Helicopter Tailplane Appendages for Low-Speed Nose-Up Control
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Solution Overview
Problem
Existing helicopter designs face challenges in achieving optimal aerodynamic behavior of the tailplane, particularly in low-speed conditions, where the downward airflow from the main rotor causes a nose-up attitude, complicating flight control and visibility, and existing solutions fail to balance longitudinal stability with reduced surface exposure to downward airflow effectively.
Innovation Solution
The helicopter design incorporates a tailplane with stabilizers featuring appendages that are spaced from the fuselage and tilted at specific angles, generating additional aerodynamic forces while minimizing interference, and includes Gurney flaps to enhance lift generation without increasing bulk or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large tailplane surface is used, then longitudinal stability in forward flight is improved, but nose-up attitude in low-speed conditions worsens
Solution Approach 1:
The tailplane surface area is made variable through a movable stabilizer that can change its projection area dynamically. In forward flight, the stabilizer extends to provide large surface area for longitudinal stability. In low-speed conditions, the stabilizer retracts to reduce surface area and minimize nose-up attitude, thus resolving the contradiction between stability and ease of operation.
Solution Approach 2:
The effective tailplane surface area parameter is changed based on flight conditions. By adjusting the stabilizer position, the surface area parameter varies between large (for stability in forward flight) and small (to reduce nose-up attitude in low-speed conditions), allowing the system to optimize performance across different operating regimes.
2Stability of the object's composition
If a large tailplane surface is used, then longitudinal stability in forward flight is improved, but visibility during landing worsens
Solution Approach 1:
The stabilizer dynamically adjusts its configuration based on flight phase. During landing approach, the stabilizer retracts to minimize tailplane surface area and nose-up attitude, improving pilot visibility. In forward flight, it extends to provide adequate longitudinal stability, thus resolving the contradiction between stability and visibility.
3Stability of the object's composition
If a large tailplane surface is used, then longitudinal stability in forward flight is improved, but maneuverability in low-speed conditions worsens
Solution Approach 1:
The variable surface area of the stabilizer enables the helicopter to adapt to different maneuvering requirements. In low-speed conditions requiring high maneuverability, the stabilizer retracts to minimize aerodynamic interference. In forward flight requiring stability, the stabilizer extends, thus resolving the contradiction between stability and maneuverability.
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 enhances longitudinal stability at high speeds and reduces the nose-up attitude in low-speed conditions, improving pilot comfort and visibility during landing operations by minimizing the impact of downward airflow, while maintaining efficient aerodynamic performance.
Implementation Method 1
The tailplane is configured as a wing profile that generates, when the helicopter is in forward flight, a first aerodynamic force, lift/negative lift, with a main component directed parallel to the first axis
Implementation Method 2
the main rotor is adapted to provide the lift necessary to sustain the helicopter in the air and to allow the forward/backward and lateral movement of the helicopter
Implementation Method 3
The tail rotor is instead adapted to counter the rotation of the helicopter that would be caused by the reaction torque transmitted to the fuselage by operation of the main rotor
Data Source
AI summary
A helicopter is described comprising a fuselage elongated along a first axis and extending between a nose and a tail boom; a tailplane with a pair of first aerodynamic surfaces elongated along a second axis; the first and second axis define a first plane; the helicopter comprises a pair of elements transversal to the first aerodynamic surfaces; and a pair of second aerodynamic surfaces generating respective second aerodynamic forces, connected to first elements, and facing and spaced from respective first aerodynamic surfaces; each second aerodynamic surface comprises one first root end connected to the respective said element, a second free end spaced from said tail boom, a first leading edge, a first trailing edge opposite to said first leading edge, a first chord at said first root end and a second chord at said second free end parallel to said first axis; the first and the second chord define a second plane tilted with respect to said first plane.