Fuel level sensors for UAVs fuel-measurement product

The Fuel level sensors for UAVs is a fuel-measurement product from Gill Sensors & Controls with a capacitive measuring principle. Fuel level sensors for UAVs are capacitive liquid level sensors from Gill Sensors & Controls, a UK manufacturer, used to measure the quantity of fuel in the tank of an unmanned aircraft. Within Gill's range, the lightweight LevelLite sensor is the design the maker positions for UAV and motorsport use, and it is the model whose datasheet figures are given here. The sensor reports the fuel level continuously, so the flight computer or ground station can follow consumption and estimate remaining endurance.

The measuring principle is capacitive and solid state, with no moving parts. Gill states that this gives reliable service where temperature changes and vibration are present, and that the sensor design gives a damped response that reduces the effect of fuel sloshing in a moving vehicle. The sensors are compatible with gasoline, diesel, kerosene-based jet fuels including JP-5 and JP-8, and Avgas, and the LevelLite datasheet also lists biofuels, oils, coolants and salt water. Each sensor is factory calibrated for the liquid it will measure, with temperature compensation, and a tank profiling function allows a volumetric output for irregular tank shapes.

The LevelLite is built from 6082 aluminium with sealed electronics. Accuracy is 1% of full scale deflection at 20 degrees C. Probe lengths from 100 mm to 750 mm are available in 1 mm steps, the mass without cable is 48 g for a 100 mm probe plus 0.256 g for each additional millimetre, and the sensor has an ingress protection rating of IP68. Its operating temperature range is -40 to +125 degrees C, subject to a derating graph in the datasheet. For a UAV integrator, the low mass and the choice of exact probe length mean that the sensor can be matched to tank depth without adding weight that would reduce flying time.

For integration, the primary output is 0.25 to 4.75 V DC as standard, with a maximum range of 0.25 to 10 V, at a resolution of 10 bits and a sample rate of 100 Hz. A secondary output is available either as a switched open-collector output rated 50 V and 1 A, usable as a low-fuel alarm, or as a temperature output. The supply voltage is 5 to 32 VDC and the supply current is below 20 mA. An RS232 data interface allows configuration with the GSlevel software through a USB to RS232 adaptor. Mounting uses 1, 2, 3 or 5 hole flanges or an M22 x 1.5 thread, with panel gasket or O-ring sealing, a flying lead cable of 1000 mm and a top or side cable exit. The sensor can be installed at the top of the tank or inverted.

The datasheet lists shock testing to BS EN 60068-2-27, vibration from 5 to 2500 Hz, and EMC testing to BS EN 60945, BS EN 61326 and BS EN 61000-6-1/2/3/4. The sensor is not designed or certified for ATEX environments. Typical applications are unmanned aerial vehicles, light aero applications, and motorsport, and Gill also supplies a liquid level display that can map the tank shape to show true volume.