Date:	8-23-2020
Number of Hours:	0.10
Brief Description:	Fuel tank pressure test - calculations
Plans call for pressure to measured with an alternator set to 1,500FT, and the tank pressurised until the altimeter reads zero. Not having an altimeter to hand I will use a water manometer. I have found in the archive that 16" of water is what to aim for to achieve this, but the maths as I see it do not support this. I'm no engineer, or even terribly bright, but I calculated an answer from online resources, backed up by rules of thumb aproximations used for performance calculations. www.mide.com/air-pressure-at-altitude-calculator At STP pressure drop for 1,500FT = 5,373 Pa Check 1,500FT / 30 FT per hPa = 50 hPa = 5000 Pa https://www.omnicalculator.com/physics/manometer At STP height of water to measure a pressure change of 5,373 Pa = 548mm = 21.6” Check P = rho x g x h = 5000 / 9806 = 0.5 m = 500mm = 19.7" So my plan is to try a water column of 550mm. Here we go!