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Why an Aero Diesel?


General Aviation, the segment of non-military aviation encompassing everything except commercial airline operations, is facing a crisis in fuel availability and cost.  The current dominant fuel for piston-engine small aircraft, 100 LL (low lead), is the only leaded fuel manufactured in the world.  Access to it is extremely limited outside the U.S. and Europe, and it is predicted to be unaffordable and/or totally unavailable globally by as early as 2010.  The existing small aircraft fleet will be crippled; in some countries it already is.

Additionally, the U.S. Military has mandated the elimination of gasoline, with the goal of using jet fuel (or other "heavy fuels" such as diesel) for all of its engines by 2010. 

One solution to the fuel dilemma is diesel-cycle engines, which also have other advantages over gasoline engines including durability and fuel savings.  

Benefits of the diesel-cycle engine include:
Desirable Fuel Type: Low flammability and worldwide availability of Jet-A or diesel fuel is valued in all applications; current fuel for gasoline aviation engines is leaded and will eventually be made unavailable making those engines unusable.

Fuel Efficiency: The DeltaHawk® is designed to BSFC (brake specific fuel consumption) of .35 lb/hp/hr versus current avgas-powered aviation engine book BSFC of .59 lb/hp/hr at 75% and above.

Lower Fuel Cost: 30-40% more range per gallon. Also, cost per gallon of Jet-A averages $0.09 less than 100LL aviation fuel in the U.S. The price differential is much greater in Europe, where 100LL aviation fuel is selling for 2.10 Euro/liter ($10.16/US Gallon as of 09/06). 

Electromagnetic Noise Elimination: Absence of an ignition system reduces interference with navigational and communication systems; for military applications, this is desirable for tactical reasons.

Simplicity of Operation: Single-lever power operation (no mixture control).

Durability: Inherent in diesels because diesel and jet fuels provide more lubricity and because no electrical system (magnetos or electronic ignition) is required.

Some further benefits from the particular DeltaHawk design decisions for our V-4 Turbo Diesel engine:

Smoothness: A two-stroke diesel has four power pulses per revolution with continuous positive torque applied to the propeller (versus two pulses per revolution with approximately 30 degrees of negative torque in four-stroke/four-cylinder engines).

Liquid-Cooling: Reduces overcooling in descents from altitude. Also, reduced thermal variance in operation allows tighter manufacturing tolerances, leading to increased power and fuel efficiency.

Durability: (1) The 2-stroke piston-ported design reduces the parts count by eliminating valves, valve train and cam shaft; (2) liquid cooling reduces fatigue; (3) unified cylinder and block design eliminates studs, gaskets and bolts.

Reliability: Fail-safe design aspects have been incorporated, including backup air, redundancy of fuel pumps and limited operation at reduced power without coolant.

Small Size and Light Weight: The V-design is stout and compact; use of advanced materials and focus on low weight as a design criteria will result in a V-8 model producing nearly 1 horsepower per pound. For new aircraft designs, the V configuration also allows a more rounded cowling, permitting aerodynamic and propeller noise reduction improvements.

Direct drive, purpose-built aviation engine:  Direct-drive (no prop-reduction gearing) for lower weight and much lower parts count; designed and built to aviation standards (not an automotive conversion).


For more information on the history of aircraft engine technology please go to:


The Aircraft Engine Historical Society is a non-profit educational and historical society, open to the public, which fosters an appreciation of the people, art, and science associated with aircraft engine development, manufacture, and use.


For more information on the air-cooled versus liquid-cooled controversy:


Should aircraft engines be liquid-cooled or air-cooled?


For more information on diesel aviation engines of the past, read:


Diesel Aviation Engines, by Paul H. Wilkinson, 1940.


And specifically read Chapter 6 - Advantages of the Diesel for Aviation


Advantages of the Diesel for Aviation


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