OS Four Stroke I C Engines
30, 40, 52, 70, 91 & 120 size
The OS design department first began work on four stroke engines in 1974 and introduced the world's first volume production four stroke engine for model aircraft, the 10cc FS60, in 1976. The company's original aim was simply to offer a quieter engine than the typical high speed two stroke, but very soon modellers were demanding more powerful and exciting engines - hence the development of the extensive range that extends from the FS-30S to the supercharged 20cc FS-120SP. Again, OS were the first to introduce a genuine supercharged model aircraft engine into their range. All current OS engines have ringed pistons and are of the pushrod overhead-valve type, with enclosed rocker valve and pushrods.
