\label{sec:trade_summary} Having found the trade-off criteria and their weights, the next step is to define the relation between the different possible configurations in the respective criteria. Therefore, they are also compared pairwise. The tables are shown in Table \ref{tab:LD} through \ref{tab:prop_eff} in Appendix \ref{app:AHP_results}.
Using the comparisons of the design options and the criteria weights, the program computes the rating of the different design options.
\label{tab:prlm_tradeoffranking}
| Design configuration | Ranking | Rating |
|---|---|---|
| Configuration 3 | 1 | 0.213 |
| Configuration 8 | 2 | 0.182 |
| Configuration 6 | 3 | 0.129 |
| Configuration 4 | 4 | 0.124 |
| Configuration 5 | 5 | 0.120 |
| Configuration 7 | 6 | 0.088 |
| Configuration 2 | 7 | 0.087 |
| Configuration 1 | 8 | 0.058 |
The results from Table \ref{tab:prlm_tradeoffranking} suggest that the conventional configuration, used nowadays, is the best, followed by the biplane, which can be explained by its good maneuverability, and the canard with one pusher propeller. The difference in score between the biplane and the canard is obvious. Thus, it is expected that the canard would need a lot of optimisation with respect to its subsystems to achieve very good results. Also, the distribution of the weights has to be reconsidered, to check if a change in weights for the criteria will alter the outcome of the trade-off dramatically.
In order to investigate how objective the trade off is, a sensitivity analysis was performed. The results of this analysis can be seen in Table \ref{tab:criteriasensitivities}. The analysis proofed that the top three is sturdy enough to use for all following calculations.
\label{sub:conf} The following design configurations were chosen based on the trade-off that was performed. These designs are refined and improved and then traded off against each other.
Design 3: Conventional configuration with one puller propeller.
Design 8: Biplane configuration with one puller propeller.
Design 6: Canard configuration with one pusher propeller.