Coaxial Propeller Propulsion Layout for Reduced Aircraft Drag
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Solution Overview
Problem
Existing propeller-type propulsion systems for aircraft are bulky, affecting aerodynamics and increasing fuel consumption due to parallel arrangement of multiple electric motors and driveshafts, which increases the diameter of the propulsion system.
Innovation Solution
A coaxial driveshaft arrangement with nested driveshafts and a gearbox input shaft sharing a single axis of rotation, coupled via gearwheels and splines, reduces the system's width and height, improving aerodynamics and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple electric motors are arranged in parallel to drive the propeller, then the propulsion system can provide sufficient power for heavy aircraft, but the system becomes bulky in terms of height and width, impairing aerodynamics and increasing fuel consumption
Solution Approach 1:
The patent applies nesting by arranging multiple driveshafts coaxially, where smaller diameter driveshafts are positioned inside larger diameter driveshafts. This nested configuration allows multiple motors to share a common axis, significantly reducing the overall diameter and height of the propulsion system while maintaining the combined power output needed for heavy aircraft.
Solution Approach 2:
The patent transitions from a parallel arrangement (two-dimensional expansion in width and height) to a coaxial arrangement (one-dimensional alignment along the rotation axis). By organizing motors and driveshafts along the same axis rather than side-by-side, the system reduces its footprint in the radial direction, improving aerodynamics without sacrificing power capacity.
2Ease of operation
If a gearbox with multiple input shafts is used to couple parallel motor output shafts to the propeller, then mechanical power transmission is achieved, but the system complexity and bulk increase
Solution Approach 1:
The patent merges multiple input shafts into a single common input shaft by using coaxial driveshafts that all connect to the same axis. This consolidation reduces the gearbox structure from having multiple separate input paths to a unified single input shaft, simplifying the overall mechanical coupling system while maintaining the ability to transmit power from multiple motors.
Data Source
AI summary
A propeller-type propulsion system for aircraft, comprises a propeller, a plurality of electric motors comprising nested coaxial respective driveshafts, and a gearbox having an output shaft onto which the propeller is mechanically coupled, and an input shaft to which the coaxial driveshafts of the electric motors are mechanically coupled. As a result, the diameter of the propulsion system, in a plane perpendicular to the axis of rotation of the propeller, is reduced. This improves the aerodynamics and the fuel consumption of the aircraft.