Light Aircraft Application

The Duke engine is the world’s only viable axial, 4 stroke, spark ignited piston engine. It is lightweight, small, valveless, vibration-free, has very high power density, and runs on most fuels, including kerosene/jet fuel. The Duke engine is a great fit for aerospace applications, including ultralight, experimental and UAV platforms.

More power in a small package

Duke Aircraft Engine #1 - 2.0 Ltr – 3300 rpm 
Power: 103 hp @ 3300 rpm
Weight: 101 lbs (no gearbox req’d)
 Size: Length: 17.3 in x Diameter: 11.6 in 

Duke Aircraft Engine #2 - 2.0 Ltr – 6250 rpm 
Power: 180 hp @ 6250 rpm
Weight: 101 lbs (+gearbox)          
Size: Length: 17.3 in x Diameter: 11.6 in 

The Duke engine is in advanced stages of development, with prototype engines operational.

The 5 cylinder, 4-stroke internal combustion engine platform offers numerous benefits in aerospace applications:

• Aerodynamically friendly cylindrical shape, with output shaft on centre line. 
• Installation in small cowlings with lower drag.
• Low weight.
• Small package size.
• Near perfect mechanical balance for very low vibration.
• Direct drive low-power or geared high-power options.
• High power density potential - over 0.7 hp/lb installed weight in direct drive option or over 1.0 hp/lb @ 2700 - 3300 rpm output shaft speed in geared option.
• Multi fuel options. Automotive gasoline with low octane requirements. Compatible with 100LL avgas.
• No cam drive train or valves.
• Low parts count.
• Simplicity of design – 3 injectors & 3 manifold connections for 5 cylinder engine. 
• Multi-point spark ignition simply achieved.
• Partial cancellation of gyroscopic effects from slow speed counter rotation of cylinder group. 
• Suitable for 50hp to 350+ hp 

These characteristics combine to offer a prospect of a Duke reciprocating engine being a viable alternative to some current smaller turbo shaft propulsion applications.

The Duke engine features many technological breakthroughs.

The Duke’s unique counter-rotating, almost vibration-free motion and the unique design methodology employed address previous limitations in axial piston engines, especially power and speed.

This also results in partial cancellation of engine-based gyroscopic torque reactions, reducing loads on mounts and structures.

With the output shaft being intrinsically “geared down” to 5/6 of the piston reciprocating speed, this allows the engine-out torque to be higher with max power developed at lower speeds. 

This combination of features allows it to produce a higher output and turn a larger propeller before high tip speeds require the use of
a gear box.

The Duke engine delivers significant weight & size savings.

Compared to conventional IC engines with similar power, the Duke can be considerably lighter and up to 30% smaller.  Use of lightweight materials could further  improve weight advantage. 

Light Aircraft continued –

The Duke engine has negligible 1st-order and 2nd-order vibrations.

The axial cylinder arrangement with near sinusoidal piston motion delivers near-perfect mechanical balance.

The superior balance and vibration characteristics of the axial Duke engine lead to lower airframe vibration, fatigue and mount isolation requirements. 


Cooling is achieved with conventional water jackets around the cylinders and ported areas.

Seals around concentric flow passages allow the coolant to enter and leave the rotating cylinder group. 

The coolant is then circulated in a conventional manner through radiators mounted on the airframe, using a pump. 

The Duke engine delivers high thermodynamic efficiency. 

The absence of hot valves in the favourably-shaped combustion chamber allows high compression ratios for efficient operation on low octane fuels. 

Current engines operate on 91 octane gasoline detonation free at compression ratios above 12.5:1 

The Duke engine offers complete fuel flexibility.

Development  will allow  operation on all appropriate fuels, including ethanol/methanol and blends, bio-ethanol, LPG, CNG, hydrogen, kerosene and diesel. Spark ignition Duke engines are currently successfully running on 91 octane gasoline and kerosene/jet-A1.

The Duke Engine is far less complex than traditional
IC engines.

The Duke Engine’s much lower part and component count (only 3 sets of spark plugs, injectors and ports for 5 cylinders with no valve train), coupled with ease of repair and maintenance and potentially lower production costs, offer potential for savings in manufacturing and operation. While the Duke uses existing materials and manufacturing processes in its construction, there is considerable scope for the use of light weight materials as appropriate.

Duke Engines is committed to Research & Development, with further advances already under way.

The Duke engine is currently in its 5th generation with latest prototypes undergoing testing. 

The Duke engine has wide IP protection.

Through out the development process, Duke Engines has filed many patent applications to protect key aspects of its technology.

Duke Engines – International Testing

Throughout  development the Duke Version 3 has been continuously tested at various national and internationally recognised testing and dynamometer facilities. 

Earlier this year the range of Duke engines was again tested in the US. 

Please contact us if you are interested in seeing our engine.

Duke Engines is actively seeking cooperations with development partners for  specific applications and platform integration.

Duke Engines Ltd. is also keen to make first contact with potential sources for capital/equity to finance our market drive in the US/Europe in 2012.

Make sure you are on the first delivery list – sign up today



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