Hybrid Helicopter Longitudinal Trim Control via Rotor Pitch
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Solution Overview
Problem
Existing rotorcraft technologies face challenges in achieving long-range, high-speed cruising flight while maintaining efficient vertical flight capabilities, often resulting in complex, heavy, and costly designs that do not optimize lift and drag ratios.
Innovation Solution
A hybrid helicopter with an integrated drive system featuring a mechanical interconnection between a rotor with collective and cyclic pitch control and a propeller, along with a turbine engine, allows for adaptive pitch control surfaces and automatic adjustment of cyclic pitch to optimize longitudinal trim and reduce parasitic drag, enabling efficient high-speed cruising while maintaining lift during vertical flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional helicopter design is used, then vertical flight capability is maintained, but forward speed and range are limited
Solution Approach 1:
The rotor system dynamically transitions between powered rotation for vertical flight and autorotation for forward flight. The rotor blades automatically adjust their pitch angle based on flight conditions, enabling the helicopter to operate efficiently in both vertical and forward flight regimes without requiring complex mechanical reconfiguration
Solution Approach 2:
The invention changes the operational parameters of the rotor system by controlling blade pitch angles. In vertical flight, blades maintain a pitch angle that generates lift from powered rotation. In forward flight, the pitch angle is automatically reduced to enable autorotation, where the rotor acts more like a windmill, capturing energy from the forward motion to maintain rotation
2Force
If rotor speed is increased for vertical flight, then lift is improved, but parasitic drag increases during forward flight
Solution Approach 1:
The rotor blade pitch angles are dynamically adjusted based on flight phase. During vertical flight, blades are at a higher pitch angle to maximize lift generation from powered rotation. During forward flight, the pitch angle is automatically reduced, allowing the rotor to operate in autorotation mode where parasitic drag is minimized while still generating necessary lift
Solution Approach 2:
The system incorporates feedback mechanisms that monitor flight conditions and automatically adjust rotor blade pitch angles. This feedback control ensures that the rotor operates at optimal pitch angles for each flight phase, automatically reducing parasitic drag during forward flight while maintaining sufficient lift
3Productivity
If complex control systems are added to optimize performance, then flight performance improves, but device complexity and cost increase
Solution Approach 1:
The rotor control system operates autonomously by exploiting aerodynamic feedback. The rotor blades automatically adjust their pitch angles based on the flight conditions without requiring complex external control systems. The system self-regulates by converting the helicopter's forward motion into rotational energy during autorotation, eliminating the need for complex powered control mechanisms
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 hybrid helicopter achieves exceptional performance by minimizing parasitic drag, maintaining a high lift/drag ratio, and reducing fatigue on the rotor mast, allowing for long-range flights at high speeds without the need for an antitorque rotor, thus optimizing power balance and reducing weight and cost.
Implementation Method 1
a rotor (10) with collective pitch and cyclic pitch control of the blades of said rotor
Implementation Method 2
at least one solely-propulsive propeller (6) with collective pitch control of the blades of said propeller
Implementation Method 3
at least one turbine engine (5) driving the mechanical interconnection system
Data Source
AI summary
A hybrid helicopter includes an airframe provided with a fuselage and a lift-producing surface together with stabilizer surfaces and a drive system including:a mechanical interconnection system between a rotor of radius (R) with collective pitch and cyclic pitch control of the blades of the rotor and at least one propeller with collective pitch control of the blades of the propeller; andat least one turbine engine driving the mechanical interconnection system. The hybrid helicopter includes first members for controlling the angle at which the at least one pitch control surface is set as a function of the bending moment exerted on the rotor mast relative to the pitch axis of the hybrid helicopter, and second members for controlling the cyclic pitch of the blades of the rotor in order to control the longitudinal trim of the hybrid helicopter as a function of flight conditions.