Rotary Wing Pitching Stabilizer Wake Configuration
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Solution Overview
Problem
Conventional helicopters experience the attitude hump phenomenon at low speeds due to air deflection from the main rotor impacting the pitching-stabilizer means, leading to nose-up attitudes and stabilization challenges, which are exacerbated by maximizing wing area for stabilizer effectiveness.
Innovation Solution
The method involves placing lower pitching-stabilizer means in the wake of upper stabilizer means, creating an aerodynamic shadow zone to minimize air impact, using at least two stabilizer means with the lower one positioned downstream of the upper, and optimizing their geometry to reduce wing area and offset trailing edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wing area of pitching-stabilizer means is maximized to improve stabilizing effectiveness, then the stabilizing effect increases, but the attitude hump phenomenon is accentuated
Solution Approach 1:
The pitching-stabilizer means is divided into an upper stabilizer surface and a lower stabilizer surface, with the lower surface positioned in the wake of the upper surface. This segmentation allows the lower surface to benefit from the wake effect that reduces air impact and attitude hump, while both surfaces together provide sufficient stabilizing effectiveness.
Solution Approach 2:
The invention introduces a vertical dimension to the stabilizer configuration by placing stabilizer surfaces at different heights (upper and lower). The lower stabilizer surface is positioned in the wake region created by the upper surface, utilizing the vertical spacing to exploit wake effects for reducing attitude hump while maintaining stabilizing force.
2Reliability
If pitching-stabilizer means with large wing area is used to improve low-speed stability, then stabilizing effect is maximized, but pilot workload increases due to attitude hump compensation requirements
Solution Approach 1:
By segmenting the stabilizer into upper and lower surfaces with the lower surface in the wake, the configuration provides adequate stabilizing effect at low speeds without generating excessive attitude hump, thereby reducing the pilot's compensation workload while maintaining stability.
3Reliability
If the wing area of pitching-stabilizer means is increased to enhance stabilizing effectiveness, then the stabilizing effect is improved, but the device complexity increases
Solution Approach 1:
The stabilizer is segmented into upper and lower surfaces, which can be implemented as separate components or integrated into the fuselage structure. This segmentation provides the wake effect benefit while allowing flexible design integration that can manage structural complexity.
Solution Approach 2:
The upper and lower stabilizer surfaces can be merged with the fuselage structure or other aircraft components, integrating the stabilizing function into the existing airframe design rather than adding completely separate components, thereby managing overall device complexity.
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 configuration reduces the attitude hump phenomenon by minimizing direct air impact on the lower stabilizer means, stabilizing the aircraft without increasing wing area, thus improving control and reducing pilot workload during low-speed operations.
Implementation Method 1
each lower stabilizer means is placed in a wake from said upper stabilizer means as generated by a stream of air passing through said rotary wing and impacting against the upper surface of the upper stabilizer means
Data Source
AI summary
A system and method of minimizing the attitude hump phenomenon of a rotary wing aircraft is provided. The rotary wing aircraft includes upper pitching-stabilizer and at least one lower pitching-stabilizer. The lower stabilizer is positioned in a wake of the upper stabilizer generated by a stream of air passing through the rotary wing and impacting against the upper surface of the upper stabilizer.