The long awaited Multistage2015 Saturn launchers. All the required add-ons and where to find them are in the PDF located in the Doc folder. Once you've verified that you have all the required add-ons installed, unzip Multistage2015 Saturns into your main Orbiter 2010 P1 directory.
Special thanks to Sputnik who allowed me to redistribute a few of their meshes from Velcro Rockets and Velcro Saturns.
EDIT: I mistakenly credited 4throck instead of Sputnik for the Velcro Rockets meshes that I used. I got the two confused and made an error. Hopefully I've gotten everything right now.