## 5 Application
Figure 13: Case A, Configuration C1; Minimum Time and Minimum Fuel climb paths, plotted over contours of: Specific Excess Power (m/s) (**a**); and Energy Efficiency (m/kg) (**b**). region. In minimum-fuel climb paths, climbs begin at lower subsonic Mach numbers than in the respective minimum time paths, trajectories being shifted towards higher altitudes for improved efficiency. In general, in all cases and in accordance with the results of Reference [4], the resulting paths look like \"smoothed\" versions of E-M paths. This is because E-M solutions do not take into account the energy loss during maneuvers and assume that the transition between equal energy levels may be realized instantaneously; if the latter are considered, climb path optimization becomes a tradeoff between accurate tracking of contours and avoidance of intense maneuvers. As far as the performance of the examined configurations is concerned; an inspection of Figures 12 and 16 denotes a clear advantage of the EJ200-equipped configurations. In the subsonic climb case; an average 14.5% reduction in fuel consumption was combined with 13.7% reduction in time to climb with respect to the aircraft's original configuration at an equal aircraft AUM (Configuration C2). The above values were further increased to 23.6% and 22.7%, respectively, if the weight reduction resulting from the reduced engine weight were considered (Configuration C3). A similar picture was observed in the supersonic climb test results: The average reduction in fuel consumption was 17.3% for configuration C2 and 25.3% for configuration C3 accompanied by a 6.7% and 18.9% reduction in climb time, respectively. Figure 14: Case A, Configuration C2; Minimum Time and Minimum Fuel climb paths, plotted over contours of: Specific Excess Power (m/s) (a); and Energy Efficiency (m/kg) (b). Figure 15: Case A, Configuration C3; Minimum Time and Minimum Fuel climb paths, plotted over contours of: Specific Excess Power (m/s) (a); and Energy Efficiency (m/kg) (b). Figure 16: Case B; comparison of fronts of non-dominated solutions obtained for Configurations C1, C2 and C3. Figure 17: Case B, Configuration C1; Minimum Time and Minimum Fuel climb paths, plotted over contours of: Specific Excess Power (m/s) (**a**); and Energy Efficiency (m/kg) (**b**). Figure 18: Case B, Configuration C2; Minimum Time and Minimum Fuel climb paths, plotted over contours of: Specific Excess Power (m/s) (**a**); and Energy Efficiency (m/kg) (**b**). A comparison of the maximum power Specific Excess Power and Energy Efficiency contours of the three examined configurations unveils the different performance characteristics of the engines examined: The EJ200 is a low-bypass turbofan engine with a higher static thrust than the J79 turbojet. This accounts for an acceleration and efficiency advantage of the former over most of the aircraft's envelope, particularly at high altitude and low-to-medium Mach numbers. On the contrary, because of its turbojet cycle, the J79 has better performance at medium altitudes in the transonic Mach number range, gradually expanding to the entire altitude range as the Mach number further increases. In Case B, this results in smaller differences in TTC between configuration C1 and configurations C2 and C3 compared to the results of Case A (Figures 12 and 16). The different performance characteristics of the two engines also become evident by comparing the minimum-time supersonic climb trajectories of configurations C2 and C3 with that of configuration C1. The J79-equipped configuration (C1) favors an acceleration at medium altitude in the transonic regime, followed by a zoom climb to reach the specified altitude (Figure 17), whereas the EJ200-equipped configurations (C2 and C3) use a subsonic climb to high altitude followed by an accelerated supersonic climb to the desired conditions (Figures 18 and 19).