I’d always thought the ‘Deltic’ was a type of British Rail diesel locomotive from the 60s and 70s, but tabbing around Wikipedia today I find the loco took its name from an engine, made by engineering firm Napier & Son. I’ve long had a bit of a soft spot for Napier, partly because in the popular imagination they and their magnificent Sabre played second-fiddle to Rolls-Royce with their flashy Merlin and Griffin – pity Bristol and the workmanlike radial Centaurus – and partly because, in my book, engineering firms should be called things like ‘Napier & Son.’ ‘Bristol-Siddeley’ was pretty good; ‘Armstrong-Whitworth’ one of the best company names of all time. Who wouldn’t rather have an Armstrong-Whitworth toaster than, say, a Tefal? But I digress…

Turns out, the Deltic wasn’t just another big diesel engine, it had an entirely radical piston arrangement. Pistons were arranged in pairs, opposed in a shared cylinder, then three such piston pairs were coupled in a triangular arrangement via three shared crankshafts. Timing issues were resolved by having one crankshaft contra-rotate, geared into the common output shaft.

The design allows each valve to be unidirectional. It’s not entirely unlike a Wankel Rotary, but retaining pistons rather going the whole hog and adopting a rotor. There’s a nifty little animation on the Wikipedia page, but what I really want to know is – what would a small one of these sound like?

(other Wikipedia finds of the day: a list of Rainbow Codes for British military projects – my favourite remains ‘Blue Circle,’ but that’s a bit of a cheat – and details on Miss Shilling’s Orifice. Which, perhaps surprisingly, is entirely safe for work. Why we never covered the eponymous inventor for Local Heroes is beyond me. Also: I never knew it was possible to fly to Ascension Island and the Falklands via RAF Brize Norton, though it’s still unclear quite how one goes about booking travel; mentions from RAF Mount Pleasant entry, Ascension Island entry. Oh, and this part of the entry on the F-4 Phantom II jet fighter:

On 10 May 1972, Randy “Duke” Cunningham and William P. Driscoll flying an F-4J with the radio call sign “Showtime 100” shot down three MiG-17s to become the first flying aces of the war. Their fifth victory was believed at the time to be over a mysterious North Vietnamese ace Colonel Toon, now considered mythical. On the return flight, the Phantom was damaged by an enemy surface-to-air missile. To avoid being captured, Cunningham and Driscoll flew upside-down (the damage made the aircraft uncontrollable in a conventional attitude) and on fire until they could eject over water.

Emphasis added.)


  1. You’ll be pleased to know that the Deltic wasn’t the only Rube Goldberg engine designed by Napier. They also did the Nomad, a post-WW2 attempt to increase the power and efficiency of piston aircraft engines.

  2. Oh yes, Armstrong-Whitworth, making things that would last, you feel. Aveling-Barford, Ruston-Bucyrus, Blaw-Knox, Massey-Fergusson, they made the stuff of life. wtf do the likes of Aviva, Seneca and Endica do, apart from all ending in a?

  3. For the sound, go to YouTube and have a search on 55 or deltic. I’ve added a good ‘un on my favs on my YouTube page, /alanbe2. You can here it from miles away, and it has to be one of the weirdest noises you’ll here. Would be cool to make a minature one.
    Owp, gotta go, I can here Spitfire kicking ten bells out of a neighbours cat…

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