From small aircraft like Cessna to large twin-engine jet aircraft like Airbus A380, all combustion powered aircraft need fuel to operate. Like internal combustion engines, they burn fuel to generate the power needed to achieve and maintain safe flight speed. Although there are several types of aviation fuel, most of them are kerosene. So why does the aircraft use kerosene instead of ordinary gasoline as fuel?

Low freezing point

Kerosene has a lower freezing point than gasoline, so it will not freeze in cold temperatures. Kerosene itself is actually a mixture of petroleum-based hydrocarbons and other compounds. Therefore, the exact freezing point of kerosene fuel is different. However, the temperature required for kerosene freezing is lower than that required for gasoline freezing.

Higher flash point

In addition to low freezing point, kerosene has a higher flash point than gasoline. Flash point refers to the temperature at which combustible chemicals or substances ignite and become steam. Compared with gasoline, kerosene has a higher flash point and provides a higher octane number to achieve greater power and efficiency. In fact, this is the main reason for using kerosene fuel on aircraft. For decades, the aircraft initially used gasoline. However, the demand for higher octane fuel prompted aviation experts to test other types of fuel, thus paving the way for kerosene. Today, kerosene is the most commonly used fuel on aircraft.

Low viscosity

In flight operation, the viscosity grade of kerosene is lower than that of gasoline, which means that it is more water, not as thick or "sticky" as gasoline. This is important because highly viscous fuel can block the internal passages of aircraft engines. However, because the freezing point of kerosene is lower than that of gasoline, the moisture and viscosity of kerosene are lower than that of gasoline during flight. Even in high altitude areas with low natural temperature, the viscosity of kerosene is very small, and it can easily pass through the engine and connecting parts of the aircraft.

Lower costs

Considering that large commercial aircraft like 747 consume about 1 gallon of fuel per minute, it is important for airlines to consider the fuel cost. The good news is that kerosene is much cheaper than gasoline. In some cases, the price of kerosene may be less than half that of gasoline. Kerosene has lower freezing point, higher flash point and lower viscosity, which is another reason why kerosene has become the preferred fuel for aviation industry.