Coaxial Propellers with Fixed Different Pitch for Aeronautical Propulsion
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Solution Overview
Problem
Current propulsion devices for vertical take-off aircraft, which use the same propellers for both take-off and cruise flight, face challenges due to increased complexity, cost, and weight from requiring variable pitch propellers that are not optimized for either flight mode, leading to inefficient thrust during cruise flight.
Innovation Solution
The use of two coaxial propellers with fixed and different pitches, where one propeller is optimized for take-off and vertical flight and the other for cruise flight, with the second propeller positioned forward to operate efficiently in moving air, and independent electric motor control allowing for feathering and fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable pitch propellers are used for both take-off and cruise flight, then the same propellers can be used for both flight modes, but the complexity, cost and weight of the engines increase
Solution Approach 1:
The propulsion system is segmented into two separate propeller units: a first propeller optimized for take-off and vertical flight with small pitch, and a second propeller optimized for cruise flight with large pitch. This segmentation eliminates the need for variable pitch mechanisms in each propeller, reducing complexity while maintaining adaptability through selective operation of appropriate propellers based on flight phase
Solution Approach 2:
The propulsion system achieves multi-functionality by having two fixed-pitch propellers that can be selectively activated based on flight mode. The first propeller handles vertical flight operations while the second propeller handles cruise flight, allowing the system to perform multiple functions without requiring each individual propeller to be variable-pitch complex
2Adaptability or versatility
If variable pitch propellers are used for both take-off and cruise flight, then the same propellers can be used for both flight modes, but the weight of the engines increases
Solution Approach 1:
The propulsion system is divided into two separate fixed-pitch propeller units with different weights optimized for their specific functions. The first propeller is lighter with small pitch for vertical flight, while the second propeller is heavier with large pitch for cruise flight. This segmentation eliminates the need for heavy variable pitch mechanisms, reducing overall engine weight while maintaining adaptability
Solution Approach 2:
Each propeller is designed with local quality optimization: the first propeller has small pitch specifically tailored for vertical flight requirements, while the second propeller has large pitch optimized for cruise flight. This localized optimization allows each propeller to be lighter and simpler for its specific function rather than requiring a heavy universal variable-pitch design
3Adaptability or versatility
If variable pitch propellers are used for both take-off and cruise flight, then the same propellers can be used for both flight modes, but the yield during cruise flight becomes very low due to incorrect pitch extension
Solution Approach 1:
The propulsion system segments the propeller functions into two specialized units: the first propeller with small pitch for vertical flight and the second propeller with large pitch for cruise flight. This segmentation ensures that each propeller operates at optimal efficiency for its designated flight phase, eliminating the yield loss associated with using incorrectly pitched propellers
Solution Approach 2:
Each propeller is designed with local quality specifically optimized for its intended flight mode. The second propeller has large pitch extension locally optimized for cruise flight conditions, ensuring high yield and efficiency during horizontal flight. The first propeller similarly has small pitch optimized for vertical flight, preventing yield loss in that regime
4Device complexity
If a single propeller is used for both take-off and cruise flight, then the device structure is simpler, but the thrust during take-off and the efficiency during cruise flight cannot be simultaneously optimized
Solution Approach 1:
The propulsion device structure is segmented into two separate propeller units rather than using a single complex variable-pitch propeller. This segmentation maintains relative structural simplicity while enabling each propeller to be optimized for specific flight phases, thereby achieving high thrust during take-off and high efficiency during cruise flight simultaneously
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 configuration provides greater thrust during take-off and vertical flight while minimizing resistance and optimizing efficiency during cruise flight, reducing complexity, weight, and cost by allowing each propeller to operate independently and reducing aerodynamic drag.
Implementation Method 1
the first propeller with a smaller pitch to exert a thrust during take-off and vertical flight
Implementation Method 2
the second propeller with a larger pitch to exert a thrust both during take-off and vertical flight and during cruise flight
Implementation Method 3
at least two coaxial propellers counter-rotating therebetween... Both propellers are used during the take-off phase and, being counter-rotating, provide a much greater thrust
Implementation Method 4
the first propeller is provided with means for feathering the blades, i.e. oriented to lie on one or more planes parallel to the movement direction of the aircraft
Data Source
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AI summary
Aeronautical propulsion device for an aircraft with carrier wings for cruise flight. The propulsion device comprises at least two coaxial propellers (1, 2) counter-rotating therebetween. Said propellers (1, 2) have a fixed and different pitch therebetween, having a first said propeller (1) of smaller pitch and having a second said propeller (2) of larger pitch.