Aircraft Auxiliary Fuel Tank Indication via Consumption Rate
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Solution Overview
Problem
Auxiliary fuel tanks in aircraft, made of flexible materials, pose challenges for accurate fuel quantity measurement due to their design and complex shapes, making it costly and complicated to install gauges for monitoring fuel levels, which is essential for safe flight operations.
Innovation Solution
A method that calculates the fuel quantity in auxiliary tanks by measuring the initial fuel capacity and fuel consumption rate, allowing for an indirect estimation of fuel remaining without the need for gauges, and switches to direct measurement from main tank gauges once auxiliary tanks are empty, providing a high-integrity fuel indication during flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuel gauges are fitted to auxiliary fuel tanks to accurately measure fuel quantity, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The main fuel tank gauges serve a dual function: they measure fuel in the main tanks directly and indirectly measure fuel in the auxiliary tanks by tracking fuel consumption and calculating remaining capacity. This eliminates the need for separate auxiliary tank gauges while maintaining measurement capability throughout the flight.
Solution Approach 2:
The system uses fuel consumption rate as an intermediary measurement to indirectly determine auxiliary tank fuel levels. By measuring the rate at which fuel is consumed and knowing the initial auxiliary tank capacity, the system calculates remaining fuel without requiring direct gauging of the auxiliary tanks.
2Measurement precision
If fuel gauges are fitted to auxiliary fuel tanks, then measurement precision is improved, but weight increases
Solution Approach 1:
The existing main tank gauge system is made multi-functional by adding calculation capabilities that allow it to also measure auxiliary tank fuel levels. This eliminates the need for additional physical gauges on auxiliary tanks, thereby avoiding the weight penalty of installing extra measurement devices.
Solution Approach 2:
Instead of installing permanent, weighty gauge infrastructure on auxiliary tanks, the system uses a computational approach that leverages temporary measurements (fuel consumption rate) to derive auxiliary tank levels. This virtual measurement approach avoids the weight of physical gauge components.
3Adaptability or versatility
If flexible auxiliary fuel tanks are used to increase fuel capacity, then adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
Instead of trying to measure fuel levels directly in the flexible auxiliary tanks (which is difficult due to their changing shape), the system inverts the approach by measuring fuel consumption rate and using that to calculate remaining fuel. This indirect measurement method bypasses the measurement difficulties posed by the flexible tank geometry.
Solution Approach 2:
The system replaces the mechanical measurement approach (physical gauges that would need to contend with flexible tank deformation) with a computational/mathematical approach. By using fuel consumption rate data and initial capacity information, the system calculates auxiliary tank levels without requiring direct mechanical measurement of the flexible tanks.
Data Source
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AI summary
One or more main aircraft fuel tanks (34) are provided with one or more fuel gauges (42) arranged to provide a measure of the amount of fuel in said one or more main fuel tanks. One or more auxiliary fuel tanks (30) are also provided. The aircraft uses fuel during a first phase of fuel consumption, upon commencement of which phase the auxiliary fuel tanks hold fuel. After the first phase said one or more auxiliary fuel tanks (30) are empty and a second phase commences. During the first phase, an indication of the amount of fuel carried by the aircraft is provided by means of summing (i) the amount of fuel in the main fuel tanks (34) as measured by said one or more fuel gauges (42) and (ii) the amount of fuel remaining in said one or more auxiliary fuel tanks (30) as calculated using a measure relating to the fuel consumption rate. During the second phase of fuel consumption, an indication of the amount of fuel carried by the aircraft is provided on the basis of the amount of fuel measured by said one or more fuel gauges (42).