Fuel measurement

Has anyone had any luck measuring fuel flow or fuel volume in a glow fuel powered aircraft?

I was contemplating using a differential pressure sensor to calculate the mass flow rate between the tank and the needle valve, but I have a hunch that the overall flow rate, and hence pressure drop is fairly low.  If this did work however, a method synonymous with the "Coulomb counter" battery measurements could be used to determine total used fuel. 

Has anyone tried this?  Or, better yet, are there any other/better ways to accomplish this? 


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  • Sorry... one more... and this time, a ready-made solution.

    The Sensortechnics capacitive-level sensor, featuring continuous contact-free (goes outside the tank) measurement, and both analog/digital outputs!


  • The L4620 Liquid Level Alarm IC measures the impedance change of a liquid, and provides a 50Hz (nominal) square wave output for sensing.

    Here's a capacitance-based liquid fuel gauge.

    The QT301 is a capacitance to analog converter, and one use is fluid level sensing.

    The Fuel Guardian is a ready-made $19 solution. You might be able to tap it's internals and get an actual voltage corresponding to resistance level, then mapping it to average flow rate.

    I believe the GEMS sensors aren't exactly what you're looking for, since they don't provide a gradient measure even though they're photon-based.

    The SLX4 uses free ions in order to sense liquid levels. It is not what you're looking for, but I'm including it for thoroughness.

    I suppose if you're a glutton for punishment you could measure the resonant frequency of the fuel tank, which would give you an indication of fuel level (and over time, consumption). The advantage of this method is that there's no moving parts, nothing to corrode (electrodes inside the tank), and can be done in a non-invasive manner from outside the tank (think piezo elements). If this idea has not yet been patented, consider this my prior art.
  • @Ryan - Your first link is a battery (i.e., electromotive) fuel gauge. I'm curious as to how you see this helping him measure liquid fuel (i.e., a combustible fluid) flow (consumption).

    @Mathias - Others have turned the fuel cell (tank) into a capacitor by installing a copper electrode at the (inner) bottom and top of the tank. The gap between fuel and top electrode determine the capacitance (which can be measured by creating a tank circuit - no pun intended). Someone else mentioned this is how HIROBO does it in their fuel level sensors, but I was unable to verify that. By taking static measurements of "near empty" and "full" capacitance you can derive the min/max range for the type of fuel you're using. By extrapolating, you can derive the fuel consumption and thus fuel flow. Hope that helps.
  • Have you seen this? http://www.digitalproductsco.com/batmon/
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