Pusher Aircraft Propulsion Cooling via Hub-Mounted Fan
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Solution Overview
Problem
Aircraft engines in pusher configurations are harder to cool than those in tractor configurations due to the absence of downwash airflow, leading to the need for additional cooling equipment that increases weight and bulk.
Innovation Solution
An aircraft propulsion system that includes a heat exchanger for facilitating heat transfer between cooling air and a fluid from the internal combustion engine, with a fan driven by the propeller drive shaft to provide cooling air through a flow path in thermal communication with the engine, and a spinner configuration that promotes beneficial airflow conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If additional cooling equipment is installed to cool the engine in pusher configuration, then the cooling effectiveness is improved, but the weight and bulk of the propulsion system increase
Solution Approach 1:
The patent combines the cooling fan with the propeller assembly, mounting the fan on the propeller hub or spinner. This integration allows the cooling function to be added without requiring separate mounting structures and reduces overall system weight by sharing common components and mounting points.
Solution Approach 2:
The propeller drive shaft serves dual functions: driving the propeller for thrust generation and driving the cooling fan for engine cooling. This multi-functionality eliminates the need for a separate power source for the cooling fan, reducing system weight and complexity.
2Temperature
If additional cooling equipment is installed to cool the engine in pusher configuration, then the cooling effectiveness is improved, but the bulk of the propulsion system increases
Solution Approach 1:
The cooling fan is nested within the propeller hub or spinner structure. The fan blades are positioned within the propeller assembly boundaries, utilizing the existing spatial envelope without requiring additional external volume. This nesting approach maintains compact system bulk while providing effective cooling.
Solution Approach 2:
The cooling airflow is directed through three-dimensional paths that utilize the vertical and radial spaces within the existing propeller assembly volume. Cooling air is drawn from below the propeller plane and discharged through pathways that efficiently use the available spatial dimensions without increasing external bulk.
3Temperature
If downwash airflow is used for cooling in tractor configuration, then the cooling effectiveness is improved, but this effect is not present in pusher configuration
Solution Approach 1:
Instead of relying on propeller downwash to provide cooling airflow (which works in tractor but not pusher configuration), the invention inverts the approach by using the propeller rotation to directly drive a cooling fan that actively generates cooling airflow. This reversed mechanism provides consistent cooling effectiveness in both tractor and pusher configurations.
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 a lightweight, compact, and effective cooling system for aircraft engines in pusher configurations, capable of maintaining engine temperature during stationary, taxiing, take-off, and initial climb phases, applicable to various aircraft types, including manned and unmanned fixed-wing aircraft.
Implementation Method 1
a heat exchanger configured to facilitate heat transfer between the cooling air and a fluid carrying heat from the internal combustion engine
Implementation Method 2
with a fan driven by the propeller drive shaft to provide cooling air through a flow path in thermal communication with the engine
Data Source
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AI summary
An aircraft propulsion system (10) comprises an engine (12), a propeller drive shaft (14) drivingly engaged with the engine (12), a propeller (16) for propelling an aircraft and a fan (22) driving cooling air along a flow path in thermal communication with the engine (12). The engine (12) may be an internal combustion engine or other engine type having heat rejection requirements and the fan (22) may facilitate cooling of the engine (12). The propulsion system may have a pusher configuration.