Gregs idea of lighting the fueltubes is brilliant. However the indication is only good on the ground or in calm air. Unless a restrictor is installed as mentioned by me before here. My indications are rocksteady, even in turbulent air.
A few words on unusable fuel. FAR 23 certified aircraft are tested with a 15° sideslip and the tanks switched on the most critical tank for this flight condition. On a Super cub with a fuel selector for each tank and the slip being flown left wing low, the left tank would be selected. On the Husky prototype such a selector was installed. As soon as the engine starts coughing, the right tank was selected and after landing the fuel remaining in the LH tank was measured. 3 times for each side.
The average remaining measured fuel was determined the UNUSABLE FUEL .
On the Husky the tanks will empty till the last pint, when flown coordinated. So keep in mind that in case of fuel starvation, rock your wings, watch the sighttubes. and if you see fuel, put that wing up 5-10 degrees. The engine will start again, but not for very long.
If your engine quits after running lean the last few seconds, and you see fuel in the sighttubes, the tankvents are blocked. Open the sliding window, stick the draincup into the LH drain and vent the tank through there. Engine will start immediatly. Tank needs to be vented every 2 min and when entering the pattern. Been there, done that, worked fine.
