A model engine is a small internal combustion engine typically used to power a radio-controlled aircraft, radio-controlled car, radio-controlled boat, free flight, control line aircraft, or ground-running tether car model.
An old Cox Golden Bee 0.049 cubic inch (0.8 cubic cm.) reed valve engine disassembled. The weight is two and a quarter ounces with the propeller and large fuel tank, but without fuel.
The same Cox Golden Bee 0.049 assembled. The left rotating propeller and horizontal cylinder contribute to keeping the control lines tight.
Glowplug engine
Diesel engine
Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula CH3NO2. It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in extractions, as a reaction medium, and as a cleaning solvent. As an intermediate in organic synthesis, it is used widely in the manufacture of pesticides, explosives, fibers, and coatings. Nitromethane is used as a fuel additive in various motorsports and hobbies, e.g. Top Fuel drag racing and miniature internal combustion engines in radio control, control line and free flight model aircraft.
Image: Nitromethane anion resonance