AvGas

Aviation Gasoline, jet fuel

AvGas 80.82 UL, 91, 100 LL, 100

Fossil

0.73 to 0.78 kg / L ( 15 ° C)

> 43.5 MJ / kg

• AvGas 100 LL: 100 MOZ

~ 30-170 ° C

AvGas, short for Aviation Gasoline, is the technical term for aviation fuel. Other or similar spellings are: avgas, or aviation gasoline AVGAS. Unlike Mogas it is designed for use at high altitudes. Currently, five types lead fouling offered (see ASTM D 910, Def Stan 91-90/2 (MIL ), ASTM D 6227 ). AvGas is used only by aircraft with a gasoline engine. Turbine -powered aircraft and aircraft with diesel engines require fuel than diesel or kerosene (JP -1 or Jet A -1).

Designation

The individual AvGas varieties are characterized by the so-called Lean rating ( see below). In some varieties of additive LL (Low Lead = bleiarm ) or UL ( Un = Leaded unleaded) is appended. With AvGas 100 LL so a variety is called the ( loosely ) a (motor) octane number ( MON) of 100 and a - compared with the variety AvGas 100 - lower lead content has. In the past the " octane " of the so-called Supercharge rating (see below) was in the denomination also listed, for example AvGas 100/130. To avoid errors in the handling and misunderstandings, the Lean rating is only used for varietal characterization.

Specifications

Lean rating / MOZ (ASTM D 2700): The Lean rating ( LR, Lean = lean mixture), developed by the U.S. Army Air Corps method (ASTM D 614), the knocking behavior of various AvGas varieties to characterize. The method is intended to describe the behavior of the fuel at a relatively low load on the motor. The procedure was similar to the motor octane number determination (MOZ ) are so strong that in 1969 a conversion table (MOZ → Lean rating ) was added to the standard ASTM 2700 and the Lean rating only one ( from the MOZ) calculated size is. In the range 75-100 MOZ both figures hardly differ. From 100, the deviations are not negligible MOZ (MOZ = 110 → LR = 128). Furthermore, the LR is called from a value of 100 as a performance Number ( PN).

Supercharge rating ( ASTM D 909): During the Second World War, the British developed a method to characterize the properties of various knock AvGas varieties with high load on the engine ( start-up phase, rich mixture). Here, - shown in simplified form - made ​​possible by the mechanical performance of the test fuel modified CFR engine with the mechanical power of a reference fuel ( isooctane / N Heptangemisch ) compared. The knocking behavior is measured using a knock sensor for the test and the reference fuel to the same - is held level - low. Allows the test fuel the same performance as the reference fuel, as its octane number ( " Supercharge Rating" by the method, SR ) is defined with the Isooktangehalt the reference mixture. This is of course only possible with octane numbers below 100. About 100 is the reference fuel consisting of a mixture of isooctane with tetraethyl lead (TEL ). ASTM D 909 provides a table to the TEL content in a so-called Performance Number ( PN) to be converted. Under certain circumstances, then two PNs result - a Lean rating characterizing and a second for the Supercharge rating. The SR is not affiliated with the research octane number (RON ) comparable.

RON (ASTM D 2699 ): The " Research octane number" plays no role in the technical characterization of AvGas. However, it is surprisingly used in the exemption of leaded commercially occupied aviation fuel ( § _27 EnergieStG: ... whose research octane number value of 100 does not fall below ..). AvGas 100 (1.12 g Pb / L ) and 100 LL (0.56 g Pb / L) would then be for commercial use only tax-exempt, AvGas 80 (0.14 g Pb / L) definitely not, for AvGas 91 (0.56 g Pb / L), it would be at least doubtful ( unleaded AvGas 82 UL anyway does not fall within the exemption ).

• DVPE: Dry Vapour Pressure Equivalent (vapor pressure at 38 ° C)

Use

AvGas is used today in the U.S. (such as Lycoming and Continental engine) and Russian aviation gasoline engines as well as for rotary aircraft engines. Some need hochverbleites gasoline with a high octane number due to their design with high compression. These conditions are met AvGas 100 (high Lean rating, high lead content ). Smaller engines of the 1940s and 1950s are designed for then usual little or unleaded fuels. AvGas 80/87 for example, was only leaded as much as is necessary to achieve the relatively low knock resistance. In accordance with good reason gasoline AvGas 80/87 is quite unleaded.

Was there a few years ago the world have different varieties of AvGas, (reduced lead content AvGas 100 LL, "low lead " ) is now used in many countries for environmental reasons (emission of lead and lead poisoning by tetraethyl lead) only a leaded variety available.

There used both hochverbleite variants ( AvGas 108/135: 1.28 g Pb / L: 0.84 g Pb / L, AvGas 115/145 ) are not considered variants with lower octane ( Avgas 73), but commercially longer be offered. For older high-performance aircraft engines, especially on machines from the period of World War II and after, the very high octane numbers need more than 100, the corresponding fuel must be specially manufactured or provided with special additives to ensure trouble-free operation. Here, the varieties AvGas 108 and AvGas are to call 115. This now very expensive special AvGas varieties are to be found mainly in the historic air shows and air racing like at the Reno Air Races. A very similar " racing gasoline " is also used for the lower classes in drag racing.

Production

AvGas 100 LL - as well as motor gasoline - a blend of various components, such as:

• Additives
• Butane (to adjust the vapor pressure )
• 1,2- dibromoethane (so-called scavenger )
• Isopentane (to adjust the vapor pressure )
• Light alkylate (C7 - C9 isoparaffins produced by the so-called alkylation process. Severity portions of the "full range " alkylate be removed in order to comply with the AvGas - final boiling point specification can )
• Tetraethyl lead (0.56 g Pb / L)
• Toluene

Wherein the synthetic light alkylate is the main component of the mixture. Furthermore AvGas still contains various additives such as an antioxidant, anti-icing additive, corrosion inhibitor and a conductivity.

Consumption

In Germany 2007, about 14,000 tons of aviation fuel were consumed, compared to 21.292 million tons of motor gasoline, a vanishingly small amount. In Germany no AvGas is produced, the whole quantity is imported from the ( EU ) countries.

Taxation

In the general aviation jet fuel each variety is mineral oil tax since 1976. Aviation gasoline ( AVGAS ) is higher in Germany taxed as car fuel. There are doing under applicable petroleum law 0.721 euros per liter fuel tax, and in addition is again imposed on amounts of untaxed price per liter and energy tax 19% VAT. In September 2008, a liter AvGas cost at the airfield Bonn- Hangelar 2.32 euros per liter. A model calculation on this basis, 1.23 euros as untaxed price per liter. Including € 0.721 mineral oil, this gives 1.95 euros per liter, along with 19 % VAT it does then 2.32 euros. The state sales tax is in this example, hence a total of 47 %. In MOGAS mineral oil proportion is slightly lower with 0.655 euros per liter. The higher compared to automotive gasoline price for AVGAS is due to the very low production volume of this particular type of fuel ago.

For commercial aviation in the carriage of passengers and freight on the other hand, there is widespread tax exemption. International case applies existing since December 7, 1944 Chicago Convention ( ICAO ), in which all Member States have committed themselves to the exemption of aviation fuel for international flights binding. This exemption is concretized within the EU guidelines. Then are basically several different cases.

The EU allows Member States to derogate from this rule and introduce taxation nationally or through bilateral agreements between Member States.

For the so-called traffic ( commercial traffic of non- aviation companies ) a test case before the Tax Court of Dusseldorf has also confirmed exemption from excise duty and justified with EU directives in October 2007. This was later withdrawn, that is, financial management has prevailed. Now, in Germany the tax exemption for aviation fuel limited to air carriers whose immediate purpose operating in the transport paying passengers or freight consists. This also includes taxi flights and the commercial, parachute jumpers.

Alternatives

Due to the high price of AvGas spread in recent years in Europe intensified so-called Mogas (short for Motor Gasoline). This corresponds exactly premium gasoline service station with a few additions. Some of the classic aircraft engines (for example, many versions of the four- cylinder Lycoming O- 320, as it is installed in many Piper and Cessna types) can be operated with Mogas without any modification, while others need to be modified consuming. With the compulsory blending of bioethanol in gasoline since 2007, but the approvals for the use of MOGAS, if it contains more than 1% alcohol. A " lead-free " AvGas ( 82UL ) has been announced by the industry for years, to date it is not yet producing

Since the beginning of the 1990s, there have been efforts in the general aviation and here especially in light aircraft with piston engines, diesel fuel and kerosene use as an alternative to AvGas. This different design principles are followed. There are both four-cycle diesel engines, two-stroke engines and rotary engines. Advantages of diesel engines are mainly due to lower consumption and - regional variations - often less expensive fuel. Due to the self-ignition process and the high compression pressures, the diesel engines are, however, more robust and thus built heavier. The higher weight means a disadvantage compared to conventional aircraft engines.

Market and approved diesel and kerosene piston aircraft engines offer the company Société de Motorisations Aéronautiques ( SMA) (part of the SAFRAN GroupSMA ), Centurion Aircraft Engines (formerly Thielert ) and recently Austro Engine. Other manufacturers are Wilksch, Mistral or DeltaHawk whose engines are currently used only in experimental aircraft and drones. The engines deliver between 88 kW and 257 kW ( 120 to 350 hp). Thus, they are in terms of performance suitable for driving most single and twin-engine light aircraft. In the power range beyond turbines are used ( turbojet and turboprop ) usually.