Single rotor turbo diesel rotary

[bexrbetter]

I visited a Chinese University yesterday after I saw a brochure for their rotary aero engine in development.

 

This is a 'Power Train University' where they develop engines for major engine manufacturers, mind you I only saw diesels as I passed by all the dynometer rooms, all were medium sized truck engines , around the 250 to 300hp, inline 6.

 

The rotary is very real, ECU diesel, turbo apparently running near 3 bar, their own design PSRU that looks not like the one in the brochure, and they were saying 300 hours on the dyno with it now, with a few repairs and modifications along the way apparently. 

 

While the casings were bespoke, with a 'peripheral port' intake (and a bit large also ('apex seals at danger' type large)), you could clearly see the Mazda heritage, and I'm certain the rotor on the disassembled one on the bench was pure stock Mazda OEM, including the stock combustion chambers. I can't say that one had been run as a diesel, I don't know about the rotor in the actual complete running diesel engine.

 

136 hp, which they were adamant as they corrected me every time I said: "So, 130 plus hp..."

 

The brochure says 80kgs, but that's just the sigle rotor engine, I figure closer to 110+ kgs/245 lbs including PSRU, mounts and cooling systems (plural, rotarys need good oil cooling) - a litle heavy for the hp, but damn good for a diesel.

 

They were quite surprised I knew so much about rotarys, including telling them about NSU and Felix Wankel, and that I had worked on NSU, Mazda AND Suzuki! They didn't even know about the Suzuki RE5 .. I didn't bother to mention the Norton ...

 

So that's about all I know, typical Chinese being ultra secretive and protective of their '20 years behind' tech, lol  ... it's not in production yet, but they say they are ready...

 

Verdit, votes, comments, interest ???

 

 

 

[turboplanner]

Jibberish

 

 

[Deskpilot]

TP, care to explain yourself? You infer that you know better than Bex. You been there? Seen it? I get so annoyed sometimes. 

 

 

[facthunter]

 Combustion chamber shape is compromised with the Wankel designs and I don't know how they would get the un pressured comp ratio high enough to start the engine easily. It would also need extra good silencing as they tend to be rather noisy exhaust wise.. Seals are going to always be a challenge.  Mazda are about he only company to achieve a market success but fuel (specific) consumption has never been good due to my first comment  Too much surface area for volume of the combustion chamber.  Nev

 

 

[turboplanner]

TP, care to explain yourself? You infer that you know better than Bex. You been there? Seen it? I get so annoyed sometimes. 

 

I inferred nothing of the sort! I just answered one of the one word questions. You have the opportunity to do the same.

 

 

[onetrack]

My comments ...

 

The rotary problems are well known, and high fuel consumption is their Achilles heel. I'm afraid the Chinese are carrying out design and testing that everyone else has already done, 30 years ago.

 

As with Ralph Sarich's Orbital engine, the basic design cannot get around the basic problems - sealing, fuel efficiency, emissions, oil consumption.

 

Having said all that, it appears that Mazda is now planning on re-introducing the rotary engine in coming models, as a range-extender for hybrids.

 

The reason for re-introducing them is reported as being their quietness. I see little sense in the reasoning, and I see little sense in re-introducing rotary engines by Mazda.

 

However, there is talk of the range-extender engines running on LPG, which could be a solution to the emissions problems of the rotary.

 

Unless Mazda has developed some entirely new and revolutionary engine design technology, that produces major improvements to the rotary engine, then all I see is Mazda grasping at IC engine straws, while they try to hold off the EV revolution. Mazda state their forward planning still sees the majority of their vehicle range, still being powered by IC engines in 2030.

 

https://www.autocar.co.uk/car-news/new-cars/mazda-previews-imminent-rotary-engine-revival

 

 

 

 

[Old Koreelah]

I'm confused. They say it's quieter? Other sources mention problems with the exhaust noise of a Wankel engine.

 

I retain a soft spot for Mazda and the rotary engine. They persisted with developing it long after other makers gave up and stayed conventional. I'd still love to see a light weight rotary suitable for small aircraft; maybe their range extender will be the one. 

 

 

[onetrack]

Old K, I'm confused, too. I see no major redesign of the new Mazda rotary that stands out as overcoming any of the rotary's inherent design problems.

 

What Mazda is doing, is shrinking the engine to the "size of a shoebox", and reverting to a naturally-aspirated, single-rotor design.

 

The aim is to try and maximise passenger space, while providing adequate power output from the smallest possible engine size.

 

I see no potential in the new Mazda rotary design for adaptation to aircraft applications.

 

https://www.motor1.com/news/266766/mazda-rotary-range-extender-patent/

 

 

[Old Koreelah]

Maybe that little shoebox can be mounted behind an electric motor for take off and climb boost.

 

 

[bexrbetter]

Rotarys have been fixed for some time by Mazda, unfortunately the old, and very true, problems they had still hang over their head. They do not have seal problems anymore, and their fuel consumption, while not exactly fixed, is at least acceptable.

 

Turbochargers use the excess heat (and lowers noise) out of them to their distinct advantage, but as Facthunter correctly says, their Achilles Heel is the amount of surface area presented by the moon shaped combustion chamber, that loses heat rapidly and has leakage and shadows. Also a rotary takes 1.5 times the time to build up to peak compression during a cycle compared to a pissed and broke engine.

 

Of that point, like Facthunter, I am also interested as to how they will ignite the charge at slow compression build up in low pressure cycles, it seems to me very difficult to achieve charge air heat to ignite the diesel injected, as the injector I saw was a basic diesel truck injector (electrictronic), with no source of atomisating air mixture apparently, as some testing has been done with. 

 

 

[bexrbetter]

I'll add that I have considered for a long time that a much larger capacity (diameter) single rotor engine, direct drive would be a good thing for us, not a Mazda sized or similar offshoots, but one that turns maximum rpm about 3000 and peak hp at around 2600.

 

 

[facthunter]

I think there would be an opportunity for a sport  aero engine , turboed and with reduction gears to a CS prop. Reason ..They rarely fail suddenly and if they start will usually keep running and get you home.. They have little mechanical noise  but the way they are ported they BARK like no other especially when supercharged. The turbo type quiets them a bit as it does on all engines and you can just keep boosting them. I think they warp cases as there's one really hot spot. I'm not up with the latest but they were doing well in racing outboards a few years ago. I've  seen a Norton one in a pterodactyl at Gympie years ago that did long trips occasionally Direct injection is the go with all new ICE motors. The fuel can be crap octane wise and it doesn't matter. It can't detonate.. Nev

 

 

[skippydiesel]

Very interesting - I have been fascinated with the Rotary ever  since by best friends father (always keen to try out new auto products & the cash to do it) purchased a new  NSU RO80 (sudo auto clutch as well). 

 

The proceeding comments pretty well cover all of the positive/negative aspects of the Rotary (including Nevs rarely fail, once started) - I would like to avery low vibration when running and low frontal area, as being attractive aspects for aircraft adoption.

 

One other (possibly ill informed) thought - I always felt that the Rotary's ability to operate at ,sustained, very high rpm, was a big plus for aircraft potential, as this may give almost turbine power to weight performance with lower fuel burn (closer to a piston engine). Of course the gear box necessary to reduce down to efficient prop speeds will have a negative impact on the power to weight but then turboprops have the same sort of problem.

 

 

[facthunter]

At high rpm they develop a chatter (wavy wear of the casing) where the seals have intermittent contact. Despite all this I do believe for special use they may be a good answer. Nev

 

Nev

 

 

[skippydiesel]

At high rpm they develop a chatter (wavy wear of the casing) where the seals have intermittent contact. Despite all this I do believe for special use they may be a good answer. Nev

 

Nev - Something's going wrong with your PC - your posts are all very very long (& blank past the script)  -- button stuck down or something.

 

I understand your "chatter" comment - All engines have some disadvantages/ problems in some situations - ultimately it's about compromise.

 

I still feel that if a fraction of the development investment ($$$ & time) in the piston engine was to be applied to the Rotary, we would solve all/most of the problems and have a fantastic aircraft engine.

 

 

[facthunter]

No, Its mucking up again.  N ev

 

 

[Downunder]

Despite all this I do believe for special use they may be a good answer. Nev

 

A number of manufacturers are making them for drones/military drones.

 

 

[skippydiesel]

A number of manufacturers are making them for drones/military drones.

 

Next step - acquire one for an RAA sized aircraft

 

 

[Downunder]

Just some....... google is your friend...

 

http://www.rotronuav.com/

 

http://3w-international.com/wankel-rotary-uav-engine-3w-180-sre-hybrid/

 

https://uavenginesltd.co.uk/products/

 

 

[skippydiesel]

Just some....... google is your friend...

 

http://www.rotronuav.com/

 

http://3w-international.com/wankel-rotary-uav-engine-3w-180-sre-hybrid/

 

https://uavenginesltd.co.uk/products/

 

Well there you go - Who has the spare $$$$$ and which one will you try????

 

 

[Geoff_H]

I like the idea of testing a design, even if it has little chance of final success, you always learn something.  Knowledge is never a load to carry.

 

Many years ago I read of people experimental Rotary engines that tacked a third rotor onto the Mazda Rotary, apparently easily done.  Obviously a new design of output shaft is required. The reports that I read said that they were having trouble with shaft breakage.  The light weight for power would mayke such an engine attractive,even if fuel consumption is higher at high rpm.

 

 

[mnewbery]

So far nobody has mentioned the four rotor abomination produced by Rolls?

 

 

 

 

 

[skippydiesel]

RR ahead of its time. The Brits have an enviable research record. Unfortunately they do not always reap the benefit of such innovation. The commercial development often being  being taken up by their cash rich relatives "across the pond".

 

Geoff H - "an engine attractive,even if fuel consumption is higher at high rpm." Fuel consumption is but one of many factors that go into engine selection. In aircraft - smooth running, altitude performance, power to weight, reliability and probably many more factors come into play.

 

 

[Old Koreelah]

Abomination? I like the concept. Still far simpler than a reciprocating diesel.

 

 

[turboplanner]

I like the idea of testing a design, even if it has little chance of final success, you always learn something.  Knowledge is never a load to carry.

 

Many years ago I read of people experimental Rotary engines that tacked a third rotor onto the Mazda Rotary, apparently easily done.  Obviously a new design of output shaft is required. The reports that I read said that they were having trouble with shaft breakage.  The light weight for power would mayke such an engine attractive,even if fuel consumption is higher at high rpm.

 

There's nothing to stop you building a rotary engine with one cylinder, or any number of cylinders. Shaft breakages can be designed out.

 

However, before sinking your money into a design, it pays to do your research, because we are in an era of rapid change, and that change is in the process of eliminating quite a few different types of power units for real or imagined reasons. 

 

M. King Hubbert came up with his "Peak Oil" analysis in 1956, which loosely showed that the fall off in new productive oil fields was going to produce a pattern where oil would become more scarce and so more expensive, and harder to pump and so more expensive as it slid down the back side of the production bell curve. He was on firm ground, some people say oil peaked in 2006, others say a bit longer.

 

Four years later, in 1960 the Intergovernmental cartel OPEC was formed, and oil prices started to go north faster.

 

Then in 1979 we had a group hissy fit and predicted the world was running out of oil without bothering to check the facts. In Australia GMH built a small platform Holden, even with a four cylinder option; Ford didn't and were caught with the big Falcon and V8, or were they? It didn't take long to expose the "oil crisis plot" and Australians switched to the Falcon and GMG went broke, showing the importance of homework.

 

In the late 1960s and early 1970s California convinced the world that we all needed to clean up our filthy cars; polution was the buzz word, and Australia introduced polution controls in 1976. No longer could you build an engine with the simple breathing systems and petrol guzzling that allowed us to buy cars so cheaply.

 

Within a decade we went from paying about $5,000 for a top of the range Falcon to $20,000.

 

We countered with Lithium Propane gas conversions, but the government quickly excised that up to the point that infrastructure was hard to fnd, and LP Gas became effectively extinct when manufacturers were unable to meet the increasingly stringent Emission reductions e.g. 97% particulate reduction between 1992 and now.

 

It became critical if you were going to try a new alternative to the tried and true petrol engine, so a lot of people went for diesel in cars.

 

It required a lot less refining than petrol, and so was selling for about half the price of petrol and most diesel engines were smaller; the little four cylinder cars could get up to 66 mpg.  I went for a two week holiday in a 4WD from Melbourne to Fraser Island including a week on sand on the island - for $330 return. But then, the cost of diesel crept up close to petrol, the engines got bigger, customers started suffering from shock at around 200,000 km when they were given $3,800 quotes for a new diesel particulate filter, and about four years ago total cost of life switched back to favouring petrol engines. It's not surprise that the very latest engine designs are including compression ignition engines which run on......petrol.

 

What has allowed this to happen is lateral thinking from engine designers; when a staple product becomes prohibitively expensive, you can still afford it if you use less, and part of the current designi strategy is to use petrol, but much less of it, so the tank-fill cost of the latest cars becomes lower.

 

So it pays to research just where the engine industry is going, what is possible now, and what will be possible in the future.

 

Sometimes you only need to look at the chemistry and physics, to know someone's GREAT NEW IDEA is going to choke itself to death.

 

Take CNG (Compressed Natural Gas).

 

It is compressed to about 2000 psi.

 

The engine burns a lot more volume than petrol or diesel

 

The burning process is slower and less efficient so power is down about 10 to 15% compared to petrol or diesel.

 

But the pressure was on from the customers so we decided to build an evaluation truck.

 

I raised the first questions when we received the gas equipment. The fuel tanks were so big that under-floor lockers would have to be scrapped, and they were made of fibreglass (spun rovings). I asked "What happens when a car T Bones the side of the tank, with 2000 psi pressure" and got the answer "The tanks are designed to deflect or squash what they hit"  Who wouldn't be nervous after that.

 

Within the first week a National carrier had decided CNG was out because the trucks were too slow, and there was no infrastructure.

 

We saved a lot of money, and CNG is virtually extinct.

 

So if you want to look at a potential power unit for a recreational aircraft, wouldn't it need to have:

 

(a) very light gross mass (engine/transmission/prop/support equipment.

 

(b) very low fuel consumption, so a fuel curve with the bottom at about maximum cruise speed.

 

So we would be looking for the basic principle of the engine design to support these two goals, wouldn't we?