Design Studies of Thin-Haul Commuter Aircraft with Distributed Electric Propulsion

Abstract

A conceptual design study of a distributed electric propulsion transport aircraft is presented. The objective is to study the applicability of distributed electric propulsion configurations to aircraft serving thin-haul airline routes. A hybrid powertrain is selected, such that shorter routes can be flown operated electric, while longer routes can be operated with a range extender, to reduce the required battery size. Two range extender options are examined: a modern turbodiesel and an advanced recuperated turbogenerator. Conventional fuel-powered aircraft are designed in parallel to the same mission and constraints, to illustrate the impact of the electric propulsion configurations on the chosen metrics. An operating cost model is assumed, to estimate the commercial viability of the different designs. The advanced concepts are generated and analyzed using purpose-built conceptual design tools, with optimization employed to minimize a weighted average operating cost of a short battery-powered flight and a longer hybrid-powered flight. The analysis tools are also used to model existing aircraft for comparison. Plots of various trade studies are presented. The results suggest that the configurations examined in this study present an advantage in operating costs over conventional aircraft, in addition to assumed noise and emissions advantages. Nomenclature APropeller disk area A u Propeller disk area less obscured area AR Wing aspect ratio AR j Aspect ratio of blown wing segment bWingspanMotor diameter eSpan efficiency e 0Oswald efficiency J Propeller advance ratio M Propeller figure of merit m wing Mass of the wing M s Propeller figure of merit (not including swirl losses) N z Ultimate load factor P min Minimum engine size P shaft Shaft power * Aeronautical Engineer, 340 Woodpecker Ridge, AIAA Member. † Chief Aerodynamicist, 340 Woodpecker Ridge, AIAA Member.

An Investigation into the Potential Benefits of Distributed Electric Propulsion on Small UAV’s at Low Reynolds Numbers

“…Another distributed electric propulsion aircraft concept design study was conducted for the thin haul commercial aviation market (Stoll & Mikic, 2016). This class of aircraft has short route missions with around ten passengers (e.g.…”

“…However, the battery power to weight ratio still needed to be improved (Stoll & Mikic, 2016). Figure 5.…”

“…Figure 5. Existing aircraft and new design concepts (Stoll & Mikic, 2016) The Joby S2 is a two-seat vertical take-off and landing application of distributed electric propulsion for personal air vehicles. This concept was designed for short to medium distances where speed, noise, efficiency, and safety are of concern.…”

Hybrid Regional Aircraft: A Comparative Review of New Potentials Enabled by Electric Power

“…As suggested in Ref. 10, the power sent to the small leading edge propellers could be that required to ensure the maximum lift coefficient with appropriate stall margin considerations and the two other bigger propellers could be used as needed to keep the -3° approach slope, be it by generating thrust or drag.…”

“…Finally, the kinetic power imparted to the flow by the propulsor is: (10) Therefore, for a given fuselage drag and rear propeller thrust the power provided by the propeller to the flow can be calculated by solving Eqs. (7), (8) and (9).…”