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Author Topic: Opposed Piston Engine  (Read 8789 times)

Offline fredymac

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Opposed Piston Engine
« on: January 04, 2016, 09:34:55 am »
I stumbled across this alternative engine program and was impressed by the level of support it has been gaining.  The design is based on opposing cylinders which has been attempted before.  However, CFD analysis and a methodical engineering approach seems to have allowed the design to get past previous drawbacks which led others to abandon or ignore it.  A joint venture with Cummins is now building a demonstrator for the US Army and commercial end users are funding continued research.  If it works, they will achieve a “step change” in fuel economy while meeting future emissions standards all while being compatible with current size/weight envelopes and production tooling.



Offline Hobbes

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Re: Opposed Piston Engine
« Reply #1 on: January 04, 2016, 11:10:42 am »
Interesting, basically a revival of the Junkers opposed-piston diesel principle. I'm surprised they can meet modern emissions standards with a two-stroke design. Also interesting; in the animation they show the intake/exhaust ports almost at the bottom of the stroke, so they'll be shut most of the time. They'll need a compressor for the engine to run at all.

Online SpudmanWP

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Re: Opposed Piston Engine
« Reply #2 on: January 04, 2016, 12:30:55 pm »
They'll need a compressor for the engine to run at all.

In this video they talk about it having a supercharger.  You can see it in the animations as the rectangular object near the top of the engine mounted on the side.

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Offline Moose

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Re: Opposed Piston Engine
« Reply #3 on: January 05, 2016, 01:13:42 am »
There's a few opposed-piston concepts making the transition to the real world recently. I've been following the Ecomotors "OPOC" off an on for awhile:

Offline Kadija_Man

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Re: Opposed Piston Engine
« Reply #4 on: January 05, 2016, 05:18:31 am »
Germany and France developed opposed engine designs way back in the 1930s.  What is spectacularly difference about this compared to their designs?  The French used one in their EBR 8 wheeled armoured car post-WWII.

Offline Hobbes

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Re: Opposed Piston Engine
« Reply #5 on: January 05, 2016, 07:09:50 am »
Availability of computer-aided analysis to optimize the design, and computer-controlled direct injection.

Offline goose

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Re: Opposed Piston Engine
« Reply #6 on: January 28, 2016, 04:18:17 am »
Anyone remember the Leyland L60? The Chieftains Achilles Heal, for the British Army to introduce an opposed piston engine than that memory will alert anyone to the dangers of introducing immature tech.
In War the latest refinements of science are linked with the cruelties of the Stone Age.

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Re: Opposed Piston Engine
« Reply #7 on: January 29, 2016, 02:37:47 am »
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« Last Edit: March 20, 2016, 09:39:52 pm by Eirigi »

Offline starviking

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Re: Opposed Piston Engine
« Reply #8 on: January 29, 2016, 06:12:31 am »
Immature for whom? By the time the Leyland L60 (and the Napier Deltic, to a lesser extent) proved unreliable in England, opposed-piston diesel engines had already accumulated hundreds of thousands if not millions of operating hours in ships, tugs, submarines, locomotives and aircraft, worldwide. The technology was perfectly mastered by companies such as Fairbanks&Morse (their engines were so reliable that they are still used to this day by the USN for auxiliary/emergency power in nuclear-powered submarines, and not counting their Soviet derivatives found in thousands of locomotives), Junkers Flugmotoren, ...

Perhaps with the L60 being used as a tank engine it encountered greater power variation in common use than many of other vehicles you mentioned?

Offline Grey Havoc

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Re: Opposed Piston Engine
« Reply #9 on: January 29, 2016, 06:19:07 am »
I think goose was referring to opposed-piston multi-fuel engines.
« Last Edit: January 29, 2016, 06:20:51 am by Grey Havoc »
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Offline goose

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Re: Opposed Piston Engine
« Reply #10 on: February 02, 2016, 01:38:06 pm »
My point is not that opposed piston engines are inherently flawed but that any unconventional engine has an uphill struggle to gain acceptance. The memory of the L60 will be the elephant in the room when discussing this engine.  I know it was underdeveloped & that is a warning to this team-it has to be right first time!
In War the latest refinements of science are linked with the cruelties of the Stone Age.

Offline Herman

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Re: Opposed Piston Engine
« Reply #11 on: February 04, 2016, 10:32:58 pm »
Reply to post #4

The EBR used a conventional flat-12, air-cooled, four-stroke, gasoline engine of 6 liter capacity. It developed about 200hp. It was remarkable for its flatness: only about 8 inches high. This meant that the engine fitted onder the turret floor. It did however mean that the turret had to be romved for major work on the engine.

Offline Herman

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Re: Opposed Piston Engine
« Reply #12 on: February 04, 2016, 10:36:02 pm »
Reply to post #6
Yes the Chieftain was a remarkable tank for its time but the whole thing was spoiled by the dismal engine. It would have been a world beater with the US Continental engine (of the M60) ot the MTU engine of the Leopard I, the other two major Western tanks from the same era.

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Re: Opposed Piston Engine
« Reply #13 on: February 05, 2016, 03:48:25 am »
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« Last Edit: February 05, 2016, 03:50:11 am by Eirigi »

Offline robunos

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Re: Opposed Piston Engine
« Reply #14 on: February 05, 2016, 02:49:25 pm »
Reply to post #6
Yes the Chieftain was a remarkable tank for its time but the whole thing was spoiled by the dismal engine. It would have been a world beater with the US Continental engine (of the M60) ot the MTU engine of the Leopard I, the other two major Western tanks from the same era.

Ahem...

The photo caption reads :-
"A rear shot of a very unusual Chieftain indeed; notice the absence of the usual exhaust box and pipes. This is because, automotively speaking, it
is the most powerful Chieftain ever built. Instead of the problematic L60 and TN12 power pack it was fitted with an MTU diesel linked to a Renk auto gear box. This combination made it powerful and very fast; it also had the ability to stop on the proverbial “sixpence” as one employee found out.
Although it is located at a museum, its interior is in poor condition and needs a lot of work.
The power pack is still classed as a commercial secret. (R. Griffin)"

Source, 'The Armour Journal', Summer 2015.

cheers,
           Robin,
Where ARE the Daleks when you need them......

Offline Herman

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Re: Opposed Piston Engine
« Reply #15 on: February 06, 2016, 03:34:04 am »
Reply to post # 14.
Robin, this is a really, really interesting piece of information. It would be very interesting to know when this prototype was built and by whom. It would also be interesting to know which MTU engine is fitted in the vehicle. The Leopard I, which corresponded with the Chieftain chronologically, was fitted with a 10 cylinder, 830hp unit but it used a ZF gearbox. The Leopard 2 had a V12, 1500hp MTU engine and that was indeed coupled to a Renk gearbox. The Leopard 2 is however a later tank than the Chieftain, corresponding more to the Challenger. Why would anybody stick a Leopard 2 powerpack into a Chieftain? It will also not be simple, technically; the Leopard powerpack is considerably larger than that of the Chieftain.

Offline Herman

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Re: Opposed Piston Engine
« Reply #16 on: February 06, 2016, 03:45:30 am »
Reply to post # 7.
I agree. The technology was mature and opposed piston two-stroke engines have been widely used, also in military vehicles. The Russians/Ukranians made/make wide use of this type of engine in various modified vesrions of the T72 tank. The Chieftain was simply a poor execution of the principle.

The attraction of this type of engine, before the era of high pressure, common rail injection, variable geometry turbocharging and electronic engine management systems, was that it offered reatively high power from a relatively small engine. Britian wanted this type of engine for the Chieftain for this reason and because it was felt that this type of engine was more suitable for multi-fuel use than conventional diesels. Multi-fuel capability was a requirement for new tanks at the time of the development of the Leopard 1, the AMX-30 and the Chieftain. Rolls Royce apparently had the design of a conventional, 4-stroke, V8, diesel intended for the Chieftain ready for production when it was deceided to rather edevlop the L60. The irony is that it apparently took fitters 24 hours to modify the engine for use with petrol.

Offline Hobbes

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Re: Opposed Piston Engine
« Reply #17 on: February 06, 2016, 09:26:38 am »
Reply to post # 7.
I agree. The technology was mature and opposed piston two-stroke engines have been widely used, also in military vehicles. The Russians/Ukranians made/make wide use of this type of engine in various modified vesrions of the T72 tank. The Chieftain was simply a poor execution of the principle.


Herman, you can use the 'quote' function to include the relevant text of the post you're replying to. That makes your posts more readable than they are now (where we have to manually look up which post was #7).

Offline robunos

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Re: Opposed Piston Engine
« Reply #18 on: February 06, 2016, 03:49:20 pm »
Reply to post # 14.
Robin, this is a really, really interesting piece of information. It would be very interesting to know when this prototype was built and by whom. It would also be interesting to know which MTU engine is fitted in the vehicle. The Leopard I, which corresponded with the Chieftain chronologically, was fitted with a 10 cylinder, 830hp unit but it used a ZF gearbox. The Leopard 2 had a V12, 1500hp MTU engine and that was indeed coupled to a Renk gearbox. The Leopard 2 is however a later tank than the Chieftain, corresponding more to the Challenger. Why would anybody stick a Leopard 2 powerpack into a Chieftain? It will also not be simple, technically; the Leopard powerpack is considerably larger than that of the Chieftain.

Here we go...

"The development of the Chieftain with a 1000hp engine and enhanced transmission was a project by Vickers Defence Industries, in partnership with the German companies RENK, MTU and Krupp-MAK, to offer a significant performance and reliability upgrade for existing Chieftain tanks. The first customer was to be Kuwait immediately before the first Gulf War. The MoD expressed an interest in upgrading their engineer vehicles and the BARV (Beach Armoured Recovery Vehicle) of the Royal Marines. Subsequently most of Kuwait’s Chieftain fleet was scrapped. The improved design was not developed further, however, leaving this unique prototype as the most powerful Chieftain Tank ever built.

The prototype was donated by Vickers Defence Industries to the Museum and delivered on 15th January 2002. The German engine and transmissions include features which are still regarded as industrial secrets and there are strict conditions relating to access attached to the donation. The tank, which still functions, has been partially restored with support from RENK, Vickers and 150 Regiment, Royal Logistics Corp."

Source :-

 http://yorkshireairmuseum.org/exhibits/historic-military-vehicles/vickers-chieftain-battle-tank/

Also, another image from the magazine article quoted in post #14; caption reads

"The strange contraption on the pack (sic) of the MTU Chieftain is actually a lifting frame to help lift one piece engine deck which is not on a torsion bar unlike a similar system in Challenger. The frame is stowed when not in use so as not to hinder traverse."


cheers,
             Robin.






Where ARE the Daleks when you need them......

Offline fredymac

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Re: Opposed Piston Engine
« Reply #19 on: November 08, 2017, 11:41:47 am »
Looks like the Army was delayed a year or more in releasing the "Advanced Combat Engine" contract to get the ball rolling at Cummins.  They finally funded a $47 Million contract to get started.  Demonstration tests are slated for 2019 with the prototype engine specified at 1000hp and 2400 foot-pounds of torque in a 4 cylinder, 14.3 liter package.



4:35 mark on video below discusses a commercial pickup engine


Offline Foo Fighter

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Re: Opposed Piston Engine
« Reply #20 on: November 11, 2017, 03:55:54 am »
Something that needs to be considered when judging chieftain is the financial situation of the time, which influenced the development of the vehicle and selection of its engine.  That being political it cannot be discussed, nor the choice of supplier of the motive power of the vehicle which influenced the development required and need of the recipient for funding to remain afloat, especially when the company involved was a politically created one.  So, looking at non political influences and reasons for the vehicle having slewed opinions of its abilities.

1.  Like many vehicles it became heavier during design and development which affects the efficacy of the powertrain.  Nothing new, take a look at the Panther.

2.  The frontal armour was in its day pretty impressive but side armour was thinner than late versions of the Panther at 38mm with 13mm of side skirt.  Not great.

3.  The gun itself was pretty good for its day with acceptable accuracy and rate of fire.  The shells fired were also reasonable for the day and the APFSDS was apparently available for Chieftain but I myself never got to load or fire it.

4.  Restrictions.  When I joined my regiment we were growing the tank force and went from four squadrons to five and three tank troops to four.  We exercised regularly with many 24 hour sessions in the vehicle with extended periods operating under NBC conditions.  After 1979 cutbacks became the norm and we were restricted initially by track miles, engine hours and then engine revolutions.  At the same time we were constantly checking fluid levels.  The biggest bain in the life of the L-60 was not the engine itself but the coolant system.  The fan belts were ripping the fans from the housing and leaving a 29 gallon yellow cloud which, if the Russians and East Germans had appreciated the fact, been a great giveaway to our locations rather than follow our moves by mark one eyeball.  The methods used to address this problem were, reducing the hours on the engine and the, drilling holes in the fan belts to prevent the belt from ripping the fan from its housing.  The result of this was that the fan belt failed and while being ripped apart, destroyed coolant lines hence, 29 gallon yellow clouds showing where we were when the failure happened.  So over maintained and with pathetic so called fix programs we had an engine with high failure rates that did not have to be.  Sorry, politics? 

5.  Apparently the last chieftains had the Perkins diesel engine so if it was possible then upgrades should have been possible.  The question should be WHY WOULD YOU WANT TO?  The hull was over reliant on it frontal arc protection when the tactical use required situation from pre prepared firing points with little manouvre being required and that being from firing point/line to the next fallback firing point/line.  While we exercised forward movement this was not something we expecting to do in an actual conflict scenario other than localised counter attacks to straighten a defensive line.  Considering the trilogy of armour, we were giving one away right from the start.  Brigadier General Sir John Hacket wrote a book about this scenario (World war three) but considered that while the warsaw pact forces WOULD get to the French border, they would have real problems with choke points and be delayed from their schedule enough that localised nuclear engagement was a realistic scenario.

6.  There was a bit of folk lore/myth about the Germans offering an MB diesel engine for free, this was during development of the Leopard 2 I believe but then folk lore/myth rarely have an interest in the truth so I offer it here for what it is, uncorroborated fish wives tales.  Apparently while developing a power pack for Leopard (?) several engines were tested, this does indeed sound like German methodology.  One engine was found to be acceptable in all areas but power, it was developing 1400bhp rather than 1500bhp, so this engine was apparently offered to the UK as a fully developed engine/transmission unit.  Obviously it was not accepted, something else quite credible.
« Last Edit: November 11, 2017, 06:29:29 am by Foo Fighter »

Offline fredymac

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Re: Opposed Piston Engine
« Reply #21 on: January 16, 2018, 02:21:21 pm »
From 2018 Detroit Auto Show.


Offline Foo Fighter

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Re: Opposed Piston Engine
« Reply #22 on: January 18, 2018, 02:15:40 am »
The Jordanian Khalid is essentially a Chieftain and had 1200bhp so is reasonably the most powerful Chieftain.

Offline fredymac

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Re: Opposed Piston Engine
« Reply #23 on: March 19, 2018, 10:52:22 am »
First application to make production is a revised Fairbanks Morse power generation engine.  Design/engineering was provided by Achates to replace an early generation opposed piston design that Fairbanks Morse had been producing since it was founded.



Interview with an Achates exec updating where the company is in bringing other projects to production.


Offline fredymac

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Re: Opposed Piston Engine
« Reply #24 on: August 27, 2018, 07:01:00 am »
Displayed at 2018 Eurosatory.  Don't know why they had to put a text balloon right over the engine.

Offline TomS

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Re: Opposed Piston Engine
« Reply #25 on: August 27, 2018, 07:13:12 am »
Same image, minus the text.

http://www.insideindianabusiness.com/story/37513588/cummins-to-design-combat-engines-that-elude-the-enemy

Quote
Cummins to Design Combat Engines That Elude the Enemy
Posted: Feb 15, 2018 9:26 AM EST
Updated: Feb 15, 2018 9:26 AM EST
By Kylie Veleta, Special Projects ReporterCONNECT
 
The Advanced Combat Engine aims to deliver more power in a smaller package.

The monstrous, larger-than-life military tanks of tomorrow could be powered by Hoosier ingenuity. A recent $47 million defense contract delivers marching orders for Columbus-based Cummins Inc.: develop the next-generation engine to power U.S. combat vehicles, and it must be stronger, but smaller, and elusive to enemies’ efforts to spot it. The project is a milestone for Cummins, marking one of the largest research contracts the manufacturer has inked with the military.

The National Advanced Mobility Consortium, which awarded the contract, has tasked Cummins with three key requirements for the Advanced Combat Engine (ACE) project. Cummins Vice President of Research and Technology Wayne Eckerle says the most challenging is to reduce heat rejection by 21 percent, compared to current combat vehicles, which are also powered by Cummins engines.

“If the engine is rejecting a lot of heat, you have a thermal signature that makes it easier for the enemy to find the tank; that heat has to be dissipated somewhere on the vehicle, because the heat signature can be seen with infrared or some other technology,” says Eckerle. “It means the tank has to have a very significant cooling system to keep the engine cool.”

The manufacturer is working with California-based Achates Power, a longtime partner that has developed an engine that Cummins’ expertise will help take to the next level and open the door to production. In addition to low heat rejection, the two companies will combine forces to meet demanding power requirements for the engine: the project aims to improve power density by more than 50 percent, compared to current combat engines.

“[The military] is after an engine that could deliver more power in a smaller package size,” says Eckerle. “Even though those tanks look very, very large, the actual space for the engine is confined. The [military] wants an engine that can put out the power needed and still be in a relatively small package size.”

Similar to reducing heat rejection, increasing power density works toward the ultimate goal of making U.S. troops safer.

“One of the reasons the engine compartment is so small is, there’s a lot of protective covering put on these vehicles,” says Eckerle. “If you can compartmentalize the engine to a smaller space, that leaves more space for putting protection on the vehicle to protect the people inside it. And because of the extra power, you can put more armor on the vehicle and still deliver the mission.”

A third requirement for the diesel engine is to reduce fuel use by 13 percent. Cummins says research and development is well underway at its Columbus headquarters and prototype parts will arrive in the coming months. The manufacturer expects to build a handful of prototype engines at its Seymour facility. Ultimately, Cummins plans to demonstrate the engine in the full power train to show it will deliver on the specifications.

“Cummins was chosen for this contract because the government wanted a company that could, potentially, take the concept into production. [Our focus] is taking Achates’ ideas and turning them into a production-viable engine; they’ve demonstrated the technology in a sample configuration,” says Eckerle. “[Cummins] is in the process of laying out how’d we take it into production, if and when that happens, and the costs that go with it.”

While the research contract is among the company’s largest in the defense sector, Eckerle believes the ACE project could open doors for advancing engines in Cummins’ commercial applications, such as marine and industrial segments—delivering Cummins’ might to more than just the military.

Offline fredymac

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Re: Opposed Piston Engine
« Reply #26 on: November 28, 2018, 08:40:13 am »