Are Rotary Engines Good?

If you are interested in the world of aviation, it’s useful to find out about different types of engines to help gather information and knowledge about your chosen hobby. Let’s look at engines in a bit more detail. 

All jet engines use the same principle. Jet engines suck air through a fan, which is located at the front. Hot air passes through a turbine, which sprays it out the back.

An engine and plane push forward as it soars into the sky. Once the jet shoots backwards, it takes hot air through the nozzle to shoot it forwards again.

Are Rotary Engines Good?

A rotary engine is a type of internal combustion engine where the pistons rotate instead of reciprocate. Rotary engines were invented in Germany by Dr. Felix Wankels. These engines use fewer moving parts than other types of engines. 

Rotary engines are more efficient because they do not need valves or spark plugs. Rotary engines are used in cars, airplanes, trucks, motorcycles, lawnmowers, snowblowers, and appliances such as vacuum cleaners.

A rotary engine is an internal combustion engine that consists of three main parts: a crankcase, cylinder block, and head. The crankcase contains the crankshaft, camshaft, and connecting rods. 


In the early years of the 20th century, engineers tried different shapes and sizes for their engines. Some designs were better than others. Eventually, the best engine designs became the standard.

Rotaries were used by many companies including Ford, General Motors, Chrysler, and even Rolls-Royce.

The first successful commercial use of the rotary engine was in 1919 when the Wright brothers flew their first airplane using a Wright R-3350 Cyclone rotary engine. 

The Wright Brothers’ plane had a top speed of 62 mph and could fly for over an hour. This was the first time people saw a plane fly.

Gnomes and le Rhones were developed separately, but they later merged into one company. They made more than 100,000 engines during the First World War. Most of them were used in airplanes.

Rotary engines produce more power than reciprocating ones but they are noisy and hard to control.

Pilots learn to use the ignition cutoff switch to shut off the engines’ ignition and restart them when they need power. Gyroscopic precession makes rotary engines difficult to handle. 

Rotary engines were used until the 1970s when they were replaced by turbochargers.

Rotary engines were limited because the number of cylinders could be only one per engine. Multi-row rotaries were difficult to make and limited in size.


Rotary engines use fewer moving parts than other types of engines. This means fewer maintenance costs, which makes them more affordable.

Rotary engines are simple, light, and easy to maintain. They are very powerful compared to other engines. There are many different types of rotary engines, including internal combustion, steam, electric, and gas. 

Rotary engines are commonly found in cars, trucks, motorcycles, lawnmowers, snowblowers, tractors, boats, airplanes, helicopters, and even space shuttles.

Rotary engines produce more power than piston engines because they operate at a higher RPM. In the event of an engine failure, the rotary engine will not stop running while the piston engine will cease to function.

A rotary engine runs smoothly because it doesn’t vibrate as much as a piston engine. When a piston engine fails, it stops running immediately.

Rotary engines continue to run even if they lose compression or have other problems. This makes rotary engines a much safer choice for pilots.


Rotary engines are very efficient because they burn oil making them a popular choice amongst aviation enthusiasts.

The exhaust contains oil that helps cool the engine. Also, there are squirters in the airbox that help direct oil into the combustion chamber.

However, burning oil isn’t environmentally friendly since it produces greenhouse gasses.

Rotor sealing is another challenge to engine efficiency. Cooling the rotor helps reduce some of these challenges. Emissions killed off the rotary engine.

Combustion efficiency, inherent oil burning, sealing challenges, and lack of competitiveness resulted in the demise of the rotary engine.

Radical Engines 

Radial engines use a rotating cylinder band, instead of a piston, to turn the crankshaft. Rotary engines don’t have a crankshaft, but a rotor attached directly to the crankshaft spins inside the engine.

An engine that radiates air outwards from a center crankcase is called an “air-cooled” engine. Radial engines were used in early aircraft but are now rarely found.

Wankal Rotary Engine 

The Szorenyi Rotary Engine Prototype uses a hinged rhombohedral rotor instead of a triangular rotor. This makes it more compact than a conventional Wankel engine.

The new rotor also allows the engine to be lighter, simpler, and more reliable. However, the new rotor has a different shape than the original.

A unique change to the typical rotary engine is the Szorenyi Rotary Engine. It has been created by the REDA.

While the stator, the non-moving part of the Szerenyi engine, is reminiscent of the Wankel engine, the design of the engine rotor, the Szerenyi rotary engine, is a rhombus. 

The engine has 4 chambers, instead of Wankel’s three.

Each rotation of the crankshaft, translates to the Szerenye engine producing one revolution of the engine rotor and a complete engine cycle in each of the four combustion chambers: or four power strokes. 

In contrast, the Wankle engine produces one power stroke per crankshaft rotation. Rotary engines are engines that rotate around a central axis. 

Each 4 stroke Szorenyi rotational module is equivalent to an 8 cylinder reciprocating or opposed piston. The Szoreny engine is also more optimized for multi-rotor configuration.

The ability to easily configure multi-rotor, 4-stroke engines could result in rotary power plants generating power equivalent to 8-,16-,24-cylinder reciprocating engines. 

Furthermore, the development standardization of modules could reduce the manufacturing cost as well as the lifecycle maintenance costs.

The Wankel engine is limited to 3,000 revolutions per minute. A balanced rotor means less stress on the crankshaft.

This allows for higher rotational speeds. The Szorenyis use a balanced rotor, allowing for higher rotational speeds without crankshaft damage. This makes the Szorenyi more efficient than the Wankel engine. 


So, there you have it! Rotary engines are highly reliable and have the ability to successfully work with other fuel types, including hydrogen.

Hopefully, this guide will have helped you understand the pros and cons of rotary engines.

Jacob Stern
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