Gentlemen:
A summary of key technical results and conclusions from my High Power Rocketry Magazine tech article "Departures from Ideal Performance for Conical Nozzles and Bell Nozzles, Straight-Cut Throats and Rounded Throats" is now on the High Power Rocketry web site at:
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The summary equations and a summary plot of nozzle thrust coefficient versus straight-cut throat L/D are included. The summary plot shows the large jump in nozzle thrust coefficient for straight-cut throat L/D's < 0.45. I recommend the following design criteria; straight-cut throat L/D