What is the composition of aviation fuel?

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What is aviation fuel made of?

Aviation fuel – from Wikipedia

Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft; it is generally of a higher quality than fuels used in less critical applications such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures, amongst other properties.

Most Aviation fuel available for aircraft are kinds of gasoline used in engines with spark plugs i.e. piston engines and Wankel rotaries or fuel for jet turbine engines which is also used in diesel aircraft engines. Alcohol, alcohol mixtures and other alternative fuels may be used experimentally but are not generally available.

Avgas is sold in much lower volumes, but to many more individual aircraft, whereas Jet Fuel is sold in high volumes to large aircraft operated typically by airlines, military and large corporate aircraft.

The Convention on International Civil Aviation, which came into effect in 1947, exempted air fuels from tax. Australia and the USA oppose a worldwide levy on aviation fuel, but a number of other countries have expressed interest.

Contents

1 Avgas

2 Jet Fuel

3 In use

4 Energy content

5 Safety Precautions

6 See also

Avgas

See Main Article for Avgas.

Jet Fuel

See Main Article for Jet fuel.

In use

Aviation fuel is often dispensed from a tanker or bowser which is driven up to parked aeroplanes and helicopters. Some airports have pumps similar to filling stations that aircraft must taxi up to. Some extremely large airports also have permanent piping to parking areas for large aircraft.

Regardless of the method, aviation fuel is transferred to an aircraft via one of two methods: overwing and underwing. Overwing fuelling is used on smaller planes, helicopters, and all piston-engine aircraft. Overwing fuelling is similar to automobile fuelling — one or more fuel ports are opened and fuel is pumped in with a conventional pump. Underwing fuelling, also called single-point, is used on larger aircraft and for jet fuel exclusively. For single-point fuelling, a high-pressure hose is attached and fuel is pumped in at up to 50 PSI. Since there is only one attachment point, fuel distribution between tanks is either automated or it is controlled from a control panel at the fueling point or in the cockpit. As well, a dead man's switch is used to control fuel flow.

Because of the danger of confusing the fuel types, a number of precautions are taken to distinguish between AvGas and Jet Fuel beyond clearly marking all containers, vehicles, and piping. AvGas is treated with either a red, green, or blue dye, and is dispensed from nozzles with a diameter of 40 millimetres (49 millimetres in the USA). The aperture on fuel tanks of piston-engined aircraft cannot be greater than 60 millimetres in diameter. Jet Fuel is clear to straw in colour, and is dispensed from a special nozzle called a "J spout" that has a rectangular opening larger than 60 millimetres in diameter so as not to fit into AvGas ports. However, some jet and turbine aircraft, such as some models of the Astar helicopter, have a fueling port too small for the J spout and thus require a smaller nozzle to be installed in order to be refuelled efficiently.

Energy content

The net energy content for aviation fuels depends on their composition. Some typical values are:

Avgas, 43.7 MJ/kg or 31.0 MJ/L
Wide-cut jet fuel, 43.5 MJ/kg or 33.2 MJ/L
Kerosene type jet fuel, 43.3 MJ/kg or 35.1 MJ/L

Safety Precautions

Any fuelling operation can be very dangerous, and aviation fuelling has a number of unique characteristics which must be accommodated. As an aircraft flies through the air, it can accumulate a charge of static electricity. If this is not dissipated before fuelling, an electric arc can occur which may ignite fuel vapours. To prevent this, aircraft are electrically bonded to the fuelling apparatus before fuelling begins, and are not disconnected until fuelling is complete. Some regions require that the aircraft and/or fuel truck be grounded as well.

Aviation fuel can cause severe environmental damage, and all fuelling vehicles must carry equipment to control fuel spills. As well, fire extinguishers must be present at any fuelling operation, and airport firefighting forces are specially trained and equipped to handle aviation fuel fires and spills. Aviation fuel must be checked daily and before every flight for contaminants such as water or dirt.

Related topics @ Wikipedia

Rocket fuel

http://en.wikipedia.org/wiki/Aviation_fuel

Jet Fuel

Content derived from Wikipedia article on Jet fuel

Jet fuel is a type of aviation fuel designed for use in jet-engined aircraft.

Flash point: 38 °C
Autoignition temperature: 210 °C
Freezing point: -47 °C (-40 °C for JET A)
Open air burning temperatures: 260-315 °C (500-599 °F)
Maximum burning temperature: 980 °C (1796 °F)
Density at 15 °C (60 °F): 0.775-0.840 kg/L

Contents

1 Modern fuels

1.1 Jet A

2 History of jet fuel

2.1 Commercial fuels

3 Piston engine use

4 See also

Modern fuels

The most common fuel is an unleaded/paraffin oil-based fuel classified as JET A-1, which is produced to an internationally standardized set of specifications. In the United States only, a version of JET A-1 known as JET A is also used.

The only other jet fuel that is commonly used in civilian aviation is called JET B. JET B is a fuel in the naptha-kerosene region that is used for its enhanced cold-weather performance. However, JET B's lighter composition makes it more dangerous to handle, and it is thus restricted only to areas where its cold-weather characteristics are absolutely necessary.

Both JET A and JET B can contain a number of additives:

Antioxidants to prevent gumming, usually based on alkylated phenols, eg. AO-30, AO-31, or AO-37;
Antistatic agents, to dissipate static electricity and prevent sparking; Stadis 450, with dinonylnaphthylsulfonic acid (DINNSA) as the active ingredient, is an example
Corrosion inhibitors, e.g. DCI-4A used for civilian and military fuels, and DCI-6A used for military fuels;
Fuel System Icing Inhibitor (FSII) agents, e.g. Di-EGME; FSII is often mixed at the point-of-sale so that users with heated fuel lines do not have to pay the extra expense;
Militaries around the world use a different classification system of JP numbers. Some are almost identical to their civilian counterparts and differ only by the amounts of a few additives; JET A-1 is similar to JP-8, JET B is similar to JP-4. Other military fuels are highly specialized products and are developed for very specific applications. JP-5 fuel is fairly common, and was introduced to reduce the risk of fire on aircraft carriers (has a higher flash point - a minimum of 60° C). Other fuels were specific to one type of aircraft. JP-6 was developed specifically for the XB-70 Valkyrie and JP-7 for the SR-71 Blackbird. Both these fuels were engineered to have a high flash point to better cope with the heat and stresses of high speed supersonic flight. One aircraft-specific jet fuel still in use by the United States Air Force is JPTS, which was developed in 1956 for the Lockheed U-2 spy plane.

Jet fuels are sometimes classified as kerosene or naphtha-type. Kerosene-type fuels include Jet A, Jet A1, JP-5 and JP-8. Naphtha-type jets fuels include Jet B and JP-4.

Jet A

Jet A is the standard jet fuel type in the U.S. since the 1950s and is only available there. JET A is similar to JET-A1, except for its higher freezing point of -40° C (vs -47° C JET A-1). Like JET A-1, JET A has a fairly high flash point of 38° C, with an autoignition temperature of 410° F (210° C). Jet A can be identified in trucks and storage facilities by the UN number, 1863, Hazardous Material placards. Jet A trucks, storage tanks, and pipes that carry Jet A will be marked with a black sticker with a white "JET A" written over it, next to another black stripe. Jet A will have a clear to straw color if it is clean and free of contamination. Water is denser than Jet A, and will collect on the bottom of a tank. Jet A storage tanks must be sumped on a regular basis to check for water contamination. It is possible for water particles to become suspended in Jet A, which can be found by performing a "Clear and Bright" test. A hazy appearance can indicate water contamination beyond the acceptable limit of 30ppm (parts per million).

The U.S. commercial fuels are not required by law to contain antistatic additives, and generally do not.

History of jet fuel

Fuel for a piston-engine powered aircraft (usually a high-octane gasoline known as Avgas) has a low flash point to improve its ignition characteristics. Turbine engines can operate with a wide range of fuels, and jet-aircraft engines typically use fuels with higher flash points, which are less flammable and therefore safer to transport and handle. The first jet fuels were based on kerosene or a gasoline-kerosene mix, and most jet fuels are still kerosene-based.

Commercial fuels

Commercial jet fuels had their origins in military fuels, but commercial use worldwide now greatly exceeds military use. As noted above, Jet-A is similar to JP-8, while Jet-B is a mix similar to JP-4.

Piston engine use

Jet fuel is very similar to diesel fuel, and a few aircraft engine manufacturers, most notably Thielert, have begun offering piston engines which run on jet fuel. This technology has great promise as a way to provide light, powerful, and environmentally-friendly engines for the general aviation market while simplifying airport logistics and phasing out leaded avgas. The current political climates make widespread adoption of this technology likely. However, economic factors mean it will probably take decades before avgas is completely eliminated.

Jet fuel is occasionally used in ground vehicles, often instead of diesel. The United States military makes heavy use of JP-8, for instance. However, jet fuel tends to have poor lubricating ability in comparison to diesel, thereby increasing wear on fuel pumps and other related engine parts. Civilian vehicles tend to disallow its use, or only allow it in the rare circumstances when other fuel is unavailable.

http://en.wikipedia.org/wiki/Jet_fuel

Credits & Copyright: This page is licensed under the GNU Free Documentation License. It uses material from the Wikipedia articles Jet fuel & Aviation fuel

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