Length-Adjustable Link for Tiltrotor Blade Transition Control
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Solution Overview
Problem
Tiltrotor aircraft face limitations in maximum airspeed during forward flight due to forward airspeed induced proprotor aeroelastic instability, which restricts their high-speed cruising capabilities.
Innovation Solution
The implementation of a length adjustable link and a transitioning mechanism that allows the tiltrotor aircraft to switch between rotary and non-rotary flight modes, utilizing a swash plate, pitch link, pitch horn, crank, and blade lock assemblies to adjust the angle of rotor blades, enabling efficient transition from helicopter mode to airplane mode, thereby overcoming aeroelastic instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tiltrotor aircraft use proprotors for forward flight, then vertical takeoff and landing capability is maintained, but maximum airspeed is limited due to proprotor aeroelastic instability
Solution Approach 1:
The patent applies dynamics by making the proprotor blade length adjustable during flight. The blade length changing mechanism allows the rotor blade to transition between different effective lengths, enabling the aircraft to overcome aeroelastic instability at high speeds while maintaining vertical flight capability. This dynamic adjustment resolves the contradiction by adapting the blade configuration to different flight regimes.
Solution Approach 2:
The patent changes the physical parameter of proprotor blade length to resolve the speed limitation. By adjusting the blade length parameter, the aircraft can operate at higher forward speeds without experiencing aeroelastic instability, thus improving maximum airspeed while maintaining the versatility of proprotor-based flight modes.
2Device complexity
If proprotor blade length is fixed, then structural simplicity is maintained, but aeroelastic instability occurs at high forward airspeeds
Solution Approach 1:
The patent transforms the static proprotor blade into a dynamic structure with adjustable length. The blade length changing mechanism, including components like the internal adjuster member and threading mechanisms, allows the blade to adapt its length based on flight conditions, improving airspeed stability while accepting increased structural complexity.
Solution Approach 2:
The patent employs a nested structure where the internal adjuster member is positioned within the proprotor blade structure. The threading mechanism and rod ends are nested within the blade assembly, allowing compact integration of the length adjustment functionality without excessive external complexity.
3Reliability
If a length adjustable mechanism is added to the proprotor, then aeroelastic instability is overcome, but device complexity increases
Solution Approach 1:
The patent reduces the impact of added complexity by nesting the adjustment mechanism components within the existing blade structure. The internal adjuster member, threading mechanisms, and rod ends are integrated into the blade assembly, minimizing external additions while achieving the function of variable length adjustment for improved airspeed stability.
Solution Approach 2:
The patent implements a self-adjusting mechanism where the threading system and rod ends automatically adjust the blade length based on operational requirements. The internal adjuster member works with the threading mechanisms to provide automatic length adjustment, reducing the need for complex external control systems and minimizing overall device complexity.
Data Source
AI summary
An exemplary length adjustable link includes a tube having an internal bore and internal surface, a first rod end having a first shaft disposed in a first end of the internal bore, a second rod end having a second shaft disposed in a second end of the internal bore, and a member threadably connecting the first rod end to the second rod end.