An Optimization Method for Improving Efficiency of Electric Propulsion System of Electric Seaplane

Abstract

The takeoff process of a seaplane is different from that of a conventional land-based plane owing to the influence of hydrostatic, hydrodynamic, and aerodynamic forces. As a result, more energy will be consumed by the electric propulsion unit (EPU) of a seaplane during takeoff. Given the limited energy density of contemporary batteries, the energy consumed by the seaplane during its flight mission profile was minimized in this study by improving the efficiency of the EPU using a proposed optimization method. To meet the performance requirements of the seaplane EPU, the pitch angle of the propeller was taken as the optimization variable and the system loss was mathematically modeled. The performance of the EPU was thereby optimized, its consumption during flight was reduced, and the seaplane endurance was increased accordingly. The proposed optimization method was subsequently verified using a prototype test of a twoseat electric seaplane. The results show that the proposed method can reduce the energy consumption of the EPU by more than 5% during a single flight. INDEX TERMSElectric seaplane, electric propulsion unit (EPU), energy efficiency optimization, prototype test. NOMENCLATURE ρ Air density. C T Propeller thrust coefficient. β Propeller power coefficient. S Wing area. C D Aerodynamic drag coefficient. C L Aerodynamic lift coefficient of the aircraft. c r Water friction resistance coefficient. ρ w Water density. B Float width. N P Number of floats. EPU Electric propulsion unit. θ Pitch angle.The associate editor coordinating the review of this manuscript and approving it for publication was Adamu Murtala Zungeru .

An Energy Efficiency Optimization Method for Electric Propulsion Units during Electric Seaplanes’ Take-Off Phase

“…In contemporary aviation research, the theoretical calculation of propeller flow field parameters involves momentum theory, blade element theory, and vortex theory [13,14]. Specifically for our application on the RX1E-S electric seaplane, we have designed a threeblade fixed-pitch propeller, as shown in Figure 3.…”

“…The unique operational environment and intricate power requirements of electric seaplanes underscore the critical role played by the performance and efficiency of the EPU [13,14]. However, the current EPU for electric seaplanes still has several issues, such as a low power-to-weight ratio and lower energy density [15].…”

“…Particularly during take-off, an electric seaplane must overcome water surface resistance and generate sufficient thrust to lift off the water. Studies have shown that an electric seaplane consumes approximately 30% of its total energy requirement during the take-off phase in a single-flight mission [13].…”

“…The electric seaplane exhibits several characteristics distinct from land-based electric aircraft during the take-off taxiing phase. Based on its hydrodynamic and aerodynamic properties, the entire take-off taxiing process can be segmented into four stages: taxiing, transitional taxiing, high-speed taxiing, and floating off water [13]. The variations in hydrodynamic and aerodynamic resistance encountered by the electric seaplane within these four stages are depicted in Figure 1 [13].…”

“…Based on its hydrodynamic and aerod properties, the entire take-off taxiing process can be segmented into four stages: transitional taxiing, high-speed taxiing, and floating off water [13]. The variation drodynamic and aerodynamic resistance encountered by the electric seaplane these four stages are depicted in Figure 1 [13]. During the take-off taxiing of a seaplane, the taxiing stage marks the initial p operates at relatively lower speeds, usually maintaining a lower speed range while on the water surface.…”