Glow fuel is a term used to tell about fuel used for model airplanes, helicopters, cars and boats. Glow fuel can be burned by very simple two-stroke engines or by four-stroke engines. Engines like this provide lots of power in a small size.
Sometimes, glow fuel is called nitro or just model fuel. Some model fuel has only a little bit of nitro, but some fuel has none at all. It is called "FAI fuel." "FAI" stands for Fédération Aéronautique Internationale. They say that models used in racing or other competition under their rules may not have any nitro in their mix.
Methanol is the main ingredient. It provides most of the fuel's ability to burn. In order to burn the glow fuel, a glow engine must have a glow plug. The glow plug burns very hot as the engine runs because of a catalytic reaction with the methanol. Since the engines turn very fast, a phenomenon known as thermal inertia helps to keep the plug glowing as the engine runs. A small amount of electricity is used to cause the glow plug to glow as the engine is started. Once the engine is running, the electricity is disconnected.
Nitromethane is added to the fuel for more power and to make the engine easier to tune. Nitromethane contains less energy than the same amount of methanol, but it requires less oxygen. This means that more of it can be put into an engine during each turn of the engine. This leads to more power.
Fuel for most model planes, boats and helicopters has 5% to 15% nitromethane. For use in race cars, the nitromethane can be from 30% to as much as 65%.
Nitromethane is hard to get in some countries since it is known as an explosive. In these countries, glow fuel sometimes has no nitromethane at all.
Since the engine doesn't have its own supply of oil, it's instead added to the fuel to help lubricate the moving parts and to keep them from burning up. The oil can be castor oil or synthetic oils. Some fuels include a mixture of the two. The oils included in glow fuel are not burned by the engine. Instead, the oil comes out of the exhaust. Not only does the oil lubricate the moving parts, but the oil which comes out the engine helps carry away extra heat.
Glow engines should be run slightly "rich." This means that the mix of fuel and air going into the engine has to have a bit more fuel in it than it can burn at once. This unburned fuel and oil help keep the engine cool. After a model has been run, it is coated with a film of oil and must be cleaned. Ordinary window cleaner and a paper towel do a nice job of removing the oil.
Glow fuel is not difficult to make, but some of the ingredients are dangerous in large amounts. Instead, most modelers buy their glow fuel already made. Some very small engines require more oil than larger engines. More oil may be needed in the fuel. The proper oil can be found at a hobby shop. Companies which make glow fuel mix their fuels with the help of computers. This helps each batch of fuel be of the highest quality it can be.