Adam Dickson

Improved correlated fuel tank tests with better sealing and compensated molar calculation

The previous correlated tests were repeated, but with better ambient temperature control, better sealing of fuel tank filler ports, supplementary sealing of fuel drain ports with additional EZ-lube and tape, fuel overflow ports with tube seals and EZ-lube, and better clamping of AN6 plugs with additional EZ-lube.

Measurements were conducted at a conditioned temperature of 18 degree celsius, with several hours allowed for the tank to reach thermal equilibrium.

Excluding measurement I, which has an invalid temperature of 22 degree recorded, the results are as shown. The alignment between the left and right fuel tanks is extremely good, and the temperature and pressure corrected estimate of the molar content of each tank varies over a range of 1-2 parts per thousand over 10000 minutes (about 1 week), with no trend evident.

The zero time measurement differs markedly from subsequent measurements. This was explained by liguid clinging temporarily to the tube walls after initial setup. This took several 10's minutes to resolve.

I have assumed a tank deformation coefficient of 5e-8 m^3/Pa, but the graph appears much the same of this is neglected

The absence of a molar trend in each the tanks (at least undetectable under the "noise") but especially the fact that the two tanks follow each other almost perfectly without and tendency to diverge from each other confirms the absence of any significant leakage in either of the tanks. I would say that perfect correlation maintained over an extended period is quite enough to confirm this, without bothering to perform any temperature or ambient pressure compensated molar calculations. This was the earlier intuition.

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