VTOL Ejector Thrust Augmentation and Force Balance
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Solution Overview
Problem
VTOL aircraft face challenges in engine sizing and force balance, particularly during horizontal flight, where thrust requirements are smaller but engine weight is excessive, and achieving balance is difficult due to concentrated thrust sources.
Innovation Solution
The use of thrust augmentation systems with ejectors/thrusters designed to produce 2-3 times the thrust of conventional turbojets, combined with a closed wing shroud for additional thrust, and distributed thrust across multiple locations on the aircraft, allowing for improved thrust-to-weight ratio and force balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high thrust-to-weight ratio engine is used to achieve vertical take-off, then the aircraft can achieve VTOL capability, but the engine weight becomes excessive for horizontal flight where thrust requirements are smaller
Solution Approach 1:
The propulsion system is divided into multiple independent thrust sources distributed at different locations on the aircraft. Instead of relying on a single large engine, the system uses several smaller thrust generators (jets, rockets, or propellers) positioned at strategic locations to provide both vertical lift and horizontal propulsion, resolving the contradiction between needing high thrust for VTOL and avoiding excessive engine weight for cruise flight.
Solution Approach 2:
The thrust generation capability is made dynamic and adjustable. Each thrust source can be independently controlled to vary its output, allowing the aircraft to optimize its total thrust for different flight phases - using all thrust sources at high power for VTOL, and selectively reducing or shutting down certain sources during horizontal cruise to match lower thrust requirements and reduce effective engine weight.
2Device complexity
If thrust is concentrated in one location (e.g., rear portion), then the engine design is simplified, but the aircraft cannot maintain balance during flight due to unbalanced moments around the center of mass
Solution Approach 1:
The single concentrated thrust source is segmented into multiple distributed thrust sources located at different positions on the aircraft - including front, rear, and lateral positions. This segmentation allows the system to generate balanced moments around the center of mass by coordinating the thrust output from each location, thereby achieving stable flight without the complexity of a single large engine while maintaining balance control.
Solution Approach 2:
Different locations on the aircraft are assigned different thrust-generating elements with specific characteristics suited to their positions. For example, smaller jets or propellers are placed at the nose and wings for balance and control, while larger thrust sources may be positioned at the rear for primary propulsion. Each local thrust source is optimized for its specific role, achieving overall balance while simplifying individual component design.
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
This solution enables VTOL aircraft to achieve level flight with reduced engine load, increased maneuverability, and efficient propulsive performance, with thrust augmentation exceeding the aircraft's weight, allowing for faster acceleration and reduced fuel consumption, while maintaining balance and control.
Implementation Method 1
The use of thrust augmentation systems with ejectors/thrusters designed to produce 2-3 times the thrust of conventional turbojets
Implementation Method 2
ejectors/thrusters themselves are designed to allow for augmentation exceeding 2:1
Implementation Method 3
combined with a closed wing shroud for additional thrust
Implementation Method 4
Balance is one of the most important drivers for the design of a VTOL aircraft. During the take-off phase, the thrust has to be distributed around the aircraft, and moments are balanced around the center of mass
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A vehicle, includes a main body. A fluid generator is coupled to the main body and produces a fluid stream.. At least one fore conduit and at least one tail conduit are fluidly coupled to the generator. First and second fore ejectors are fluidly coupled to the fore conduit, coupled to the main body and respectively coupled to a starboard side and port side of the vehicle. The fore ejectors respectively comprise an outlet structure out of which fluid flows. At least one tail ejector is fluidly coupled to the tail conduit. The tail ejector comprises an outlet structure out of which fluid flows. A primary airfoil element is coupled to the tail portion. A surface of the primary airfoil element is located directly downstream of the first and second fore ejectors such that the fluid from the first and second fore ejectors flows over the such surface.