Thrust Vectorable Propulsor for Aircraft Drag and Lift Management
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Solution Overview
Problem
Conventional aircraft designs face inefficiencies in structural, aerodynamic, and fuel efficiency, particularly in takeoff and landing configurations due to the limitations of propulsor arrangements, which result in high thrust, reduced lift at low power, and increased drag, as well as the need for high-speed approaches and deadweight airbrakes.
Innovation Solution
An aircraft equipped with a thrust vectorable propulsor that can switch between providing forward thrust and drag, ingesting boundary layer airflow, and a deployable high-lift device, allowing for efficient lift during landing and reduced fuel burn in other flight stages, while also reducing the size of control surfaces and tail volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If propulsors are positioned to provide high thrust during takeoff and landing, then lift capability is improved, but drag increases during cruise flight
Solution Approach 1:
The propulsor thrust vector angle is made variable to dynamically adjust between providing forward thrust during cruise and generating drag during landing. The thrust vectorable propulsor configured to selectively vary the exhaust efflux vector between a first mode providing net forward thrust and a second mode providing net drag, resolving the contradiction between needing high thrust for lift and minimizing drag for efficient cruise
2Speed
If airbrakes are deployed to increase drag during landing, then deceleration capability is improved, but aircraft performance deteriorates during the remainder of flight due to deadweight
Solution Approach 1:
The thrust vectorable propulsor serves multiple functions: it provides forward thrust during cruise, generates drag during landing to replace airbrakes, and can be vectored to provide lift assistance. This multi-functionality eliminates the need for dedicated airbrakes that would be deadweight during other flight phases
3Force
If flaps are deployed to increase lift during landing, then lift capability is improved, but nose-down pitching moment increases requiring larger control surfaces
Solution Approach 1:
The thrust vectorable propulsor provides an upward force component that counteracts the nose-down pitching moment generated by flap deployment. By vectoring the propulsor thrust upward, the system compensates for the adverse pitching moment, allowing smaller control surfaces to suffice
4Use of energy by moving object
If propulsors ingest boundary layer air to increase propulsive efficiency, then fuel efficiency is improved, but thrust generation capability is reduced
Solution Approach 1:
The propulsor system dynamically adjusts its operating mode based on flight phase: during cruise it ingests boundary layer air for high propulsive efficiency, while during takeoff and landing it ingests freestream air for maximum thrust generation. This dynamic operation resolves the contradiction between efficiency and power
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enables high-lift capability at low speeds, reduced fuel consumption, and increased operational flexibility by providing additional drag when needed and forward thrust when efficient, without representing deadweight, and allows for smaller control surfaces due to vectorable thrust compensation.
Implementation Method 1
Boundary layer air extends from a wetted surface to a thickness normally defined as the distance from the wetted surface at which the viscous flow velocity is 99% of the freestream velocity (the surface velocity of an inviscid flow). Consequently, boundary layer air moves more slowly than the freestream flow. As such, the propulsors will accelerate the airflow to a greater extent for the same exhaust velocity, thereby increasing propulsive efficiency.
Data Source
AI summary
An aircraft including trailing edge flaps, a wing mounted propulsor positioned such that the flaps are located in a slipstream of the first propulsor in use when deployed. The aircraft further including a thrust vectorable propulsor configured to selectively vary the exhaust efflux vector of the propulsor in at least one plane. The thrust vectorable propulsor includes a ducted fan configurable between a first mode, in which the fan provides net forward thrust to the aircraft, and a second mode in which the fan provides net drag to the aircraft. The fan is positioned to ingest a boundary layer airflow in use when operating in the first mode.