Do you need a continue fuel level ? or just an indicator telling a predefined level ?
On my motorbike, the fuel level warning light is made using a PTC (or NTC, can't remember). The 12V power supply is applyed to the PTC through another resistor, forming a voltage divider. The PTC is fixed in the tank at the predefined level. As long as fuel is covering it, it is cooled down and the voltage is more or less stable. When fuel lower and the PTC is in the air, temp raise and voltage change. The voltage is fed in a micro-controller which displays a symbol on the dash.
I love you Justin...I was just thinking of this yesterday. I've seen some nice ones made by Gills for UAV autopilots but have no idea how they could incorporate into APM.
Here is the link to their sensor page:
The specifications states that they have an analog ouput range of .25V to 4.75V sensing range.
Since it's analog voltage based is there a way you can use the APM to monitor the voltage to represent a certain fuel level?
I have no idea on the cost of these things BTW. But it seems like its the only ready-made UAV fuel sensor available. They used them on the Peguin B.