The Rotary Engine

The rotary engine: a bold, unconventional design that’s fascinated car builders for longer than you might think. Join us as we dive into Felix Wankel’s revolutionary creation and explore why it still captures the imagination of engineers and gearheads alike.

 

"Fuel for the Future" is presented by State Farm Insurance and driven by America's Automotive Trust. Visit americasautomotivetrust.org for details. 

Episode Transcript

(00:04):
If I were to ask you to
visualizeand then explain how an engine works.
I bet most of youimagine pistons and a crankshaft.
But what about an engine that rotates?
Instead ofusing these traditional components.
This is the core conceptof the rotary engine, a term
for probably all familiar with.

(00:24):
It's a fascinating engineering marvel,and one of its early adopters
was the aircraft, but not cars.
That is until German engineer Felix Wankelenvisioned the unique engine
that he theorizedwould power the cars of the future.
This is fuel for the future.
Presented by State Farm Insuranceand driven by America's Automotive Trust.

(00:46):
I'm Michael Mann.
So what is a rotary engine?
In simple terms,it uses a spinning rotor to generate power
instead of reciprocating pumping pistons.
This design allows for a smootherand more compact engine that delivers
high power with fewer moving parts,instead of cylinders.

(01:09):
The rotary enginethat originated with Felix Wankel for cars
relies on a triangular rotor movingwithin a chamber, which creates intake,
compression, combustion, and exhaust,all in this continuous circular motion.
As a friend of mine said to mewhen I mentioned
I was preparing an episodeon the rotary engine,
he described it as having less bitsand bobs.

(01:31):
Well,that doesn't sound sane or professional,
but there is something to that.
The Wankel rotary engines are smaller andcan be very advantageous in certain cars.
The roots of the
rotary engine,however, stretch back to the 19th century.
In 1887,a French engineer named Felix Miller
developed an early rotary styleinternal combustion engine

(01:54):
that was used in his motorcycle buildsbefore the turn of the century.
Around the same time, inventors in Europewere experimenting with rotary designs
in hopes of creating more efficientpropulsion systems
for various mechanical applications.
By the early 20th century,the rotary engine had found its
first widespread use,not in cars but in aviation.

(02:17):
During World War One, rotary engines were
commonly used in fighter planessuch as the Sopwith Camel.
Due to the power to weight efficiency.
In the 1920s and 30s
rotary engine saw use and more motorcyclesas well, particularly
with European manufacturers experimentingwith compact designs for two wheelers.

(02:39):
One of the prime examples ofthis is the Megillah, a German motorcycle
produced between 1921 and 1925.
Fascinatingly, the engine was mountedwithin the front wheel of the bike
and cylinderswould rotate around that axle.
Apparently, Jay Leno ownsone of the few megaliths that survives

(03:00):
in that first half of the 20th century.
If you look into this, you will find thatother builders and designers
tinkered and experimentedwith rotary engines with cars,
but none of them were worthyof going to market or being mass produced.
And that's partlybecause there are inherent inefficiencies
of early rotary designs, such as high fuelconsumption and high oil consumption,

(03:23):
which kept them from migratinginto the mainstream car market.
That was until Felix Winklesadvancements in the mid 20th century.
Felix
Wankel was born in 1902, in La Germany,
and he was fascinated by mechanical designfrom a young age.
He envisioned an engine that rotatedsmoothly, eliminating

(03:45):
many of the inefficiencies and a lotof the vibrations of conventional engines.
By the 1920s, Wankel had begun
working on his ideas, and it was in 1929
that he received his first patentfor a rotary engine.
Initially,the concept was not for an automobile,
but for industrial and aviationapplications.

(04:07):
During World War Two,Wankel worked for the German Luftwaffe
for developing rotary compressorsand superchargers for aircraft.
After the war, in the 1950s, Wankel gotan opportunity that led to a breakthrough.
NSU, a German automaker,partnered with Wankel.
At first, he designed a superchargerfor their motorcycles,

(04:28):
but then began developing a rotary enginefor cars.
By 1957, he had a working prototypeknown as the DK him,
which used rotating housingand a triangular rotor.
To be fair and honest,the DXM had some issues, so to progress
this projectalong the NSU development, Chief Engineer
incorporated work by Hans Dieter Paschke.

(04:50):
Posh case designs made the enginemore robust and cheaper to mass produced,
and this new engine was called the K him
and I wanted to mention thisbecause I personally think that Hans
Dieter's work gets overlooked,
which makes sense because the Wankelengine is named after Wankel,
and Hans Dieter deserves

(05:10):
credit because he's the one that was ableto take this project to the next level.
Not to mention that Wankel was knownto be difficult to work with.
He also had been a Nazi during the war,and even the Nazis
didn't always get along with him.
But that's a story for another podcast.
NSU saw the potential for the KCM engine,

(05:32):
and in 1963 introduced the NSU spider,
the first production carwith a Wankel rotary engine.
Then, in 1967, NSU released
a sedan with a two rotorWankel engine with 113 horsepower,
and it won the car of the yearvery quickly.
Other car manufacturers took notice,and NSU

(05:52):
began licensing the Wankel engine.
The real explosion of rotary poweredcars came in 1967,
when a small Japaneseautomaker named Mazda
launched the Cosmo Sport 110 S.
Mazda's engineers had spent yearsrefining the Wankel engine,
solving some of its mechanical issueslike what they called the nail

(06:14):
marks of the devil,which were scratch marks,
and they were caused by a lot of wearand tear on the housing.
Mazda made it more viable
for everyday useand cut down on all of this wear and tear.
The rotary engine offeredsome clear advantages it was compact,
had fewer moving parts and could producehigh power output relative to its size.

(06:35):
Mazda fully embraced this technology,integrating it
into some iconic modelsthe R, the RS7, and our X8.
The R seven is worth mentioningspecifically here because it's the iconic
Wankel rotary engine sportscar built from 1978 through 2002.
Over 800,000 of them were made.

(06:57):
It's also well known for its racingpedigree.
In the 1990s, the RS7 made the podiumin honestly too many races to list.
Some highlights though, include the MiamiGrand Prix, and it also won the IMSa
supercar race at Sebring in 1994.
And obviously,
if you know racing,I can't forget to mention that in 1991,

(07:19):
the Mazda 787 be powered by a four rotorengine, became the first
and only rotary powered carto win the prestigious
24 Hours of Le Mans.
Some other makes and modelsto use the Wankel engine include
the Citron bi rotor,the experimental Mercedes-Benz C1 11,

(07:39):
the Chevy Aero Fedand the Curtiss-Wright Mustang, and more.
Despite its advantages,
the rotary enginehad some notable drawbacks.
It was less fuel efficient than pistonengines.
It has higher emissions,and these factors, coupled with stricter
emissions regulations,started to lead to the rotaries decline.

(08:02):
Mazda was the last major
automaker still producingrotary powered cars and in 2012,
the NX eight was discontinued,marking the end of an era.
But the rotary engine is not extinct.
In 2023, Mazda reintroduced
the rotary engine in the NX30 Rev, a plug in hybrid vehicle

(08:23):
which can use a Wankel rotary engineas a range extender.
Its small size makes it perfectto fit into hybrids and EVs.
Also, the Mazda R eight hydrogenr e is a sports car that used a Wankel
rotary engine configured to run on eitherhydrogen or gasoline.
Now, these two examples showthat the rotary engine is not dead

(08:44):
when it comes to its use in cars.
More and more designs and applicationswill be viable as technology advances.
So we have not
seen the last of the rotary engine.
Thank you for joining us on fuelfor the future, presented
by State Farm Insuranceand driven by America's Automotive Trust.

(09:05):
Learnmore at America's Automotive trust.org.