Damping Sublayer for Tiltrotor Wing Stability
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Solution Overview
Problem
Tiltrotor aircraft experience instability and structural issues due to forward airspeed-induced proprotor aeroelastic instability, such as proprotor whirl flutter, which limits their maximum airspeed and performance.
Innovation Solution
Incorporating a damping sublayer between the outer skin and the wing airframe core assembly, made from elastomeric materials like rubber compounds with a high loss tangent, to reduce wing deflections and stabilize the wing during forward flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wing is designed to be stiff and light to prevent aeroelastic coupling, then wing stability is improved, but the maximum airspeed is limited due to proprotor aeroelastic instability
Solution Approach 1:
The patent changes the physical parameters of the wing structure by introducing a damping layer with specific material properties (loss tangent, damping coefficient) between the wing skin and core assembly. This modifies the wing's vibrational characteristics and natural frequencies to prevent resonance with proprotor instability, thereby enabling higher airspeeds while maintaining stability.
Solution Approach 2:
The patent employs composite material construction by combining the wing skin, damping layer (made of elastomeric or viscoelastic materials), and core assembly into a multi-layer composite structure. This composite approach allows the damping layer to selectively absorb vibrational energy while the overall structure maintains the required stiffness and light weight for aerodynamic performance.
2Reliability
If a damping sublayer is added to reduce wing deflection, then wing stability at high airspeed is improved, but the device complexity increases
Solution Approach 1:
The damping sublayer is nested between the wing skin and the core assembly, creating a compact multi-layer structure where each component is integrated within the existing wing architecture. This nesting approach adds the damping function without requiring external attachments or significantly increasing overall structural complexity.
Solution Approach 2:
The damping sublayer is implemented as a thin film or layer with flexible elastomeric or viscoelastic material properties. This thin-film approach provides effective damping while minimizing the additional thickness and complexity of the wing structure, allowing easy integration into the existing airframe 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
The damping sublayer effectively reduces wing deflection and vibration, enhancing stability and allowing tiltrotor aircraft to operate at higher airspeeds without structural failure, thereby improving performance and safety.
Implementation Method 1
The damping sublayer reduces the deflection of the wing, thereby stabilizing the wing during forward flight
Implementation Method 2
the damping sublayer may include an elastomeric material. In some embodiments, the elastomeric material may include a rubber compound having a loss tangent greater than natural rubber
Data Source
AI summary
A wing airframe for a wing of a tiltrotor aircraft includes a wing airframe core assembly and a wing skin assembly disposed on the wing airframe core assembly. The wing skin assembly includes an outer skin and a damping sublayer, the damping sublayer interposed between the outer skin and the wing airframe core assembly. The tiltrotor aircraft includes a pylon assembly subject to aeroelastic movement during forward flight. The wing is subject to deflection in response to the aeroelastic movement of the pylon assembly. The damping sublayer reduces the deflection of the wing, thereby stabilizing the wing during forward flight.