| If you want a change from flying electric model airplanes, then you could try out gasoline-powered planes. These planes come with a choice of either 2 stroke or 4 stroke engines. 2 stroke engines have a glow plug instead of a spark plug in its cylinder head. The glow plug consists of a small coil, which heats up once a small voltage is applied to it. Once it turns red hot due to the heat, the fuel inside the cylinder ignites and the 2 stroke engine bursts into its noisy life. 2 stroke engines are basically noisier than 4 stroke engines. They tend to let out more smoke than 4 stroke engines. But they are cheaper to buy than 4 stroke ones. They also require more oil than 4 stroke engines. The reason is that since 2 stroke engines have a higher rpm [rotations per minute] than 4 stroke engines, the oil consumption as well as the fuel consumption also goes up. Since oil is pre-mixed with the fuel, you should specify the stroke of your engine, when buying your fuel supplies. Since you could run a 2 stroke fuel in a 4 stroke engine, running a 4 stroke engine on a 2 stroke fuel might overheat the engine due to less oil being mixed in the fuel. 4 stroke engines run a lot cooler and are more silent as compared to 2 stroke engines. However, there are lots of people who like 2 stroke engines, since it sounds more realistic to an airplane engine due to its high-pitched sound. The fuel, which is used to power 2 stroke and 4 stroke engines, is normally methanol along with a percentage of oil mixed in it. This fuel might also contain additives to improve its combustibility, especially for special purpose applications. 4 stroke engines are more complicated than 2 stroke engines and contain more moving parts, and are hence costlier to manufacture. These engines are normally operated by pushrods instead of cams and might also have side or rotary valves. Both the engine types get their fuel supply through a carburetor, which can be adjusted to set the desired rpm. A diesel 2 stroke engine is also available, which uses ether, kerosene and oil mixed together as its fuel and has an adjuster to change the compression ratio instead of a glow plug. This engine can used to rotate a bigger propeller than a similar gasoline 2 stroke engine. The exhaust of all these engines might just end with a simple header pipe or might go into a silencer to lower the sound. A 4 stroke engine will need to have its valves adjusted after specific 'flying hours'. A 2 stroke engine normally requires less maintenance than a 4 stroke engine. But, a new technology is slowly increasing the usage of 4 stroke engines in model planes. So, check out the above features, before you decide to buy a gasoline engine plane. Also test 'fly' some 2 stroke or 4 stroke planes to get a 'feel' of the speed and response time of these planes. After all, its different strokes for different folks. |
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