**The Wankel Rotary Engine: A Unique and Revolutionary Design**

In this episode of Science Garage, we're going to delve into the world of rotary engines, specifically the Wankel engine. Developed by Felix Wankel, a German engineer, this innovative design has been used in various applications, including sports cars like the Mazda RX-7.

The Wankel engine is essentially a single-rotor, four-stroke engine that uses a triangular-shaped rotor to generate power. The rotor is attached to a eccentric shaft, which makes it spin three times for every turn of the rotor. This unique design allows the engine to rev very high, often exceeding 10,000 rpm.

The rotors are mounted on an eccentric shaft, with round lobes that fit over one end of each rotor. As the rotor follows its path around the housing, it pushes on the lobes, creating torque in the shaft and making it spin. This design allows for a more compact engine compared to traditional piston engines.

One of the key benefits of the Wankel engine is its simplicity. With fewer moving parts than traditional engines, there's less chance of mechanical failure. Additionally, the engine doesn't require four, five, or six cylinders to deliver consistent power, making it an attractive option for high-performance vehicles.

However, the Wankel engine also has some drawbacks. It uses a lot of gas due to its low compression ratio, which can lead to poor fuel economy and increased emissions. The engine is also lubricated with oil throughout the housing, which burns when hot, releasing more unburnt hydrocarbons into the air.

Another potential issue with Wankel engines is the apex seal, which can be prone to failure if not properly maintained. When an apex seal blows, it causes the chambers created by the rotor to bleed into one another, losing their benefits and requiring costly repairs.

Despite these challenges, the Wankel rotary engine remains a unique and fascinating design. Its high-revving capabilities make it ideal for sports cars, where power and responsiveness are essential. Additionally, its compact size and simplicity make it an attractive option for manufacturers looking to create high-performance vehicles without sacrificing space or complexity.

If you're interested in learning more about the physics behind the Wankel engine, we recommend checking out Brilliant.org's Physics of Everyday course. This comprehensive series gets into the nitty-gritty of how things work, including the principles that govern the behavior of rotary engines like the Wankel.

For now, let's take a look at some other benefits of Wankel engines and why they remain popular among car enthusiasts.

**Benefits of Wankel Engines**

* Fewer moving parts means less chance of mechanical failure

* No need for four, five, or six cylinders to deliver consistent power

* Compact design makes it ideal for sports cars

* High-revving capabilities make it suitable for high-performance applications

However, there are also some drawbacks to consider:

* Low compression ratio leads to poor fuel economy and increased emissions

* Engine lubricated with oil throughout the housing, which burns when hot

* Apex seal can be prone to failure if not properly maintained

Overall, the Wankel rotary engine is a unique and innovative design that continues to captivate car enthusiasts around the world. Its high-revving capabilities, compact size, and simplicity make it an attractive option for manufacturers looking to create high-performance vehicles without sacrificing space or complexity.

**Additional Resources**

* Brilliant.org's Physics of Everyday course

* Up to Speed: The RX7 episode

Follow us on Instagram @bidsbarto and Donut @donutmedia for more content and updates. Subscribe to our channel for new episodes every Wednesday!

WEBVTTKind: captionsLanguage: en- We've talked about engines before,and I don't know if I'llever get tired of it.The air gets compressed by the piston,and the spark...What?No, stop it!There's no piston here!What if I told you we couldskip all of that crap?Not worry about turning downwardforce into rotational forceand cut the size of thegall dang engine in half?That's the Wankel rotary engine!In 1951, Felix Wankelgot this idea in his headthat if you put a triangularrotor in a well-designedcircely, oval-ish shape,you could make an enginethat took care of intake,compression, combustion,and exhaust, just like thetraditional piston-driveOtto Cylce engine.And because it's a spinningmotion, you wouldn't needto worry about crankshaftsand valves and timing beltsand lifters and all thatcrap that other peopleare goofin' around with.He had some troublegetting it right, though.So it was in 1961 that Mazda,intrigued by this idea,helped him out, and here's how it works.A curved triangle sits in the engine.It's what'll drive thedriveshaft, which is also weird.Instead of a piston, this magictriangle is called a rotor,because it spins.The rotor sits insideof a housing and rotatesaround a fixed gearattached to the housing.This gear makes sure that therotor follows the right path,so it's not just floating around in there.The rotor then spins aneccentric output shaft,and this is what'll give the car moving.You can call it a driveshaft if you want,I'll know what you're talking about.But just the names of theparts should let you knowthat the Wankel rotary engineplays by its own rules.Now that we know the parts,let's see how they fit togetherand make the boom.We'll start with the intake.As the triangle-shaped rotordraws away from the wallof the housing, it's creating a vacuum.As it passes the intake hole,it continues to pull awayfrom the wall, drawingthe air-fuel mixtureinto the chamber it'screating, just like a pistonwould draw air in on its intake stroke.When the peak of the rotorpasses the intake port,well, now that chamber's sealed.The rotation of the triangle,still sealed againstthe housing, begins tocompress the air-fuel mixtureas it continues its rotation.When the air is as compressedas it can be and the rotorhas just a bit more mass onthe other side of the chamber,a spark triggers the combustion.The combustion chamber is long.If there's only one plug, theflame would spread too slowlyto be effective at producing power.Most rotary engines have two sparkplugs.When the sparkplugs ignitethe air-fuel mixture, kapow!It forces the rotor to move in a directionthat allows the combustionreaction to expand,continuing the rotor'sjourney around the housing.The combustion gasses continueto expand, moving the rotorsand creating power, untilthe peak of the rotorpasses the exhaust port.Just like the rotor compressedthe air-fuel mixtureagainst the wall with thesparkplugs, on this sideof the housing, the rotorpushes the exhaust gassesout of the exhaust port.And if you look at theother point of the triangle,the rotor is beginning to drawair into the intake chamberjust as it's finishingwith the exhaust down here!So the cycle continues,over and over and overand over and over and over,and it continues to goover and over and over.But unlike the jerky up-and-downmotion of the pistons,the rotor moves, justlike my favorite band,in one direction.♪ You don't know you're beautiful ♪There's so much rubbinggoing on between the rotorand the housing that thatgave Wankel a lot of problemsas he was designing.Engineers realized that ahole to let in the engine oilwould reduce wear onthe rotor and housing.Also, to make sure that nochamber of the combustion cycleloses pressure, apex sealscap the point of the triangle.These tweaks are what tookWankel's early underwhelmingexperiments fromcuriosity to practicality.And look at this triangle!With three sides, assoon as one side begins,let's say, combustion,another side is completingexhaust while the third sideis drawing in air and gas!So, unlike a traditionalpiston-driven engine,which would need threecylinders to do that,like the rare but very realin-line three, you only needone active component, therotor, to have three stagesof engine combustionoccurring simultaniously.The way Mazda did it on their engines,like what powered the RX7 and RX8,was to put two rotors thatcomplimented each-other,so when one rotor was entering combustion,the other was about to enter combustion.You can see how evenlya Wankel rotary enginecan deliver power versusthe herky-jerky up and downof a piston-driven engine.This evenly-driven rotationalforce spinning the rotorsdrives the output shaft.The output shaft has roundlobes mounted eccentrically,meaning they're offset fromthe center line of the shaft.Each rotor fits over one of these lobes.The lobes act sort of like the crankshaftin a piston engine.As the rotor follows itspath around the housing,it pushes on the lobes.Since the lobes are mountedeccentric to the output shaft,the force that the rotorapplies to the lobescreates torque in theshaft and makes it spin.This makes the eccentricshaft move three turnsfor each turn of the rotor,and that's why these enginescan create such high rev.(engine revving)And if you check out thehorsepower versus torque video,you'll know horsepower is how quicklyforce can be produced.A high-revving enginedoesn't need as much torqueto generate more horsepower,because it's delivering it so quickly.And, like Mazda did with theRX7, they can be turboed,just like any other engine.And again, because they'rerevving so high, a turboed Wankeldoesn't have to worryhalf as much about lag!Some lag!So, what are some otherbenefits of a rotary engine?First, there's fewer moving parts.No lifters, no push rods, no camshafts.All those little thingsthat can go wrong ina traditional engine simplyaren't there in a Wankel,so they can't break.In a two-rotor Wankel, yougot two rotors and one e-shaftto worry about, that's it.And that means theseengines can rev higherand not bust any of those intricate parts.And also?You don't need four, five, six cylinders,you've got an enginedelivering consistent power,making awesome noises!(engine revving)And taking up half theroom of other engines!Oh!And sometimes, when itgets moving really quick,you get this!(backfiring)That is pretty cool!But that's also a drawback.Wankels use a lot of gas because they havea low compression ratio.When they get moving likethat, they make thosesweet-ass flames 'cause they'reshooting out exhaust gasseswith unburnt hydrocarbons.That's not good for fuel economy,and it's not good for the air!Also, remember how they're lubed with oilthroughout the housing?That oil burns when it's hot.That means more burntless clean hydrocarbons,which is tough for emissions.You remember how they sealedup the different chamberscreated by the rotor.Remember, from before?Uh, yeah.You can blow an apex seal,and if that happens...(screaming)Those chambers bleed into one anotherand you lose most of the benefitsthat made you fall in lovewith your screaming rotaryengine in the first place.Between being different and being good,Wankel rotaries are pretty rad.Wankel rotary engines!If you like the way weshow how things workon Science Garage, then youreally need to check outBrilliant.org.Brilliant is math andscience enrichment learning.It's engaging, and insteadof just getting talked atabout how thing worked,Brilliant is set upto let you really get in there and applywhat you're learning.The sequences lead youto thought-provoking,challenging problems, andthat helps you understandconcepts at a deeper level.Actively solving problemsbecomes an addictive,interactive experience,and I gotta tell you,it's pretty cool.How do you think the braintrust we just talked aboutcreated the Wankel rotary engine?They had a deep understanding of physicsand practical applicationand problem-solving,just like the courses at Brilliant.org.A great place to start iswith Physics of the Everyday.This course gets into howthings work, things you useevery day, just like wedo here on Science Garage!To learn more about Brilliant,go to Brilliant.org/sciencegarageand sign up for free!Also, the first 200people to go to the linkwill get 20% off theirannual premium subscription!I'll see you there!Brilliant!And follow me on Instagram, @bidsbarto,and follow Donut, @donutmedia.We got shirts like this, andwe got new designs comin' soon.Guys, we do this every Wednesday!Make sure you subscribe,hit the yellow buttonso you get notifications!Like the RX7, you can learnabout turbochargers here,and you can learn aboutthe RX7 in this episodeof Up to Speed!Don't tell my wife theseengines can be a hassle,'cause I'm trying to get one.