Ys Rc Engines

The OS is a trademark, the YS is a subtype of the mark.

The choice is (for propeller aircraft with engines) between 2-stroke and four-time, and in many cases electric.

Electric has the advantage of not needing fuel and to be quiet, but in most cases is totally unrealistic to her. It also has a longer flight time limited due to the weight of the battery.

2-stroke is easier, cheaper and more powerful for its size.
4-time is used more on large aircraft as it "sounds" more realistic, but requires a larger engine because it is only triggered once each other. (Most kits of aircraft, etc. ARF motor list of good size in both 2 and 4 times for this plan, so it is not low power or conquered, whether what is bad in most conditions.)

For general use, I use 2-stroke engines for use on a large scale and / or large models that I use 4-stroke (like .60 or more, stunt bi-planes, fighters, etc. )