How to calculate the best climb rate and glide rate?
Did you ever consider to look at the units in your calculation?

You can't just throw together some numbers and expect a correct result. Start by converting all input to the much more sane SI units and see how it goes from there. If you plug in the units instead of the numbers on the right side of the equation, you can check for correctness by comparing to the intended unit on the left side.

Hint: 1 Newton = 1 kg·m/s².