Lee Berger designed and built this Berger 7-cylinder radial model airplane engine in 2001. This is the first successful 2-cycle radial engine using a common crankshaft with a master rod and articulating rods inside a common crankcase. Since every cylinder of a 2-cycle engine fires on every revolution, an even or odd number of cylinders can be used. In 4-cycle engines, however, each cylinder fires every other revolution, thus requiring an odd number of cylinders.
Two-cycle engines require pressure inside the crankcase to force fuel into the combustion chamber on the intake cycle. In order to accomplish this, Lee Berger designed a positive-pressure pump (supercharger) in the back of the crankcase that maintains constant pressure in the crankcase during operation. A supercharger increases the atmospheric pressure to create more horsepower. Lee designed and built this Berger 7-cylinder radial model airplane engine in 2001. The engine is 8”-long, 8”-wide, and 9”-high.