Stopped Rotor Braking Control for Low-Drag Forward Flight
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Solution Overview
Problem
Current aircraft designs excel in either hovering or forward flight but not both, leading to inefficient power consumption and limited flight range/time, and lack the capability to stop rotors mid-flight, which increases drag and noise.
Innovation Solution
A stopped rotor aircraft system that includes a stoppable rotor capable of rotating about a vertical axis, optimized for vertical flight, and combination rotors for forward thrust, with a control system to manage rotor positions and torque for efficient hovering and forward flight, allowing the rotor to be stopped mid-flight with blades positioned for low drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotor continues rotating during forward flight, then thrust is maintained, but drag increases and noise increases
Solution Approach 1:
The rotor system transitions from a static rotating state to a dynamic stopped state during forward flight. The rotor blades are designed to be stoppable and positionable at specific angles, allowing the system to adapt its configuration based on flight phase. This dynamic reconfiguration enables the rotor to be stopped during forward flight to reduce drag and power consumption, while still capable of rotating during hover or vertical flight phases.
2Object-generated harmful factors
If the rotor is stopped mid-flight, then drag and noise are reduced, but control precision becomes more difficult
Solution Approach 1:
The control system calculates a braking start point in advance before the rotor needs to be stopped. By determining the optimal moment to initiate braking based on predicted flight conditions and rotor state, the system can smoothly transition the rotor to a stopped position without sudden control inputs. This preliminary planning maintains control precision while achieving the noise and drag reduction benefits of stopping the rotor.
3Reliability
If aircraft are designed for efficient hovering, then hovering performance is improved, but forward flight performance deteriorates
Solution Approach 1:
The aircraft employs a dynamic rotor configuration that can switch between rotating and stopped states. During hover operations, the rotor rotates to provide vertical thrust, ensuring excellent hovering performance. During forward flight, the rotor stops and blades are positioned to minimize drag, optimizing forward flight efficiency. This dynamic adaptability allows the same aircraft to excel at both hovering and forward flight without compromise.
4Loss of energy
If the rotor is stopped with blades in specific position, then drag is reduced, but the system complexity increases
Solution Approach 1:
The control system continuously monitors rotor position, flight conditions, and performance parameters to determine the optimal braking start point. By using feedback from sensors and actuators, the system can automatically adjust the braking timing and blade positioning to achieve minimum drag configuration. This closed-loop control manages the system complexity by automating the coordination of multiple components, making the overall system more manageable despite the increased complexity of stoppable rotor mechanics.
Data Source
AI summary
While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.