Mazda Rotary Engine

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rv7charlie

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Google 'specific heat of oil vs water'. There's good reason you almost never see oil as the primary cooling fluid. (Though I did have a 1970 Alfa Romeo Spyder that gave it a shot, before I pulled the head to install the missing O-rings in all the block-to-head oil passages.)

I think we've discussed this here in the past; a single rotor rotary pays a big weight penalty compared to a 2 rotor, due to balance requirements. It'll likely pay another penalty in the reduction drive, due to increased weight requirements in the flywheel, 'damper' assemblies, and gears, because of the higher and lower frequency peak-to-average torque pulses.

Charlie
 

TFF

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My Alfa Spider drools the oil out the right front corner. Never special mix though. I have put up with it for a long time. If the o ring is missing, I don’t know who to blame.
 

rv7charlie

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Mine was missing *all* the O-rings in the pressure-fed paths from block to head. I realized it when delicious looking pale chocolate milk starting overflowing out the radiator reservoir.
 

Billrsv4

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I would think the best possible surface would be chrome like the rotor housings. Grinding the HardChrome flat would be relatively easy.
Aircab you might think that chrome was best but the early Powersport tried many surfaces. The reason for the braised side plates is that they can be nitrided hard. That is a chemical change of the material itself on a molelecular level. It can’t flake or peel like chrome can. That was the best anyone, including Mazda came up with. Excepting the detonation gun coating used on the Le Mans engine. That was the best and incredibly expensive! Had to be Diamond ground, but worked if you were willing to pay 10-20 times the normal price.
Bill
 

erkki67

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Its not a Mazda, but have a look at the not so new Geiger Wankel engines. They claim to have found the solution for the exesive oil and fuel consumption.


they have a 50 and 100hp engine, and they have coupled 2 100hp engines via a gearbox.
 

Powersport Aviation

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Greetings from Powersport! A few of you have sent emails to me looking for information, but I see that others state they have not heard back. Please make sure you use the correct ending: .org The .com domain name was stolen and we cannot get it back, so we went with the reasonable alternative.
tjames@powersportaviation.org
The chatter about the "super light" engine is interesting, and much of the information is correct. However, I do have the original engine on my shelf, and I can tell you that there are many issues are that led to the evolution to the current engine. The "super light" was relatively powerful but not durable and would be very expensive to produce.
I will try to respond to emails as my time permits.
 

Lendo

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Urquiola, It's got to do with the expansion rate of water in the combustion chamber. If it leaks a little, it most likely will get worse.
George
 

AIRCAB

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Aircab you might think that chrome was best but the early Powersport tried many surfaces. The reason for the braised side plates is that they can be nitrided hard. That is a chemical change of the material itself on a molelecular level. It can’t flake or peel like chrome can. That was the best anyone, including Mazda came up with. Excepting the detonation gun coating used on the Le Mans engine. That was the best and incredibly expensive! Had to be Diamond ground, but worked if you were willing to pay 10-20 times the normal price.
Bill
The braised housings would have realized consible weight savings, otherwise what's the point. It would be interesting to know what post treatment the aussie are doing to their replaceable inserts. I have been told by some racers, that most do NO treatment after grinding and lapping.
 

Urquiola

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Google 'specific heat of oil vs water'. There's good reason you almost never see oil as the primary cooling fluid. (Though I did have a 1970 Alfa Romeo Spyder that gave it a shot, before I pulled the head to install the missing O-rings in all the block-to-head oil passages.)

I think we've discussed this here in the past; a single rotor rotary pays a big weight penalty compared to a 2 rotor, due to balance requirements. It'll likely pay another penalty in the reduction drive, due to increased weight requirements in the flywheel, 'damper' assemblies, and gears, because of the higher and lower frequency peak-to-average torque pulses.

Charlie
Deutz in Cologne produces some industrial engines with oil instead of water as cooling fluid, about heat transport features, the 'BOSCH Manual of Automobile technique' includes data about most materials used in automobiles; from the heat transport, viscosity, specific gravity properties of oil and water, you can calculate the pump, the radiator,...
Old twin-flat Citroën Series A cars engines (2CV, Ami, Dyane, Mehari) had Air Cooled cylinders, but some parts had oil cooling, with the help of a pump and a radiator. The Voisin designed 'Biscooter' micro-Biscuter a.jpgBiscuter b.jpgcar, all aluminum, there was aluminum surplus after WW II, with a 2-Strokes engine, had a large engine head, filled with oil, to avoid too much cooling and shock cooling on highway, overheating in traffic lights, oil acting as a 'heat buffer'.
OMC had hard chrome working surface in their Snowmobile Wankel RCEs, it seems was deposited by electric means; after layer was complete, they reversed polarity for some 15-20 min, in order of having porosity in working surface allowing lubricating oil to attach. Suzuki seems used a flame sprayed technology, from Canadian patents by Alfred P Grazen; NSU, Comotor, had nikasil.

About torque steadiness in a single rotor Wankel, it are comparable to a three cylinder engine, it's not that good as a twin-rotor, having the torque uniformity of a 6 cylinder engine, but is good enough, Daewoo and other carmakers offer three cylinder engines, no specific complaints.

The advantage in a single rotor Wankel is with its reduced displacement compared to units with more discs, chances are most time engine will be working in a favorable BMEP environment, and this is a core element in economy and emissions.
An ordinary auto, running on a flat road at 55 mph may use no more than 25 HP, please read:
+ 'How much overall energy does the Automobile require?', SAE Journal Automotive Engineering, vol 80, n 7, pp 36-38, Jul 1972
+ 'How much Energy is needed to produce an Automobile?', SAE Journal Automotive Engineering, vol 80, n 7, pp 39-40, Jul 1972.
+ SAE paper 2013-32-9161: 'The Intake and Exhaust Pipe effect on Rotary Engine performance', from Taiwan.

About power needs in airplanes, lots of references and charts were added in this HomebuiltAirplanes.com site.
The 'How green is green energy?' article is from Scientific American (SciAm)
Blessings +Balancing Condition of RE -K Yamamoto a .jpgBalancing Condition of RE -K Yamamoto b.jpg
 

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EzyBuildWing

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New MAZDA WANKEL "Range Extender" for it's SUV should enable ALL electric-aircraft much more practical and smoother.
For low-power electric aircraft, you can easily design your own.....see vid below.
I think Aixro Wankel already makes a 25kW range-extender. Pipistrel cruises on 20kW.

 

AIRCAB

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Aircab you might think that chrome was best but the early Powersport tried many surfaces. The reason for the braised side plates is that they can be nitrided hard. That is a chemical change of the material itself on a molelecular level. It can’t flake or peel like chrome can. That was the best anyone, including Mazda came up with. Excepting the detonation gun coating used on the Le Mans engine. That was the best and incredibly expensive! Had to be Diamond ground, but worked if you were willing to pay 10-20 times the normal price.
Bill
Interesting, this builder has moved away from nitriding.
 

dwalker

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Mar 6, 2021
Messages
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Interesting, this builder has moved away from nitriding.
Kyle is selling a service that does not provide nitriding, which is in fact a very necessary thing to have in a rotary engine for it to live a long life, so I am not surprised to hear him say that. Chip sends his side housings to Tennessee (not to far from where I sit, actually) to have them nitrided. Pick a longtime rotary engine builder- Rob at Pineapple, Dan at Atkins, Chip at Chip's Motorsports, Darrel Drummond, etc. and they will all wantplated to be nitrided after having been ground. And they are right.

Mazda has experimented themselves with Nikasil rotor housings, which some of us have duplicated with a US company, and this shows promise as far as wear and reducing friction/improving sealing. Goopy Performance in New York now able to rechrome the rotor housings to like new condition. IF I were still experimenting with the rotary I would have a set of side housings ground .010 then Nikasil lined and built back up .015 and lapped/resurfaced back to true, the rotor housings stripped of the chrome lining down to the steel insert then plasma sprayed, nikasil lined and lapped surfaced. This would result in a very durable and wear resistant surface that would also seal exceptionally well.
The reason these processes have not gotten the attention or development in any of the rotary applications, other than drone engines, is the availability of new parts at reasonable cost from Mazda and options in the aftermarket. If that changes, we may see much more technology applied in the Wankel rotary.
 

Urquiola

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Madrid, Spain
New MAZDA WANKEL "Range Extender" for it's SUV should enable ALL electric-aircraft much more practical and smoother.
For low-power electric aircraft, you can easily design your own.....see vid below.
I think Aixro Wankel already makes a 25kW range-extender. Pipistrel cruises on 20kW.

You already have the Aixro, the Wankel Supertech, the AIE.uk, the Austro. If Mazda produces the well expected Wankel RCE Powered Range Extender, no guarantee they will sale it to everybody, D-Motor in Belgium refused selling their side valve engines to homebuilders, just to regular makers. Blesssings +
 

dwalker

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Those Planes you mention also fall into that less than 10% Bracket of Larger Aircraft. Lancair's, I don't think are even being Sold as a Kit anymore are they? When was the last Canard Aircraft you seen being even Built, let alone with a Rotary? Don't get me wrong, I like the Rotary engine, had (3) RX7's. Even had a 13B Turbo Engine I thought of putting into a Long Ez. But Married, Kids, Job, No Space, got in the way, so it didn't happen. As I said, there is probably less than 100 being used in the World out of 8 Billion People, and it's really probably less than 50.

With all the technology we have available today, with 3D CAD Modeling on Home Desktops, with Home CNC Machines, that we don't have a purpose built Rotary Engine for Aircraft use. 90% of the Home Built Aircraft made need less than 100hp. A Rotax based 670, 2 Stroke makes that easy!

Aircraft with a Rotax Rick 670, 2 Stroke in it.
View attachment 106019
Actually, I am building a Long-EZ with rotary power..
 

dwalker

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Mar 6, 2021
Messages
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This surprises me, as I tried to order complete engines like this, and was told the only way to obtain them was through Mazda Motorsports affiliate, and are not for resale to the general public. That is why they are so reasonably priced. Can anybody clarify this source.
A bit late to this party but:

Back in about 2014 Mazda made a (wise) decision to stop using contracted engine remanufacturers for thier complete engine replacements, and the 13B-REW as used in the 3rd generation Rx7 was the first application released. I have heard rumors but not actually seen part numbers or pricing of factory new 13B-MSP Renesis motors available as well. The new motors are assembled in Japan from new parts, tested for water leaks, compression, etc. then shipped in batches to the US etc. Mazda USA gets about 3-4 shipments a year, and they tend to sell quickly to dealers and rotary specialist shops.

You do not need to be a Mazda Motorsport member, but it might help save a few bucks.
 

EzyBuildWing

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This chap Edy in Switzerland built a 13B powered Breezy. Edy kindly supplied me with the following info:
( Note that VR3 Engineering - Precision Tube Fabrication produces full Breezy tubes-kits......all tubes have precision CNC milled fish-mouths for fast "perfect-jigging and welding" . They also happen to produce many other perfect-jigging tube-kits for other aircraft, race cars and dragsters).

Thanks for your interest(in my 13B powered Breezy).
At first, my website www.breezy.ch is on the Web since 2001, I did no vids from flights on the page because the people has to fly with me, naturally not virtual.
My Wankel is operating in a perfect way. There is only one little problem, it use approx. 5% more fuel than a "normal" engine with the same power. Also it needs 1 liter oil for 128 liters of gasoline.
I fly now for 46 years as a private pilot. I had no problems with motors any way, so i think the reliability of my Wankel is as good as it is for the normal piston engines, maybe better in the matter of less parts.
My diameter prop is 63" and the rated engine speed 6000 RPM (prop. 2100 RPM with a planet-gear).
I used the Breezy tubes-kit from spruce aircraft USA. I fit all the tubes by myself as you can see on my website.
So if you stay the next time in Switzerland, you have to visite me at home, bed and breakfast included.
For your information, a friend of mine in Germany, Karl Schmidt, is also building a breezy. He will take off for his first flight next spring 2016.
Kind regards
Edy Schuetz
Switzerland
 

Lendo

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Edy,I thought the Mazda might be a wee bit heavy for Breezy. There is a German Professor of Mechanical Engineering Chap who has produced a Wankel Rotary but hasn't managed to get financing to mass produce them. He tried to entice Mistral, but they wanted the larger Mazda engine, as it turns out. 6,000 rpm (or there abouts) is perfect for the Rotary, as the rotor is only doing 2,000 rpm. Needless to say a reliable PSRU is required, so what do you plan on using with a 2.857 ratio.
George
 

EzyBuildWing

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Duncan Aviation( Rt.1, Box 256, Camanche, Ok. 73529) marketed a Single-Rotor MAZDA direct-drive..... specs were maximum 60 hp at 4000 rpm 143 lbs installed including radiators and coolant and oil, starter, Posa carby, and alternator...but no exhaust. Don't know what happened to them...maybe someone does? They also had belt-reductions and twin-rotor models and turbo's.
 

Lendo

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Building a Single rotary is not so easy, the Eccentric shaft has to modified or a new one turned-up and hardened, The natural Rocking couple will no longer be available to help with balancing and even when balanced the Torque pulses are high, think Torsional Vibrations on a Gearbox (PSRU). however it is doable if your skilled enough and with enough testing and patience. Belt reductions seems to be OK up to 100 hp. but I have heard some are used on 200hp engines, I think they would be highly specialized and expensive.
 

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