Aircraft Propulsion Assemblies for Omnidirectional Ground Maneuvers
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Solution Overview
Problem
Current aircraft designs, such as fixed-wing, tiltrotor, and tiltwing, face limitations in omnidirectional ground maneuver capabilities and transition efficiency between forward flight and vertical takeoff and landing modes, particularly due to downwash inefficiencies and control difficulties during hover.
Innovation Solution
The aircraft features a distributed propulsion system with independently controllable propulsion assemblies, each comprising a nacelle, rotor assembly, and tail assembly, allowing for tilting and rotating configurations to generate a horizontal thrust component perpendicular to the wheel axis, enabling omnidirectional ground maneuvers and seamless mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If tiltrotor aircraft use fixed wing for forward flight, then forward speed and range are improved, but downwash inefficiencies occur during vertical takeoff and landing due to interference from the fixed wing
Solution Approach 1:
The aircraft divides the propulsion system into multiple independent proprotors distributed across the airframe, with each proprotor capable of independent tilt rotation. This segmentation allows the downwash from each proprotor to be directed independently, enabling efficient vertical lift without interference from the fixed wing during VTOL operations, while maintaining forward speed capability through horizontal configuration.
Solution Approach 2:
The proprotors are designed with dynamic tilt rotation capability, allowing them to change orientation from horizontal to vertical and vice versa. This dynamic adjustment enables the aircraft to optimize proprotor positioning for each flight phase - vertical orientation for efficient VTOL operations and horizontal orientation for forward flight, eliminating the fixed wing interference problem.
2Power
If tiltwing aircraft rotate wing to vertical orientation for VTOL, then vertical thrust efficiency is improved, but control during hover becomes more difficult requiring additional control mechanisms
Solution Approach 1:
The aircraft segments the lift generation function across multiple independent proprotors rather than relying on a single rotating wing. Each proprotor can be independently controlled in terms of tilt angle and thrust magnitude, providing fine-grained control authority during hover and eliminating the need for complex cyclic rotor control or additional thrust stations.
Solution Approach 2:
The control system dynamically adjusts multiple parameters including individual proprotor tilt angles, rotation speeds, and thrust vectors. By changing these parameters independently for each proprotor, the aircraft achieves both efficient vertical thrust and precise hover control without requiring the wing to be in a fixed vertical orientation.
3Adaptability or versatility
If aircraft use distributed propulsion system with independently controllable assemblies, then omnidirectional ground maneuver capability is improved, but device complexity increases
Solution Approach 1:
Each proprotor assembly is designed as a universal unit capable of performing multiple functions: generating vertical lift, providing forward thrust, enabling lateral movement, and facilitating omnidirectional ground maneuvers. This multi-functionality is achieved through the tilt rotation capability and independent control of each proprotor, allowing a single configuration type to replace what would otherwise require multiple specialized systems.
Solution Approach 2:
The invention merges the functions of lift generation, propulsion, and steering into a single integrated proprotor assembly. By combining the rotor, tilt mechanism, and control systems into one unified unit, the aircraft reduces overall system complexity compared to having separate systems for each function, while still achieving omnidirectional ground maneuver capability.
Data Source
AI summary
An aircraft having omnidirectional ground maneuver capabilities. The aircraft includes an airframe and a plurality of propulsion assemblies attached to the airframe. Each of the propulsion assemblies includes a nacelle having a mast axis, a rotor assembly having a tilting degree of freedom relative to the mast axis and a tail assembly rotatable about the mast axis. The tail assembly includes at least one wheel having a rotational axis. A flight control system is operable to independently control each of the propulsion assemblies including tilting each rotor assembly and rotating each tail assembly. For each propulsion assembly, the rotor assembly and the tail assembly have complementary configurations in which a thrust vector generated by the rotor assembly has a horizontal component that is generally perpendicular to the rotational axis of the wheel, thereby enabling omnidirectional ground maneuvers.