Why the Rotary is the ULTIMATE Light Airplane Engine 

Mazda CX90 hybrid keeping the Wankel alive apparently so start with that I would recommend anyways.

​@@doolittlegeorgeThe Mazda CX90 does not have a Wankel engine

I'd like to make a bold prediction, now that Mazda has taken my advice and is producing a wankel range extender engine. I predict that hybrid electric short-flight aviation will use motor driven ducted turbines with in-line Liquid Piston motors for takeoff and climbing, and the fuel will be hydrogen. Hydrogen fuel can combusted very efficiently by the LP motors but can also be run thru fuel cells, and burns very clean. The LP motors are compact enough to actually be hub mounted, and they have the efficiency and emissions that wankels cannot achieve. They have limited life, but that doesn't disqualify them because of the low hours they'd be used- just for takeoff and climbing. They'd be better than small hydrogen-combusting turbines, as hub-mounting runs into room constraints in both intake and exhaust, along with the tiny turbine fitting on a huge shaft (for the motor-driven fan) You heard it here first, and I predicted Mazda would make a small wankel range extender. I knew they would because Sandervanderkammen said they wouldn't.

@@someotherdude *Stop by your local Auto Mall and ask to drive a 2024 model with a Wankel engine*

​​​@@someotherdude*LiquidPiston is a hoax... a big vaporware investment scam.* *The company is not legitimate in its financial or engineering integrity.* *There have been no private sales, no production, no independent reviews or third-party laboratory testing.* *Nothing but "trust us bro" and hand over your money we promise to give it back.*

The Sachs Wankel engines developed for the Fanliner were too unreliable, they were abandoned in favor of the more powerful and reliable gas turbine engines

if i remember right they were taken from the car manufacturer nsu and maybe modified a bit, but not completely new engines... correct me if i'm wrong

@@StefOne-nw9un Sorry, my mistake. The KC-60 Wankel engines were developed by Sachs specifically for the Fanliner program. Sachs sold the KC-60 in 1975 to Norton and were sold as the Norton 588.

thanx for that insight... i thought it were standard nsu car engines, and wiki also names them as such... been a while since i watched that documentary about those planes ;-)

with "as such" i meant the name nsu... but could be they subcontracted it to sachs, a car parts supplier (e.g. my car's shock absorbers are from them)

A story that has been repeated many, many times in the aviation industry.... no Wankel engine has ever been reliable enough to pass the FAA or EASA airworthiness certification test

That's a very dubious story considering that Mazda never patented the Wankel KKM design. _NSU Motorenwerke GmbH._ patented the Wankel engine in 1957. Mazda became a NSU-Wankel licensee in 1961 and paid 40% royalities to NSU now Audi Division of Volkswagen group. Wankel engines are obsolete technology today for the simple fact that they are inferior to reciprocating engines and have reached the end of their development potential.

Rechargeable batteries have extremely low energy density and their weight is the same whether they are fully charged or completely flat... not a practical alternative for any transport aircraft application.

@@sandervanderkammen9230 You know more about it than I. thx.

@@sandervanderkammen9230 it is or is on the verge of being viable for very short flights, since amps cost 1/4th as much as BTUs. Places like the Philippines, etc. So we are about one big advancement away from short electric flights quickly becoming very common. The reason is that the tickets for such flights will be absurdly cheap, since plane tickets are mostly to pay for fuel. That you wouldn't already know this is alarming.

​@@someotherdudeYes, but _Watts_ are same.

I saw the RU-vid video on the liquid piston with a clear window showing the combustion chamber. Am I correct in saying that it has three cylinders? It seemed to be a great improvement on the standard rotary engine.

@@MrDhandley It has 3 combustion chambers, yes. According to their website the power to weight, which is not better than your average reciprocating engine is when all 3 combustion chambers are firing per revolution. But they state the economy is only when a single combustion chamber is firing. It also refers to cooling (basically issues) when all three are firing continuously. From looking at it, it will be no better than a wankel, even worse in the sense that it has worse cooling than a wankel. Basically in sustained operation its power to weight will be worse than your average reciprocating engine. There are no demonstrations of it running at high load for a long time. Once it builds up with carbon it will score itself just like a wankel and efficiency will be even worse or no power.

Yes but wo the apex seals can be cooled

Unfortunately LiquidPiston is not a legitimate company, it's a scam

Sanders will shortly police this thread and tell you they aren't apex seals then. He's the grammar and wankel police! He'd be right about it, if it's not on the apex of the rotor, it's a rotor seal, not an apex seal.

*That is absolutely, completely False.* *"Tax Displacement" is not recognized as a legitimate or valid method of calculating swept volume displacement of the Wankel engine.* *Tax Displacement is a marketing scheme conjured up by the PR department of NSU Motorenwerke GmbH which licensed the technology around the world, in particular in countries that based vehicle registration taxes on engine displacement.* *The Mazda 13B series has a total swept volume displacement of 3.9 liters and the 2x Conversion formula correcting for the 1080°degrees firing order sequence we consider the 13b a 2.6 liter for the purpose of comparison with reciprocating Otto and Diesel engines.* *Any questions?*

They honestly need boost if your only running a few rotors but you can make crazy power and low tq is not a issue turbines have even less tq but seting up the drivettain and gear ratios is important. Honestly more power and cheaper than turboprop when built properly 2 rotor motors can be pushed to 2000+ hp so 1200hp is doable with decent service intervals for a high performance airframe

​@@mddunlap03Wankel engines are completely incompatible with aircraft applications and are too dangerous for passenger aircraft.

​@@mddunlap03 The Wankel can't come anywhere close to the power-to-weight ratio performance of gas turbines which also have an order of magnitude greater reliability and endurance.

I thought a 20B had plenty of both hp. and Tq. so it didn't have to be turbocharged.

@@robertreasor7522 The stock 20b was turbocharged from the factory. It was designed for a heavy, luxury model Cosmo. The 20b is not a performance engine and cannot handle high stress or high horsepower

I CERTAINLY HOPE NOT. Any fixed wing aircraft that is tail heavy will stall and crash... the aircraft's weight and balance must equal across the CoG.. I think you are referring to the landing gear balance, which can change considerably when a different engine is installed from the original design (which is not uncommon) and ballast weight is added to compensate for the new powerplant.

​@@sandervanderkammen9230 You are correct, I meant to say the aircraft on its own, without any counterweights. A Large jet will be pretty spot on, but small discrepancies will need to be resolved by adding counterweights. And, slightly nose heavy is preferred than slightly tail heavy (if you must have one or the other, which realistically doesn't happen often), as it is easier to recover from a dive than a stall.

The James Richardson from Portsmouth, New Hampshire??

Air injection _Increases_ the EGTs by providing fresh oxygen to burn any remaining fuel in the catalyst. Damaged apex seals increases the amount of unburned fuel in the exhaust, EGTs skyrocket and the catalyst is quickly destroyed. Wankel engines are inherently unreliable and cannot pass the FAA certification test.

You can easily run a Mazda rotary engine without the cat converters, and they run a whole lot better without them. They only throw big flames when tuned to dump fuel into the engine during off throttle. This can be tuned out quite easily with the ECU. Having hotter than average exhaust is nothing that can't be engineered around.

@@streddaz All engines run better without catalysts, what's your point? High EGTs are a symptom of low efficiency, this low efficiency in inherently fundamental to the Wankel engine design. It cannot be engineered around, no solution to the Wankel engines low efficiency has ever been found and will never be found.

@@WilhelmKarsten my point was to the comment above that stated that removing the cat causes much lower torque and for flames to spit out the exhaust, which is not true.

​@@streddaz Removing the catalyst from an engine designed to operate with one will reduce low end torque. Modern emissions controlled engines are tuned and calibrated to operate with a specified amount of enduced backpressure so the catalyst works at optimum efficiency, simply removing the cat will reduce low end torque characteristics. Proper retuning and remapping of the fuel, ignition curves and valve timing is required for optimal performance. Wankel engines like the Mazda RX require further modification of the port timing. Anyone claiming to race Mazdas should already know this. Which casts serious doubts on some of your dubious claims of expertise on this topic.

Amen! Anyone that has driven a car with one would be completely horrified by the idea of their life relying one of these keeping you in the air!!!!

The fact that Citroën, of all companies, gave up on the Wankel, should be evidentiary that it is a dead-end. If there was ever a company known for ripping up the rule book and innovating what a car could be, it was Citroën, and they dropped it like a stone. It’s a good example of how, just because an idea is good, doesn’t mean that it will work, and just because it works, it doesn’t mean it will work well.

More reasons to use a rotary even over jet engines… much less likely to fail and easier to repair if it does fail… It’s literally the best engine for both jobs… anyone that says different hasn’t ever owned one? Or rather tried to maintain one…

@@pazsion Jet engines have an _Order of Magnitude_ greater reliability and durability, they are the most reliable engines know to mankind. Wankel engines are so inherently unreliable that they cannot even pass the reliability test for general aviation use...

​@@pazsion*You can't use them in aircraft! They can't pass airworthiness certification... seals are too weak to last at P-100*

The MTBF (average time between failures) is so low the they cannot meet minimum stanards for type-rated passenger aircraft. There are no Wankel engines available with a airworthiness certification

@@sandervanderkammen9230 but is there a tbo number from the manufacturer? I have extensive experience with the rotary from the Shadow. Tbo was 250.

@@scottboelke4391 The 741 is the old Sachs engine designed in the early 60s...it was sold to Norton in 1974 and acquired by UAV after Norton went tits-up in 1990. No Airworthiness certification, so the TBO is just suggested as there are no legally required annual inspections or limit on hours before overhaul.

​@@scottboelke4391 Austro Engines sells the the larger 294cc version from the Hercules W-2000 motorcycle and the Norton Classic. It has no FAA certification but it does have an EASA exemption (part 22) for unpowered gliders, the TBO is 50 hours. Part 22 test requirements are only 120 minutes with 60 minutes at full power. FAA certification requires *150 hours*

There problem is the apex seals are so unreliable that these engines cannot pass a FAA or EASA airworthiness certification test. Basically they are too dangerous to install in any type-certified passenger aircraft.

FYI: these are not Rotary engines, they are WANKEL ENGINES. ROTARY type engines were once very successful in aircraft during WW1.

@@sandervanderkammen9230 the ceramic material, although expensive, apparently solves the problem.

​@@someotherdudeApparently not, considering that ceramic seals were developed by an aircraft engine manufacturer...

Wankel engines cannot be used in type-certified passenger aircraft because they cannot pass the reliability requirements for FAA or EASA airworthiness certification

Old wives tales. With a PSRU and cruise power, the rotary can run all day with a prop speed of 2,000RPM and the engine turning 6,000 to 8,000 RPM. This will not degrade engine life. Most certified recips are TBO at 2,000 hours and some break cranks or rods before that. Then there is valve heads breaking off. Rotaries do not suffer those problems. The oil injection pump can be separated from engine oil and take 2 stroke oil from a separate oil reservoir. Paul Lamar prior to his passing from age related causes, was working on a Turbo Compound to reclaim waste exhaust energy and through a fluid coupling and reduction drive put that power back into the eshaft. This could bring the BSFC up quite a bit.

@@daledavies2334 *Please name a single Wankel engine that can pass the PFTR for a FAA or EASA airworthiness certification for passenger aircraft.?*

@@daledavies2334 *Paul Lamar sadly suffered from mental illness and his unhealthly obsession with Wankel engines in aircraft was a manaifestation of his illness.*

The biggest problem is they can't pass the reliability test for aircraft certification

Well, the 1960s Sachs KC-60 was developed for aircraft long before it became a troubled motorcycle engine for Norton and rebranded by Mid-west... Ever since Curtiss-Wright began development of Wankel engines for aircraft in 1958 the Wankel has left a 65 year long trail of failure and bankruptcy

@@sandervanderkammen9230 we all know you can't stand it that Mazda is again making and selling rotary engines.... It's driving you crazy. It's eating you alive!

@@someotherdude Wankel engines dumbass, don't you know the difference yet?

​@@someotherdude*Mazda has never sold a single Rotary type engine in its entire history.* *Mazda became a NSU-Wankel KKM57 licensee in 1961.*

@@sandervanderkammen9230 The CEO of Mazda casually refers to Wankels as 'Rotaries' in a recent interview, and if he does it, it's good enough for the rest of us. You really, really need to relax about that point. You might also go look at the YT videos which show rotary(wankels) Mazda is currently producing. By the way, a couple other companies are thinking of licensing deals because they too are shopping for a range extender engine.

Rotaries reject a lot of heat into the oil. Need a large oil cooler.

Overheating is not the primary failure mode of Wankel engines, they cannot pass the PFTR test because the MTBF (mean time between failure) of the apex seal ls is too low.

​@@formericeNot compared to most air-cooled engines which rely on the lubrication circuit to remove a significant amount heat during high power output.

It's the apex seals that fail, Wankel engines are completely unable to complete the same endurance test that reciprocating piston engines easily pass to earn a flight rated certification

Wankel engines quickly overheat when the apex seals get damaged and the engine is pushed hard with low compression

NEVER use a synthetic oil for rotaries, most rotaries have oil injectors, synthetic oils are hard to combust and you're just gonna spit oils out of the exhaust, always use mineral oils, unless you want to delete the oil injection and do a heavier premix, carbon build up can easily solved by revving it or use automatic transmission oil put into the rotor housing from the spark plugs, and for apex seals they're not as fragile as the internet says, heat is the enemy, so having peripheral port exhaust is important, you can also have peripheral intake for better colling to the center of the apex seals, the devil's marks is old issues, you won't see it in a smoothly ported engine

@@youtubebannedme that's the idea... The oil doesn't combust, but stays as a liquid. Mineral oil burns and leaves ash and residue in the ports and chambers. My dad's Honda NSR150 2-stroke used to get clogged up in the exhaust power valve when running mineral oil. He went to Motul synthetic race oil, and the valve cleared itself up and there was only a thin coating of synthetic throughout,showing that it has good adhesion and stability at high temps.

​@@youtubebannedmeNever you say? Synthetic is perfectly fine on engines with the 2 stoike oil adapter or pure pre-mix that doesn't pump oil from the factory oil sump. Now of course you dont want to use synthetic on factory engines that uses the OMP.

@@rotaryperfection yeah i put "unless" in my paragraph

@@rotaryperfection Never use 2-stroke oil in an engine only rated for 4-stroke oil.

For anyone not yet familiar with all the pros and cons of the redrive I linked a video that covers this in-depth at 5:47

Pretty much all the Rotax engines use reduction boxes so why is this a problem now because it's rotary?

@@rotaryperfection Rotax makes engines that are certified, there are no Wankel engines certified for passenger aircraft.

​@@rotaryperfection*Rotary engines all have the propeller bolted directly to the engine case.* *We are discussing WANKEL KKM57 ENGINES* *Not understanding basic aviation terminology makes you look like an uneducated amateur... which is probably an accurate discription.*

@@sandervanderkammen9230 And yet this video has the MAZDA rotary plastered all over it.

Looks like just another vaporware investment scam like Freedom, LiquidPiston and Rotron... No FAA or EASA airworthiness certification either.

If you don't crash!

Not True!

@@robmcquilkin3316 absolutely true.

@@robmcquilkin3316 Wankel can't pass even the minimum PFTR reliability requirements for FAA certification... they require overhauls too often.

You put it in quotes, but thats not what I said. I said "many" ways, not "every" way. Big difference.

It is an irrefutable fact that Wankel engines offer no significant advantages and have several major disadvantages which is why they were the most expensive failure in the history of the engine manufacturing industry

Indeed, if Wankel engines were superior? Every aircraft manufacturer would be using them.

@@LetsGoAviate you don't know what you're up against with this Sander Van Der Kammen. At the very least, install security cameras, or stop advocating for Wankel engines. This guy won't rest until you agree with him! Just remind him that Mazda is in fact selling cars that have rotary engines. It's like holding up a Crucifix in the face of the devil!

​​​@@someotherdude​ *You wouldn't be so obviously a troll if your comments were even, at least in the slightest way relevant to aviation or aircraft engines.*

Well, I regret to inform you that you have been lied to and given some very bad information... everything you have been told is wrong. First off, your car doesn't have a Rotary engine, it has a Wankel KKM57 engine. Mazda sold these engines under the trademark brand _Mazda Rotary®_ Which unfortunately is very deceptive and confusing. Wankel engines are inherently unreliable and much less durable than reciprocating engines, Mazda RX models typically suffer significant degradation of performance and compression loss at around 50-60 k miles.. to find a healthy engine with over 100k miles is extremely rare, 200? Never going to find one. Wankel engines cannot be used in type-certified passenger aircraft because they are too unreliable to pass the certification test. No Wankel engine has ever been reliable enough to pass a FAA or EASA airworthiness certification test, they all suffer from low MTBF (average time to failure) Apex seal failure and compression loss is the primary failure mode. Any questions?

@@sandervanderkammen9230 Thank you so very much! You have saved me so much time and money I would have had to put out when my car's engine needed to be replaced.I cannot tell you how much I appreciate the honesty and integrity you have. You are indeed a grand and extra special person that gets whatever you need or want.I will never be able to repay you your kindness and your exceptional grasp of the wankel rotary engine has enlightened me so much I want to donate the rest of my time on this earth to the worship of you oh great @sandervanderkammen9230 ! At last my life truly has purpose and meaning. All hail you! oh great one!

@@robertreasor7522 I have a question. A completely honestly question, no sarcasm. What compelled you to buy a 25 year-old Mazda RX7?

In Oz a 700hp 13BT is just a phone call way, this power level is easily achieved thee days.

So why are Wankel engines so unsuccessful in motosports? Mazda left racing completely without ever winning a single world class championship title. Rob Dahm? Are you talking about the coke dealer that sells T-shirts with his name all over them? Who has a long history of spectacular engine failures? Who pays other people to build his engines because he is a "software designer" and not a mechanic? That Rob Dahm???

​@@kingcosworth2643And compression loss can easily be achieved in one day....

Wankel engines are hopelessly unreliable, so unreliable in fact that they are unable to complete the endurance test required for production aircraft.

That will self destruct after few hours in service. Not really, Australia is just decades behind the rest of the world in engine technology

Why does Australia have so many bogus engine tuners that scam thier customers?

@@sandervanderkammen9230 You have no idea what you are talking about. They are saying that in Australia there are many performance workshops that build modified versions of Mazda's rotary engine. Australia and New Zealand lead the world in full billet engines and 3, 4 and 5 rotor variants.

@@streddaz Australia and New Zealand are decades behind in automotive technology, these countries no longer produce cars. These places are also rife with engine technology scams, people who live there are very gullible and niave regarding engine technology.

@@sandervanderkammen9230 I'm pretty sure the Australians know what they're buying and whether it gets the job they want done. In fact, they run a helluva country in pretty much every way.

Nothing comparable to the horrible lack of reliability, Wankel engines cannot be used in certified passenger aircraft because they cannot pass the minimum PFTR reliability requirements..

@@WilhelmKarsten False! No one ever attempted to certify an RCE for General Aviation because there is no series produced Aircraft in the Wankel power range. What about the Austro rotaries? Before reckless assertions, please check and consult references. Is anybody in the Aviation Industry paying your slander, or you are just a troll, hunting for independent minds? People like you support Zelenski, Netanyahu, war criminals.

​​@@joseveintegenario-nisu1928 LOCKHEED CURTISS WRIGHT NSU LYCOMING CESSNA BEECHCRAFT CONTENINTAL VAZ CITROËN RBF GRUMMAN SACHS MID-WEST MISTRAL HAVE ALL ATTEMPTED TO CERTIFY WANKEL ENGINES FOR PASSENGER AIRCRAFT!!!

​@@joseveintegenario-nisu1928Austro does not offer any Wankel engines that are certified for use in powered passenger aircraft.

*Austro Engines doesn't meet FAA and EASA airworthiness certification for passenger aircraft.*

Wankel engines have less than half the fuel efficiency of reciprocating piston motors and are simply too unreliable for passenger aircraft, he'll they are too unreliable even for cars! The Mazda 787B was a turd, only won a single race and that was pure luck. Mercedes beat Mazda for the 1990 le man's Championship cup and they lost to Jaguar in 91 too. Mazda doesn't race anymore... no more factory racing campaigns

@@WilhelmKarsten they lost after having the rotary banned Plus, whoever made the board who made the claim rotary unreliable, are the same who made the claim that the Subaru 360 should be banned for being to small than realizing cars where getting too big. I've seen rotary engines with much better fuel consumption thanks to proper maintenance and the fact they don't Rev like mad men on 2nd and 3rd gear when highway cruising; that's the only explaination on how the RX8 had even worse fuel economy than a V8 when the US government released it's data. Most of what I've seen are 20MPG and that's for stop and go scenarios in which the rotary only fails in.

@@MUSTDOS That's a popular but completely false urban myth. Mazda announced over a year earlier that the 787b would be retired and replaced by the Judd powered Jaguar chassis. The FIA never banned the 787b, why would they? The car lost 20 out of 21 races and never posted a single pole position or fastest race lap... it was a disappointing turd. It's an irrefutable fact that Wankel engines cannot compete with reciprocating piston engines in reliability or durability. That cannot be legally installed in certified passenger aircraft because they cannot pass the FAA reliability test. The Wankel engine typically has BSFC performance nearly half that of most reciprocating piston engines, they consume twice the kilograms of fuel per Horsepower/hour.

787B was a success given it didn't catastrophically fail; it was a new design and not backed like other engines. And the RX8 would've been far more reliable if Mazda didn't make its manual sparse and had a quite faulty thermal temps especially in the engine. A similar RX8 engine is still used in Formula Mazda and didn't suffered catastrophic failures. Much better than the unholly hybrids in the long run.

@@MUSTDOS The Mazda 787b was an epic failure that failed to bring Mazda a championship title. The Renesis suffered from horrible reliable issues directly related to it being the highest static compression ratio of any production Wankel engines, pushing the limits of the Wankel engines primitive non-vortex combustion chamber well beyond what was possible. Formula Mazda no longer exists, Mazda no longer supports any Wankel engine motorsports and has left racing completely. Audi has won Le Mans 9 times with a Diesel engine proving that even the Diesel engine is a superior racing engine compared to the Wankel.

No Wankel engines have ever passed the FAA or EASA minumum PFTR reliability test required for airworthiness certification.

@@brianb-p6586 Part H is an Exemption from meeting EASA Airworthiness Certification Standards. The AE50R can only be used in non-powered gliders. It is illegal to install one in a certified passenger aircraft as it does not meet the minimum reliablity requirements.

@@brianb-p6586 A Glider requires no engine to operate safely. Conventional aircraft need a reliable engine... otherwise people will die.

@@brianb-p6586 Most gliders have no engines, they are completely unpowered.

@@brianb-p6586 Glider aircraft are specifically designed and engineered to operate safely without any engine. They have been flying without engines for over a century. Most regulatory agencies place restrictions on when and where gliders can operate that do not apply to certified passenger aircraft and powered gliders must exhibit the same flying characteristics as their non-powered version of the glider.

Why not? Is it the reliability?

Where do you get this kind of egregious misinformation from? Nothing in your comments is accurate or true.

@@WilhelmKarsten I’m just a stupid Mechanical Engineer and a pilot since 1969. So you’ll have to be specific as to the errors in my thinking.

@@danbenson7587 It's not unusual for a Lycoming air-cooled engine to have a BSFC of 0.4 or less... thats less than half the fuel consumption of a typical Wankel engine. Wankel engines cannot safely run 'Lean-of Peak' either, you must cruise with a rich mixture. That's wishful thinking considering that no Wankel engine has ever been reliable enough to pass a FAA or EASA PFTR requirements for airworthiness certification. The cost of parts and repairs for automobile engines will always be much cheaper than a type rated aircraft engine because they are not certified! Completely moot point. When just comparing automobile engines the Wankel has a higher initial cost and higher operating costs than a reciprocating engine. So no cost advantage with the Wankel. The Wankel has overall poor torque characteristics and BMEP is terrible compared to reciprocating engines. The primary failure mode of all Wankel engines is apex seals and compression loss. The issue is high brisance and ablative damage during continuous high IMEP conditions like take-off and climb out. The apex seals have an extremely low MTBF, too low for safe use in passenger aircraft. Carbon build up is a symptom of low compression, no different from reciprocating piston engines. Carbon is a good indicator that the seals are damaged and compression is below acceptable readings. Unfortunately no, Wankel engines are very poorly suited to combined cycle exhaust gas turbines, the Wankel engine's extremely low combustion chamber efficiency and low conversion rate make the EGTs too high for reliable operation. Much richer AFRsare needed to quench the EGTs thus canceling out any advantages of additional heat recovery cycles. Any questions son?

@@WilhelmKarsten Adults disagree w/o being snippy (eg ‘son’). Returning to the debate EFFICIENCY. Gas turbines like PT6, T250, TPE331 are less efficient than a piston (say .63 vs .45 sfc) Their success in the +300 hp market means fuel efficiency is not a primary market requirement. If sub 300 hp GTs were available, I’m sure they would replace Lycoming and Continental . To the aviation market, reliability trumps efficiency. Rotary’s combustion chamber and large wetted area stink vis a vis a piston engine. But rotary auto engines are tuned for broad rpm range, whilst aero engines run between 70% and 100% power. The point: a rotary tuned to aero requirements would enjoy an appreciable sfc improvement. Lyc getting .40 sfc is a pipe dream. The compression ratio is 6.5 to 7, open (non squish) chamber, air cooled. But I’ll concede if you can provide a source. RELIABILITY . I’m my view, the rotary is the poor man’s turbine. A two chamber rotary has 3 primary moving parts versus 22 primary moving parts on a 4 cylinder Lyc. The rotary fails by loss of performance, not catastrophically. Lyc. fail how many ways?...dropped valves, cracked cranks, cylinders completely blown off, spun bearings etc. I had an C-172 w/ O-300 Cont. catch fire; it was a close run thing. DURABILITY. Mazda whipped the apex seal issue decades ago. They are currently producing the MX-30 engine. Would Mazda invest billions if apex seal life was an issue? (BTW ...RU-vid has MX-30’s being built). In addition, The rotary has excellent balance so benefits spill over to reduced airframe cracks. Lycoming and Continental engines’s broad cylinder spacing, ‘S’ shaped crankshaft throws, sloppy tolerances, and air cooling are antipodal to long life. I am amazed they do as well as they do as they beat the shit out of themselves every revolution. REBUILD. For a rotary, it’s disassemble, replace seals, reassemble with new oil and water pump, then test. Lycoming and Continental disassemble, magnaflux, measure, refurb cylinders, new pistons/rings and on and on. All with paperwork. Then after spending 40-50$k you still have an engine with an unknown remaining fatigue life. FAA. I don’t know the rotary’s certification history. I do know Certification is more than witness testing the product, it’s the whole paper trail: calculations, quality system certification, building process, material traceability, certificates of conformance. (Thus why auto engine conversions are near impossible to certify). These impediment dissuades all aero engine manufacturers from product improvement.. but that’s another story. There is no intrinsic reason a rotary running on mo-gas is un-certifiable. COST. Rotary’s have fewer parts are going to be cheaper in the diminutive aero market. From above, it’s not just a part..it’s the paperwork. TORQUE. The aero engine torque output must simply exceed the prop’s n^2 requirement. Non issue. COMBINED CYCLES. Wilkepedia ‘Mazda Rotary’. Find a list of turbo’d rotary engines. A few remarks about turbo...The pressure rise across the compressor and the pressure drop across the turbine are practically the same. A turbo engine effectively runs at an overall higher pressure. When the exhaust opens, The engine blows down from a pressure about equal to the cylinder compression pressure at TDC. The turbo compound engine captures this blowdown energy. (These remarks are first order, it’s more complicated) In a piston engine full turbo pressure is across the rings and piston. In a rotary, the full turbo pressure is across the side seals. The apex seals are pressured from BOTH sides. Raising the rotary’s overall pressure via turbo is not fully visited on the apex seal. The bug with turbo compound piston engines is exhaust valves crapping out. The rotary hasn’t exhaust valves to crap out. Mazda’s turbo success suggest EGT a non issue. Turbo rotaries are over boosted, whereas Lycoming and Continental are turbo normalized. A turbo rotary potentially has superior specific weight. TECHNOLOGY. Mazda has the monopoly on rotary tech. Piston tech is ubiquitous. At the end of the day the market and certification hurdles dictates Lycoming and Continental. An aero Rotary is a dream and always shall be. Nonetheless I think a good fit for planes, a poor man’s turbine. But so what? It’s not going to cost me sleep. The aero market crawls toward the Diesel cycle, not for efficiency, but JP4. This mutes our rotary versus Lycoming discussions. Cheers D

@@danbenson7587 Wow! That is a comment filled with wishful thinking, pure speculation and outright fantasy. The PT6 achieved 0.49 BSFC when it was introduced in 1961. The EPI TP-400 achieves 0.350!!! Thats 40% TFE!!! There are no sub 300hp GTs because of COST, they are too expensive for GA. However GTs have rendered reciprocating piston engines obsolete in commercial and military aviation because of the incredible horsepower-to-weight performance and long term financial benefits of their long service life which is an order of magnitude better. In General Aviation cost trumps everything, reliability is regulated by government agencies. Not a valid argument, as peak BSFC efficiency occurs at WOT, exactly where the Wankel engine shows its biggest weakness. That comment is a major blow to your credibility, here you are again talking pure speculation without any shred of evidence or a functional understanding of the topic. The IO-720 was the first the Lycoming engine to break the 0.40 BSFC, that was back in 1961! In my view, you sound like someone who is a poor man, too poor to own a plane anyway. Unfortunately automobile engines have proven unsuitable for aircraft applications except for the most reliable manufacturers like Porsche and Mercedes-Benz, and even then with limited success due to higher costs. You mean the O-300? That's a type rated aircraft engine. There are no type rated Wankel aircraft engines... they all failed to meet the minimum PFTR requirements for airworthiness certification. Mazda went bankrupt in 2009 after one of the biggest premature engine failure recalls in history involving apex seals in the Renesis. Mazda has never made a profit from Wankel engines and has gone bankrupt twice because of them. Both Lycoming and Continental developed Wankel engines but they consistently failed the same durability and reliability tests that thier reciprocating piston engines easily passed. You obviously know nothing about FAA or EASA airworthiness certification. No Wankel engine has ever been reliable enough to pass certification.... Apex seals have proven too unreliable. Wankel engines are more expensive and they have many tiny fragile seals that are the source of their unreliability. Wankel engines offer no advantages in torque or horsepower characteristics, that is a matter of propeller selection and efficiency. Reciprocating engines are ideal for props because of their low rpm torque and horsepower output. Mazda's disappointing failures with turbocharging speaks for itself... turbos and apex seals don't mix! Just ask Tom Parkes or CJ.Jackson, they both crashed because a broken apex seal took-out their turbochargers during a critical climb-out phase. The reliability of turbochargers on reciprocating piston engines is excellent and not in question. JP-4 is obsolete son, has not been used in many years.

Too unreliable for passenger aircraft... plus terrible fuel efficiency reduces range and payload

Great comments Love it when I see smart people leave comments, usually the RU-vid comments section is populated by those on the other side of the Bell Curve. Cheers!

If you're putting a rotary in a air plane and using a factory intake, you simply don't know what you're doing. It's only for rotary experts who KNOW how to build intakes that leverage low rpm torque and HP.

@@rotaryperfection If you are putting one in an aircraft you are either crazy or suicidal.

​@@rotaryperfection*AVIATION EXPERTS KNOW THE DIFFERENCE BETWEEN A ROTARY ENGINE AND A WANKEL ENGINE.*

@@brianb-p6586 *There are no Wankel Rotary engines, only a single DKM54 prototype exists in a museum.*

As explained towards the start of the video at 0:19

@@LetsGoAviate yes, but it is still called a rotary.

@@FairladyS130 Yes, but actual rotating cylinder "rotary" aviation engines are so rare they're not even worth mentioning, and were quite rightly abandoned 100 years ago.

@@boydw1 Seen plenty of videos of those 'abandoned' real rotaries recently.

@@FairladyS130 Maybe you're confusing them with radials. There's still a few aviation rotaries out there, pretty much exclusively on restored ww1 era vintage aircraft.

Rob Dahm? The guy who made a video about the benefits of mixing cocaine and Adderall? Who sells guady T-shirts with his name all over them? Who pays other people to build his engines because he is not a mechanic or an engineer? Who's engines always blow-up??? That Rob Dahm??? Aren't drones made to be disposable? I think the Wankel is too, sounds like a perfect match!!!

@@sandervanderkammen9230 lol did your missus run off with a RX-7 owner or something :) You seem very silly and stupid, but it did make make smile so there is that.

​@@ATomRileyAWhat kind of pathetic loser drives a 30 year old Mazda?

@@sandervanderkammen9230 then you have literally just admitted wankels are excellent for something the world will always need, which are drones.

​@@someotherdude*WHO WANTS TO FLY IN A PLANE WITH A DISPOSABLE ENGINE????* *DAMN YOURE IGNORANT SON!*

Excellent comments. True, the Wankel engine has an inherently low MTBF and no manufacturer has ever achieved and maintained a FAA or EASA airworthiness certification for passenger aircraft

Redline failure will also apply to a piston engine. Look at all the piston failures at take off? If someone is building a rotary and gearing it to redline for full power in an airplane application, they simply don't know what they're doing. The 787b lived between 7-9k for 24hrs at lemans and still could have ran a 2nd 24hrs. Not a single piston engine can do this under those stresses in that event. Sweet spot for rotary in airplane is geared max prop speed of 2,700rpm and engine running at 5,000rpm with a large turbo making 7psi or less and running 10.5 afr. The large turbo wont heat the air as much due to it's better efficiency which will help the smaller intercooler do its job. Oil and water cooling then becomes the biggest problem which is why I would build my setup to max at 5,000 rpm to help keep all the temps in check. No need to build a rotary setup above this rpm range (unless it's NA) when you can make the power you need between 4-5k. You will essentually double the engines reliability and extending the TBO by lessening the apex seal tip speed and their centrifugal forces on the rotor housings. The only problem with rotary is too many people try to build a setup to fully take advantage of the engines high rpm capability. Not neccessary as its far to difficult to cool them. Thats when you'll have problems.

​@@rotaryperfectionName a single Wankel engine that has a FAA certification?

​@@rotaryperfectionWhy is there no production aircraft powered by a Wankel engine???

​@@rotaryperfection*You shouldn't have to worry about a "redline" failure unless your pitch control fails or you overspeed in a dive.. (perhaps if your propeller falls off)*

*The United States Military, the world's largest user of UAVs is completely eliminating Wankel engines from its inventory.*

Yes explained here 5:27

0:19

​@@LetsGoAviateYour video is unfortunately confusing and inaccurate. You say "Wankel rotary" and show an image of the DKM54 But you clearly described the Non-rotary version called the KKM57??? Are you not aware there are two types of Wankel engines?

Great comment and good points, apart from the troll thing. Really? No the video is not a "troll". I raised a hypothesis that the Rotary is the ultimate light airplane engine and presented some facts and my reasoning for my proposition. If you think it's a developmental dead-end, you better let Mazda know quickly! Maybe if you said it's a dead-end for primary propulsion, it would have hit harder, since it's viability for range extenders in EV's are excellent. Closer to home (aviation) Diamond also don't seem to buy into it being a dead end. If you agree that fewer parts doesn't always mean better reliability, then by extension you know that more parts doesn't always mean worse reliability. Thus I don't agree that a gear reduction unit is a "damning case" against the rotary, it certainly isn't a "damning" case against the Rotax 9 series engines, as an example. If the PSRU is of a good design AND is maintained as per manufacturers instructions, they have an excellent track record with failures being extremely rare. I maintain the reason the rotary isn't developed much more is because of it's emissions problem which can't be fully solved (as opposed to reliability problems which can be solved). The emissions however isn't as big an issue in general aviation as in motoring, but don't take my word for it. AVweb's Paul Bertorelli recently released an excellent video called "Decarbonize Aviation? Good Luck to Us" which explains it well.

@@LetsGoAviate I apologize since you seem serious about the question. But really, after you understand the short comings of the design, I think you might look at things differently. I would be happy to go over every aspect of the engine with you to help you understand why the wankel design is a poor choice and has issues that can never be fully resolved. These include but are not at all limited to: complicated sealing, uneven heating, poor thermodynamics, noise, carbon buildup issues, and decreased range for a given output. Mazda does not pursue the engine because its superior, they pursue it because its a novelty.

EXCELLENT COMMENTS

Standardized propeller design is why the need for gear reduction. Change the geometry of the propeller may allow for high rpm without gear reduction. Might be able to use for auto gyro work as well.

​@@doolittlegeorgeYes simply reducing propeller blade length allows higher propeller rpm, but longer propellers are more efficient, which is why airplane propeller blades for the most part have always been as long as is possible.

It's way harder to produce and has a very limited life, and a scary hollow crankshaft.

Rotary engines became obsolete in the 1930s. Gasoline powered aircraft are not going anywhere for a long time.. there are currently no viable alternatives.

No Wankel engine has ever been reliable enough to pass a reliability test for FAA or EASA airworthiness certification. It is illegal to install a Wankel engine in any certified passenger aircraft because they are too unreliable!

Great for NA, not so much with turbos.

No, no one has even solved the problems with apex seals, they are unreliable by design.

They make alot of things on the aftermarket that are garbage and all hype.

Ianetti ceramic seals are race proven (NA) and have been for decades.

@@CrazyTony65 Ceramic seals have been around for decades and have consistently proven too unreliable for aircraft.

Those Wankel engine manufacturers haven't tried hard enough. Mazda made a wankel engine and put it on a race car. They won one Le Man 24 hours endurance race. It was full power 24 hours reliability test.

@@catchnkillCurtiss-Wright, Lycoming and Continental also tried and failed. Mazda only won a single race, pure dumb luck. Mazda has never won a single world class championship title and left motorsports in failure. Mazda discontinued Wankel engines because they were too unreliable for cars!!!

@@catchnkill Full power? No, the Mazda R26B was severely detuned and ran at half of its full rated power during the race. Ir was the largest engine 7.8 liters

@@sandervanderkammen9230 Motor racing is about rules. Wankel engines are treated differently. Thus it all depends on the c.c. conversion ratio with traditional 4 strokes engine. Audi won several Le Mans on a diesel engine racing car. Again it was about rules. When they tightened the rules against diesel engine cars, they bowed out. So winning a world class rate or not is not the main issue here. Is this type of engine not reliable? Not enough data to prove. At least those Wankel engines cannot be not reliable engine if they finish a 24 hours endurance race.

@@catchnkill Diesel engines are one of the most reliable type in the world. Wankel engines are obsolete because they are inherently unreliable.

Wankel engines cannot even pass the PFTR reliability test for FAA or EASA airworthiness certification

Wankel engines cannot pass a 150 hour FAA or EASA PFTR reliability test required for certification.

And extremely unreliable

@@sandervanderkammen9230 so unreliable that Mazda is again putting them in cars.

​@@someotherdude*Mazda Wankel engines are so horribly unreliable that they cannot be used in type-certified passenger aircraft.*

Wow! Are you even old enough to drive yet kid? Everyone knows that Wankel engines like to shit their apex seals out the exhaust in the most unpredictable fashion... these things are too unreliable even for cars, Forget airplanes unless you're feeling suicidal! Hahaha!!!!

they have found solutions to the motors twisting internally, usually people add extra dowel pins and or studs to keep the engine from over torquing itself, don’t forgot people have also made two piece and 3 piece e shafts to keep that from happening.

@@thatcornfedrx8guy372 No solution has ever been found to make Wankel engines reliable, they are obsolete technology today... the sole domain of hacks, crackpots and con men.

Horrible torque producers. Needs boost for any power too. The power vs SWEPT volume is horrible too.

The wankel rotary has a lower compression ratio over a 4 stroke piston type thus lower torque. It gets it power advantage from sheer speed ( rpm) the best engine power to weight is the axial flow jet turbine . A old model in a museum once visited had a 100 lbs turbine developing 1000 hp! Pretty hard to beat. Downside? Cost, fuel efficiency , emissions and maintenance. You cant have it all.

@@waynegarfield6607 Good comments! The rotary also uses the ‘displacement’ of just the compression chamber, not the swept volume. So the true power vs displacement gets even worse.

Then why are Wankel engines obsolete? Mazda's 787b was never banned, it was patheticly slow and uncompetitive losing 20 out of 21 races. The fluke win at Le Mans was pure dumb luck, Mazda was defeated by Mercedes-Benz and Jaguar for the Le Mans championship title and Mazda left racing without ever winning a single world class championship. Wankel engines were an absolutely unmitigated failure in the motorcycle industry bankrupting many of the great bike companies. The Wankel today is the sole domain of crackpots and con men

​@@waynegarfield6607The Wankel engine has poor torque characteristics because of the extremely short stroke and it operates at a mechanical disadvantage, it was developed originally as a supercharger not an engine, so the geometry is actually backwards from a proper engine design. The Wankel has no advantages in power output which is one of the reasons why they are obsolete

Apex seal failure is the primary failure mode of all Wankel engines. No aircraft engine manufacturers have ever resolved the problem of apex seal failure during airworthiness certification testing.

@@sandervanderkammen9230 What causes apex seal failure? What is an apex seal failure?

@@jdoe9518 Apex seal failure is caused by erratic combustion and detonation in the Wankels very primitive non-vortex type combustion chamber, this creates high brisance and ablative damage to the surface of the apex seal directly exposed to the burning gasses. They are unlike piston rings which are protected from damage by the piston crown and ring lands. Apex seal failure is typically the inability of the seal to continue forming a gas tight seal and the resulting loss of compression and engine power. Catastrophic Apex seal failure can cause broken seal and tension spring parts to detach a contact the housing wall or end plates.

@@jdoe9518 Aircraft engine manufacturers must complete a PFTR (Preliminary Flight Test Rating) before they can apply for a FAA or EASA airworthiness certificate. Depending on type of application the engine must be run in a test cell at P-100 (full rated power) for typically 100 hours or more without any failures and no significant loss of power. No Wankel engine has ever been reliable enough to pass and maintain a FAA or EASA airworthiness certification. The primary failure mode during these tests is Apex seal failures. The MTBF is simply too low for Wankel engines to be safely used in type-certified passenger aircraft. They can only be legally used in gliders, UAVs and experimental aircraft. Any questions?

@@sandervanderkammen9230 So exactly how erratic is the combustion? It sounds like these engines are lucky to run at all? Are all apex seal materials effected in the same way? Ceramic v steel v carbon seals So piston rings run in ring lands what do apex seals run in? Oh and do apex seals prevent combustion pressure entering the sump?

Porsche's 911 engine is so durable and reliable that it was granted a FAA airworthiness certificate (PFM 3200) Mercedes-Benz is the only other automobile engine that is full certified for passenger aircraft (OM640 - Centurion 2.0)

Porsches have a dry-sump lubrication system like aircraft They are the King of endurance racing having won the 24 hours of Le Mans 19 times!!!.

@@sandervanderkammen9230 Porsche's foray into diesels didn't go well at all. And since I know you have so much pride wrapped up in the Germans, let me remind you that at present, German cars are an utter embarrassment. Still wonderful to drive of course, but unreliable, filled with electrical gremlins (especially VW and BMW) and highest cost of ownership over a 10 year period. That is NOT what German prices should buy you. And then there was Dieselgate. So don't be so smug on all things German. At the moment, the state of their cars is shameful.

@@someotherdude *Porsche has won Le Mans 19 times and their production Auto engines can pass FAA airworthiness certification... something that no Wankel engines ever has.*

@@someotherdude *BMW is famous for making some of the best aircraft engines in history.*

All Wankel engines operate using the 4-stroke principle. Beware of LiquidPiston, it's not a legitimate company, just another scam

The truth is the average automobile engine is simply not designed to handle the conditions found in aviation. Your average production car would struggle to complete the 24 hours of Le Mans at a reasonable speed. The FAA requires a minimum test of 150 hours at full power with no significant loss of power. The cost to redesign a car engine to pass the certification test is spread out over very few engines compared with cars which are sold in the millions. This explains the higher cost for aircraft engines and why so few car engines become aircraft engines.

@@sandervanderkammen9230 Jes that I understand. But Toyota dit redesign that spicific V8 to run at 80-90% max power and rpm. 180kw+- I have looked at the research.

@@andrekemp5059 Did it receive FAA airworthiness certification like Porsche and Mercedes-Benz did???

@@sandervanderkammen9230 Jes TOYOTA LEXUS YAMAHA 1UZ-FE 1UZ-GE FAA US Federal Aviation Administration Production Approved FV2400-2TC twin turbo 360hp For Airplanes. Boat inboard Toyota Epic S2 1998 Epic S22/SX22 1999-2001 Epic X22 2001 Ambulance Lifesaving Toyota HiAce HiMedic Race car engine SARB MC8-R LE MANS 24HOUR

@@andrekemp5059 What is the BSFC performance and cost vs. a comparable Lycoming or Continental engine?

THAT IS COMPLETELY FALSE, Wankel engines average roughly Twice BSFC fuel consumption compared the reciprocating engines. There is no evidence to support otherwise. Wankel engines are inherently unreliable and extremely prone to failure at continuous high power output typical of aircraft applications. No engine manufacturer has ever managed to achieve a FAA or EASA airworthiness certification for a Wankel engine. The MTBF of the apex seals is far too low to be safe for passenger aircraft. No solution to the inherently unreliable apex seals has ever been found.

@@sandervanderkammen9230 Why then did Mazda win the 1991 24 Hours of Le Mans with a Wankel engine only getting minimal wear and tear? Care to explain that to me?

@@Subar_Sama *PURE DUMB LUCK!* Mazda's win at Le Mans was nothing more than a fluke. The Mazda 787b was hopelessly slow and uncompetitive, it lost 20 out of 21 Le Mans series races and never posted a single pole position or fastest race laps. The 1991 24 hours of Le Mans race started out with a massive wreckage that knocked the series points leaders, Mazda qualified in the back of the field ans so far back they avoided the massive pile-up. Mazda walked across the finish line with a record low numbers of laps and the slowest average speed.

@@sandervanderkammen9230 You're clearly trolling at this moment. Goodbye.

@@Subar_Sama Serious as a heart attack kid. Check the records yourself. I watched the race in 1991, were you even born yet?

Same old ponzi scam that people keep falling for.

BEWARE OF LIQUIDPISTON it is not a legitimate concern and is a investment vaporware fraud

Great comments

Mazda RX owners admit their cars are not reliable enough for daily driving requirements. No aircraft company would consider using them.

And then there is also that pesky little problem with Wankel engines not being able to pass the reliability test for FAA airworthiness certification.

BEWARE OF LIQUIDPISTON It's not a legitimate company. LP is a fraudulent vaporware investment scam

They don't have the durability. It's an interesting engine for sure, but I think tough to produce. That hollow crankshaft? I don't like it. But great for certain niche purposes.

@@someotherdude You would have to be very gullible and niave to believe that LiquidPiston is legitimate

@@sandervanderkammen9230 You're really a strange guy with a strange take on the world. Because there is no doubt whatsoever that LiquidPiston is a legitimate company, and they are very likely to find some niche applications of their engine.

@@someotherdude *PROVE IT!* *I have found zero evidence to support that LP is anything more than a fraudulent vaporware investment scam*

Interesting theory, if you could get a hybrid system to pass airworthiness certification without a certified ICE? (this seems doubtful) why not use an existing flight rated APU gas turbine like a Solar T62 or Rover 2EG... they are lighter, more powerful much more fuel efficient, quieter and less vibration than a Wankel and offer an order of magnitude greater reliability and service life... and they don't need Avgas or Mogas which is often not available at your local AFO. Of course the real question is why lug around heavy, inefficient rechargeable batteries that pose a very real fire risk.. and the fact that available battery technology is not sustainable or environmentally friendly as some might claim. My money is on air-cooled, reciprocating engines being around for a long time and Wankel engines will be in museums and history books.

@@WilhelmKarsten Because we are commenting nostalgia for Wankel engines. But I do not think these turbines are cheaper than serially produced Mazdas. I doubt that they are more efficient under low load and more durable under heavy. If you have 2 engines and small battery certification should be easy. I think the best alternative will be electric engine made from many engines for drones coupled by reductor and array of range extenders for drones. Maybe based on free piston.

@@peceed Nostalgia indeed, the brief heyday of the Wankel engine ended decades ago. Yes more expensive but all FAA certified engines are extremely expensive compared to a Mazda automobile engine. No need for low power output efficiency in an aircraft application and high output durability of gas turbine engines is unmatched by any other type of ICEs. Certification is very difficult for Wankel engines, none of the dozens of manufacturers that have attempted this have succeeded, no Wankel engine has ever been reliable enough to pass a FAA or EASA airworthiness certification.

@@peceed Electric motors are very efficient and reliable, unfortunately rechargeable batteries are not and the most efficient batteries available are not inherently stable and pose a risk of thermal runaway. Range and payload for electric aircraft is extremely poor with little potential for significant improvement in performance. Drone engines are by definition disposable which prevents them from ever being a viable option for passenger aircraft. Even the UAV and Ultralight market has shunned the unreliable, inefficient and noisy Wankel, preferring the horizontally opposed reciprocating engines by a vast majority. The US military has phased out Wankel powered drones, the last one still in service has been set for retirement... perhaps it really is time to retire the Wankel engine completely.

​@@WilhelmKarsten I was referring to very specific accumulator type - sodium ion using "prussian white" based electrolyte, do research. Wankel from Mazda was one the cheapest engines that could be used for light aircraft. It was used in military drones due to its small size that could be integrated with fans, it lost this advantage in electric/hybrid era.

Wankel engines cannot support Diesel Cycle mode operation, static compression ratios above 12:1 or high manifold pressure. Apex seals are inherently unreliable and have an extremely low MTBF. No Wankel engine has ever been reliable enough to pass a FAA or EASA airworthiness certification. Above 300hp Wankel engines are completely unable to complete with Gas turbine engines in horsepower-to-weght ratio performance, they are also more fuel efficient and have an Order of magnitude greater reliability and durability.

In applications where size and power to weight ratio performance is critical, gas turbine engines are used as they can deliver an order of magnitude greater power-to-weight performance and reliability. Wankel engines cannot be used in certified passenger aircraft because they cannot pass the minimum requirements for reliability. Even in drones and ultralight applications Wankel engines do not offer any competitive advantage.

A Wankel will require a prop speed reduction unit and a liquid cooling system, negating much of the weight advantage.

Aircraft that require high power-to-weight ratio performance are fitted with turboshaft engines

All Wankel engines reciprocate and orbit simultaneously. The Mazda 13b has 2 triangle shaped pistons and a 30mm stroke

@@sandervanderkammen9230I am quite familiar with the construction of rotary engines and how they operate. The displacement is determined by 3 values; 1: eccentricity, of the eccentric shaft 2: radius, of the rotor 3: width, of the rotor and rotor housing. When I mentioned that rotaries do not have the stop and accelerate forces a piston engine has, they do not. The rotor continues its rotation and varies rotational speed only according to engine RPM changes. The rotor turns at 1/3 the speed of the e-shaft, which helps reduce any stress forces that could be created. A very robust design and light for the power output. With turbo compound they could be quite fuel efficient.

@@daledavies2334 The Mazda 13B series has a 30mm STOKE created by the 15mm offset throw of its eccentric-crankshaft. The triangle piston reciprocating left and right once per crankshaft revolution. Any questions son?

@@daledavies2334 The Wankel engine has never been robust or durable, it cannot be used in type-certified passenger aircraft because of its incredibly low MTBF. No Wankel engines have ever been reliable enough to pass a FAA or EASA airworthiness certification test. The Wankel engine is unable to compete with reciprocating engines in general aviation and in military and commercial aviation the Gas Turbine engines offer an Order of Magnitude greater power-to-weight ratio performance and infinity greater reliability and durability. Unfortunately the Wankel is much less thermally efficient and rejects much more heat energy out the exhaust, of course the problem with adding a heat recovery turbine or turbocharger is the much higher EGTs Much richer AFRs are required by the Wankel engine to quench the EGTs and those negates any thermal fuel efficiency gains from a turbine. Any questions? I suggest you go study some more

@@sandervanderkammen9230The rotor does not reciprocate left and right. The rotor bearing follows a circular motion around the e-shaft. Thre rotor and stationary gears impart a 1/3 revolution of the rotor as the e-shaft makes a full revolution. The apex seals follow the epichotroidal shape of the rotor housing inner surface. No reciprocation involved. Any questions sonny boy?

Please stop posting lies and ignorant misinformation about a topic that you are completely unqualified to discuss intelligently!!!

@@WilhelmKarsten Sorry, your terror style is known from long time. I'm a SAE member. Hit the road, young guy, and don't you come back no more, no more, no more...

R U located in the Netherlands, mr Karsten? Same as the Orange, who made crimes in Spain to protect the bonds of KLM with Air France, who are enslaved to Buckingham and the City, soon you'll be way down below the Ocean, from Ice thawing, global warming, triggered by the insane avidity of your oil Industry and the financial system behind it. You have no future! God save the queer!

@@josega6338 You sir a A FAKE AND A PROVILER... please stop spreading ridiculous misinformation about a topic that you have absolutely no formal education or professional experience in.

@@josega6338 YOU ARE A FAKE

Without any doubt, the weather man is more reliable than a Wanker engine!

Not even close. Porsche had a disaster with diesels, and Cadillac had a mega-disaster with them.

​​@@someotherdude*Lol!!!! You're hilarious lad!!!!* *Porsche has won Le Mans 19 times!!!* *And its flat 6 engines are so reliable that they passed FAA airworthiness certification.* *Even Cadillac made aircraft engines in WW1 and WW2.*

​@@someotherdude*Mercedes-Benz Diesel engines are so reliable that they meet both FAA or EASA airworthiness certification.* *You can buy a brand new fully certified aircraft with an Mercedes-Benz engine that came right off the automobile engine assembly line for W168 and W414 class cars.* *Mazda wouldn't even warranty an RX engine in most countries.!*

If that was true? Why is it that not a single Wankel engine has ever passed the minimum reliability requirements for FAA or EASA airworthiness certification??? Wankel engines are inherently unreliable and there has never been a solution to this fundamental design flaw

@@WilhelmKarsten The biggest issue in this conversation is people’s ignorance. There are definitely two rotary engines being offered at this moment by Diamond Aircraft and both engines have been approved. Adding, there have been others in the past but unfortunately, like so many other companies in General Aviation, have fallen to the wayside due to financial difficulties. I wasn’t trying to start an argument or hurt anyone’s feelings, but folks really need to start keeping up with information on technology and design, and stop relying on rumor and conjecture.

@@mattdavis9642 Indeed, you are very confused and misinformed regarding this subject. There are no FAA or EASA certifed Wankel engines currently available for General Aviation use. No Wankel engine has ever passed the minimum PFTR reliability requirements for airworthiness certification. Apex seals have repeatedly proven to have inherent issues that are revealed by MTBF testing. This was discovered many years ago by the largest Wankel Aviation development program conducted by Curtiss Wright in partnership with the FAA and NASA. Any questions young man?

Nothing regarding the Wankel engines' reliability problems has ever been "fixed" It's called a PFTR test... aircraft engines are run in test cells for hundreds of hours at max rated power until they run repeatedly repeatedly without failure or loss of power. Wankel engines cannot pass these tests. Diamond Aircraft no longer makes engines... They use engines made by German company *Thielert* and are based on production Mercedes-Benz automobile Diesel engines.

@@WilhelmKarsten Ok, I see what is happening. You are correct, the information you are relying on was “YEARS AGO”. As for FAA approval, we all know how on the ball the FAA has been especially in recent years. I apologize for not including government oversight in a conversation about advancements in technology. I’ll try to be more clear about the original topic of reliability through development. Most of the issues with the rotary engine or “Wankel” rotary engine have been addressed and has been approved by several countries to include Australia, the U.K. (That’s more then one country) and several other countries in Europe. The rotary or “Wankel” rotary engine can be used under the experimental clause in the states to prove this advancement in this technology. How can so many people and countries be wrong, and you and the FAA but right? I will provide the information to assist the elderly with self education. This will help in an official capacity in understanding when private citizens, companies, and even government agencies continue to develop or assist in development through funding said continuing development how things can change and get better. DiamondAircraft.com - Taken directly from Diamond Aircraft’s website: “The AE50R is a single stage rotary engine that generates 41 kW and is the only rotary engine worldwide that is certified according to EASA Part 22 Subpart H on today‘s market. The remarkable power-weight ratio (2 hp : 1 kg) makes it the ideal engine for unmanned vehicles. With more than 1,400 engines produced, the AE50R has proven its reliability in both, manned and unmanned applications.” This is just one of there engine models they provide. As for most people reading this they will realize and understand that from the beginning I was speaking to fixing or fixed issues with the “Wankel” rotary engine. And I freely admit that I did not include government oversight or felt the need to rely on said oversight in a discussion of what has been addressed and continues to be addressed on a conversation about mechanical issues and reliability. I have provided a company that provides said updated engine on the open market, an agency of the government type that has approved it, and only a matter of time based on continued development, reliable operating hours, and other data to be provided that the FAA will approve. Thanks to the individuals and companies around the world continuing this development, the rotary engine has not only gained in popularity around the world in aviation, but has seen a huge resurgence in racing that will only continue refinement. Unfortunately for some it is more important for them to be right, than to follow the scientific data that may prove them wrong. Thank you Pappy, for correcting me on the importance of government regulation and oversight, no matter how short sighted and antiquated it may be.

You should inquire about a refund on those degrees... because if you're not lying they're not worth the paper they're written on son...

"Rotary Radial" is an _Oxymoron_ An engine can only be one or the other, not both.

*Which Wankel engine? One is Rotary and the other is not.*

Your comment reveals someone completely unfamiliar with aviation or engineering... inventing your own "slang" terminology is ill-advised.

Wankel engines = ticking timebomb