Collapsible Large Propeller for Quiet Aircraft Loitering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft propellers with small diameters are noisy during high-speed operations but insufficient for take-off and climbing, while larger, slower propellers are quieter but inadequate for propulsion during these phases and prone to ground strikes.
Innovation Solution
An aircraft design featuring a small high-speed propeller for take-off, climbing, and landing, and a large collapsible or foldable propeller for loitering, which is kept folded during take-off and landing to minimize drag and deployed at lower speed for quiet, efficient loitering, with the option to disengage the smaller propeller during loitering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a small diameter propeller is used, then the propeller can provide sufficient propulsion during take-off, climbing and landing, but it spins at high speed which generates excessive noise during loitering operations
Solution Approach 1:
The aircraft propulsion system is segmented into two separate propellers: a small diameter propeller for high-power operations (take-off, climbing, landing) and a large diameter propeller for quiet loitering operations. This segmentation allows each propeller to be optimized for its specific function, resolving the contradiction between power and noise by eliminating the need for a single propeller to perform both roles simultaneously
Solution Approach 2:
The large diameter propeller incorporates foldable blades that can dynamically change configuration between extended (for quiet loitering) and retracted (for high-power operations). This dynamic adaptability allows the system to switch between noise-reduction mode and power-generation mode, resolving the contradiction by making the propeller geometry variable rather than fixed
2Object-generated harmful factors
If a larger diameter propeller is used for quieter loitering operations, then noise is reduced, but the propeller provides insufficient propulsion during take-off, climbing and landing and is likely to strike the ground
Solution Approach 1:
The propulsion system is divided into two specialized propellers: a large diameter propeller optimized for quiet loitering and a small diameter propeller optimized for high-power operations. This segmentation allows the large propeller to be designed without ground strike constraints and with sufficient diameter for noise reduction, while the small propeller handles all high-power phases
Solution Approach 2:
The large diameter propeller features foldable blades that can be retracted parallel to the rotor shaft during take-off, climbing, and landing operations. This dynamic reconfiguration eliminates ground strike risk and reduces drag during high-power operations, while allowing the propeller to extend for quiet loitering, thus resolving the contradiction between noise reduction and propulsion capability
3Object-generated harmful factors
If a large diameter propeller is used, then quieter loitering is achieved, but the propeller creates excessive drag when not in use and risks ground strikes during maneuvering
Solution Approach 1:
The large diameter propeller incorporates foldable blades that can be retracted parallel to the rotor shaft during high-speed operations and maneuvering. This dynamic reconfiguration minimizes the propeller's cross-sectional area, reducing aerodynamic drag to minimal levels during take-off, climbing, and landing, while allowing the blades to extend for quiet loitering operations
Solution Approach 2:
The dual propeller system segments the drag-reduction function: the large propeller with foldable blades handles drag reduction during high-speed operations, while the small propeller handles high-power operations. This segmentation allows the large propeller to be optimized for noise reduction without permanently incurring drag penalties
Data Source
AI summary
An aircraft has a small high-speed propeller used during take-off, climbing and landing maneuvers, and a large collapsible or foldable propeller used for loitering. The large collapsible or foldable propeller is kept in a folded configuration during take-offs and landings to minimize drag and to avoid ground strikes. During loitering operations, the large collapsible propeller is unfolded and used at a lower rotational speed than the smaller high-speed propeller to permit efficient and quite loitering. During loitering operations, the smaller high-speed propeller may be disengaged so as to spin freely or held in a non-rotational position. One or more foldable propellers may be paired with at least one conventional propeller. The propellers may be arranged as twin tractor, tractor-pusher, or nearly any other type of layout on the fuselage or wings, or on pods of the fuselage or wings.