the switching point where the superior concept is changed. This sometimes makes the designer conservative and leads to the selection of a concept with too high a penalty. There is also a risk for the opposite and perhaps worse scenario: That the designer strives to reduce weight and cost and therefore, accidentally, chooses an under achieving concept and thus induces large downstream cost if late redesign or retro modifications are necessary.

This paper shows how optimization has been successfully used at Saab Aerospace as a tool that supports concept selection. The example shown is the choice of fuel transfer method for a ventral drop tank. The example also illustrates the impact of top-level requirements on low-level practicalities such as fuel system design.