Compound Helicopter Asymmetric Wings for Rotor Interference Reduction
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Solution Overview
Problem
The aerodynamic interference between the rotor and fixed wings in compound helicopters reduces flight efficiency by increasing drag and requiring additional power, and cyclic pitch control further exacerbates this issue by reducing the lift-drag ratio.
Innovation Solution
The system employs asymmetric fixed wings and reduces the cyclic pitch control operation to allow a lift difference between the advancing and retreating sides of the rotor, combined with asymmetric wing configurations to minimize aerodynamic interference, thereby balancing the rolling moments and optimizing lift and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If cyclic pitch control is performed to equalize lift between advancing and retreating sides, then flight stability is improved, but lift-drag ratio decreases and flight efficiency deteriorates
Solution Approach 1:
The patent applies asymmetry by making the fixed wings asymmetric to each other. Specifically, the right fixed wing (on the retreating side) has a larger wingspan than the left fixed wing (on the advancing side). This asymmetric configuration compensates for the lift difference between advancing and retreating sides without requiring cyclic pitch control, thereby maintaining flight stability while preserving the lift-drag ratio and improving flight efficiency.
2Stability of the object's composition
If cyclic pitch control is performed to eliminate lift difference between advancing and retreating sides, then aerodynamic balance is improved, but additional power is required and flight efficiency deteriorates
Solution Approach 1:
The patent employs asymmetric fixed wings where the right fixed wing has a larger wingspan than the left fixed wing. This geometric asymmetry creates a deliberate lift difference that counterbalances the aerodynamic interference from the rotor, achieving aerodynamic balance without cyclic pitch control. Consequently, additional power consumption is eliminated and flight efficiency is improved.
Solution Approach 2:
The patent converts the harmful aerodynamic interference from the rotor into a beneficial effect. By making the right fixed wing larger, the patent utilizes the stronger downwash from the retreating side to generate additional lift on that side, thereby balancing the overall aerodynamic forces without requiring additional power input or cyclic pitch control.
3Ease of manufacture
If symmetric fixed wings are used, then manufacturing simplicity is maintained, but aerodynamic interference from rotor increases drag and reduces flight efficiency
Solution Approach 1:
The patent transitions from symmetric to asymmetric fixed wings, where the right fixed wing has a larger wingspan than the left. This asymmetric design, while slightly more complex to manufacture, significantly reduces aerodynamic interference drag by balancing the lift distribution. The improved aerodynamic efficiency results in reduced drag and better flight performance, justifying the moderate increase in manufacturing 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 improves flight efficiency by reducing the need for additional power and maintaining stable flight attitudes without pilot intervention, enhancing the lift-drag ratio and aerodynamic performance.
Implementation Method 1
influence of an aerodynamic interference between the rotor and the fixed wings is reduced
Implementation Method 2
Lift that supports the weight of the compound helicopter is generated by the rotor in hovering, while in forward flight it is generated by the fixed wings as well as the rotor
Data Source
AI summary
Provided is a flight efficiency improving system for a compound helicopter with a rotor and fixed wings. In forward flight of the compound helicopter, the flight efficiency improving system does not perform a cyclic pitch control of the rotor so as to allow a difference in lift generated by the rotor between an advancing side and a retreating side of the rotor, or the flight efficiency improving system performs the cyclic pitch control to an extent that does not completely eliminate the difference. The fixed wings are provided respectively on left and right sides of a body and are asymmetric to each other so that influence of an aerodynamic interference between the rotor and the fixed wings is reduced.