7 ms·

Needs more Napier Deltic: https://en.wikipedia.org/wiki/Napier_Deltic https://en.wikipedia.org/wiki/Napier_Deltic (It's a two-stroke cycle diesel but not as w

Needs more Napier Deltic: https://en.wikipedia.org/wiki/Napier_Deltic https://en.wikipedia.org/wiki/Napier_Deltic (It's a two-stroke cycle diesel but not as we know it -- three cylinders arranged in a triangle with a crankshaft at each vertex, one of them counter-rotating relative to the other two, and six pistons, two of them opposed in each cylinder! There is an animation on the wikipedia page. Tracking it will make your head hurt. This thing was a mainstay of the British railway industry in the late 1950s to 1960s ...)

jacquesm 6y ago
That's a pretty clever design, thank you for posting this, I never even heard of it before. I really like the opposing piston trick to get rid of the heavy head, but it does make you wonder how they dealt with the spot where the fuel has to be injected, it's hard enough to get reasonably efficient combustion when you're injecting into the center of the cavity. Did it use multiple injectors per cylinder?
- rleigh 6y ago
  This part is dead simple and quite clever. It's on the animated diagram in dark blue, and you can also see one port on the cutaway engine block photo (I've been to see this in real life; the engineering is phenomenal). On the blue diagram I think it's air+fuel at one end and exhaust at the other. When the pistons reach their maximum opposing distance, the injection and exhaust ports are briefly exposed, allowing for entry of fuel/air and exit of exhaust in a single linear movement from one end of the cylinder to the other. Maybe the air is injected before the fuel or at a higher pressure. And if you time the speed of the exchange just right in time for the exhaust ports to be closed over before the compression stroke, you get complete exchange with no fuel wastage. Absolutely nothing like a 4-stroke engine, and not much like common 2-stroke designs either.
  - jacquesm 6y ago
    Clever, and no valves to adjust. I really like this design, and I'm wondering why it never caught on more, it looks as though it would have worked well in a boxer like engine as well, instead of two camshafts and one crank you'd end up with no camshafts and two cranks.
    - Judgmentality 6y ago
      > While the Deltic engine was successful in marine and rail use and very powerful for its size and weight, it was a highly strung unit, requiring careful maintenance. This led to a policy of unit replacement rather than repair in situ. Deltic engines were easily removed after breakdown, generally being sent back to the manufacturer for repair, although after initial contracts expired both the Royal Navy and British Railways set up their own workshops for overhauls. I guess nobody wanted to maintain them.
    - cstross 6y ago
      What you describe is the Junkers Jumo 204, and the Deltic design was allegedly directly inspired by it. https://en.wikipedia.org/wiki/Junkers_Jumo_204 https://en.wikipedia.org/wiki/Junkers_Jumo_204
      - jacquesm 6y ago
        Wow, what a beast. The displacement to weight ratio is incredible, unfortunately it doesn't seem to produce a whole lot of power for all that weight, though since it is a diesel the torque is probably quite impressive (even though it is for aircraft, where engines typically are fairly low torque). Add a supercharger or a turbo assuming the pistons can stand it and this could very well still be a competitive engine. What a nice design. Thank you once again.
        Judgmentality 6y ago
        Not to take away from how neat that design is, but my favorite thing about that link is learning that it was manufactured by a now defunct company called Junkers. https://en.wikipedia.org/wiki/Junkers https://en.wikipedia.org/wiki/Junkers
ggm 6y ago
Absolutely amazing engine noise, you couldn't mistake it pulling out of Waverley station in Edinburgh. As a trainspotter I stood on the platform and saw all 22 over the years. I believe the tested engine used to be in the science museum in London but is now in the York museum. The baby deltic was a more prosaic workhorse, the deltics delivered the 100mph Edinburgh London service for decades.
- quercusa 6y ago
  The York RR museum is an excellent place to spend a day.
- redis_mlc 6y ago
  > As a trainspotter OK, limey. :) Maybe you can explain the appeal of trainspotting to a US audience. Haven't heard much about that over here.
- totetsu 6y ago
  the noise for the curious https://m.youtube.com/watch?time_continue=54&v=gtv0s1JQ0D4&feature=emb_title https://m.youtube.com/watch?time_continue=54&v=gtv0s1JQ0D4&f...
  - ggm 6y ago
    I swear you can hear three notes in the thrummm. I know it's a projection from my memory and desire, but in both pitch, and it's tonality it isn't like normal diesel locomotives. I don't think the YouTubes do it justice, a bit like rocket launches: you have to be there to get a chest-beating throb.
martinmunk 6y ago
My dad collects old kerosene engines, and used to have a simplified version of this. A 2 cylinder, 2 crankshaft, 4 piston, 2 stroke Diesel engine. Used by German forces to power plane-spotting projectors, so presumably manufactured in the late 30s or 40s.
- userbinator 6y ago
  The general type is known as https://en.wikipedia.org/wiki/Opposed-piston_engine https://en.wikipedia.org/wiki/Opposed-piston_engine
vvanders 6y ago
That's pretty incredible, and here I though the Wankel was a fairly unique engine. Not directly related but learning about the diesel-electric locomotives and the transition from PWM DC to 3-phase VFD with the traction improvements(I seem to recall they doubled available traction but would have to check my sources[1]) was also something that caught me by surprise. All these EVs out there now owe a lot to the work that happened back in that industry. Edit: found the one of the sources I remember reading. [1] http://www.republiclocomotive.com/ac-traction-vs-dc-traction.html http://www.republiclocomotive.com/ac-traction-vs-dc-traction...
nimbius 6y ago
Diesel engine mechanic here and I learned about these during my apprenticeship. "high strung" is the understatement of the fucking century. Deltics are garbage compared to a modern inline 8 or 16 cylinder locomotive diesel. cheerleaders for deltics will always measure their effectiveness in the guesome "miles per casualty" figure, completely ignoring the fact this system had astronomical service costs as the design compounds stress on cast parts. you had to have starter cartridges (explosives) to start the things, and it wasnt uncommon for them to give up the smoke just cranking them. they have horrendous emissions as well compared to inlines. diesel and lube oil would roll out of the exhaust in massive plumes (you would never get these approved in the US today.) Usually on startup large diesels have monitored exhaust temperatures but in a Deltic your eyes had to be glued to the meter because the stack was always a blond one away from runaway (catching fire.) As tolerances drifted during service most fleets just fed these things more lube oil and in turn, worse emissions and efficiency. again, complexity. Your tolerances for a deltic were insane compared to what you had at the time for an off-the-shelf diesel. repair parts too had to be custom fitted to the engine as it had worn and take into account things like piston bore cavitation damage from overprimed starter cartridges/overspeed/overtemp/etc...The shop down the road could not fabricate deltic parts so lead times were considerable. Whoever worked on these had a dedicated machinist (not just a miller) cutting parts off a dialed-in colchester lathe or something with a very good tolerance.
- willyt 6y ago
  Yes but you are comparing 1950s technology to 2020 technology. Sounds like the mechanical design was a bit ahead of the capabilities of materials science and readily accessible metal fabrication technology at the time. I expect if you could add the amount of refinements and digital augmentation that modern diesels have, you could get the maintenance down to similar levels, but like the Wankel rotary engine no-one is willing to bear the cost of redoing the last 70 years of engineering optimisations that have been done to the standard Diesel engine configuration.
  - Judgmentality 6y ago
    > but like the Wankel rotary engine no-one is willing to bear the cost of redoing the last 70 years of engineering optimisations Mazda tried bringing this back with the RX-8. It was a failure, and while everybody loves the "spirit" of the wankel, outside of the infamous 787B I think people are always going to remember it for the theory instead of the application. If we're going to talk about using modern engineering capabilities, perhaps we should be discussing the quasiturbine engine? At least in theory it solves many of the problems of the rotary engine, although I suspect it will be a nightmare of complexity that never becomes reliable. https://en.wikipedia.org/wiki/Quasiturbine https://en.wikipedia.org/wiki/Quasiturbine

jacquesm 6y ago

That's a pretty clever design, thank you for posting this, I never even heard of it before. I really like the opposing piston trick to get rid of the heavy head, but it does make you wonder how they dealt with the spot where the fuel has to be injected, it's hard enough to get reasonably efficient combustion when you're injecting into the center of the cavity. Did it use multiple injectors per cylinder?

rleigh 6y ago
This part is dead simple and quite clever. It's on the animated diagram in dark blue, and you can also see one port on the cutaway engine block photo (I've been to see this in real life; the engineering is phenomenal). On the blue diagram I think it's air+fuel at one end and exhaust at the other. When the pistons reach their maximum opposing distance, the injection and exhaust ports are briefly exposed, allowing for entry of fuel/air and exit of exhaust in a single linear movement from one end of the cylinder to the other. Maybe the air is injected before the fuel or at a higher pressure. And if you time the speed of the exchange just right in time for the exhaust ports to be closed over before the compression stroke, you get complete exchange with no fuel wastage. Absolutely nothing like a 4-stroke engine, and not much like common 2-stroke designs either.
- jacquesm 6y ago
  Clever, and no valves to adjust. I really like this design, and I'm wondering why it never caught on more, it looks as though it would have worked well in a boxer like engine as well, instead of two camshafts and one crank you'd end up with no camshafts and two cranks.
  - Judgmentality 6y ago
    > While the Deltic engine was successful in marine and rail use and very powerful for its size and weight, it was a highly strung unit, requiring careful maintenance. This led to a policy of unit replacement rather than repair in situ. Deltic engines were easily removed after breakdown, generally being sent back to the manufacturer for repair, although after initial contracts expired both the Royal Navy and British Railways set up their own workshops for overhauls. I guess nobody wanted to maintain them.
  - cstross 6y ago
    What you describe is the Junkers Jumo 204, and the Deltic design was allegedly directly inspired by it. https://en.wikipedia.org/wiki/Junkers_Jumo_204 https://en.wikipedia.org/wiki/Junkers_Jumo_204
    - jacquesm 6y ago
      Wow, what a beast. The displacement to weight ratio is incredible, unfortunately it doesn't seem to produce a whole lot of power for all that weight, though since it is a diesel the torque is probably quite impressive (even though it is for aircraft, where engines typically are fairly low torque). Add a supercharger or a turbo assuming the pistons can stand it and this could very well still be a competitive engine. What a nice design. Thank you once again.
      - Judgmentality 6y ago
        Not to take away from how neat that design is, but my favorite thing about that link is learning that it was manufactured by a now defunct company called Junkers. https://en.wikipedia.org/wiki/Junkers https://en.wikipedia.org/wiki/Junkers

ggm 6y ago

Absolutely amazing engine noise, you couldn't mistake it pulling out of Waverley station in Edinburgh. As a trainspotter I stood on the platform and saw all 22 over the years. I believe the tested engine used to be in the science museum in London but is now in the York museum. The baby deltic was a more prosaic workhorse, the deltics delivered the 100mph Edinburgh London service for decades.

quercusa 6y ago
The York RR museum is an excellent place to spend a day.
redis_mlc 6y ago
> As a trainspotter OK, limey. :) Maybe you can explain the appeal of trainspotting to a US audience. Haven't heard much about that over here.
totetsu 6y ago
the noise for the curious https://m.youtube.com/watch?time_continue=54&v=gtv0s1JQ0D4&feature=emb_title https://m.youtube.com/watch?time_continue=54&v=gtv0s1JQ0D4&f...
- ggm 6y ago
  I swear you can hear three notes in the thrummm. I know it's a projection from my memory and desire, but in both pitch, and it's tonality it isn't like normal diesel locomotives. I don't think the YouTubes do it justice, a bit like rocket launches: you have to be there to get a chest-beating throb.

martinmunk 6y ago

My dad collects old kerosene engines, and used to have a simplified version of this. A 2 cylinder, 2 crankshaft, 4 piston, 2 stroke Diesel engine. Used by German forces to power plane-spotting projectors, so presumably manufactured in the late 30s or 40s.

userbinator 6y ago
The general type is known as https://en.wikipedia.org/wiki/Opposed-piston_engine https://en.wikipedia.org/wiki/Opposed-piston_engine

vvanders 6y ago

That's pretty incredible, and here I though the Wankel was a fairly unique engine. Not directly related but learning about the diesel-electric locomotives and the transition from PWM DC to 3-phase VFD with the traction improvements(I seem to recall they doubled available traction but would have to check my sources[1]) was also something that caught me by surprise. All these EVs out there now owe a lot to the work that happened back in that industry. Edit: found the one of the sources I remember reading. [1] http://www.republiclocomotive.com/ac-traction-vs-dc-traction.html http://www.republiclocomotive.com/ac-traction-vs-dc-traction...

nimbius 6y ago

Diesel engine mechanic here and I learned about these during my apprenticeship. "high strung" is the understatement of the fucking century. Deltics are garbage compared to a modern inline 8 or 16 cylinder locomotive diesel. cheerleaders for deltics will always measure their effectiveness in the guesome "miles per casualty" figure, completely ignoring the fact this system had astronomical service costs as the design compounds stress on cast parts. you had to have starter cartridges (explosives) to start the things, and it wasnt uncommon for them to give up the smoke just cranking them. they have horrendous emissions as well compared to inlines. diesel and lube oil would roll out of the exhaust in massive plumes (you would never get these approved in the US today.) Usually on startup large diesels have monitored exhaust temperatures but in a Deltic your eyes had to be glued to the meter because the stack was always a blond one away from runaway (catching fire.) As tolerances drifted during service most fleets just fed these things more lube oil and in turn, worse emissions and efficiency. again, complexity. Your tolerances for a deltic were insane compared to what you had at the time for an off-the-shelf diesel. repair parts too had to be custom fitted to the engine as it had worn and take into account things like piston bore cavitation damage from overprimed starter cartridges/overspeed/overtemp/etc...The shop down the road could not fabricate deltic parts so lead times were considerable. Whoever worked on these had a dedicated machinist (not just a miller) cutting parts off a dialed-in colchester lathe or something with a very good tolerance.

willyt 6y ago
Yes but you are comparing 1950s technology to 2020 technology. Sounds like the mechanical design was a bit ahead of the capabilities of materials science and readily accessible metal fabrication technology at the time. I expect if you could add the amount of refinements and digital augmentation that modern diesels have, you could get the maintenance down to similar levels, but like the Wankel rotary engine no-one is willing to bear the cost of redoing the last 70 years of engineering optimisations that have been done to the standard Diesel engine configuration.
- Judgmentality 6y ago
  > but like the Wankel rotary engine no-one is willing to bear the cost of redoing the last 70 years of engineering optimisations Mazda tried bringing this back with the RX-8. It was a failure, and while everybody loves the "spirit" of the wankel, outside of the infamous 787B I think people are always going to remember it for the theory instead of the application. If we're going to talk about using modern engineering capabilities, perhaps we should be discussing the quasiturbine engine? At least in theory it solves many of the problems of the rotary engine, although I suspect it will be a nightmare of complexity that never becomes reliable. https://en.wikipedia.org/wiki/Quasiturbine https://en.wikipedia.org/wiki/Quasiturbine