Pivoting Nacelle Mechanism for VTOL Rotor Flapping Reduction
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Solution Overview
Problem
VTOL aircraft face challenges in reducing rotor flapping during maneuvers due to dissymmetry of lift, which affects maneuverability and efficiency, particularly in transitioning between airplane and helicopter modes.
Innovation Solution
The implementation of a nacelle pivot mechanism that allows the rotor tip path plane to change relative to the rotor axis, reducing flapping requirements by allowing the nacelle to pivot relative to the wing, with a damper limiting the pivot angle to prevent overrotation and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotor tip path plane is changed to perform maneuvers, then maneuverability is improved, but rotor flapping increases due to dissymmetry of lift
Solution Approach 1:
The nacelle serves as an intermediary component between the rotor and the aircraft fuselage. By allowing the nacelle to pivot independently on a hinge axis, it mediates the forces generated by rotor flapping, absorbing these forces through the pivot mechanism rather than transmitting them directly to the aircraft structure, thus reducing the harmful effects of dissymmetry of lift during maneuvers
2Stability of the object's composition
If the nacelle is made rigidly fixed to the wing, then structural stability is improved, but maneuverability deteriorates due to increased rotor flapping
Solution Approach 1:
The nacelle mounting transitions from a static rigid connection to a dynamic pivoting connection. The hinge axis allows the nacelle to rotate dynamically in response to aerodynamic forces during maneuvers, enabling the structure to adapt its configuration based on operational conditions, thus maintaining both stability and maneuverability
3Object-generated harmful factors
If the nacelle pivot angle is increased to reduce flapping, then rotor flapping is reduced, but aircraft stability deteriorates due to excessive nacelle movement
Solution Approach 1:
The pivot angle of the nacelle is optimized to specific parameter ranges that balance flapping reduction with stability maintenance. By controlling the nacelle's rotational movement within defined angular limits, the system achieves sufficient flapping compensation during maneuvers while preventing excessive nacelle movement that would compromise aircraft stability
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 enhances maneuverability and reduces rotor flapping, improving the aircraft's ability to perform yaw and roll maneuvers with reduced thrust component changes, thereby increasing operational efficiency and stability.
Implementation Method 1
the nacelle pivots relative to the wing about a nacelle hinge axis to reduce flapping required by the rotor
Implementation Method 2
a damper is operably connected to the wing and to the nacelle to limit a pivot angle of the nacelle relative to the wing
Data Source
AI summary
An aircraft includes a fuselage and a wing extending from each lateral side of the fuselage. A nacelle is pivotably se cured to each wing. The nacelle has a rotor located thereat, with the rotor having a rotor tip path plane defined by rotation of the rotor about a rotor axis of rotation. When the rotor tip path plane is changed relative to the wing, the nacelle pivots relative to the wing about a nacelle hinge axis to reduce flapping required by the rotor. A method of operating an aircraft includes changing a rotor tip path plane orientation relative to a wing of the aircraft. The rotor disposed at a nacelle, with the nacelle pivotably secured to the wing. The nacelle is pivoted relative to the wing to reduce an overall tip path plane change requirement of the rotor.