Napier Deltic Opposed-Piston Diesel Engine

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A really neat engine. No doubt, many of you have heard of it, but, I'm sure some have not.

2-stroke, 9 or 18 cylinders with 18 or 36 pistons arranged in a triangular, or, "delta" configuration, no cylinder head or valvetrain, 3 crankshafts, 1 of which turns the oppposite direction of the other 2...

Fantastic power-weight ratio compared to contemporary, conventional-design diesels and a lot more compact and approximately 1/5 the weight!

Designed in the 1950s for marine use. Also used in locomotives as well as in a one-off firefighting pump trailer rig for the NYFD!

Anybody have experience with it?

Read up on it.

https://en.wikipedia.org/wiki/Napier_Deltic
 
The Deltic is a marvelous engine. It's still in use! https://en.wikipedia.org/wiki/Hunt-class_mine_countermeasures_vessel
I was actually reading about it a couple weeks ago. I love unconventional engine designs.


I remember reading about some Russian tanks with opposed piston, opposed cylinder OPOC engines too. The things they did to achieve their goals were pretty interesting.


btw John_Pifer, did you check this out? https://en.wikipedia.org/wiki/Zvezda_M503 - this Soviet radial diesel was used to power some extremely fast missile boats; boats that went higher than 40 knots.
 
I grew up to the sound of the Commer TS3, an uncle had one, and my father used to work on them, something he specialised in at one stage. By the time I was working on trucks the TS3 was fading away...but I did get to work on some, and drive them too. My favorite sound of all time.

He's got an Eaton 2 speed diff on that one...most of them did.
 
Love those two stroke diesels. They sound fantastic. Seems like they're pretty sporty compared to four strokers.
 
Originally Posted By: xxch4osxx
Sounds similar to a Detroit diesel at certain rpms. I wonder if those Commer engines leaked oil as bad as the Detroits did?


Yes, reminded me a lot of our old city busses, which were GM units powered by 2-stroke DD's.
 
Yep. Napier specialized in weird. They seemed to go for complexity as an end in itself.

They designed the Lion W12 aircraft engine in WWI, and it was still being used as a torpedo boat engine in WWII, and even was used by John Cobb to set land speed records in 1947.

They designed the Sabre H24 sleeve valve aircraft engine in WWII for the Hawker Tempest. It was reputed capable of producing 3500HP out of its 2240 cubic inches. Manufacturing and developmental difficulties of the Sabre drove Napier into bankruptcy, and they were bought out by English Electric.

They designed the Nomad flat-12 two-stroke turbocompound diesel for commercial aircraft after WWII.

The Deltic was another in a long line of complex, unique engines. Napier had built the Culverin OP diesel aircraft engine in the 30's under license from Junkers. It was a copy of the 204 Junkers. Then they realized that by adding another crankshaft, they could add two more cylinder banks to the OP engine form. The engines in the Deltic locomotives were blown via a mechanically-driven centrifugal compressor, and made 2500 HP out of 88 liters displacement. Later developments for the Dark and Nasty-class torpedo boats used turbochargers and produced up to 4000 HP. Experimental turbocompound versions of the Deltic made up to 5600HP.

There are quite a few YouTube videos of Deltic locomotives. The engines sound like Detroit Diesels on Benzedrine. They smoke a lot, though. It would be great to put modern common-rail diesel fuel injection systems on the Deltic and see how clean and economical they could be.
 
Napier Sabre Aircraft Engine used by the British was an amazing engine designed by Britain. They tried to get some American companies interested. But it was judged unduly complicated and it would take a long time to mass produce. Of course an American company (Packard) took the Merlin engine and improved it and made more of them than the Brits.

1200px-Napier_Sabre01.jpg


The Pratt R-2800 ultimately was the best aircraft engine of WW II
 
Last edited:
Originally Posted By: Al

The Pratt R-2800 ultimately was the best aircraft engine of WW II

The best? Them's fightin' words. The Wright Cyclone is still in service today as a matter of fact, in firefighting P2V Neptunes.
 
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