What is the best fuel to air ratio of Jet A1?

• A. 1:15
• B. 15:1
• C. 1:14
• D. 14:1

Answer: (A)

Fuel-to-air ratio shows how much fuel is burned with a given amount of air. For hydrocarbon Jet A1, the ideal point for complete combustion is near the stoichiometric mix, where the oxygen in the air exactly matches what's needed to oxidize the fuel. For kerosene-based Jet A1, this stoichiometric balance is about 15 parts air to 1 part fuel by mass, so the corresponding fuel-to-air ratio is roughly 1 part fuel to 15 parts air. In other words, one kilogram of Jet A1 requires about 15 kilograms of air for complete combustion. This is why the best representative ratio is 1:15. In actual engines, mixtures may be adjusted slightly richer or leaner depending on performance and emissions, but 1:15 reflects the near-stoichiometric balance for Jet A1.