How much fuel a plane carries

Flight range depends on how much fuel is on board the aircraft and on fuel consumption per kilometre. The lower the consumption per kilometre, the greater the range that can be achieved with a given fuel supply.

The lowest consumption figures come from heavy-fuel engines — diesels running on kerosene, petrol, and other grades of fuel which, unlike petrols, are known as "heavy fuels."

In heavy-fuel engines, specific fuel consumption runs at 170-180 g per horsepower per hour. In a modern high-altitude piston aviation petrol engine, specific fuel consumption reaches 280-300 g per hp-hour. In jet engines, at flight speeds up to 700 km/h, specific fuel consumption is twice that of petrol engines. But at flight speeds above 850-900 km/h, specific fuel consumption in jet engines is lower than in petrol engines. In liquid-fuel rocket engines, specific fuel consumption significantly exceeds that of every other engine type at today's flight speeds.

For slow, long-range aviation, the heavy-fuel engine is the best engine type in terms of consumption.

That said, despite their low fuel consumption, diesels haven't found wide use in aviation, owing to their heavy weight and low power per litre. For equal power output, a diesel weighs roughly twice as much as a petrol engine. The design challenges of overcoming these drawbacks have held back the development of heavy-fuel engines.

A modern aircraft has a relatively small capacity for storing its fuel supply, limited to the centre wing section and the wings themselves, and within that space the centre of gravity shifts only slightly. Fuel tanks can't be placed in the tail section of the fuselage, because of the major effect this would have on the centre of gravity as fuel is used up, and the resulting loss of manoeuvring performance.

The amount of fuel needed to achieve a given flight range is made up of the fuel spent on engine testing and warm-up, taxiing, take-off, climb, flying at the set altitude to complete the assigned task, and the return to base. Broadly speaking, the amount of fuel depends on how long the aircraft stays airborne and on the flight regime.