Wedge Brake Assembly for HAP Propeller Descent Control
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Solution Overview
Problem
High altitude platforms (HAPs) operating in the stratosphere face challenges in maintaining directional control and preventing uncontrolled propeller rotation during descent or power loss, which can lead to entanglement with the envelope or other components, and prolonged propeller spin when not in use generates heat and overvoltage issues.
Innovation Solution
A reusable wedge brake system is implemented, controlled by a brake control module that uses an electromagnet and solenoid to engage or disengage a brake pad with the propeller hub, allowing for rapid braking and selective direction control, including immediate cessation of rotation during emergencies and prevention of free spinning when not in use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the propeller assembly is allowed to rotate freely when not in use, then the HAP can be repositioned quickly, but the propeller may entangle with the envelope or other components during descent or power loss
Solution Approach 1:
The brake system is pre-configured with brake pads positioned to contact the propeller hub, and the electromagnet is pre-positioned to engage the brake pads. When activation is needed, the system already has all components in place, enabling immediate braking action within 0.3-2.0 seconds to prevent entanglement during descent or power loss scenarios.
Solution Approach 2:
The brake pads serve as an intermediary element between the electromagnet and the propeller hub. The electromagnet activates the brake pads, which then contact the propeller hub to create friction and stop rotation. This intermediary mechanism provides controlled stopping without direct electromagnetic contact with the rotating propeller.
2Reliability
If a brake system is added to stop the propeller, then entanglement is prevented, but the device complexity increases
Solution Approach 1:
The brake system is integrated with the propeller assembly structure, where the electromagnet and brake pads are positioned to work directly with the existing propeller hub. This merging approach allows the brake function to be added without requiring a completely separate system, thereby limiting the increase in overall device complexity while achieving the safety function.
Solution Approach 2:
The patent replaces a purely mechanical brake system with an electromechanical system. Instead of using mechanical linkages or levers to activate the brake, an electromagnet is used to activate the brake pads. This substitution reduces mechanical complexity while maintaining the braking function, achieving reliable stopping within 0.3-2.0 seconds.
3Speed
If the solenoid remains energized continuously, then the brake pad stays disengaged for quick propeller spin-up, but energy consumption increases and solenoid lifespan decreases
Solution Approach 1:
The solenoid is energized periodically rather than continuously. It is activated briefly to disengage the brake pad before propeller spin-up, then de-energized. This periodic action allows the brake pad to remain disengaged when needed for quick spin-up while significantly reducing overall energy consumption and extending solenoid operational life.
Solution Approach 2:
The brake control system dynamically adjusts the solenoid activation state based on operational needs. The system transitions the solenoid between energized and de-energized states according to whether the propeller needs to spin up quickly or remain braked, optimizing both performance and energy efficiency throughout the operational cycle.
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 brake system enables rapid and controlled propeller stoppage within 0.3-2.0 seconds, preventing entanglement and overvoltage, and conserves power by disengaging when not needed, thus enhancing safety and operational efficiency of HAPs.
Implementation Method 1
causing, by a brake control module, an electromagnet of a brake assembly of the high altitude platform to energize
Implementation Method 2
causing, by the brake control module, a solenoid of the brake assembly of the high altitude platform to energize
Implementation Method 3
a brake pad of the brake assembly has disengaged from contact with a hub of a propeller assembly
Data Source
AI summary
Aspects of the technology relate to a braking assembly for a lateral propulsion system of a high altitude platform (HAP) configured to operate in the stratosphere. Power is supplied to a propeller assembly as needed during lateral propulsion so that the HAP can move to a desired location or remain on station. When lateral propulsion is not needed, power is no longer supplied to the propeller assembly and it may slowly cease rotating. However, in certain situations, it may be necessary to cause the propeller assembly to stop rotating as soon as possible. This can include an unplanned descent. Rapid braking can avoid the propeller blades from entangling in the envelope, parachute or other parts of the HAP. A reusable brake is employed to prevent uncontrolled rotation of the propeller on descent, or otherwise to prevent the propeller from spinning freely when not being used to propel the HAP laterally.