I've been playing with WinSIPP2 from Senninger, and it has been an eye opening experience. Getting reasonable DU (>85%) and SC (<1.5) is non-trivial. If you've not used the package, it allows you to try out various sprinkler arrays then calculateds the densogram and DU, CU, and SC for the plot. In addition, mousing over any location will give you the application rate. I've found a few interesting tidbits: 1. Many senniger sprinklers have a heavy watering area 2-3 feet in radius from the rotor. Spacing the sprinklers 1 radius apart is a bad idea. You get a soggy spot at each rotor. Spacing a few feet more than 1 radius works better for this kind of distribution. 2. Even with sprinklers that have a fairly flat distribution, spacing is critical. I could get uniformity differences of 10-15% by changing the spacing 2 feet. Unfortunately, Senninger doesn't have small sprinklers (Under 30 foot radius throw) that do partial arcs. Anyone know of a software package that has sprinkler data for other brands?