(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 ...)
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.
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.
> 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.
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.
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.
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?
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.
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.
> 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.
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.
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.
The English language association is a pretty negative one but in German it's just another name. Coincidentally, the house I am in right now is heated by a Junkers 'Eurostar' central heating unit.
And in Polish 'Junkers' is pretty much synonymous with water heater.
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.
> Donut Media pioneered the "suck squeeze bang blow" descriptor of the 4 stroke engine
Someone please correct me if I'm wrong but I think I've heard the term "suck squeeze bang blow" way before Feb 23, 2021 and also before 2015 (creation of that Youtube channel) so I find that claim hard to believe.
edit: and googling some more, there are instances of in being used it 1950s. And the likely first author of the saying might well be the inventor of the 4 stroke engine himself, Nicolaus Otto, who used a similar saying to describe it: Saugen, Drücken, Knall, Schlag.
> Actually, I wouldn't be surprised if the great Nikolaus August Otto, inventor of the four-cycle engine had a similar saying to explain his engine: Saugen, Drücken, Knall, Schlag...
I do see though that the breakdown of the Otto cycle on most sites including German ones (https://de.wikipedia.org/wiki/Ottomotor) is usually made in a way that just sorts of lends itself to being transformed that way.
Well, thanks for making me go through his writings, this was fun!
Something to keep in mind: several sources of actual topics have contradicted Donut Media views on certain things and DM has been known to steal video clips without crediting where they got them or use Wikipedia articles as established sources.
Not that all their videos have these issues, but some do and it gets pretty ridiculous.
it seems sort of rare on the Internet, particularly in videos, for someone to NOT be doing a 'comedic' take, along with a jump cut every 5 seconds, background music; all kinds of stuff that feels like it is desperately trying to do everything it can all at once to make someone not hit the back button. ironically, hitting the back button is the first thing i do when a video starts with 'Wats up Guyz' or something along those lines. the original post is a breath of fresh air, straight to the point. I wish the Internet was more like this in general.
These "jump cut every 5 seconds" is the reason I've been watching less youtube everyday. It completely breaks continuity and are so frequent that a significant part of the video is wasted.
Reading and watching an animation is better than video tutorials in almost every regard.
(I know it's bad form to explain a joke, but I'm going to anyway. The Tesla turbine used to be legendary (as in "urban legend") before the Internet. Anyway, it has only one moving part which is radially symmetrical and rotates about its center so there would be nothing to see in the animation!)
(It's like an inside-out Wankel engine. Instead of a triangular rotor in an oval housing, it's an oval rotor in a triangular housing. The advantage is you get a more optimally-shaped combustion chamber, which ought to improve fuel economy and emissions. Also the apex seal-equivalents are easier to lubricate as they're attached to the housing rather than the rotor. They've made a few prototypes and they're working on durability.)
Interesting twist on a Wankel style design. It looks like the apex seals are moved to the block rather than rotor. I’m also curious as to the benefit/drawback of having the flow of intake and exhaust perpendicular to the rotor.
Cool though their turbofan isn't going to work very well with the compressor being much larger than the turbine - the gas would find it easier to flow the wrong way. The Wikipedia animation has more promising dimensions https://en.wikipedia.org/wiki/Turbofan
After remarking on how boring jet engines are, the page gets vague and states that the turbofan increases "fuel efficiency", without explaining why or how. I've seen it assumed elsewhere that the efficiency of turbofans is due to thermodynamic effects. In this case, what the author wrote is vague about the mechanics of it, at best.
This has baffled me since I was two years old. The burning fuel should push in all directions equally. What makes it go more out the back than the front?
It's easier if you imagine identical fans for the compressor and turbine but gearing so the turbine can spin faster. Of course the gasses will take the easy way out the turbine. At some speed, air stops going out the compressor and comes in instead. Burning fuel keeps the gas expanding so there's still a lot more volume to go through the turbine. Then adjust blade angles and turbine diameters to get rid of the gearing.
Or another way. If the thing was symmetrical the pressure would push both ways and it wouldn't move so the designers have to make it asymmetrical so it's easier to get out the exhaust. I think in practice the compressor blades are closer to perpendicular to the flow than the exhaust turbine ones.
It's also important that there is a larger volume of gas leaving the engine than going in as it expands when the fuel heats it. So while the pressure is the same the energy is greater on the turbine side due to the greater volume so it has power to run the compressor as well as fly the plane.
That's what all the compressor stages are for. There's a pressure differential so the combustion pushes against that and exits in one direction, turning the lower pressure discs on its way out.
A long shot, but hope they could include the Wave Disk Engine (https://en.wikipedia.org/wiki/Wave_disk_engine). I could never wrap my head around the operating principle. Also, the research appears to be either slow going, or halted.
The engineer in me cringed at this. While you can definitely use shockwaves to compress the air, dealing with the repeated stresses to the engine casing and other parts is a nightmare.
The 'oldfashioned' way was using a high pressure fuel pump, basically a needle sized piston pushing a tiny little bit of fuel into a high pressure metal fuel line, the springloaded ballbearing return valve at the tip of the injector would be pushed open by the fuel and then the fuel could stream past the ballbearing to the injector nozzle.
You might be conflating how an injector turns on and if with how the fuel is pressurized. Unit injectors create the high pressure for injection in the injector, combining the high pressure pump and injector in one, fed by a low pressure rail. Theses are driven mechanically via cams to create pressure.
Common high pressure rail injectors have a separate high pressure pump connected to engine elsewhere and the injectors just turn on and off fed by a high pressure common rail.
The injector itself can be actuated mechanically or via solenoids or piezo, but there are no injectors that create pressure electrically that I know of (the closest I have seen are voicemail medium pressure gas injectors used in ETEC engines). That is the electric part of the injector only lets the fuel through, it does not force it.
The fuel injectors operate at very high pressures (200+ megapascals). Interestingly, it makes working on these systems dangerous since the atomized fuel can inject and slice through human tissue.
One neat feature it took me a moment to notice: you can step through the animations manually, if you hit the pause button and then either drag the slider or click the arrow buttons.
Lol at the hate that jet engines get for being too "simple" and "boring".
I think some of the compressor/turbine blades are drawn the wrong angle but jet engines have always looked to me like they shouldn't work at all. I know that the turbine extracts more force from exhaust than the compressor exerts on the air (while spinning up) but it's all in the diameter and blade shape since they're attached to the same shaft, and my intuition has trouble wrapping around the concept.
I really love the content here but it looks so pixelated on my high-dpi monitor. It would be awesome is someone remade something like this but using modern web technologies (maybe Lottie from Airbnb) that uses vectorized images that can scale to any size.
One of my dreams for the next few years is that computers are now fast enough to have physically realistic simulations in games - you might not be waiting for too long to be building Heath Robinson machines in VR!
If we ever had a high altitude electric plane do we think electric motors with huge props? Or would we try to recreate the turbo jet? Maybe resistive heating elements instead of fuel?
In my layman's understanding, those are related. Playing with the piston dimensions limits (but doesn't entirely prevent) fuel/exhaust mixing. Unburned fuel in the exhaust makes them dirty.
The site says:
> ... This expels the exhaust gasses out the exhaust port, usually located on the opposite side of the cylinder. Unfortunately, some of the fresh fuel mixture is usually expelled as well.
Another factor - since the fuel enters through the crankcase, it needs to be mixed with oil for lubricating the moving parts. That oil burns when it gets to the combustion chamber. Pretty sure that also increases unwanted emissions.
It's entirely possible modern CFD and chemistry could improve on those issues... I'd be curious if anyone else knows about recent R&D on two-strokes. They're hard to beat on power-to-weight.
Direct injection two-strokes like ETEC's avoid the burnt fuel in the exhaust by not injecting any fuel until the exhaust port is closed. They also typically have specific oil injection points reduce the amount of oil needed to be burned. They are generally as clean as modern 4-stroke engine.
There's a lot of engines I've never heard of here, but my new Subaru Outback has a CVT (Continuously Variable Transmission) which isn't represented here which is somewhat disappointing
not an engine, but (in the name...) a transmission - a mechnism for transmitting power from the engine to the wheels. normally cars use a gearbox (automatic or manual) and possibly a driveshaft (to connect to the wheels that are at the other end from the engine.)
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 ...)