The rotary engine was an early type of
internal combustion aircraft engine, used
mostly in the years shortly before and
during World War I. It is also used in a few
motorcycles and cars.
 In concept, a rotary engine is simple. It is a
standard Otto cycle engine, but instead of
having an orthodox fixed cylinder block with
rotating crankshaft the crankshaft remains
stationary and the entire cylinder block
rotates around it.
Among most of the rotary engine
the most notable is the pistonless
rotary engine ,the wankel engine.
The Wankel rotary engine is a
type of internal combustion
engine, invented by German
engineer Felix Wankel, which uses
a rotor instead of reciprocating
pistons. This design delivers
smooth high-rpm power from a
compact, lightweight engine.
Rotor Wankel engine, a single
oval (technically a epitrochoid)
housing surrounds a three-sided
rotor (a Reuleaux triangle) which
turns and moves within the housing.
The shaft turns 3 times for each
rotation of the rotor around the
lobe and once for each orbital
revolution around the eccentric
The Wankel engine works on a
typical Otto cycle
Wankel rotor housings are constantly
heated on one side and cooled on the other,
leading to high local temperatures and
unequal thermal expansion.
Therefore material used are exotic alloys
and ceramics.
The shape of the Wankel combustion
chamber prevents preignition, it also leads
to incomplete combustion of the air-fuel
charge, with the remaining unburned
hydrocarbons released into the exhaust.
Fuel consumption is high.
Have higher output for similar displacement and
physical size.
It is simple and have fewer moving parts.
No need for connecting rods, a conventional
crankshaft, crankshaft balance weights, etc.
Smoother flow of power but also the ability to
produce more power by running at higher rpm.
fuel of very low octane number can be used
without preignition or knock.
It’s substantial safety benefit makes it useful in
Time available for fuel to be injected into a Wankel engine is
significantly shorter .
More complicated fuel injection technologies are required .
In terms of fuel economy, Wankel engines are generally less
efficient than four stroke piston engines .
Sealing loss is high.
the compression ratio is lower. This lowers the thermal
efficiency and thus the fuel economy.
It is difficult to expand the engine to more than two roters.
Used in aircraft.
 Racing car.
 For mini, micro, and micro-mini engine
 The most exotic use of the Wankel design is
in the seat belt pre-tensioner system of some

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