Have you ever stopped and wondered about the strange substance we call jet fuel that powers the airplanes you fly on? Perhaps you’re even curious about the nitty-gritty aspects of it, such as what is it made of, how much of it is carried on board every flight, where it is stored, and perhaps how much of it is burned every flight. Look no further, as I’m about to show you all there is to know about jet fuel.
1. What is jet fuel, and what is it made of?
Jet fuel is a specific type of fuel that has been designed to be used in the gas-turbine engines that power modern jetliners. The two most commonly used type of jet fuels worldwide are Jet A and Jet A-1. Both of these are kerosene-based fuels modified with additional additives and produced to a precise international specification. Jet A-1 is very similar to Jet A, except it contains an anti-static additive and has a lower freezing point (-47 degrees Celsius versus -40 degrees Celsius). Jet B is another type of jet fuel designed to be used in colder climates and is a mixture of 30% kerosene and 70% gasoline. As it is more dangerous, Jet B is only used in extreme climates where its -60 degrees Celsius freezing point is needed to prevent engine clog.
2. How much fuel do airplanes carry and burn every flight?
Unlike with cars, airplane fuel tanks are rarely ever filled to the brim before a flight, as the additional weight of the extra fuel would hinder aircraft performance and increase fuel consumption. Essentially the fuel will be wasted carrying itself around, which is quite ironic if you think about it. Therefore, before every flight the pilots and dispatchers must always precisely calculate how much fuel should be loaded to make sure that they have enough fuel for the flight but not too much that it’ll be wasted. The FAA minimum requires that all flights carry enough fuel to reach to their destination and continue to their designated alternate airport in case of a diversion, and then additional fuel enough for 45 minutes of flying time. It is then at the captain’s discretion to add more if necessary. Before the flight the crew will also calculate how much fuel they would expect to have left once they reach each waypoint on the flight plan so that they can monitor fuel levels in-flight and ensure that there is enough left. If you want the precise numbers, a Boeing 757-200 flying from New York JFK to Los Angeles LAX (a distance of 5250 nautical miles or 6040 standard miles) will typically carry around 116,400 pounds of fuel: 106,400 pounds to reach the destination, and the remaining 10,000 pounds as reserve fuel. In total, this equates to around 1,700 gallons of fuel. This is enough to power a Toyota Camry with 31.4 miles to the gallon a total distance of 53,380 miles.
3. Where is the fuel stored?
It’s hard to imagine how engineers would be able to fit tanks capable of holding thousands of gallons of fuel on board an aircraft that is already packed with passengers and cargo. The solution is probably not what you were expecting, and it is in the wings. While only some aircraft have center fuel tanks (for example the A330-300 doesn’t), all aircraft store the majority of their fuel in tanks that are located in the wings. Though this solution may seem very bizarre and unnecessary, it works out very well. Airplane wings are much thicker than they appear to be, and much of the space inside would otherwise be empty as the only system running through the wings is for the flight control surfaces and it takes up very little space. Therefore, there’s plenty of room inside the wings to store all of the fuel that the aircraft will need. As an additional benefit, the fuel stored in the wings weigh them down, counteracting the natural upward-flex of the wings that occur during flight.
In the face of much more mysterious and interesting things that go on in the world of commercial aviation, fuel is not one that many people are particularly curious about. But nonetheless, there are still several quirky and fascinating pieces of trivia on jet fuel that you hopefully enjoyed learning about. If you’re still keen to learn more on this topic, check out some of these articles below.
Aviation fuel by Wikipedia – https://en.wikipedia.org/wiki/Aviation_fuel
How much fuel a 747 can hold – http://www.herebeanswers.com/2010/10/fuel-tank-of-airplane-boeing-707.html
Awesome explanation of why fuel is stored in the wings – https://www.quora.com/Where-is-fuel-in-a-passenger-aircraft-stored-and-what-is-the-typical-capacity