Turboprop Power Indicator Using Composite Parameter PIT
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Solution Overview
Problem
Turboprop engine power indicators fail to provide a coherent power parameter across the entire operating range, as torque-based parameters are representative only at constant rotational speeds, lacking the ability to indicate power variations from maximum forward thrust to maximum reverse thrust drag.
Innovation Solution
A piloting indicator that calculates a power parameter (PIT) using the ratio of current turboprop power to maximum power without air bleed at sea level, incorporating propeller and turbine parameters, and displays this on a graduated dial, accounting for reference power, blade incidence, and operational modes to provide a unified indication of power and reserve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque on the propeller shaft is used as the power parameter, then the parameter is simple to measure and process, but it is representative of engine power only at constant rotational speed and cannot indicate power variations across the entire operating range
Solution Approach 1:
The patent transforms the power parameter representation by changing from torque-only measurement to a composite parameter that incorporates both torque and rotational speed variables. The new parameter PIT = 100 × A × (TQc.NPc - PWRr) / (PWRmax - PWRr) dynamically adjusts based on operating conditions, allowing accurate power indication across the entire operating range from maximum forward thrust to maximum reverse thrust drag.
2Loss of information
If a unified power parameter is provided across the entire operating range, then the pilot gains comprehensive power information, but the parameter calculation becomes more complex requiring multiple inputs and processing
Solution Approach 1:
The patent creates a universal power parameter PIT that serves multiple functions simultaneously: it indicates current power level, shows power reserve, works across all operating modes (traction and thrust reversal), and provides transient phase information. This single multi-functional parameter replaces what would otherwise require multiple separate indicators and calculations.
Solution Approach 2:
The patent introduces an intermediary processing system that receives multiple input parameters (torque TQc, rotational speed NPc, blade incidence β, reference power PWRr, maximum power PWRmax) and transforms them into the unified PIT parameter. This intermediary calculation layer simplifies the presentation to the pilot while comprehensively processing the underlying complex data.
3Device complexity
If traditional torque-based indicators are used, then the display is simple and straightforward, but the indicator cannot provide meaningful information during transient phases or thrust reversal operations
Solution Approach 1:
The patent makes the power parameter dynamic by incorporating the sign of (β - β0) which automatically adapts to different operating modes. During thrust reversal when blade incidence becomes negative relative to ground idle, the parameter naturally reflects negative traction, providing meaningful information throughout the entire operational envelope without requiring separate indicators for different modes.
Data Source
Figure 1~2
Figure 3A~3C
AI summary
The invention concerns a piloting indicator (1) comprising data sources (2) which determine the parameter values concerning the propeller and the turbine of the turboprop, as well as the parameter values concerning the aircraft, processing means (3) which calculate, based on said values, a power parameter which takes into account the ratio between the current power of the turboprop engine and the maximum power obtained without air bleed at sea level in standard atmosphere, and display means (5) which display, on a viewing screen (7), at least one characteristic symbol (11) illustrating said power parameter.