Tiltrotor Descent Rate Limiting During Mode Transition
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Solution Overview
Problem
Unmanned tiltrotor aircraft face challenges in maintaining stable descent rates during mode transitions due to lack of vestibular and haptic feedback for remote pilots, leading to potential loss of control and catastrophic failures.
Innovation Solution
A flight control system with a descent rate limiter logic that automatically adjusts the collective pitch angle of rotor blades based on predefined conditions, ensuring the aircraft does not descend too quickly by switching between operator-controlled and aircraft-controlled collective pitch angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic descent rate limiting control is implemented during mode transitions, then flight stability and safety are improved, but device complexity and control system complexity increase
Solution Approach 1:
The descent rate limiter logic automatically monitors descent rate and adjusts collective pitch angle without requiring pilot intervention. The system self-regulates by comparing actual descent rate to target descent rate and autonomously modifying rotor blade pitch to maintain safe descent rates during mode transitions.
Solution Approach 2:
The system continuously monitors actual descent rate and uses this feedback to adjust collective pitch angle. The control logic compares measured descent rate against target descent rate and modifies pitch angle accordingly, creating a closed-loop feedback control system that maintains flight stability during transitions.
2Reliability
If automatic collective pitch control is used during mode transitions, then loss of control is prevented, but pilot autonomy and manual control capability are reduced
Solution Approach 1:
The descent rate limiter applies automatic collective pitch control selectively only during critical mode transitions when descent rate exceeds safe thresholds. The system uses engagement logic to activate automatic control only when needed (when descent rate > target descent rate), otherwise allowing full manual pilot control, thus balancing safety with pilot autonomy.
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 solution provides stable and smooth collective responses, preventing unstable flight conditions and potential crashes by automatically controlling descent rates during airplane-to-helicopter mode transitions, thus protecting the aircraft from vortex ring states and overcorrections.
Implementation Method 1
controlling a collective pitch angle for a plurality of rotor blades of the propulsion systems based on the descent rate condition
Data Source
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AI summary
A method (400) for an aircraft (100) is provided in one example embodiment and may include determining (402) a transition from an airplane mode to a helicopter mode for a propulsion system (110, 112) of the aircraft (100), wherein the propulsion system (110, 112) comprises a plurality of rotor blades (121, 131); determining (404) whether a descent rate condition is satisfied, wherein the descent rate condition is associated with a maximum allowable descent rate for the aircraft (100); and controlling (406) a collective pitch angle for the plurality of rotor blades (121, 131) based on the descent rate condition.