Describe the primary types of fuel used in reciprocating engines.

The primary types of fuel used in reciprocating engines are Avgas and Mogas.

Avgas, which stands for aviation gasoline, is specifically formulated for use in aircraft piston engines. It contains a higher octane rating compared to standard automotive gasoline, which helps prevent engine knocking and allows for higher compression ratios. Avgas is typically colored blue (100LL) to distinguish it from other fuels, and it's designed to meet stringent safety and performance standards required for aviation.

Mogas, or motor gasoline, refers to the fuel commonly used in automobiles. It is suitable for some general aviation aircraft engines that are certified to run on this type of fuel, often allowing aircraft to utilize a more widely available and economical option.

While the other fuels mentioned, such as petrol and diesel, are indeed used in various engines, they don't specifically apply to the context of reciprocating engines as used in aviation. Biofuels and ethanol are emerging in various applications but are not standard for reciprocating aviation engines. Kerosene and Jet A are fuels used for turbine engines rather than reciprocating engines.

Therefore, the reference to Avgas and Mogas encompasses the fuels that are most relevant and widely used in the operation of reciprocating engines, particularly in the aviation sector.