Bruline makes a filter for model airplane engines. There are two filter options (coarse and fine). I use them on C/L stunt planes with inverted engines operating off grass fields. I have also used them on RC planes. They don't create many problems once you have your engine set up properly and don't need to look down the barrel of the carb much. They are VERY nice when you pull the engine out of the dirt in a cornfield and don't have a glob of mud or dirt in the barrel of the carb when you start cleaning up the mess. Good luck, Dzl