Similar to the principle
involved in a four stroke cycle, a rotary engine goes through four
steps in order to complete one combustion cycle. The following steps
are involved in each cycle.
The first step involves the movement of a combustible mixture of
air and gasoline into the first area of the combustion chamber. In
other words, fresh air mixed with fuel is drawn into the engine as
one tip of the rotor passes through a particular point, through
the intake opening.
The rotor then begins to compress
the fuel-air mixture when the next tip of the rotor passes the
One or two spark plugs then ignite this mixture. This burning
mixture of gases undergoes expansion and it causes the rotor to
move around the output shaft.
The burned gases leave the chamber
through an exhaust port after the rotor tip passes through it,
thereby uncovering the port.
This completes an entire
combustion cycle and the entire process is repeated all over again.
A rotary engine operates
continuously. Each full rotation of the rotor is associated with
three full combustion cycles. That is to say, a single revolution of
the rotor produces three power strokes or the output shaft connected
to the rotor makes three revolutions for a single revolution of the
A single rotor engine
produces one power stroke per rotation of the rotor. On the other
hand, a regular piston engine produces one stroke when the piston
moves up or down once. A dual rotor engine is therefore an
equivalent power-producing engine as that of a four-cylinder piston
How is it different
from a piston engine
A rotary engine has fewer parts than a piston engine of the same
power. It uses lower-octane gasoline, burns less efficiently and is
The noise and vibration
produced by a rotary engine is opposite to that of a piston engine.
At high speed, it operates smoothly and more quietly than a piston
engine. At low speed, it is noisier and tends to vibrate more.
When introduced, the
rotary engine was smaller and lighter than a piston engine of equal
power. This drawback was, however, overcome in the 1980’s where
comparably smaller, lighter and more efficient piston engines were