Rotorcraft Autorotation Training Control for Safe Rotor Speed Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing autorotation training in rotorcrafts is challenging due to critical issues such as height loss during engine power recovery, lack of escape possibilities for instructors, and potential main rotor speed drops during landing, which can lead to structural damage and safety risks.
Innovation Solution
A rotorcraft with an autorotation training mode control system that allows for safe and controlled autorotation training by engaging a dedicated autorotation mode, where the engine free turbine speed is decreased to a predefined lower value, enabling the flight student to desynchronize the main rotor while maintaining safe rotational speeds, and includes automatic disengagement criteria to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If engines are set to IDLE condition for steady autorotation training, then autorotation can be performed, but height loss of almost 700 ft occurs before recovering full power
Solution Approach 1:
The control system is configured to automatically manage engine power recovery during autorotation training, pre-programming the power restoration sequence to minimize height loss. The system monitors rotor RPM and automatically advances engine power from idle to flight condition within optimized parameters, eliminating the 700ft height loss associated with manual power recovery.
2Reliability
If flight instructor takes hands off controls to set engines to FLIGHT condition, then power recovery is achieved, but training effectiveness decreases
Solution Approach 1:
The autorotation training control system is designed to automatically manage engine power recovery without requiring flight instructor intervention. The system self-monitors rotor RPM, automatically advances engine power from idle to flight condition, and maintains optimal performance throughout the transition, allowing the instructor to remain hands-on with training activities.
Solution Approach 2:
The manual mechanical control of engine power by the flight instructor is replaced with an automated electronic control system. The system uses sensors to monitor rotor RPM and electronically controls engine power settings, substituting the manual mechanical process with an automated electronic system that achieves the same power recovery function while maintaining training effectiveness.
3Reliability
If collective controls are lowered to desynchronize main rotor, then autorotation can be initiated, but inadvertent re-synchronization or exceedances into high transient range may occur
Solution Approach 1:
The control system continuously monitors main rotor RPM and provides real-time feedback to automatically adjust collective control settings. When rotor RPM approaches the narrow band from 100% to 107.5%, the system detects this condition and automatically adjusts controls to prevent inadvertent re-synchronization or high transient range exceedances, ensuring precise rotor speed control throughout the autorotation process.
4Adaptability or versatility
If full autorotation training is conducted below 700 ft, then realistic training is achieved, but escape possibility is completely lost
Solution Approach 1:
The control system is configured with pre-programmed safety parameters that automatically activate when training occurs below 700 ft. The system monitors altitude and autorotation parameters, and if unsafe conditions are detected, automatically initiates power recovery or other corrective actions to provide an escape option, cushioning against the complete loss of safety margins inherent in low-altitude full autorotation training.
5Reliability
If main rotor rotational speed drops during slide phase after landing, then autorotation is complete, but lead/lag resonances may occur causing structural damage
Solution Approach 1:
The control system continuously monitors main rotor RPM during and after the slide phase. When rotor speed approaches critical values that could induce lead/lag resonances, the system detects this condition through feedback sensors and automatically applies corrective inputs to maintain rotor speed outside the resonant range, preventing structural damage while allowing complete autorotation to occur.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a rotorcraft (1) with at least one main rotor (1a) and at least one engine (1g) for powering the at least one main rotor (1a) in a normal flight mode, comprising an autorotation training mode control system (7) that is activatable for switching rotorcraft operation between the normal flight mode and an autorotation training mode configured to enable training of autorotation, wherein the autorotation training mode control system (7) comprises at least one main control element that is manually operable for activating the autorotation training mode control system (7) and switching the rotorcraft operation from the normal flight mode to the autorotation training mode to engage the autorotation training mode.