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An aircraft fuel system allows the crew to pump, manage, and deliver aviation fuel to the propulsion system and auxiliary power unit (APU) of an aircraft. Fuel systems differ greatly due to different performance of the aircraft in which they are installed. A single-engine piston aircraft has a simple fuel system; a tanker (such as the KC-135), in addition to managing its own fuel, can also provide fuel to other aircraft.
Fuel is piped through fuel lines to a fuel control valve (usually known as the fuel selector). This valve serves several functions. The first function is to act as a fuel shut-off valve. This is required to provide the crew with a means to prevent fuel reaching the engine in case of an engine fire. The second function is to allow the pilot to choose which tank feeds the engine. Many aircraft have the left tank and right tank selections available to the pilot. Some Cessna airplanes feed only from both tanks; and many have the option to feed from left, right, or both tanks. The reason to have left only and right only options is to allow pilots to balance fuel load to reduce the banking moment. In some aircraft, the shut-off function is a different valve located after the fuel selector valve.
Typically, after the selector valve—situated at a low point in the fuel run—there is a gascolator — a fuel filter that can be opened on the ground and drained of fuel impurities denser than petroleum, mainly water and sediment. Other drainage points are in each tank (often more than one contaminant collection sump per tank) and at the injection pump.
Each tank is vented (or pressurised) to allow air into the tank to take the place of burned fuel; otherwise, the tank would be in negative pressure which would result in engine fuel starvation. A vent also allows for changes in atmospheric pressure and temperature.
The fuel level indication system in the simplest form in aircraft is a transparent window on the tank side and in its usual application a float-driven potentiometer installed in the tank. After the TWA Flight 800 disaster, a revision was made to aircraft fuel systems to address the potential explosion hazard of electrical components located in the fuel tank. Single-engine piston aircraft fuel level systems moved to utilize float level gauges from the CNG and LPG industries which had the float drive a magnetic coupling and relocated the potentiometer outside the fuel tank.
Some single-engine aircraft use capacitive probes in the fuel tanks. As fuel is burned, more air enters the tank and the capacitance increases; this is read by a computer and the fuel amount is calculated and displayed to the pilots.
Recent advances in magnetoresistive technology have evolved new fuel level sensors for general aviation applications. This system is not affected by any additive or fuel combination to replace 100LL for piston-powered aircraft.
Single-engine light aircraft fuel tanks are usually in the wings, but some aircraft have a small "header tank" between the normal fuel tank and the engine, to facilitate reliable fuel flow to the engine. On many small or very old single-engine header tanks (and even main tanks) are often mounted above and/or immediately behind the engine. A few (particularly ultralight aircraft) have them in the fuselage or on the airframe behind the pilot and/or passenger(s).
Adding tanks and engines increases the complexity of the fuel system and its management. Additional features found in multi-engine aircraft are:
All of the considerations made for the twin piston are applicable to turbine fuel systems. Additional consideration apply because of the higher altitudes, different fuel, lower temperatures, and longer flights.
To avoid water condensation or the fuel itself solidifying at low temperatures (-55 °C), fuel tanks have thermometers and heating systems. Many are pressurized with engine bleed air to keep moist air out and ensure positive pressure feed to the pumps. In larger aircraft, fuel tanks also are in the fuselage and their load affects the center of gravity of the aircraft. This imposes limitations on the amount of fuel carried and the order in which fuel must be used. Turbine engines burn fuel faster than reciprocating engines do. Because fuel needs to be injected in to a combustor, the injection system of a turbine aircraft must provide fuel at higher pressure and flow compared to that for a piston engine aircraft.
The refueling system of larger aircraft includes a single positive pressure refueling point from which all tanks can be fueled. How much and to which tanks fuel is fed during refueling operations is determined by the controls in the refueling panel, usually installed nearby and accessible to ground crews.
External tanks are used to extend the range of an aircraft. Drop tanks are used by combat aircraft that need to discard them after use for performance reasons. To transfer fuel from the tip tank to the main tank on each side, there must be a fuel pump in the tip tank.[ dubious ]
A carburetor or carburettor is a device that mixes air and fuel for internal combustion engines in an appropriate air–fuel ratio for combustion. The term is sometimes colloquially shortened to carb in the UK and North America or to carby in Australia.
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many small UAVs have used electric motors.
The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine. The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through the turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany, developed the concept independently into practical engines during the late 1930s.
Aerial refueling, also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring aviation fuel from one military aircraft to another during flight. The two main refueling systems are probe-and-drogue, which is simpler to adapt to existing aircraft, and the flying boom, which offers faster fuel transfer, but requires a dedicated boom operator station.
A ram air turbine (RAT) is a small wind turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.
Aircraft engine controls provide a means for the pilot to control and monitor the operation of the aircraft's powerplant. This article describes controls used with a basic internal-combustion engine driving a propeller. Some optional or more advanced configurations are described at the end of the article. Jet turbine engines use different operating principles and have their own sets of controls and sensors.
A fuel pump is a component in motor vehicles that transfers liquid from the fuel tank to the carburetor or fuel injector of the internal combustion engine.
Aviation fuels are petroleum-based fuels, or petroleum and synthetic fuel blends, used to power aircraft. They have more stringent requirements than fuels used for ground use, such as heating and road transport, and contain additives to enhance or maintain properties important to fuel performance or handling. They are kerosene-based for gas turbine-powered aircraft. Piston-engined aircraft use leaded gasoline and those with diesel engines may use jet fuel (kerosene). By 2012 all aircraft operated by the U.S. Air Force had been certified to use a 50-50 blend of kerosene and synthetic fuel derived from coal or natural gas as a way of stabilizing the cost of fuel.
The J-2 is a liquid-fuel cryogenic rocket engine used on NASA's Saturn IB and Saturn V launch vehicles. Built in the U.S. by Rocketdyne, the J-2 burned cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) propellants, with each engine producing 1,033.1 kN (232,250 lbf) of thrust in vacuum. The engine's preliminary design dates back to recommendations of the 1959 Silverstein Committee. Rocketdyne won approval to develop the J-2 in June 1960 and the first flight, AS-201, occurred on 26 February 1966. The J-2 underwent several minor upgrades over its operational history to improve the engine's performance, with two major upgrade programs, the de Laval nozzle-type J-2S and aerospike-type J-2T, which were cancelled after the conclusion of the Apollo program.
The Monosoupape, was a rotary engine design first introduced in 1913 by Gnome Engine Company. It used a clever arrangement of internal transfer ports and a single pushrod-operated exhaust valve to replace the many moving parts found on more conventional rotary engines, and made the Monosoupape engines some of the most reliable of the era. British aircraft designer Thomas Sopwith described the Monosoupape as "one of the greatest single advances in aviation".
The Learjet 25 is an American ten-seat, twin-engine, high-speed business jet aircraft manufactured by Learjet. It is a stretched version of the Learjet 24.
American Airlines Flight 157, a Douglas DC-6, departed on November 29, 1949, from New York City bound for Mexico City with 46 passengers and crew. After one engine failed in mid-flight, a series of critical mistakes by the flight crew caused the pilot to lose control of the plane during the final approach to a routine stopover at Love Field in Dallas, Texas. The airliner slid off the runway and struck a parked airplane, a hangar, and a flight school before crashing into a business across from the airport. 26 passengers and two flight attendants died. The pilot, co-pilot, flight engineer, and 15 passengers survived.
The Aeronca 15AC Sedan is a four-seat, fixed conventional gear light airplane which was produced by Aeronca Aircraft between 1948 and 1951. Designed for personal use, the Sedan also found applications in utility roles including bush flying. The Sedan was the last design that Aeronca put into production and was the largest aircraft produced by the company.
The Aeronca Model 7 Champion, commonly known as the "Champ", or "Airknocker", is a single-engine light airplane with a high wing, generally configured with fixed conventional landing gear and tandem seating for two occupants.
A turbine engine failure occurs when a turbine engine unexpectedly stops producing power due to a malfunction other than fuel exhaustion. It often applies for aircraft, but other turbine engines can fail, like ground-based turbines used in power plants or combined diesel and gas vessels and vehicles.
A pressure carburetor is a type of fuel metering system manufactured by the Bendix Corporation for piston aircraft engines, starting in the 1940s. It is recognized as an early type of throttle-body fuel injection and was developed to prevent fuel starvation during inverted flight.
This article briefly describes the components and systems found in jet engines.
Of the three types of carburetors used on large, high-performance aircraft engines manufactured in the United States during World War II, the Bendix-Stromberg pressure carburetor was the one most commonly found. The other two carburetor types were manufactured by Chandler Groves and Chandler Evans Control Systems (CECO). Both of these types of carburetors had a relatively large number of internal parts, and in the case of the Holley Carburetor, there were complications in its "variable venturi" design.
Many variations of aircraft engine starting have been used since the Wright brothers made their first powered flight in 1903. The methods used have been designed for weight saving, simplicity of operation and reliability. Early piston engines were started by hand, with geared hand starting, electrical and cartridge-operated systems for larger engines being developed between the wars.
An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to. This replaced the external combustion engine for applications where the weight or size of an engine was more important.