Influence of Electric Wing Tip Propulsion on the Sizing of the Vertical Stabilizer and Rudder in Preliminary Aircraft Design

Abstract

During preliminary aircraft design, the vertical tail sizing is conventionally conducted by the use of volume coefficients. These represent a statistical approach using existing configurations’ correlating parameters, such as wing span and lever arm, to size the empennage. For a more detailed analysis with regard to control performance, the vertical tail size strongly depends on the critical loss of thrust assessment. This consideration increases in complexity for the design of the aircraft using wing tip propulsion systems. Within this study, a volume coefficient-based vertical tail plane sizing is compared to handbook methods and the possibility to reduce the necessary vertical stabilizer size is assessed with regard to the position of the engine integration and their interconnection. Two configurations, with different engine positions, of a hybrid-electric 19-seater aircraft, derived from the specifications of a Beechcraft 1900D, are compared. For both configurations two wiring options are assessed with regard to their impact on aircraft level for a partial loss of thrust. The preliminary aircraft design tool MICADO is used to size the four aircraft and propulsion system configurations using fin volume coefficients. These results are subsequently amended by handbook methods to resize the vertical stabilizer and update the configurations. The results in terms of, e.g., operating empty mass and mission fuel consumption, are compared to the original configurations without the optimized vertical stabilizer. The findings support the initial idea that the connection of the electric engines on the wing tips to their respective power source has a significant effect on the resulting torque around the yaw axis and the behaviour of the aircraft in case of a power train failure, as well as on the empty mass and trip fuel. For only one out of the four different aircraft designs and wiring configurations investigated it was possible to decrease the fin size, resulting in a 53.7% smaller vertical tail and a reduction in trip fuel of 4.9%, compared to the MICADO design results for the original fin volume coefficient.

A simplified automated approach for a preliminary safetyassessment of distributed electric and hybrid propulsionsystems

“…In the present stage of implementation the DATCOM study [15] as adopted by ROSKAM [26], [27] is used in order to estimate aerodynamic derivatives. The application of this method, according to Ciliberti [6] and as discussed in [4] is still applicable for our considered high wing aircraft configuration, involves the evaluation of a large number of diagrams as intermediate step to calculate the derivatives. To allow an automatic calculation of derivatives for different flight states, diagrams for all flight state dependent quantities have been digitized.…”

“…In a similar way, 3 to 5 can be used to find the maximum absolute value of yaw moment that can be considered controllable in each scenario. Generally, rudder control authority is limiting in this consideration [4]. Therefore, rudder deflection is set to its maximum value according to [26] and instead, the yaw moment to compensate N f ailure is treated as unknown.…”

“…In order to find the optimum combination of technologies, components and their arrangement the design space has to be explored. Thereby, due to the possible complexity of the architectures a nominal system behaviour must be taken into account as well as the implications of single or even multiple component failures [22], [4]. However, involving disruptive technologies and increasing the number of key components within the powertrain architecture leads to an increasing number of failure cases to be considered.…”