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Author Topic: Opposed Piston Engine  (Read 9107 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.

Offline 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.

Eirigi

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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.

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