The Duke Axial Engine

[kgwilson]

I don't know if this has been posted before but this has great potential for aviation. It is a 4 stroke with no valves, light weight, vibration free, 5 pistons, only 3 spark plugs & fuel injectors, is resistant to detonation, has the same number of power strokes as a conventional 6 cylinder engine & runs on any spark plug ignitable fuel such as petrol or kerosene.

 

Check it out at http://pixelbark.com/13045/how-the-duke-engines-increases-the-efficiency-of-the-internal-combustion-engine

 

More detail on Aviation at http://www.dukeengines.com/application/aviation/

 

 

[horsefeathers]

How do the intake and exhaust ports seal?

 

 

[facthunter]

It is a massive rotary valve. I would wonder at this myself, as most rotating hot ,hard to lubricate surfaces are a problem to keep sealed. Nev

 

 

[Old Koreelah]

Good post, KG. A perspex model of this engine was demonstrated at Temora a few years back. Those innovative Kiwis again. Several axial engines were tried in the distant past, but advances in materials- particularly seals- might make this an idea whose time has come.

 

 

[kgwilson]

There is no information on fuel consumption or potential consumption as far as I can see. Fuel consumption pretty much killed off the rotary engine which was light & powerful as well. The website has a short video of one installed in a car demonstrating its lack of vibration with a NZ$2.00 coin standing on its edge with the engine being revved.

 

If they have managed to deal with the sealing issues & they get reliability & good fuel consumption, success is pretty much just around the corner.

 

 

[facthunter]

Current piston engines are only there because we are waiting for something better. Poppet valves although looking terrible are the most common, and a round piston is easier to seal than most other things.

 

I did not like the "Wankel" but Mazda fixed? the seal problem. and I reckon it (turbo ed) would make a suitable sport plane engine Fuel consumption is not as bad as a two stroke and it is reliable in the short term. ( It doesn't fling bits out of its cases)... A hopped up and flogged Lycoming like in a Red Bull racer wouldn't have a long service life either, so it doesn't have a lot to beat.

 

Turbo fans are a quantum leap in reliability, but bigger and higher are where they are at. The axial engine might need a bit of oil added to the fuel. but so does a Wankel..Nev

 

 

[Marty_d]

They have some general info about seals...

 

http://www.dukeengines.com/technology/faq/#Seals

 

 

[Garfly]

What ever happened to  the Duke ... ?

 

 

[Kyle Communications]

Died a death like most of these unconventional designs

 

[Bruce Tuncks]

Remember the Sarich engine? same thing. I have flown in a self-launching glider powered by a wankel though, and it was very smooth. 

On the Duke engine, it was not clear to me how the reciprocator worked. I wonder if this was not the downfall. 

[facthunter]

It's built like a variable output oil pump and is OK for that purpose.. Wankels are smooth but have seal and temp distortion problems and are not economical as the combustion chamber shape is compromised. Too much surface area for the volume. Nev

[Bruce Tuncks]

There is a youtube on the duke engine and the guy says that the swash-plate is not as robust or as simple as the crankshaft. He likens the action to how we naturally turn a crank. 

On the other simplifications, I think that idea of eliminating poppet valves and camshafts and push-rods is so good that it is surprising to me that a 2 stroke engine is not more reliable than a 4. These ideas can of course be done with a crankshaft engine.

[Bruce Tuncks]

I agree about the wankel Nev. AND its hard enough to seal a circular cylinder, I've never seen an old wankel, but I bet they would fare worse when they got old and leaky.

[facthunter]

Harder to lubricate and boost a two stroke engine, Also more polluting. Reciprocating engines are self destructing with load reversals . Poppet valves have stood the test of time and seal well relatively speaking. . Flow is surprisingly good too when fully developed. . While ICE  piston engines have character they are not efficient or reliable . They are good compared to what they were 40 years ago.  and about 120 years of development. all told. Nev

[facthunter]

The surface often gets a chatter wear pattern. IF they will start they will get you home. I think there's still a role for them in sport planes. Noisy and thirsty. and probably always have trouble meeting pollution standards because of lubrication issues.  Nev

Edited February 26, 2021 by facthunter

[onetrack]

The Duke engine has ended up in the same scrap bin, or is still in its 30 yr "development" stage, as the ....

 

Revetec Engine

 

Coates Rotary Valve Engine

 

Sarich Orbital Engine

 

Higgs Diesel Engine

 

Gemini Diesel

 

Etc, etc ,etc ......

 

Every single one of the above simply promises or promised more than it could deliver in a commercial production package.

 

In other words, they all fall short in being unable to overcome basic design faults, or they cannot/did not achieve the required reliability, efficiency, and astounding performance, that they all promised.

 

The totally new IC engine design world is a cruel world, it's littered with thousands of failures, that looked so promising on paper.

 

 

[IBob]

The Wankel-powered RO80 got NSU Car of the Year in '68, but subsequently finished the company: the early versions had so many rotor tip failure problems that owners would hold up how many fingers/warranty tip replacements they had had as they passed each other. It didn't help that one of the selling points was 'the faster you go, the more economical it is', due to the peculiar power curve: the autobahns had no upper speed limit, so RO80 owners drove very economically indeed.
A pity, as it was a very advanced and well built car in many ways.

 

More recently, there is still a strong contingent of Mazda rotary fans among the petrolheads. And I have to say they sound great when they're going. But I'm also told they are forever needing to rebuild them.

[onetrack]

The rotary is not dead yet, it's apparently being planned as a small range-extender power source for a number of new Mazda hybrids, such as the MX-30.

 

Mazda claim to be able to meet all current IC engine emission requirements with the new, small rotary. How they actually do this is unknown, they are being coy on the details, but Mazda have apparently lodged a slew of new patents on the new, improved rotary engine design, that is planned as the range extender engine. I understand this new rotary is only around 1 litre, but puts out some fairly impressive power for its size.

[onetrack]

Upon further research and later information, I find the Mazda rotary range extender engine is only 330cc, and it produces 28kW. In essence, simply a modest-sized genset engine.

It is specifically designed to recharge the 35.5kW MX30 battery, and does not provide direct power to the wheels.

 

The idea is, the MX30 is basically a "town car", with a relatively limited range of about 200kms on the battery - but this range can likely be doubled, by utilising the little rotary engine range extender.

The use of the rotary for what is basically a genset engine application, is designed to take advantage of the engines light weight for high power output - and the steady rev range required for genset use, also gets away from the rotarys problems of poor torque, high exhaust emission levels, and the accelerated wear that comes with regular hard acceleration, when the bigger rotary is used as the main power plant.

 

Engineering details of the rotary range extender engine are not currently available because this model will not become available until late 2021 - even though the MX-30 is already on sale, in pure EV form.

And Mazda have had the little rotary range extender in use since 2013 in prototypes - which they let journalists write up about, as well.

 

Mazda are also obviously eyeing off the small genset market, because it appears that, not only they have made the range extender rotary engine in a "bolt-in" arrangement, so it can be fitted to other EV models - but they're talking about utilising the little genset as an independent power source. This could be used independently to power electrical tools, provide lighting power in blackouts, and recharge other batteries.

 

I wouldn't be surprised to see an application for the little rotary genset in light aircraft. You could reduce your needed battery size, whilst the lightweight little rotary genset provides redundancy as well as extending your range.

All well and good, provided you don't run out of genset fuel, too, I guess!

[pmccarthy]

You could put it in a trailer or on the roof rack of the competitor's EV.

[onetrack]

I don't know how that would pan out. The little rotary hums at speeds between 4500rpm and 6000rpm, to get its efficiency. It's apparently a bit noisy, and as such, needs soundproofing, as it's mounted behind the rear seat in the MX30.

Reports are, that the engine sound is muted by the Mazda engineers, to an acceptable hum to passengers in the rear. I guess if it came in a soundproofed enclosure package, it might be viable to mount it on the roof.

[scsirob]

On 27/02/2021 at 2:57 PM, onetrack said:

The Duke engine has ended up in the same scrap bin, or is still in its 30 yr "development" stage, as the ....

 

Etc, etc ,etc ......

 

 

Can we add Zoche to this list?

[onetrack]

I'm sure you can. There's no information forthcoming from Zoche for at least 3 years. Undated website pages are a fairly good indication that a company has no definite timeline for progress.

Design "problems" always seem to crop up regularly and certification is always promisingly "close" - but it never actually appears.

Funding for addressing continuing and constantly ongoing design problems, usually falls well short of the hundreds of millions required, and the company is eventually liquidated. It's repeated, ad nauseum.

 

http://www.redbackaviation.com/zoche-diesel-aircraft-engine-design/

 

The EPS Graflight V8 diesel is another one in the same position. Reputedly ready for certification in 2018, it just hasn't happened.

The major problem with many of these new designs is that problems only raise their ugly heads after extended test hours.

Sealing problems, oil consumption problems, heat dissipation problems - they are endemic to all new engine designs.

 

https://www.aopa.org/news-and-media/all-news/2018/january/17/progress-on-diesel-engine-reported

 

https://eps.aero/

 

Many of these designs will be failures because they are in the dying era of the IC engine. IC engines have been in serious development since 1886, when Karl Benz built the worlds first successful 4-stroke automobile engine.

But electrification is now the buzzword, and with the majority of vehicle manufacturers seeing the writing on the wall for the IC engine as a primary power source, it means the era of IC engines is essentially closing.

 

Edited March 1, 2021 by onetrack

[Kyle Communications]

Until they get the battery technology far better you wont see them in aircraft....not only the length of time available in the air is the issue but then its charging. If you fly out west you just cant plug it into a tree. You need a good base powersupply to be able to plug in your charger..the more capacity you require in your battery for time of flight then it totally depends on charge time..Charge time depends on how quickly the battery can accept the charge and of course you need a powersupply supply good enough to supply that rate of charge.

 

No good flying somewhere then have to overnight or spend 2 days to get enough charge in the battery to go the next part of your trip.

 

I think it will still be a long time before we see any improvement in this

 

Dont get me wrong...I would love to see electric powered aircraft but I still think I will be pushing up daiseys before it happens

 

 

 

[onetrack]

I personally believe we will soon see a major ramp up of battery and electrification technology and abilities. The amount of R&D effort going into this now is staggering - and I believe the Chinese may well be leading the West in this area.

Remote areas will still always pose a problem - but then again, so do adequate fuel supplies in remote areas, also pose a problem. It's all about careful planning.

There are plenty of big cheap diesel gensets that can still always provide backup power in remote areas - and solar power generation is expanding at an increasing rate. The missing link is a satisfactory cheap electricity storage method.

However, S.A. is leading the way with renewable power generation, and the big Tesla batteries appear to be standing up to their performance promises.

I believe we'll see an increasing range of alternative, integrated power generation systems appear in the near future - such as pumped hydro. Stand-alone power systems are rapidly coming in for rural regions in W.A.

 

But the bottom line is, another increase in battery energy density is needed, to really narrow the gap between fossil fuels and electric motive power.

I believe that will come within 5 years - maybe not due to any one major advance, but in incremental advances that will add up.

Then there's still efficiencies to be made in electric motor design as well. Electronics are really playing their part there, and will continue to do so.

 

https://www.westernpower.com.au/our-energy-evolution/projects-and-trials/stand-alone-power-systems-round-1/