Posted on 04/30/2026 8:10:23 PM PDT by Red Badger
What happens when engineers build something that works perfectly — and the world still finds a way to make it disappear? The Napier Deltic was a genuinely bizarre piece of engineering: a diesel engine shaped like an equilateral triangle, with three crankshafts, thirty-six pistons, and no cylinder heads at all. Born out of postwar desperation at D. Napier and Son — a company that had built some of the most powerful aircraft engines of the Second World War and suddenly had no aircraft left to power — the Deltic went on to serve in Royal Navy minesweepers for over thirty years and haul the Flying Scotsman up the East Coast Main Line at speeds no other single diesel engine in Britain could match. This video tells the full story: why the opposed-piston two-stroke layout made it so extraordinarily power-dense, how the triangular three-crankshaft configuration worked mechanically and why the phasing gear train was both the engine's defining feature and its most unforgiving weakness, what the three-thousand-hour overhaul cycle meant for the depot staff who lived with these locomotives, and why the decision to withdraw them had almost nothing to do with the engine's ability to do its job. The Deltic didn't fail. It was outlasted — by cheaper engines, corporate reorganisations, and the slow dispersal of a specialist knowledge base that nobody had figured out how to preserve. Six of the twenty-two Class 55 locomotives survive in preservation today. This is the story of what they represent, and what went away with the rest.
30 Minute VIDEO AT LINK.................
DIESEL HISTORY PING!...................
Bring back the Wankel.....
Too many Wankers already...
This is the Wanker Engine.............
The Deltic also powered the USN Nasty Class Patrol Boats (https://en.wikipedia.org/wiki/United_States_Nasty-class_patrol_boat)
In 1972, I had a FRiend whose brother was involved in overhauling the PTFs in Subic Bay, RP. He arranged for several of us to get a ride on a PTF after the overhaul was complete.
The PTF had two Deltics; 6200 hp! I will tell you that was one Hellofaboat!
That day is one of my more memorable days in WESTPAC!
That is a great story!
What does Keir Starmer have to do with this?
Thanks!
There is more — the hull was kevlar armor plated on the INSIDE of each engine room. An overspeeding “runaway” Deltic could explode with the force of a 500 lb bomb, so the kevlar armor plating “contained” the explosion and prevented the hull FRom getting holed!
AND, the doors to each engine room were thickly armored as well. Operators did not go into the engine room when the Deltics were above idle speed.
As you can tell, I was absolutely captivated by the Deltics!
36 cylinders to generate 3300 horses, in the British Rail Class 55 locomotives.
And just four years later, General Motors’ Electro-Motive Division came out with the V16 645 turbocharged engine that produced 3000 horses. Much less mechanical complexity for just as much power and for less cost . . .
The “delta” design looked like a real PITA to repair-especially on a locomotive. The same with the Fairbanks-Morse opposed piston diesels used in their locomotives. Which is why the V- shaped diesels became the standard on diesel locomotives in the US.
Getting the timing right after a bit of wear was likely a challenge.
The mazda rotary engine is a fuel hog...
This isn’t a Wankle................
It had to be rebuilt after 3000 hours..........
I think it was “rethought” as the Wankel engine in the late 50s, and became re-rethought as the Tri-Dyne in the late 60s - then was just termed, “Rotary”.
This isn’t a ‘rotary’ engine. It has pistons and three crankshafts...............
Very true. My parents bought an RX-3 wagon back around 1974 to save money on gas compared to our 1963 Ford station wagon. Wrong! The Mazda got 16 mpg on the highway on a good day.
Also, that '63 Ford wagon is highly collectible these days. Too bad my sister ran it into the ground.
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