Variable-Pitch Turboprop for Emergency Power Without Ram Air Turbines
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Solution Overview
Problem
Existing turboprops with ram air turbines have a significant onboard mass due to the inclusion of a dedicated propeller, electric generator, and actuator system, which are not used during normal operation, necessitating an alternative energy source for emergency power without increasing mass.
Innovation Solution
A turboprop with a variable-pitch propeller and an electrically operated oil pump that supplies the hydraulic circuit for pitch adjustment, allowing the propeller to be rotated by windmill effect, providing emergency energy without additional equipment, and optimizing energy production across a wide range of aircraft speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated ram air turbine system is installed to provide emergency power, then emergency energy availability is improved, but onboard mass increases significantly
Solution Approach 1:
The patent makes the existing propeller shaft system multi-functional by enabling it to operate in both propulsion mode (driven by the turbine) and emergency power generation mode (driving the generator via windmill effect). The propeller shaft, originally designed solely for propulsion, is modified to can also rotate the generator when the turbine fails, thus providing emergency power without adding a separate dedicated ram air turbine system.
Solution Approach 2:
The patent merges the propulsion function and emergency power generation function into a single integrated system. The propeller shaft serves dual purposes: transmitting torque from the turbine during normal operation and driving the generator during emergency conditions. This consolidation eliminates the need for separate dedicated emergency power equipment, thereby reducing onboard mass while maintaining reliability.
2Power
If the propeller pitch is made variable to enable windmill effect, then emergency energy production capability is improved, but device complexity increases
Solution Approach 1:
The variable-pitch mechanism, originally designed for optimizing propulsion performance, is made multi-functional by enabling it to also control the propeller for windmill effect during emergency power generation. The same pitch control system serves both propulsion optimization and emergency energy production, avoiding the need for separate control mechanisms.
Solution Approach 2:
The existing propeller pitch control system serves itself by being repurposed for emergency power generation. The hydraulic or mechanical pitch control mechanism that was already installed for propulsion purposes is utilized to adjust the propeller blades into the optimal windmill configuration during turbine failure, eliminating the need for additional dedicated control systems.
3Reliability
If an electrically operated oil pump is used instead of turbine-driven, then emergency operation capability is improved, but dependency on external power source increases
Solution Approach 1:
The oil pump system is made dynamic by implementing a dual-drive capability. The pump can be driven by the turbine during normal operation and switched to electric motor drive during emergency conditions. This dynamic adaptability allows the system to maintain functionality across different operational states, ensuring the propeller pitch control remains operational even when turbine power is unavailable.
Solution Approach 2:
The electric motor serves as an intermediary power source that bridges the gap between turbine failure and the need for oil pump operation. When the turbine is unavailable, the electric motor temporarily assumes the role of driving the oil pump, enabling the pitch control system to function during emergency power generation until the situation is resolved.
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 turboprop configuration reduces onboard mass by eliminating the need for a ram air turbine, enabling precise propeller pitch adjustment and energy production, while maintaining conventional propulsion and lubrication functions.
Implementation Method 1
the turboprop does not contribute to propulsion. It is thus possible to adjust the pitch of the propeller in order to rotationally drive the propeller by windmill effect and therefore rotate the propeller shaft and the rotating electric machine that is mechanically coupled thereto
Implementation Method 2
at least one oil pump designed to supply a hydraulic circuit for adjusting the pitch of the propeller, the oil pump being designed to be electrically operated
Data Source
AI summary
A turboprop includes a propeller, a propeller shaft carrying the propeller, the propeller being a variable-pitch propeller having a propeller pitch, a rotating electric machine having at least a first configuration in which it is mechanically coupled to the propeller shaft and at least one oil pump configured to supply a hydraulic circuit for adjusting the pitch of the propeller. The oil pump is configured to be electrically operated. An aircraft can include such a turboprop and methods can control such a turboprop and such an aircraft.