\label{sec:wfd} In order to visualise the functional flow of the work that needs to be performed during the DSE project a Work Flow Diagram (WFD) has been constructed, which is given in Figure \ref{fig:WFD}. This section also includes an elaborate description of the processes from the WFD. The WFD divides the total project in four phases. The first two phases were the initialization phase and early conceptual design phase, which were thoroughly discussed in the project plan and baseline report already. The conceptual design phase is focusing on the selection of the most suitable configuration for its mission. Since this phase was more far ahead at the moment of initialization phase, more detail is given in the WFD which is part of the Mid Term Report and the Final Report.
\label{fig:WFD}
The Initialization Phase and Early Conceptual Design Phase were discussed already in the Project plan and Baseline Report. During the Initialization Phase the group was first organised by appointing functions with each its specific responsibility like chairman, secretary, editor and quality controllers. A first set up of the WFD, WBS and Gantt-chart was performed. All stakeholders were identified to collect all requirements for the RBAR. This was based on the Mission Need Statement that was chosen for which an extensive Market Analysis was performed. In the Early Conceptual Design Phase the main focus was on finding reference aircraft and perform literature study.
In view of the Mid Term Report and Final Report the Conceptual Design Phase was updated to be more specific on what must be delivered. It was initialized by constructing sets of requirements for each individual subsystem (block C1). In addition, a literature study is performed on each subsystem (block C2) in order to construct a Design Option Tree (DOT) per subsystem (block C3). The subsystems are propulsion, wing, fuselage, empennage, landing gear, power and energy recovery system. Before constructing the DOT for the complete conceptual designs, first some subsystem options are eliminated (block C4) based on numerous criteria, like for example key requirements or non-feasibility. Based on the remaining subsystem options and keeping in mind the compatibility of the different subsystem options the complete conceptual design DOT is constructed resulting in 8 concepts (block C5). All 8 concepts are considered and traded-off by means of analytical hierarchy process (AHP) criteria & weights (block C7). To rely on a mathematical method to choose the weights a literature study was performed on the AHP method (block C6). Finally, this trade-off will decide on the three best design concepts (C14) where a sensitivity analysis can help in this process (block C13). Also AHP critera & weights are selected on all subsystem levels (block C8) to perform subsystem design trade-off (block C15).
Parallel in time with the above, the Class I method is performed. As soon as the Initialisation Phase and the Baseline are established, the first actual design steps can be done. In order to perform the Class I weight estimation a literature study is performed to find an applicable Class I method (block C10), as well as applicable reference aircraft (block C9). The output of the Class I method is an initial weight estimation of the entire aircraft and also the wing area and power which can be used as input for Class II estimations (block C19). The subsystem design trade-off and the Class I method are combined in the Class II estimation to find the aerodynamic characteristics (block C24) and a stability and control (block C25) estimate. Based on these characteristics another conceptual design trade-off will be done where only one concept is chosen to be worked out in the preliminary design, this is the point where the E-SPARC aerobatic racing aircraft is actually born and deserves its name. The Validation & Verification procedures provide a strategy that the aircraft meet the requirements imposed by the stakeholders for the final design (block C29). The RAMS characteristics will address a list of safety critical functions and the expected reliability and redundancy based on the chosen design (block C30).
Additionally the track simulation model will be defined (block C27). Therefore a literature study is first performed on the racing tracks that Red Bull has (block C26) and a performance analysis which addresses the quantified performance of the primary functions of the design (block C17).
The Preliminary Design Phase will kick-off after the MTR with the preliminary subsystem design for E-SPARC. Here the structural characteristics are added to the design with loading diagrams and calculations on the stresses and bending that act on the structure of the chosen design (block D2), also showing the materials characteristics in terms of yield stresses and fatigue. Also the aircraft system characteristics like the fuel and hydraulic system layout and an auxiliary power estimate are given (block D3). These can have design driving characteristics which will make it useful, together with the structural characteristics, to perform a subsystem sensitivity analysis (block D5). This was also already done in the Conceptual Design Phase to get from 8 concepts to the 3 most suitable concepts. The designer has to iterate back, if necessary, to the preliminary subsystem design (Block D1) to investigate if a design solution changes a lot for major system parameter inputs.
Finally, after doing the iteration process until the optimum design is reached, a manufacturing plan and an assembly & integration plan can be carried out (block D6 and D8). They give a time ordered outline of the activities required to construct the product from its constituent parts. This is only useful if the design is more or less fixed and therefore this is done near the end of the project. Likewise the return on investment is performed (block D7) to determine the market price and volume of the product and the development cost. As a final step E-SPARC aircraft will be validated and will consider if the system is doing what it is required to do (block D9). It will be shown that the system meets the requirements that Red Bull, the Certification Regulations and the Project Guide stated. This is supported with a compliance matrix with tick marks for all the requirements that are met (block D10).
During both the Conceptual Design Phase and the Preliminary Design Phase the Risk and Contingency Management will also be updated continuously, this is a iterative process during the full project.