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E6B Flight computer:

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During my practice test, I tried to use the wikipedia provided equations to calculate Density Altitude and ended up with different results than the E6B. In this case, it looks like the E6B uses something like 130FT/DegC as opposed to posted 118.8 indicated on Wikipedia.

Is there a source for the actual equations and constant values they used for the values on the E6B?

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The Aviation Formulary curated by Ed Williams is probably the best all-around source for the equations. His going-in assumption is that you have a working understanding of the specific concept and are just looking for the formulas, it is not a tutorial about how to understand the concepts.

Pay special attention to both to his "worked examples" and the excel template that is linked from the introduction section just below the contents. You have to look for it to find it, but it's a goldmine.

It's a treasure trove and I keep a downloaded copy of each version in case it just goes away someday.

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Given the era it was developed and it's Navy origin, I suspect the basis for the E6B atmosphere calculations was NACA Report 218, written by Walter S Diehl of the Bureau of Aeronautics, Navy Department.

The US Standard Atmosphere was first published in 1958. Later editions of that model and the ICAO Standard Atmosphere differ only above normal altitudes for aviation. The equations you found on Wikipedia are probably based on the US/ICAO standard atmospheres.

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