The F-18 will probably fly with as small as a 90 if light enough. I have a converted Dynamax-Scorpion in mine. There are a myriad of choices,but keep it as light as possible. Depending on your budget, if you fans are Dynamax's you can convert them or go to a prebuilt system such as Stumax or TamJets. XPS by all accounts is rather heavy for this application. What ever your choice is you will probably be 10-12s so figure about four pounds of batteries.
John