David, well, there are several 4 stroke gas engines available today that have about the correct displacement But nothing is available at present in 4 stroke gasoline powerplants that has all the features pattern requires. The current offerings are limited by their lower power delivery and their heavy weight. Reliability is largely unknown and so is maintenance

The OS33 is an excellent powerplant for what we do. I also hear from Claude and Stephane in France that the RCGF32 is excellent.Of course,both are 2 stroke engines and are light weight. I know for a fact that the OS has been a practically zero maintenance engine (after the very early crankcase cover problem mine had) for several hundred flight so far. Reliability has been flawless. It's been "gas-up, fly, repeat".....All things considered, the best engine I've ever used in Pattern. When I have several hundred flights on my DLE55 / Delta I might change my opinion, but right now, it stands