IF Statement in VBA

[arthur1974]

Hi,

I have devised an Excel Motor Calculator Spreadsheet, however I'm having trouble calculating a certain variable, the motor displacement. This is due to the motor displacement having two different formulas, which obviously use different variables. The two formulas in question are below:

(1) MotorDisplacement = (Flow * 1000 * VolumetricEfficiency) / Speed

(2) MotorDisplacement = (MotorTorque1 * 20 * 3.142) / (PressureDifferential * MechanicalEfficiency)


I'm guessing I need to use an IF stament to basically say - IF Volumetric Efficiency, Flow and Speed are known, use equation (1) to calculate the displacement, or IF Motor Troque, Pressure Differential and Mechanical Efficiency are knoqn, use equation (2).

Please could someone assist me with the code?

I've attached the spreadsheet in question.

Thanks.