Spinning Engines

The flywheel worked well, but it added a lot of extra weight to the engine. Another type of engine, the rotary engine, solved this problem. The engine’s massive cylinders spun around like the spokes of a wheel. The spinning cylinders did the same job as the fly­wheel, so the heavy flywheel was no longer needed. Famous World War I fighter planes, such as the Sopwith Camel, were powered by rotary engines.

The rotary engine was popular because it produced a lot of power for its weight, but it caused some problems. A heavy weight spinning on the nose of an aircraft affects the way it flies. Pilots who flew the Sopwith Camel found that it turned swiftly to the right, but it was much slower to turn to the left.

It also was difficult to build increas­ingly powerful rotary engines. As the cylinders tried to spin through the air, the air pushed back against them. This air resistance, or drag, slowed the cylin­ders down. The engine had to use some of its power to overcome this drag.

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Spinning the cylinders faster or adding more cylinders to produce more power caused even more drag and wasted more of the engine’s power.