Steam Engine Replica From LEGO

If engineering choices a hundred years ago had been only slightly different, we could have ended up in a world full of steam engines rather than internal combustion engines. For now, though, steam engines are limited to a few niche applications and, of course, models built by enthusiasts. This one for example is built entirely in LEGO as a scale replica of a steam engine originally produced in 1907.

The model is based on a 2500 horsepower triple-expansion four-cylinder engine that was actually in use during the first half of the 20th century. Since the model is built using nothing but LEGO (and a few rubber bands) it operates using a vacuum rather than with working steam, but the principle is essentially the same. It also includes Corliss valves, a technology from c.1850 that used rotating valves and improved steam engine efficiency dramatically for the time.

This build is an impressive recreation of the original machine, and can even run at extremely slow speeds thanks to a working valve on the top,  allowing its operation to be viewed in detail. Maximum speed is about 80 rpm, very close to the original machine’s 68 rpm operational speed. If you’d prefer your steam engines to have real-world applications, though, make sure to check out this steam-powered lawnmower.

Thanks to [Hari] for the tip!

25 thoughts on “Steam Engine Replica From LEGO

    1. Yeah, this is a weird take on their part. The “engineering choices” were to extract far greater work from a given chemical reaction. As catastrophically bad as the Internal Combustion Engine is for our climate stability, External Combustion is far, far worse.

    2. I think if you jumped in a time machine and handed Herr Otto’s and Herr Diesel’s fathers a condom at the right/wrong moment, killing internal combustion, the following could have transpired… higher development of the Stirling engine for small power installations, known since 1816, steam piston power would again probably reach it’s heyday in the 30s and 40s, before being replaced by steam turbines, with 80% efficiency. Powered flight might have not happened until 30 years later (Though there would have been higher interest in developing the steam motor for it, so knock off 10 maybe) but even then turbines were looking more promising. Electric power would have been more widely considered for jobs small IC engines do, as neither Stirling, steam piston, or steam turbine are “instant on” techs, they need to warm up, and are best suited to steady state operation.

      However, even if we completely eluded the reciprocating internal combustion engine, I don’t think it would have been much delayed that pulse jets and turbine technology melded together and became internal combustion jet engines. In ground transport, I think we’d be running cars on a Stirling engine based tech and buses and trucks on jet turbines right now, possibly the train and electric trolley bus or tram would have maintained superiority. Electrification of rail may have been more universal, when it was cheaper to keep big turbines running than many smaller ones.

      1. Otto and Diesel weren’t the only people trying to solve the engine problem, and Stirling engines have the disadvantage that you need extreme working gas pressures to get any power out of them, and you can’t throttle it easily (except by throwing away efficiency).

        1. Internal combustion engines lose a lot of efficiency when they are throttled too. Pumping against the partial vacuum caused by a partially-closed throttle butterfly has awful efficiency, so car engines used at light loads have awful power per unit of fuel. I think in the car industry this is called “brake specific fuel consumption.”

      2. > In ground transport, I think we’d be running cars on a Stirling engine based tech

        The ASE project tried that, but ultimately failed to produce a competetive Stirling car engine. They got up to about 83 HP with a fuel economy of 41 MPG and 5.5 lbs/HP in 1983. It took 36 seconds to start from cold, but a couple more minutes before it would gather enough pressure for power.

        The challenges of a Stirling engine are twofold:

        1) The firebox needs a complicated heat recovery system from the exhaust to the intake to maintain efficiency. It must maintain a very high temperature over 600-700 C at the hot side, and it must not allow any of the heat to escape other than through the Stirling engine.

        2) The Stirling engine must reject heat from the cold end to maintain a temperature differential, which requires large and intricate radiators which are easily clogged up and corroded away in the operating environment. The power output of the engine is limited by its ability to shed heat, which is limited by how large a radiator you can fit in a car.

        In the end, it was these radiators and heat recycling that proved difficult and costly, the same problem as with the Chrysler turbine car which needed a “recuperator” to recycle heat from the turbine exhaust back to the inlet to have any fuel economy whatsoever. This is why a Stirling engine is most suitable when it’s either very small so the heat rejection becomes easy, or it is connected to a cold source such as water piped from a river.

        In an otto/diesel engine, the heat rejection happens by the exhaust gasses and there is no need to pre-heat the intake air, so the engine’s operation doesn’t depend on heat exchanging radiators.

          1. Or it would be considered a curiosity and not be used at all, because the applications in which it would be used (cars, planes, trains, ships) would not exist as such.

            Certainly in the larger machines like trains and ships, turbines and electric power would dominate. In smaller machines, steam power with flash boilers would dominate over Stirling engines, because steam engines don’t have the same control problems, and they can vent steam when extra power is required.

    3. For the state of technology at the time, these were efficient, reliable and easy to maintain. Coal was cheap and plentiful; easy to transport and provided more BTUs that wood. All technologies are eventually replaced at higher prices.

  1. Nice build!
    But I disagree with “If engineering choices have been slightly different…” It’s not a question of choices, it’s a question of physics. With an internal combustion engine you do not need an extra, heavy boiler or a consumable water supply. And also the ability to burn coal is not so much an advantage, when liquid fuels are so much more convenient.
    It’s all mostly a question of efficiency and ease of use.

    1. Is a ‘heavy boiler’ absolutely necessary? I could imagine a steam engine with a ‘boiler’ that vaporises the water needed for each cycle from cold on demand. I suppose that’s getting close to internal combustion, something like ‘just right next to but not quite inside’ combustion.

      1. The Doble Steam Car company developed a coiled burned that keeps a minimum amount of water in a copper tube around the fire, although they basically stole the idea from kerosene water heaters.

  2. All you preachers need to consider use-cases.
    I’m sure that basically 100% of base load power generation would switch to internal combustion in a heartbeat if your proclamations about efficiency were universally true – no matter the fuel. As far as I know, the only use of IC in such plants uses gas turbines because a fuel that would otherwise most often be flared can be used – so cheap that the increased maintenance costs of IC tech can be amortized, and at that, it’s not used for base loads.

    Sure, you might do better for vehicles with IC, and we do (now, the first ones were pretty crappy too).
    But even there, we’re going electric and using fixed plants to make the juice for that. Those who use solar
    (obviously also fixed-plat) to charge their cars as I do are fairly rare.

    Good grief, people.

    1. Something power generation seems to be tolerant of by using steam power is the use of a variety of heat sources. If it can boil water, it can be used to generate electricity. I don’t know if the boilers need to be radically different for various fuel types, but even if there are changes needed, the turbines extracting work from the steam and turning the generators are likely to be pretty much the same regardless of that.

      For an internal combustion engine, the design is based on the fuel. You can’t run a gasoline engine on diesel fuel (no matter how bad GM wanted to). The same is generally true of continuous combustion engines such as the turbojet. The designs have to take properties of the fuel into account. That would mean swapping the entire mechanically complex engine for a change in fuel instead of replacing a boiler system which is a much simpler from a mechanical design standpoint.

      It’s probably not worth chasing any potential gains in efficiency from a different energy cycle as they won’t offset the reduced cost of existing steam powered designs.

      1. That said, large marine diesel engines ARE now commonly used for power generation because they’re the only ones able to respond rapidly enough to large grid load/supply variations while maintaining high efficiency, because we’ve been adding so much wind and solar power to the grids. Gas turbines are either fast or efficient (combined cycle), but not both.

        They burn natural gas with a squirt of oil for ignition.

  3. All polemics about internal/external combustion aside, the brilliance in the model’s operation lies in using suction rather than pressure to run it. In doing so, the components are in compression (which Legos will withstand very well, if you’ve ever stepped on one in bare feet), whereas with compressed air, the snap-joints would just pop open.

    1. For the forces involved, it’s not too difficult to make the parts hold together, especially if you allow lego technic parts.

      Rather, the whole thing leaks so much air that it’s difficult to keep up the necessary air flow. Out of the choices to power the thing, it’s more difficult to find something that pushes out a large volume of air at a moderate pressure, than one that sucks in a lot of air (a vacuum cleaner).

    1. Imagine if every car on the road was filled with several hundred pounds of a reactive mixture consisting of an oxidizing agent and a reducing agent dissolved in a flammable hydrocarbon fluid, and separated by a thin semi-permeable plastic membrane, which if perforated would start the two reacting together violently and set the whole thing on fire in a matter of seconds, making it very improbable that any injured or unconscious person could escape or get rescued from the car before they succumb to the toxic smoke and flames.

      A steam leak sounds positively benign in comparison.

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