Wingtip-Mounted Propellers: Aerodynamic Analysis of Interaction Effects and Comparison with Conventional Layout

Aerodynamic Performance of a Wingtip-Mounted Tractor Propeller Configuration in Windmilling and Energy-Harvesting Conditions

“…A prime example is the tipmounted propeller, that promises significant aerodynamic benefits due to integration synergies. A recent comprehensive experimental study by the authors [2] discussed the aerodynamic interaction effects for wingtip-mounted tractor propellers, and confirmed the potential aerodynamic benefit compared to a conventional propeller-wing layout in case of inboard-up rotation. The results complemented previous work [3,4] and recent research related to the NASA X-57 Maxwell [5,6].…”

Aero-Propulsive Efficiency Requirements for Turboelectric Transport Aircraft

“…In all cases, the secondary system enhances the aerodynamic and/or propulsive performance of the aircraft. For example, the tip-mounted propulsors decrease the lift-induced drag of the wing, effectively increasing the equivalent aspect ratio or span efficiency of the wing [35]. The leading-edge propellers can increase the maximum lift coefficient of the wing [32], leading to a significant increase in wing loading [23,38].…”

“…And secondly because, even though several turboelectric aircraft design studies have been performed [13,18,30,31], there is still a large uncertainty regarding the benefits of such aircraft, especially due to the lack of propulsion-airframe integration studies. While the aerodynamic benefits of novel propulsion-system layouts such as leading-edge distributed propulsion [32], over-the-wing propulsion [33], under-the-wing propulsion [13], boundary-layer ingestion [34], or tip-mounted propulsion [35] have been studied at subsystem level, it is still unclear which of these configurations leads to the greatest benefit at aircraft level. Although such propulsion systems do not necessarily need a hybrid-electric powertrain [36], many radical aircraft configurations with improved propulsion-airframe integration are only viable when combined with HEP, and thus the overall benefit is highly dependent on the maturity of the powertrain components [37].…”

Preliminary Sizing Method for Hybrid-Electric Distributed-Propulsion Aircraft

“…At low thrust settings, on the other hand, the trends are less clear. While some studies predict a decrease in span efficiency [29], others show an increase in span efficiency due to improved swirl recovery [52]. Since these effects cannot be quantified with the information available in the preliminary sizing phase, the change in span efficiency is neglected.…”

“…The predictions are also compared to the experimental data of Sinnige et al [52], to check whether the model is accurate for other propeller configurations. These experiments studied a single tractor propeller mounted on a low-aspect-ratio wing.…”