Dennis Helder Dir. Of Eng. Research South Dakota StateUniversity Ethanol Based Fuels for Aviation

Where can ethanol be used as a fuel? Automotive, Small Engines, and Aviation Fuel Advancements -- Greater Markets for Ethanol

Where can ethanol be used as a fuel? Automotive, Small Engines, and Aviation Fuel Advancements -- Greater Markets for Ethanol

Where can ethanol be used as a fuel? Automotive, Small Engines, and Aviation Fuel Advancements -- Greater Markets for Ethanol

Why Aviation Grade E-85? EPA Ban of 100LL aviation gasoline The 1970 EPA Clean Air Act has mandated removal of all leaded fuels - including aviation gasoline. AGE-85 is the best alternative: Only fuel that will operate in all piston aircraft engines Most economically viable alternative Demonstrated good cold starting capability Performance comparable to or better than avgas 300,000,000+ gallon annual market! Aviation market over the past 10 years has varied from 3 to 6 hundred million gallons(1-2 hundred million bushels of corn) Decreased dependence on foreign oil ! ETHANOL IN AVIATION

Ethanol virtually eliminates engine detonation or “knocking.” Detonation greatly reduces engine life, and can even lead to sudden engine failure. Ethanol burns at a lower temperature than Avgas and produces more power. Ethanol thus improves engine life and safety. Ethanol also burns cleaner than Avgas. Build up of combustion deposits in the engine is greatly reduced, as is contamination of engine oil. Current estimates are that the time between overhaul (TBO) can be safely doubled for engines using ethanol. If proven to be true, this will significantly reduce the cost of operating alcohol-fueled aircraft.

Background: 100LL 1970 EPA Clean Air Act Availability of Tetraethyl Lead Not a question of if, but when… Alcohol Common usage circa 1900 Use in Europe during WW II 1970’s Energy Crisis -- Dr. Max Shauck Ethanol Based Fuels for Aviation

PARADIGM SHIFT Old approach: Modify engines/airframes to work on alcohol. New approach: Design an ethanol-based fuel first, then modify engines/airframes as needed. Ethanol Based Fuels for Aviation

Property 100LL Ethanol Energy DensityGoodLess ThermodynamicGoodBetter efficiency Vapor PressureGoodLow DetonationGoodSuperior Gum/VarnishGoodSuperior CorrosionGoodSuperior Flame VisibilityGoodLess

Ethanol Based Fuels for Aviation Ethanol is: a single compound; produced primarily from corn; typically 99.99% pure; 1.5 billion gallons annually. Properties of Fuel Grade Ethanol ASTM D1613 (Acidity) ASTM D512 (Chloride) ASTM D1688 (Copper) ASTM D5501 (Ethanol Purity) ASTM D381 (Gum) ASTM E1064e (Water by Karl Fischer for Ethanol)

Ethanol Based Fuels for Aviation Problem: Low vapor Pressure Solution: Blend with same petroleum product used to control RVP in gasoline! Also increases flame visibility -- equivalent to 100LL Pentane Isomerate Approx. ComponentVolume % Isobutane 1 n-Butane 1 Isopentane 53 n-Pentane 4 Dimethyl- 11 butane Isohexane 23 n-Hexane 1 Cyclohexane 5

Problem: Possible corrosion during engine storage Solution: Blend biodiesel to protect exposed surfaces! Biodiesel: made from soybeans and other sources; ASTM PS121 provisional specification; coats cylinder wall and head surfaces; added protection for all fuel-wetted components. Ethanol Based Fuels for Aviation

Aviation Grade Ethanol 85 ComponentVol% Ethanol Pentane Isomerate Biodiesel

Ethanol Based Fuels for Aviation Comparison of 100LL and AGE-85 Property100LLAGE-85 Motor Octane Number (est.) Tetraethyl Lead (TEL/L) RVP (psi)5.5 to to 8.0 Min. Net Heat Comb.112,20088,200 (Btu/gal.) Density (lb/gal) to 6.5 Max. Sulfur Content0.050 (weight %)

Ethanol Based Fuels for Aviation AGE-85 Performance: Modifications 1. Increase fuel system flow capacity by 20%. Typical aircraft systems allow 12:1 air/fuel ratio at full rich Increase fuel flow capacity to allow 10:1 air/fuel ratio on AGE-85 --full rich on AGE-85 at sea level temp./press. 2. Ensure material compatibility of the fuel system Metal components have shown no corrosion in over 3 years Most polymer materials used in aviation the past 15 years are alcohol compatible

Ethanol Based Fuels for Aviation AGE-85 Performance: Flight Testing

Ethanol Based Fuels for Aviation AGE-85 Performance: Flight Testing Engine Performance Power Output Durability 500 Hour Test Cool Climb Hot Climb In-flight Engine Restart Detonation Project Aircraft: 1962 C-180E Engine: O-470U/TS

Ethanol Based Fuels for Aviation

Flight Testing: Cool Climb Test

Ethanol Based Fuels for Aviation Flight Testing: Cool Climb Test

Ethanol Based Fuels for Aviation Flight Testing: Cool Climb Test

Ethanol Based Fuels for Aviation Flight Testing: Hot Climb Test

Ethanol Based Fuels for Aviation

Flight Testing: Hot Climb Test

Ethanol Based Fuels for Aviation Flight Testing: Comparisons

AGE-85 Performance: Corrosion and Lubricity Ethanol Based Fuels for Aviation

Flight Testing: Engine Teardown

Ethanol Based Fuels for Aviation Flight Testing: Oil Analysis

Ethanol Based Fuels for Aviation SUMMARY AGE-85 has been STC’d for C-180 and C-182’s. Dual fuel STC’s have also been obtained --AGE-85 and 100LL can be blended at any ratio. Lycoming and Pratt & Whitney engines currently under investigation.

CONCLUSIONS Ethanol alone has many attractive and some detrimental properties: great anti-detonation property, low vapor pressure, etc. Ethanol-based fuel equals or exceeds aviation gasoline in most properties. Single exception is energy density. Engine/airframe modifications are minimal. Extended engine life is indicated. Dual fuel operation is not a problem. Ethanol Based Fuels for Aviation