Rotating Wing Tip Device for Ground Clearance and Aerodynamic Efficiency
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Solution Overview
Problem
The length of downwardly extending wing tip devices on aircraft is limited by airport operating rules governing clearances, which restricts their use for both flight and ground operations, necessitating a configuration that balances aerodynamic benefits with ground clearance requirements.
Innovation Solution
A wing tip device that can be configured between a high-altitude cruise mode with downward extension and a ground-operating mode with rearward extension, allowing for increased ground clearance while maintaining aerodynamic benefits, using a moveable region that rotates about an axis out of the wing tip device plane to adjust its position and reduce effective span.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a long downwardly extending wing tip device is used to improve aerodynamic performance, then induced drag is reduced and lift is increased, but ground clearance is insufficient for airport operating rules
Solution Approach 1:
The wing tip device is made movable between a downwardly extending configuration during flight to reduce induced drag and a rearwardly extending configuration on the ground to increase ground clearance. This dynamic reconfiguration allows the same device to satisfy both aerodynamic performance requirements and airport operating rules.
Solution Approach 2:
The wing tip device transitions from extending in the vertical dimension (downwardly) during flight to extending in the horizontal dimension (rearwardly) on the ground. This dimensional change allows the device to maintain its aerodynamic function while complying with ground-based clearance restrictions.
2Force
If a long downwardly extending wing tip device is used to improve aerodynamic performance, then lift is increased, but the effective span increases violating airport clearance rules
Solution Approach 1:
The wing tip device is made movable between a downwardly extending configuration during flight to increase lift and a rearwardly extending configuration on the ground to decrease effective span. This dynamic reconfiguration allows the same device to satisfy both aerodynamic performance requirements and airport operating rules.
3Length of stationary object
If upwardly extending (dihedral) wing tip devices are used to avoid ground clearance issues, then airport clearance rules are satisfied, but aerodynamic performance is reduced compared to downwardly extending devices
Solution Approach 1:
The wing tip device is made movable between a downwardly extending configuration during flight to reduce induced drag and a rearwardly extending configuration on the ground to increase ground clearance. This dynamic reconfiguration allows the same device to satisfy both aerodynamic performance requirements and airport operating rules, overcoming the limitation of fixed upwardly extending devices.
Data Source
AI summary
An aircraft including a wing, the end of the wing having a wing tip device, wherein the wing tip device includes a moveable region that is rotatable, about an axis of rotation extending out of the plane of the wing tip device, between: (i) a high-altitude cruise configuration in which the moveable region extends downwardly below the wing; and (ii) a ground-operating configuration in which the moveable region extends rearwardly behind the wing such that the ground clearance of the wing tip device is increased.