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Wankel Rotary


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A relatively new engine, suitable for we peasants in the 95-10 category, is the Phantom XR-40 Rotary (Wankel) Engine from www.phantomaeronautics.com located in Michigan US of A. The engine is a detuned version of the AIXRO XR-50 gocart engine from Germany. It (the XR-40) makes about 40hp at 7600rpm (compared with 50 at 10000from the XR-50) and when combined with a 3.4:1 belt redrive has a total mass around 30kg.


You can hear the appropriate sounds and see it flying in a Phantom ultralight (part 103 approved) on the website.


Any comments?





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Guest micgrace



I like it. Esp when they have a twin rotor. Redrive seems really good value compared to some. Price doesn't seem too excessive.


But, I wonder what rotor tip seals they use? Dual ignition would be nice. I thought most rotaries used them.


I wonder how long before we see one in Oz??





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Bruce, :;)5:


Would you please outline a little more on the rotary. I checked the website and it seems very interesting. However you mentioned the engines were expensive, do you know how expensive?


What was the canard that was shown in the video?





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I'm not positive...I think the canard in the video is a Rutan VariViggen.


The prices of Wankel aircraft conversions seemed high to me while I was 'surfing the web'. I started with a Google search of 'aircraft wankel'. Have a look at www.ultralightnews.com/sunfun99/wankel.html...the prices there are 1999 vintage.





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I am a rotary engine lover, both my cars are powered by them, one is a


13B and the other a 12A, both by mazda, i have seriously considered


putting one of these engines in my Savannah when i get it, but looking


through the other aircraft application of the Mazda rotary, the power


output has been up around the 200 Hp or more. a little too powerful


for what i intended.


what i have bene considering is de-tuning a mazda 10A engine to produce


approx 100 Hp. or even using a standard 13B motor that usually


puts out approx 200 hp at 5000 rpm , and using it to turn a direct


drive prop and limit the RPM to 2800, therfor giving it approx 80 to


110 Hp.


Im not sure about the reliability of other manufactured engines, but


experience with the Mazda engines has shown me they are extremely


reliable if treated correcty, my old 12A got 280,000km before the


steel lining failied. even so, the blown motor still produced enough


power to get the car to over 100Km/h quick enough. a new rebuilt


replacement engine cost just under $2000.






redrive unit is here, no belts needed, just direct gear drive.




sadly there isnt anyone in OZ making a redrive for the rotary.


the cost for a redrive gearbox is US$2400


makes for an attractive option.





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About 30 years ago Suzuki produced a bike using a Wankel rotary. The RE-5 was dropped after about 3 years because of lack of sales...a great pity because all of the engine bits in a Wankel are turning in the right direction instead of the high speed stopping and starting in a reciprocating engine.


I luv all types of engines and a Wankel in an aircraft seems a logical way to go.


Gotta go...more talk later.





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Guest micgrace



I'd use a non turbo 13B (series IV or later). Steel tipped rotors, 100:1 fuel oil mix. Wire the oil pump open. Plentifull. 12A, 10A rather old, bit hard to find now.


Very mild cleanup of intake port (don't port it!) Fuel injection or a downdraft carby Weber IDA (manifold /carby readily available in car aftermarket, with no real power difference between injection/carby)with some sort of carby heat.


Redrive essential say, 2.6:1 limit max revs to 6,500. They produce stuff all torque down low, so you need it. So forget direct drive.


Separate ignition circuits, raided from a 12A one for leading plug and one for trailing plug. There are adaptors made (aftermarket)


Radiator, water and oil (essential) need attention. Plus assembly NO foreign bits or complete destruction of rotor housings/seal tips assured.


Plus exhaust system needs to be a bit like a 2 stroke.


Pluses. probably produce 80hp continuous (13B non turbo, don't believe the hype). Very compact, except for surrounding equipment. Not prone to complete mechanical failure. Even loss of compression isn't a problem. Though hard to start when cold. A few quick squirts of oil "fixes" that. Very fast to rebuild. Also from above.


Minuses. Somewhat higher fuel consumption than piston engine. Can be hard to start cold. Foreign material destroys rotor tip seals easily. Loud. Need special (expensive) compression guage. Damage to ONE rotor tip seal knocks out 2 combustion chambers.


Unfortunately the price of the redrives (about $5,000 OZ) puts this engine off my list. So I'm sort of stuck with the usual piston (Rotax, VW type)


I have worked on these type of engines in the past and are really quite simple to repair (if different). Just start throwing worn out parts, not really reconditionable apart from machining rotor/housing faces. The parts are available from Mazda, although the local parts place gets a bit funny if it's not in a car it came out in. I wouldn't even mention aircraft.





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FYI, I have pinched the following from the latest post on this subject on the RV builder's Forum .... where the Lycoming & Rotary supportersare getting a bit twitchy/het-up & trading methods of engine"failure" jibes about things in this debate. If the following are true and replicable, then they are good hours, though:




Since you asked, I know of several mazda engines that have run very near 2000 hrs in an aircraft- the most time I know of was in a training gyroplane, where the service cycle is probably greater than in fixed wing service- that engine went over 2400 hrs before overhaul which turned out to be unneeded. I believe Tracy Crook took his 13B to around 1800 hrs before he traded it in on a newer Renesis motor, mostly to test his new redrive/big prop, not that it needed replacing- that engine had NO measurable wear in any of the bearings or apex seal, and that engine was taken out of a junk yard (used RX-7) if memory serves.




The only reason you have not yet seen more reports is simply that the Mazda conversion parts have only become available commercially in the last few years, and it takes a bit of time for the GA pilots I know to log 2000+ hours




FWIW, The complete overhaul kit in a Mazda costs around $600, if it is ever needed. The most common failure (I believe) involves rubber seals that can can become damaged with excessive heat (cooling system failure). To claim wear-conditional parity with a Lycomming is absurd; many Lucs do not make it anywhere near TBO for whatever reason, though granted, some do if babied, maintained, and used regularly. I do know that a Lyc overhaul costs a bit more than a Wankel.




Im glad you are happy with your Lyc- it is an excellent choice for most of our clan. I really only object when I hear false reporting and biased facts thrown out, which gives a twisted impression on an engine that appears to be as good, if not better, based on engineering principles.




I think you can bank on the fact however, that a properly tuned Mazda engine will run a lot longer at rated full power, 6000 rpm, than a Lyc will at 3000. I suspect we will be able to say the same thing about Subarus as well, though I think the Wankel has an inherent advantage over any reciprocating engine operating at continuous "high" rpm. (remember, the rotors turn at 1/3 crankshaft speed in a continuous motion < do not change direction 4 times per power stroke>, and the rotors do not need to be made light/flimsy like alumimum pistons and connecting rods).




Mike Parker


RV-9a under construction,


planning Mazda 13B rotary power





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I'm a fairly conservative old bugger, but I will not be surprised when 'Wankel' engines replace reciprocating engines in GA and LS aircraft as the engine of choice within the next 5 to 10 years.


Wankel rotaries have too many advantages over piston engines in aircraft to be ignored.


With ceramic seals (albeit at a high cost) TBO's in the order of 20,000 hours are being considered!


And the 'baskets' are resistant to seizing!!!





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Thats the main reason i would prefer a rotary in my aircraft, the


engines are reliable, and if a failure occurs, they will still produce


enough power to fly you to safety. My RX7 engine expired after


nearly 300,000 Km, a good 100Km from help, and still managed to


maintain 110 Kph on the freeway and drive through syd to my


mechanic, all on 1 rotor. sure it sounded terrible, but i still


made it home. not only that i have plenty of spares including a


complete rebuilt 13B 6 port motor.


Unfortunatly there doesnt seam to be much in Oz for fitting a rotor to


any aircraft except RV's and i would loe to put one in a Savannah if




I have heard rumours of a Jabiru being built in Oz that will be


powered by a rotary, if so, it would be interesting to see how it will


go with engine mounts and locating radiators and building an exhaust




One snippit of info im finding hard to find is what is the weight of a 13B engine in its airworthy form?



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Guest micgrace

Hi All


They don't seize in the classic sense. The rotor tip seals is all that is really in contact with the rotor housing they go first (side seals on side plate). And it takes the failure of ONE only to drastically reduce power. But they'll still run well. Not at all like a piston engine under simalar circumstances (heaps less vibration)


There are carbon tip seals available. don't use them too fragile. Cermaic seals can be a bit of a problem, but not as bad as carbon.


The ultimate is blackceramic seal (very expensive)


The best is the original Mazda steel seal. Use the later series IV engine.


Most failures stem from, but especially, oil, foreign material and overheating.


Mandatory requirement of large oil cooler. Oil is essential for rotor tip life. Even add it to the fuel (100:1)


As for TBO? who knows. Check the compression every now and then (need special guage) then overhaul if in doubt. No real time limit to service.


The clue to compression being down is difficulty starting cold. Plus some start to miss at idle, but it's a little hard to recognize. (not as obvious as a piston engine).


Surface gap s/plugs are preferred to conventional and plug change needs to be as frequent as a 2 stroke. They foul plugs quite easily.


Don't try to put a conventional 13/16 plug in the side (they fit) USE the special Mazda one (NGK) or have fun getting them out. Normal plug spanners do not fit. (some people always TRY to save some dollars)


I did a 13B bridgeport N/A for someone It ate plugs for lunch, but when tuned I'd say nearly 300hp at some ridiculous 8,500 rpm. Had microtech computer efi, makes the job easy.


There is also a difference between timing covers (if you change to the earlier type twin dizzy) that requires modification, or no oil pressure. (straight to sump)


Also another potential trap concerns auto flexplate. Mazda uses separate counterweights on these.


There are traps for the unwary that are not found in piston engines so be aware of them.


I'm actually surprised there is no aircraft that I know of in OZ with one yet.


a "SIX" port 13B not bad basis. Easy port mod. (J port, mild)


For those that aren't familiar, fuel/air mix in a rotary comes into the combustion chamber through the side plate. Guys modify these hence the names.


The ultimate is a Peripheral Port (can't spell) where the side plate is closed and a direct hole straight at the rotor is created.


The power output is incredible, but must be limited to 9,500 due to rotor gear skipping. Expensive parts can bring it to 12,000+ and still the damn things won't blow up. Try that with a piston engine!!


Micgracesmiley1.gif micgrace



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I have to dissagree on the plug thing, i have iridium plugs in my


Rotor, and i pull them out regularly, though every time i do (every


5000Km) i wonder why i did, never need to gap, no sign of tip


wear, and never fouled, the same plugs have been in there now for


nearly 40,000km.


(since my rebuild) and i run my RX7 with a


premix fuel as well as the IMP still operating, so my mix is about


100:1 According to the Guys at pac performance who built


my engine after 300,000 Km, the optimal mix for a street use


rotary is approx 250:1


A lot of people seam to have trouble starting in colder weather, i have


never had any difficulty in starting mine, pull choke all the way out


and NEVER touch the throttle, just hit the starter. usually starts


after about 2 turns, on cranky days or after sitting for a week or 2 it


will crank over 4 times.


If there is a TBO life limit for a rotary, it will be dictated by the


housing liner wear, the cause of my engine death was exactly


that. the chrome/steel rotor housing lining eventually wore thin


enough for a small section to break away and destroy all apex seals,


and talking to george at PAC, thats about the usual lifespan for a well


maintained engine using standard steel apex seals.


If there is an achilies heel to the rotary, it would have to be the O


ring seals in the water jacket between housings, if one of these


leaks, it requires a complete engine pulldown to replace. so it


pays to keep the coolant clean, full of corrosion inhibitor and changed


regularly. the other key to longevity is as mentioned by


Micgrace, Oil. change Oil filters religiosly, as well as


air filter,and keep the oil cooler clean, as the oil system is an


integral part of its cooling. rotor cooling is done by the oil


system via the eccentric (crank) shaft.


Does anyone know of any rotary powered aircraft in the RAAus fleet?


edit, i finally found some figures on airborne weight of a 13B


" a 2 rotor 13B comes in


at about the same weight as an IO 360 when the redrive and cooling


systems are included. I think the 20B is around the same as an IO540.


When comparing numbers be sure to compare apples with apples - e.g.


everything firewall backward (or forward depending on your orientation)."


I guess a 13B would be a little too heavy for a Savannah. 051_crying.gif.fe5d15edcc60afab3cc76b2638e7acf3.gif





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Guest Fred Bear

I took the attached picture on Thursday.


The aircraft pictured - an UAV is fitted with a Wankel Rotary. It's a British Aerospace Engineering research project.


They have made a significant investment in it. There were 6 laptops looking after all of the numbers for it. It is yet to fly, although a smaller model has. It uses differential GPS to land.



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I know thai aircraft well, the engineers requested a copy of my


cri Cri plans for the wing to see if they culd use the design or


similar for the drone.


The rotory engines they are using are not made by Mazda unfortunatly. i


did have links to the sites they used for engine supply but i have lost


them in a recent IE crash, but ill chase them down again.



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Hello Ultralights,


What do you think of my chances of converting a 13B Mazda motor to a single rotor unit. I'd like to make a light weight rotary producing about 35 to 40 hp. I have some ideas but I'd appreciate your input.





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Guest micgrace



I'd say you would need to find a single rotor eccentric shaft. Try Guru Motorsport, Only company in Australia making eccentric shafts and bits(You may have to go through Pac Performance, Mazspeed or some other lot, but, then, maybe not) , they make a lot of unique bits for rotaries


With the engine being modular, apart from that unique part not much of a problem, the rest would betime consuming but shouldn't be particularly hard.


Shorter studs, cut sump, smaller carby, not a real lot.


Never tried it, should be interesting.





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Guest micgrace



Just wondering if PAC Performance did a standard rebuild for you or some very mild porting. PAC are well reknowned for outstanding work.


Fouling of plugs really depends on the type of driving you do. In Brizzie, the traffic kills them fast.


Oil is so critical to these things it cannot be emphasized enough as you point out.


Number one leading cause of failure, close behind is foreign material. Followed by corrosion in rotor housing, but so easy to prevent.


Some maufacturers are moving to solid zinc in radiator in preference to inhibitor. The local Repco store keeps this, or your friendly GMH dealership. Worth checking out.


Just some notes that may be of use.





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I remember having a small air cooled, single rotor engine of about 300cc I think?


I think it was by SACHS (Germany?) and was part of a ground generator unit.


It was missing the magneto section, and I ended up donating it to the local TAFE colledge engine shop.


NORTON also made some air cooled rotarys for aircraft use, but very noisey and thirsty.





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Hello Micgrace,


Thanks for those links to Mazda specialists.


The following is the response I got from 'Guru Motorsports':


'Thanks for your enquiry. We’re actually working on a single rotor engine at the moment. It does require manufacture of special parts to suit (eg eccentric shaft). Keep an eye out on our website www.xtremerotaries.com. Information will be published there once we’ve finished manufacturing & testing the product.'


However, after looking at the prices of parts on their website,I suspect the final product might be a little expensive for an old bloke like me...but let's wait and see. One must not be pessimistic eh?


In the meantime I'll research the practicalities of building one from a used series 5 13B.


Bruce<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><O:P></O:P>





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  • 3 months later...

Interesting. With the high EGT's on these engines would not turbocharging be the logical way to achieve good specific fuel consumption figures, The poor combustion chamber shape ,ie. high surface area to volume tends to reduce thermal efficiency. What accurate specific fuel consumption figures are available? Not that fuel efficiency is everything,particularly in a sports type aircraft.They are most likely better than two strokes in any case. Is silencing a problem?The turbocharger would take a bit of the bark out of the exhaust noise..initially but they seem to be pretty loud.The ability to keep going & lack of vibration are good features and the reduction drive should not be too hard to engineer. This has potential, in aircraft application. . N...



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Guest micgrace

Hi Neville


Pretty good engine really. And you don't have to worry about it throwing a leg out the side or dropping a vavle. plus power to weight more like a 2 stroke.


Fantastic power output available with turbo, which really suits these engines along withsome sane port changes. Reliability is excellent if redline kept to a sane level. best engine is considered to be an injected series 4/5 13B Turbo.


Since the engine is a sort of sandwich construction it can give rise to triple rotor (20B) with turbo. I have also seen a race ready 4 rotor.


Turbo somewhat muffles them, but even with a turbo insanely loud.You can muffle them to a respectable level but it drastically cuts power output.Fuel consumption is better than a comparable 2 stroke as it really is a 4 stroke. But not quite as good as a piston type.


Fuel injection is definately the go on them with many competing aftermarket systems available. With twin dizzy or multi coil available to fire off the leading and trailing plugs.


Reduction drive isn't a problem as readily available from USA. But not cheap. With the two main types being a belt drive and a gear type. Apparently some of the components of a turbohydromatic g/box are used to construct it.


If I had the funds, and was building a somewhat larger aircraft this engine would be in consideration.





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