Automatic Nacelle Conversion for Tilt Rotor Aircraft
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Solution Overview
Problem
Tilt rotor aircraft pilots face high workload and safety risks due to the need to manually modulate nacelle angles during flight, which complicates achieving desired speed and altitude settings, especially during transitions between helicopter and airplane modes.
Innovation Solution
The AUTO NAC function provides an automatic nacelle conversion system that uses active and passive modes to optimize nacelle positions based on current and final speed, altitude, and deceleration rates, reducing pilot input and workload by employing a computer system to calculate and display optimal nacelle angles and control actuator movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual nacelle modulation is used during flight, then pilot control over nacelle position is maintained, but pilot workload increases and safety risks increase
Solution Approach 1:
The system allows the aircraft to automatically manage its own nacelle configuration based on flight conditions. The flight management system autonomously determines optimal nacelle positions and coordinates conversions without requiring continuous pilot intervention, enabling the aircraft to serve itself in configuration management while the pilot focuses on flight path control
Solution Approach 2:
The system pre-calculates and prepares nacelle conversion sequences based on anticipated flight conditions and transitions. By anticipating required configuration changes before they are needed and pre-positioning nacelles appropriately, the system reduces reactive pilot workload during critical transition phases
2Ease of operation
If automatic nacelle conversion is implemented, then pilot workload is reduced, but system complexity increases
Solution Approach 1:
The flight management system performs multiple functions including flight path management, performance optimization, and nacelle configuration coordination through a single integrated control architecture. This multi-functional approach avoids adding separate dedicated systems for each function, thereby limiting the increase in overall system complexity while achieving automatic nacelle conversion
Solution Approach 2:
The system combines nacelle control functions with the existing flight management system rather than creating a separate standalone control system. By merging the nacelle coordination logic into the existing flight management architecture that already handles flight path and performance management, the system achieves automatic conversion capability without proportionally increasing system complexity
3Stability of the object's composition
If coordinated nacelle control is used during mode transitions, then aircraft stability is improved, but control complexity increases
Solution Approach 1:
The system continuously monitors flight conditions, nacelle positions, and aircraft performance parameters, using this feedback to dynamically adjust conversion rates and coordinate control inputs. This closed-loop feedback mechanism ensures stable transitions by automatically correcting deviations from the desired conversion path without requiring complex manual coordination procedures
Solution Approach 2:
The system dynamically adjusts conversion parameters including rate limits, sequencing, and control coordination based on real-time flight conditions such as airspeed, altitude, and aircraft configuration. This dynamic adaptation allows the control system to optimize stability during transitions without requiring fixed complex control schedules for every possible flight condition
Data Source
AI summary
Systems and methods for displaying to a tilt rotor aircraft pilot an optimum nacelle position and/or automatically controlling movement of the nacelles for the pilot. An automatic nacelle conversion function employs an active flight director speed mode to provide a current desired speed and a final speed. When the automatic nacelle conversion function is in a passive (uncoupled) mode of operation, the pilot follows visual cues, manually achieving the commanded nacelle position by rotating a thumbwheel. When in an active (coupled) mode of operation, the automatic nacelle conversion function provides a fully automatic nacelle controller requiring no pilot input. This automatic nacelle controller provides a variable nacelle rate along with several angle versus speed schedules tailored for different guidance speed modes and a wide range of aircraft configurations. The automatic nacelle conversion function is improved though the inclusion of altitude, rate of climb, and deceleration rate commands.