Auxiliary Propulsive System for Compound Helicopter Speed
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Solution Overview
Problem
Conventional single rotor helicopters are limited by retreating blade stall, which restricts their top speed, and compound helicopter designs attempting to overcome this issue face challenges with performance, stability, control, safety, and reliability.
Innovation Solution
A fully compounding rotorcraft design incorporating wings for lift compounding and an auxiliary propulsive system for propulsion compounding, featuring a twin boom configuration, empennage, anti-torque system, and a hybrid turboshaft and turbofan engine with a pneumatic thruster system or ducted fans to offload lift and thrust requirements from the main rotor, enhancing forward airspeed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional single rotor helicopters increase forward airspeed, then retreating blade stall occurs causing loss of lift, but adding wings and auxiliary propulsive systems increases device complexity
Solution Approach 1:
The helicopter is divided into distinct functional modules: main rotor system for vertical lift, wing components for lift compounding, auxiliary propulsive system for thrust compounding, and twin boom structure for structural support. This segmentation allows each component to be optimized independently while working together to resolve the retreating blade stall limitation.
Solution Approach 2:
The auxiliary propulsive system serves multiple functions: providing additional thrust during forward flight to overcome retreating blade stall, enabling higher top speeds, and potentially providing thrust during hover or low-speed operations. The wing structure similarly provides both lift compounding and structural support functions.
2Speed
If auxiliary propulsive system is added to offload thrust requirement, then forward airspeed increases, but performance, stability, control, safety and reliability remain elusive
Solution Approach 1:
The patent combines multiple propulsion sources (main rotor thrust and auxiliary propulsive system thrust) into a unified propulsion system. The control system integrates both thrust sources to work together, allowing the auxiliary system to offload thrust requirements while maintaining overall flight stability through coordinated control of both propulsion sources.
Solution Approach 2:
The control system incorporates feedback mechanisms to monitor flight conditions and adjust the auxiliary propulsive system operation accordingly. This allows the system to maintain stability by dynamically balancing the contribution of the main rotor and auxiliary propulsion based on real-time flight state, ensuring reliable operation at higher speeds.
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 design allows for increased forward airspeed while maintaining stability and reducing vibration and structural instability, achieving high-speed flight with improved ride quality and reduced acoustic signature.
Implementation Method 1
An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight
Implementation Method 2
first and second wings coupled thereto and configured to provide lift compounding responsive to forward airspeed
Implementation Method 3
An anti-torque system includes a tail rotor rotatably coupled to the empennage
Data Source
AI summary
A fully compounding rotorcraft includes a fuselage having first and second wings extending therefrom and configured to provide lift compounding responsive to forward airspeed. A twin boom includes first and second tail boom members that extend aftward from the first and second wings. An empennage is coupled between the aft ends of the tail boom members. An anti-torque system includes a tail rotor that is rotatably coupled to the empennage. An engine is disposed within the fuselage and is configured to provide torque to a main rotor assembly via an output shaft and a main rotor gearbox. An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight, thereby providing propulsion compounding to increase the forward airspeed of the rotorcraft.