UAV Wankel / Rotary Engines

Rotary engines are a form of internal combustion engine that rely on different operating principles to traditional piston-driven engines, using a rotating component to carry out work instead of the linear reciprocating motion of pistons.

Rotary & Wankel Engine Design

The most common design of the pistonless rotary engine is the Wankel engine, which uses a rotor spinning within a housing to carry out the four stages of the combustion cycle – intake, compression, power, and exhaust. The fuel intake on one side of the rotor occurs nearly simultaneously with the power stroke on the other side, giving the engine a smooth power delivery.

Rotary and Wankel engine designs provide a number of advantages that make them highly suited for use in UAVs (unmanned aerial vehicles).

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  SP-180 SRE Hybrid Wankel Rotary UAV Engine by Sky Power International

  They have an excellent power-to-weight ratio, making them ideal for smaller drones that have restricted SWaP (size, weight and power) budgets.

• They have fewer moving parts than piston-driven engines, making maintenance simpler.
• They also have reduced vibration and lower heat and noise signatures, and are thus useful for drone platforms carrying sensitive, high-accuracy payloads and sensors, as well as ISR (intelligence, surveillance and reconnaissance) platforms requiring enhanced stealth.

Some UAV rotary and Wankel engines are multi-fuel, meaning they can run on gasoline as well as heavy fuels. This results in a reduced logistical footprint and is also critical for achieving single-fuel objectives for military forces.

Advances in UAV Engine Technology

80S 15 BHP Wankel Rotary Engine

Rotary and Wankel engines have traditionally suffered from a number of issues that have limited their uptake, including wear caused by the rapid spinning of the rotor, as well as sealing issues.

Some manufacturers have managed to lessen these effects thanks to advances in modern materials and manufacturing technologies, as well as enhanced cooling methods and the use of software algorithms to achieve optimal engine control and fuel mapping.