Rational Method in OpenRoads

Hello,

I am noticing that ORD Rational Method seems to calculate catchment flows which do not seem to reflect q=CiA.  Below is a snip image of catchment utility properties.  Please note that the feature definition of the catchment shape is 'Grass' but that the Runoff Coefficient is overridden by a value calculated in Excel.

The first image may be hard to see, but C=0.72, i=8.52in/hr, A=0.426 acres.  I would expect q~2.6 cfs, but instead the program calculates 3.29 cfs; this difference is ~25% which makes me think something is off, either with my understanding of how this equation is supposed to work, or with how the program is performing the calculation.

I read in the program information that there is a 1.008 conversion factor to account for conversions between acres, square feet, inches, but that would ultimately produce negligible differences for small watersheds.

Also please note that the program is also calculating C*A, and this value is what I would expect from 0.72*0.426 (=0.307 acres), however 3.29 does not equal 0.307 * 8.52, so I don't know if/how it is applying the C*A value when calculating q.

Thanks,

Nathan