It Can Save The World - The Simple Genius of Hot Air aka Stirling Engines

[@d4a]

Single: bit.ly/4895cZz V4: bit.ly/3EuFaCy 10% Off Coupon Code: d4a More stirlings: bit.ly/3LglOVu Motivation: kzbin.info/door/t3YSIPcvJsYbwGCDLNiIKA

[@Anomalous-Plant]

You should look into the philips stirling generator! :) If it was still made, I'd love to own one

[@Eduardo_Espinoza]

Why don't we run these on volcanos instead of coal etc.?

[@woodzyfox4735]

""it's not like we have external combustion engines"" DO you know know how they work? external couldnt be a thing..

[@theblackhand6485]

Time to build an car engine based on nuclear waist. Heat, electricity, steam could be one of the key words

[@reypolice5231]

@d4a, do you have the link to the commercial New Zealand manufacturer or the other company?

[@davidblalock9945]

The interesting part about these engines is how efficient they can operate with some engineering considerations. A propane fired engine can operate extremely efficiently. The expansion of the fuel can be used to cool the cold side of the engine, while the fuel heats the hot side. The one i built for my engineering class was a radial 6 motor, as this worked out best for piston timing. The propane heated an flame to oil heat exchanger, the oil then got pumped round the hot pistons. The fuel lines the fed the burner were rapped around the cold side pistons. The entire engine case was sealed and pressurized to 10 bar. The motor operated at 44% thermal efficiency. Putting it on par with diesel engines. Volumetric power density was its one design flaw. But, I still think it was commercially viable for a standing power generation prime mover.

[@kindbrute4640]

If you ever decide to try it please come back to this comment and let me know, I'd happily invest in that. Even if it's just crowdfunding for a hobby level version

[@TheColorsInGreyLife]

because of this comment I ended up thinking about a way to cool a straight 6 with propane while powering it with the propane. The basic premise is a standard super turbo setup with a bigger turbine, have a 3 way heat exchanger with air (like an intercooler) pass through to help chill the air coming in and preheat the liquid propane. Then add more liquid propane in the rear and have it fill up the coolant lines in the engine, make a nice engine coolant exit at the top near the manifold for the fuel rail to add in standard port injection. With a direct injection added to the heads, also going to need to add the engine coolant (propane) to that manifold too. Anyways run the mix lean, add tons of boost, then fire the direct injection after the initial burn to continue burning fuel and have a little left over to help with cooling, if you want. I mean you have liquid propane, so I dunno if you need to. Anyways back to the turbine, since its a long block anyways might as well have equal length tube headers to a longer more efficient turbine with a vacuum spring (its like a tension spring) valve setup up to them (they have tear drops in the ends of the tubes then as air flows out that is fast and hot it produces a vacuum, the spring makes the valves return in place with minimal loss of flow velocity) with some basic single wall vacuum tube insulation around them to help retain heat to improve turbine efficiency. Anyways, I ended up thinking about the remaining liquid propane in the engine an was thinking using a phase change of the liquid propane with the air intercooler to make it cool down. Using some batteries I'll just run a compressor and a basic pulse tube jules thomson combo stirling cooler after the phase change heat exchanger. its still going to be initially too warm with the compressor to go back to being a liquid, so if i use another strong after cooler that works to help condense while I'm sucking out the propane into the liquid propane storage then it should work. Just need to run it with some battery power for a while after shutting it off. I can then do a refill process during start up. It will help the air be cold, the engine get to temp, propane pressures be nominal, and everything run and operate smoothly. Edit: using a torque converter/coupler setup or a from the supercharger (which i forgot to mention I would use a venerator setup where it starts at a large gear, uses a spring to compress it back to a smaller gear that slowly gets to a large gear again using the weights then disengages using a solenoid at a given rpm then has the turbine kick in, after that the turbine kicks runs the serpentine belts and pumps plus if there is any left over it connects it to the crankshaft via a torque converter/coupler) to the crankshaft. I have to say the fueling for the after spark ignition is a Lemke cycle because its a constant burn (i call it that because i came up with it) that with off load its power into the turbine. Now because the turbine takes its power and adds it into the rotation of the crankshaft its now more efficient on work energy capture as well as thermal efficiency through the use of the liquid propane

[@johnsmith1474]

@@kindbrute4640 - Lol, yes write your tel # on the sidewalk in chalk and he'll get back to you.

[@johnsmith1474]

@@TheColorsInGreyLife - Bullshitter.

[@ianmangham4570]

😮AWESOME 🤘

[@fireblow44]

The 4 cylinder version looks like a steampunk contraption. I'm in love

[@d4a]

It looks amazing in person and it's super heavy when you try to move it around, it's a real conversation starter 😁

[@kefhomepage]

I too , it looks awesome 😋.. not quite practice , but hey looks fantastic

[@SoulExpension]

I love the sound actually.

[@deusexaethera]

Steampunk is an accurate description, actually, as it's a Victorian-era technology that has continued to be advanced far beyond practical needs.

[@funeralhouse6280]

​@@d4ashow it to elon musk 😊

[@CarlStreet]

Excellent production values: lighting; audio levels; content; scripting; pacing; explanatory graphics -- Well Done, Sir.

[@SA_bluemonday]

Not to mention the props!

[@parsonscarlson7984]

Dito!

[@NoobieToob]

​@@SA_bluemonday Candle waxes and even petrol are very clean. Patrol aren't as clean as candle waxes tho.

[@KennethScharf]

Steam engines are also external combustion.

[@milesromanus7041]

And far more powerful

[@lil----lil]

Incredible. Deadly simple and eliminate 97% of engine parts. Virtually maintenance free. Near ZERO pollutions & NO dangerous chemicals.

[@mapple35]

how is there no pollution or chemicals? you still need combustion from some fuel source, even in this vid theres combustion.

[@OmegaLaser-xy4ip]

lol if it was really that much better we would all use it

[@jfk720]

And you still have to make one.

[@TheKmaki]

No torque. 🎉

[@Will-fs7oz]

@@mapple35did you watch the video? The whole point is running off waste heat.

[@flyonbyya]

I Need a big block version !

[@slartibartfast2649]

I think d4a didn't do much research on this one, unfortunately. He didn't even mention the distinction between alpha, beta and gamma types. High power Stirling engines were investigated in the 50s and 60s by GM (I think) but they never got far because of the high complexity and cost needed to achieve significant power output. Not only that, but they are poorly suited to rapidly changing rpm, which makes them a no-go for anything but generators and the like. Cool tech, but not particularly useful for anything beyond desk toys and multi-million dollar submarines. I suppose you could build a simple one to run off coal or wood as an emergency generator, but power output would be low.

[@Channelscruf]

@@slartibartfast2649He mentioned the lack of rpm variation problem, actually.

[@mixmashandtinker3266]

Ask Kockums in Sweden. They build the Stirlings for Swedish submarines. :)

[@verttikoo2052]

@@mixmashandtinker3266 We 🇫🇮 definitely need some excellent Swedish 🇸🇪 subs 🥳

[@verttikoo2052]

@@mixmashandtinker3266 Swedish makes the best 🇸🇪 Greetings from 🇫🇮

[@Jeroen74]

They can also run in reverse and then work as a heat pump creating a temperature difference between the reservoirs. They are used as cryocoolers, Philips developed these in the 1950's and a spin-off company still manufactures these to this day.

[@boudewijnb]

There are multiple companies manufacturing Stirling cryocoolers

[@MrBradshawbenjamin]

I wondered about that when he started to turn it by hand.

[@X3R0D3D]

holy crap, so you could build a water-powered A/C unit with a stirling engine and a water turbine... i need to live on land with a creek.

[@boudewijnb]

@@X3R0D3D I'm pretty sure normal ac units use compressors you could also drive with a water wheel.

[@X3R0D3D]

@@boudewijnb true, good call! hard to say which is more practical given the input.

[@RicardoTolomelli]

This gave me so many ideas! I'm planning my house around the fireplace to harness the heat in many ways, and this is definite a good way of using the wasted heat, maybe to help circulate the hot air around the ambient, or move cold water into coils to heat up, or to help regenerate electricity. Thank you very much for presenting this kind of engine!

[@therealchayd]

You can buy Stirling engine powered fans that go on top of wood and coal burning stoves, using the waste heat to circulate air. You can also get thermoelectric ones, which are more efficient, but engineering-wise, they're not as interesting.

[@codetech5598]

@@therealchayd Yeah, reading the comments, people are thinking the Stirling engine is something new and magical with great potential to solve the world's energy needs.

[@goatsplitter]

@@codetech5598 we cant all know everything all the time forever and always, especially with not so widespread things like this. Give people a little credit and be happy for their excitement in learning something new. Maybe it's old hat to you, but it's cool to others.

[@dustinbrueggemann1875]

@@codetech5598 The same kind of thing was said about Boolean algebra when he invented it in 1854. It was mostly an academic novelty until 70 years later when electrical engineers used it to design a control relay board and invent the first computer. Old ideas are not bad ideas, and we'll never know the extent of a technology's uses if people don't keep picking it up and playing with it.

[@codetech5598]

@@dustinbrueggemann1875 People have been experimenting with Stirling engines for decades. It was really big in the 1970s if I recall correctly and various big companies were involved. But, for most uses, it is not very practical and certainly is no breakthrough.

[@elchupacabra1193]

It's cool that it's on a sub, I'm a retired US Navy Mechanical Tech (Machinist Mate rating) and when you were describing this the first thing that popped into my mind was these would be absolutely amazing on sea vessels. I would also think small trains may find something like this useful as well.

[@oldbatwit5102]

@tandme2342 But they are not immense, and they have been fitted to submarines for 35 years.

[@kayakMike1000]

​@@oldbatwit5102big ones can be very quiet

[@Tuppoo94]

​@tandme2342 The Swedish and Japanese navies have attack submarines equipped with Stirling engines.

[@sierraecho884]

They are perfect for boats too since sea water is cold and perfectly suited to cool the cold side basically for free.

[@RailsofForney]

Steam locomotives used 1-stroke Sterling engines. Except instead of burning Ethanol (as shown here) they burned coal and - in the later years - oil.

[@paulhaynes8045]

A really impressive video. I've known about Stirling engines for ages and watched and read much about them, but I've never really understood how they work - or their advantages/disadvantages - until now. So, thank you for this - its wonderful to FINALLY understand something thats bugged me for decades!

[@dy7296]

Well, frankly speaking, steam engine and steam turbine as used by power plants are technically external combustion engines as well. The fire burns outside the motor in a separate chamber, not inside the engine. edit: Nuclear power still counts as a combustion. Also, that's the point of these kinds of engines. The type of heat source is flexible. And even more flexible on Stirling engine as it doesn't require extreme temps to work decently. For Steam turbine, you can take nuclear as mentioned magma heat, or even recycled from gas turbine exhaust. And on Stirling, it can even run on the warmth of the hand if tuned correctly. That type is called Low-Temperature Differential Stirling Engine. HOWEVER, stirling engines may not be as efficient as Steam Turbine hence why it ain't widely used today.

[@3UZFE]

Correct

[@johnsmith1474]

Great grasp of the extremely obvious.

[@dy7296]

@@johnsmith1474The beginning of the video mentions people who still can't really distinguish between external and internal combustion yet. So I just think I might have to make it clearer.

[@robertpayne5499]

People that don’t understand that “internal combustion” implies the existence of “external combustion” are most definitely apart of the problem in this world😅

[@winzracingNZ]

You think? Great insight. Thanks

[@Rickster621]

It's the quiet operations that submarines use them for. I made one for machine shop class, but the displacer cylinder was made of borosilicate glass and cracked due to handling.

[@paradiselost9946]

i was going to make one for my old highschool metal project... then i looked into getting inconel and stainless... pricey. then i looked into getting a slab of either wirecut, EDM... and decided to make something else. main issue that i see is the serious lack of surface area. was going to get a piston and cylinder cut with deeply finned internal surfaces, like a splined shaft but taken to the extreme. seems easier and better than the "loops of pipes" that i think the phillips used. 25 years on, guess i could get them 3d printed now. all i see is people with plain stainless cylinders, glowing redhot, transferring mere watts through the metal to the working fluid contained within... needing it to glow redhot just to overcome its own losses... andy ross had a few good attempts, shame he tried soldering his internal fins rather than cut from solid... or printed.

[@PDXDrumr]

In 2004 I was reviewing a proposal (gov) for Stirling engine solar generators. They were being developed at a NM gov lab. Expensive to produce, but the results were pretty good apparently. They used a parabolic dish at the heat source.

[@jebise1126]

but since than price of solar panels did drop a lot...

[@bizjakboris]

I was thinking the same. This to me looks like better solution than solar panels in long run.

[@wiegraf9009]

@@bizjakborisHow so? Isn't the wear of moving parts an inherent disadvantage?

[@wiegraf9009]

This was my first thought on seeing the toy engine haha

[@Menon9767]

@SaltyShaman There is a nice amount of usable compost that you can turn into electricity or hot water. But it will be just a few % of what a country needs

[@Smarty1171]

It’s a pleasure to see a video that doesn’t have an edit every five seconds. Thank you.

[@oidkqw]

I think the big missing reason on why these engines are not used is indeed their low power to weight ratio. But even with stationary applications, Stirlings tend to also be much larger than their equivalent power ICE counterparts, which in turn drives up costs. Those engines seem to rev quite fast, but the missing bit is the output torque, which will be very low for its size because air (and other gases) are very compressible, meaning that they don't push very hard on the pistons compared to steam or the far hotter air-fuel mix in ICE.

[@Jalcordoba]

What about a gas that is better at transferring energy than normal air?

[@oidkqw]

@@JalcordobaI think people have tried to use helium, nitrogen, or even hydrogen in Stirlings, because of their higher thermal conductivity, but it doesn't seem to be enough to make them competitive. From what I remember, there's more power to be gained by pressurizing the crankcase, so that the atmosphere doesn't steal force from the stroke. But overall, it seems to be a lot of engineering for too small gains to make Stirlings competitive. Perhaps the biggest merit of Stirlings are their versatility on the source of heat. You can use anything from burning trash, to solar energy, to residual heat.

[@maistooo]

If this engine is coupled with Concentrated solar system it would generate electricity per square meter more than PV cells and also eliminate water usage for steam turbines in arid climates.​@@oidkqw

[@davelowets]

Stirling engines are MUCH less efficient than I.C.E. engines are

[@MalawisLilleKanal]

Would be cool to have a small stirlig electricity generator hooked to the pipe of a wood burning stove.

[@archygrey9093]

A similar engine is the Manson engine, it is basically a stirling engine but instead of cooling down and reusing the air it simply exhausts the hot air and draws in cool fresh air, very simple the displacer is part of the piston, don't think it scales up quite well though since you can't compress the air in it like with a stirling to increase energy density. Another cool one is the vacuum engine, these work in the opposite way, they draw in hot air to the cylinder usually from an open flame and then cool it down, this creates a vacuum that pulls the piston forward, these engines actually saw commercial use for things like pumping water back in the steam engine days due to how simple and safe they were

[@paulhaynes8045]

Most (if not all) early 'steam' engines were in fact vacuum engines, only using steam to heat the air in the cylinders, and then dousing them in cold water to create the vacuum that actually powered the engine (or rather the air pressure on the outside powered the engine). Proper steam engines weren't practical until the technology improved enough to handle the pressures required.

[@paradiselost9946]

@@paulhaynes8045 the old "atmospheric". and like all vacuum motors, limited to surface area/ pressure differential, and at 15PSI max force, rather useless. not even 15PSI. and thats only when one pulls a "perfect" vacuum". and that vacuum quickly ISNT a vacuum as pistons rise in cylinders, volumes decrease, or seals leak... 10PSI is a far more likely value. a "flame licker" probably cant get past 5psi... cant say ive ever hooked one up to a MAP sensor to check? a smart man, knowing air doubles in volume for every 249C, could probably figure it out with a little pencil given a flame temperature... and james watt made the small step of pulling that vacuum outside the cylinder, thus negating the large loss of energy from the cylinder itself having to heat up and cool down.

[@billyk8161]

Sir, I believe you are Vincent Price reincarnate! Returned to tell the story of combustion engines in such a magnificent way! Not only a strong resemblance but the intriguing suave voice, superb demonstration of intellect and ability to explain a 'story' in such a compelling manner as the late great Vincent Price. I was scared, thrilled and had such joy listening to and watching this video! Thank you...

[@boutrosboutrosboutrosboutros]

Wow haven't heard that name is a while, I am a huge fan, but never saw young Vincent photos. You are correct!

[@PowerScissor]

I've seen hundreds of sterling engines, and 99.9% of them have been desk toys. They really are great for that. I have about 25 of them, and they are great fun when kids come over.

[@ronarmstrong835]

Several have been built that power cars. One was installed in an old Porsche Berg Spyder and was driven 120 MPH.

[@tkenben]

Aren't they used in submarines?

[@robertrobinson3861]

Not being pedantic, but it's spelt Stirling. It was the inventors name.

[@PowerScissor]

@@robertrobinson3861 I think most know it's Stirling. People are usually typing on a tiny phone keyboard that is going to Auto-correct or Auto-complete words...especially ones based on names that are similar to other more common words.

[@pathos2853]

@@ronarmstrong835 source?

[@nigelliam153]

NASA was experimenting with these using them in a sealed system with a gas similar to a refrigerant and using mirrors to focus the suns rays to provide heat source. The aim was to provide power for the space station

[@AingusOg]

I really like the video and I am a Stirling fan too (I have a 2-cylinder version of your V4). What I did not like is when you tell, after putting off the candles that the engine runs on "nothing". In fact the engine runs on the very energy that you needed in the beginning to heat up the hot cylinder. You use up that initial energy (to a not 100% extent) with a time shift. By the way, there are already a lot of companies working on solar powered Stirlings (instead of photovoltaic), if you can preserve the heat, you can run the Stirling later - this overcomes the biggest problem of solar power.

[@KennethScharf]

Just capture the heat from the sun in a tank of water which surrounds the displacer cylinder of the engine(s).

[@Acidalley]

wow man, awesome video. I can imagine how much hard work goes into researching for these videos and then again even harder work to produce them with all the visuals and graphics and illustrations. Seriously your channel is much underrated.

[@littleshopofelectrons4014]

Steam turbines and piston steam engines are also external combustion engines. The most interesting application that I have seen for Stirling engines is for solar power plants. Each reflective mirror has a small Stirling engine and generator at its focal point. When hundreds of these are combined, a substantial electric power output can be achieved.

[@CrollyVonHalfman]

IIRC, Boeing and the maker of the submarine mentioned in the video (Kockums, now Saab-Kockums) made a test plant in the Nevada desert, I think, some years ago. It worked just like that.

[@DisabilityExams]

The steam engine, invented by Thomas Newcomen in 1712, is an external combustion engine.

[@kokisthegangsta]

and more efficient than the sterling

[@jinz0]

English really were incredible

[@thrillchaser9492]

Interesting fact...all steam engines are external combustion engines.. Every spacecraft uses a sterling engine to make electricity. they use a decaying radioactive isotope for the heat source.. they run for decades.. Voyager 1 and 2 have had sterling engines without stopping since 1975... if you can't use solar panels you going to use a sterling engine with a generator

[@williamjames9515]

I just bought this little engine. Easy assembly, excellent instructions, stongly built. I highly recommend it!

[@BOBK-jf4qx]

Forst one is on Temu and the other on AliExpress

[@PJ-3]

Wow! I can’t believe it never even crossed my mind to consider “external” combustion. Brilliantly described as ever. I’m learning so much from your channel. Keep up the amazing work.

[@802Garage]

Remember the solar farms that use mirrors to direct sunlight at a heated element? Could use the same principle to heat a Stirling engine. Just kind of a cool concept.

[@PhoenicksUK]

Exactly what I was thinking. Banks of these feeding into the grid for more free energy!

[@iowasucks9494]

That already is patented and some companies sell a style of this design as a water pump with the water providing the cooling. They were never adopted widely for power production as the dish needs to align itself with the sun, so having a reciprocating mass applying torque on a gyroscopic mount created maintenance problems. Also, losing potential power produced through parasitic loss by requiring said power to actuate a dish proved to consume quite a bit of useable energy. BUT it could work if you use an acrylic cylinder like some small stirling models use, you could make a greenhouse effect within the cylinder enough to spin a low rpm generator. Would be enough to power lights (LEDs most likely in this case) in your house but thats about it. If you were to scale it up and gear it to an efficient generator, you could probably get it store enough energy in a battery source to run a single house hold. Would only work in the summer, in the desert, on clear days though so really would only be good in very limited uses. Interesting to think about the energy savings however!

[@Blaquer17]

​@@iowasucks9494You should actually get somewhat decent efficiency year-round with a greenhouse effect on the hot cylinder. You only need a temperature differential for it to work, and sure, the hot side isn't as hot, but the cold side would be colder than in the summer with ambient winter temperatures.

[@jebise1126]

@@iowasucks9494 basically there is simple solution. long row of mirrors that heat a tube and that tube has water that runs stirlig engine in the end of a row. no need to move at all. i think one such plant is in north africa. but solar panels are very cheap...

[@iowasucks9494]

@@jebise1126 thats a power tower that heats a medium (some form of salt if i remember correctly? Theres no stirling engine in that one) i was giving this more thought the other day and putting the cold side underground and only having the acrylic or glass cylinder exposed. Maybe having several in a row hooked up yo several generators? Hell even having an actual greenhouse, just filled with child sized stirling engines sticking out the ground? Expensive initial investment but could work. What do you think?

[@mellissadalby1402]

Very nice video. Nice explanation of the tirling engine. A way to mitigate the apparent limitation of the Stirling engine in terms of power modulation would be to use it in a Stirling/Electric system. The Stirling engine would generate electricity, which would go into a storage battery and the "throttle" of the system would be the control on the electrical current being drawn off of the battery system. No problem really.

[@drg9812]

Seems like a great way to power those pumps on a nuclear sub; there is already so much heat you need to dissipate...

[@IntenseGrid]

Yes, exactly! And downsize the batteries, and use super capacitors for millions of cycles instead of thousands, and provide heat for the cabin instead of wasting electricity for that. This is the kind of hybrid car I want!

[@cavalieroutdoors6036]

It would make a perfect little generator motor, but then you're right back to the problem of burning a fuel source to power the vehicle. It does make one wonder how well it would work though, especially given that Stirlings don't care what the fuel source is. You could burn almost anything for it, wood, candles, you name it...and you could probably circumvent the battery issue entirely by using an electric generator rather than any sort of power storage. Maybe a generic 12 volt car battery for the internal electronics, but that would be all that's needed if the generator were powerful enough to drive the electric motors without needing to fuss with any sort of power storage.

[@paradiselost9946]

@@cavalieroutdoors6036 none of this addresses the actual fundamental FLAW of the stirling engine. its just silly ways of using one. heat transfer. you have to transfer het from the outside world, through a cylinder wall, and RAPIDLY apply it to large amounts of fluid (air). you then have to just as rapidly get all that heat back OUT of the air. they may not care what fuel is used, sunshine seems to work fine, along with say... thermal mass, like hot sand, or salt, etc... but nothing will overcome that inherent "surface area to volume with time constraints" issue they all suffer from.

[@netdoctor1]

Pretty amazing. The future looks bright.

[@edwardallan197]

This guy is gifted at explaining engines of all kinds. I learned about my motorcycle engines here. He'd make a great classroom teacher or prof! In addition to virtual like this.

[@lfmsimoes1]

Hello. I am a Portuguese viewer of your channel. I was enjoying this video a lot, but enjoyed even more when you put the water bottle on the table and noticed it was Vitalis, a well-known Portuguese brand of bottled water.

[@zuzuspetals923]

I am an American viewer who was also enjoying the video a lot. I enjoyed it even more when I saw Vitalis on that bottle and had a flashback to my childhood recalling Vitalis hair tonic among Dad's grooming supplies. I googled and was amazed to find the stuff is still in production, and the bottle looks the same as I remember! And now I've learned there's a Portuguese bottled water by the same name😮😂

[@fridaycaliforniaa236]

If I can add some little facts : - Stirling engines don't need oil or cooling liquids, but given the fact that they get more and more efficient thanks to temperature differences, a cooling circuit on the regenerator side can help a lot in incresing efficiency (if I'm right they use sea water in this role in the Gotland submarines, simple and available everywhere ^^). And of course, lubricants can help reduce noise and friction losses. - Stirling engines have been tested with solar energy, in some sort of solar ovens, as they only need hot gas to be operated (in some ways, we could say it's "free energy" ^^). - For the same reasons, they are planned to be used as relatively powerful generators for space probes that usually run on RTGs, because their plutonium fuel produces much heat but not so much electrical power. - For the same reasons they are good for submarines, they also could be used for big ships, like tankers. They could actually use a small part of the gas their carry to directly run the onboard Stirling engines. - And last fun fact, Stirling engines are reversible : il you move the engine, you can get some really low temps on the part that usually receives the flame. If I remember right they are used to create cryogenic fluids.

[@whitbayles8773]

Gives way to many that love a challenge in finding a cleaner and safer energy source that can run off of the dangerous heat emissions industries and the problems going all electric in vehicles causing batteries to ignite from overheated or overcharging, too fast trying to transition from fossil fuel based industries and transportation into all electric is the results we are seeing the most from studies all over the world. Think , design, inspire honest ways to create a better life for our next generation.

[@dustinbrueggemann1875]

Important to note that RTGs do not directly produce electricity. They use semiconductor junctions to produce voltage from heat in a process very similar to a PV solar panel with light, and those junctions are actually quite delicate in the face of atomic forces such as the intense heat and radiation emitted from nuclear decay. The Stirling engine is being explored for RTGs because not only can they be more efficient in total, they also don't rely on atomic scale behaviors to run and thus won't degrade when you weld them to a kilogram of plutonium.

[@larsjrgensen5975]

@@damonhall3931 Yes but will it be better cost/power then normal solar panels? It requires a lot more maintenance then solar panels that is for sure.

[@rianmacdonald9454]

@@larsjrgensen5975 All I suggest is too look in it what it cost to make solar panels. From all the mining, transportation of said mined good, manufactory, transportation of raw material from manufacturing, to processing(making the solar panels) then transportation to place the panel. Solar panels are the worst idea ever, I feel for it 20 years ago, since then I have looked in to them properly and like I said solar panels are the worst idea going, complete waste of time. Now with the idea of a Sterling Engine, there is more than enough scrap metal, in scrap yards (I worked as a HGV driver doing 4 or 5 runs a day, picking up 30 tons of scrap metal each time - add another 10 trucks daily like me) and that was 1 site for 1 company in UK. There is a very very cheap source of materials in which to make thousands of Sterling engines - I like the idea of adding them to current power plants for any waste heat, along with other applications - hell in places like Australia(well, any country with a damn desert really), using a Parabolic dish reflector out in the middle of their deserts - the heat over there - there is a huge source of electricity production. I can see a lot of usage for Sterling engines - granted as stationary power generation - but still more than enough to help with the swap from fossil fuel power stations to Fully Nuclear.

[@larsjrgensen5975]

@@rianmacdonald9454 So how much does it cost to melt down scrap and build a precision stirling engine with a usable output? The one he shows lights up a 1-2W LED, that is nothing compared to a old engine running on cooking oil, connected to a car generator, if you want to go cheap. You can not add stirling engines to collect waste heat in a powerplant, they mostly heat up steam and run steam turbines. Water heating to steam needs less temperature difference then a stirling engine needs, so every watt of waste energy a stirling engine could produce, could have been used better for heating up water instead. By adding multiple stirling engines you are essentially mounting generators onto the wheels of a electrical car and thinking that the car now will run forever because 10 generators are feeding back energy into the battery. I can buy a 175W solar panel for 100$ with 25 years of warranty that it will produce 80% of rated output, a stirling engine has no chance competing against that.

[@seankirby1327]

They were used as water pumps at wells for years.I believe one of the 1st types used for this..run very well at a fixed rmp .

[@leelemon3373]

I bought a sterling engine as a show piece at home. You taught me how smart that engine is. I can now explain how smart they are. Thank you. 😎

[@glennaltpeter8917]

I made one in College (Mechanical engineering) -1976 suggested it be use in automotive applications. Different temperature between exhaust and radiator temperature. Could power accessories to allow for smaller sized engines.

[@Greeneyes3005]

I wonder if a magnifying glass set to the correct distance could heat the sun’s rays enough to run it from solar heat …. Scaled up it could be pretty phenomenal as a water pump or to run lighting Etc 🤔

[@HardDrive-r6t]

This is a wonderfully detailed explanation of a little know type of engine. The models are well developed and add to the visual appeal of the subject at hand. Pacing, demonstrations and introductions are all well done and very informative.

[@3UZFE]

Wonderful video, great as always. Stirling engines maybe old but their relative simplicity and use of waste heat makes them quite compelling for specific stationary use cases.

[@Branislav-d6y]

1st time I saw your channel 1) Very good explanation (simple and easily understandable for everyone) 2) Immediately understood by looking at the well - imaged engines 3) Last but not least - You have a fantastic voice!

[@Geek-A-Hertz8707]

they already have combined cycle electric plants. i think a steam turbine is used to harness waste heat from gas turbine exhaust.

[@ludwigreiser4053]

Thanks a lot - great explanation! Range extenders for electric vehicles could be one of the right use-cases. And the waste heat is welcome in wintertime to warm up the batteries and the interior.

[@HiTechDiver]

I love Stirling engines. I want to combine a good size Stirling engine with a fresnel lens that tracks the sun, for an absolutely free heat source. Should be interesting.

[@spiritlevelstudios]

Decent idea. You mean free power source?

[@dallassukerkin6878]

Sterling idea! See what I did there? :D

[@nickgrazier3373]

The British Industrial Revolution has a lot to answer for, all these things that were invented and no one’s bothered in a substantial way! Thanks for showing what this can do, of course what you showed does mean also that you don’t need to continuously use heat on the engine just enough to raise it to working temperature. This means it is more economical than it looks if you are using a non linear heat source. So! Heat on to heat, stop heat, sense low temp, heat on to heat - continue. Cheers Aah Kid! Keep up the good work mate!!

[@murrieteacher]

I have played with Stirling engines for years but I have never seen one like that. What a great video. I had never really extended the use of these engines the way you mentioned.

[@georgebarnes8163]

It is a copy of the mass produced model Stirling manufactured by the Phoenix engine Co of Arizona

[@Google_Does_Evil_Now]

Can it be solar powered by using it with a Magnifying Glass focused on the hot air bulb?

[@justmechanicthings]

Very neat, I could visualize a sterling engine in a hybrid electric car working as a range extender rather than being connected to the drive in order to mitigate the power modulation issue. Maybe energy from the battery could even help preheat the engine from a cold start. Still not the greatest application but would be a cool engineering experiment

[@davidjones-vx9ju]

in your dreams

[@vincentl.9469]

@@davidjones-vx9ju You would think by now , if this worked , it would be in wide spread use?

[@davidjones-vx9ju]

they work, but don't have any ,or very much , HP@@vincentl.9469

[@georgebarnes8163]

My wood pellet burner has a Stirling engine which runs of the waste flue heat, it runs a generator which can produce up to 1.5 Kw @ 230 volts.

[@davidjones-vx9ju]

1.5 K / .... hour?@@georgebarnes8163

[@slartibartfast2649]

High power output Stirling engines are substantially more complex than ICEs. They have very sophisticated cooling and heat regeneration systems, as well as highly intricate piston sealing and lubrication designs to cope with the extreme and continuous pressures and temperatures required for high power output, as opposed to very short periods of high temperature and pressure in an ICE. On top of this, to achieve high efficiency, a working fluid with high thermal conductivity and low viscosity is required. This is usually Hydrogen, which can permeate straight through most metals!

[@d4a]

High power output anything is usually complicated, ICE too. But you don't need high power output to reap the benefits of these engines.

[@slartibartfast2649]

@d4a it's true, but when GM (I think) tried building one in the 50s and 60s, they managed parity in terms of power and superiority in terms of efficiency, but much worse emissions and a huge increase in weight and cost. They also don't like changing rpm, so anything like automotive applications is off the cards. Unless you can foot the high price (like in a sub), the only application I can think of is low power pumps or generators that run off natural fuels for rural areas and the like.

[@dannypipewrench533]

@@slartibartfast2649 Automotive applications come back if you consider series hybrids. Change in rpm is not too important as the goal is to run the engine at its optimal efficiency and let electric motors powered by a battery charged by said engine do the hard work of acceleration. We do not need particularly high power, and as a result, the greater weight for the same output is not too problematic. The greater efficiency is the main goal, not power. In 1986, NASA did manage to greatly reduce emissions with their Stirling engine design, so I am going to pin poor emissions on GM, the era, or technology in general.

[@cristianseres1353]

Excellent video! Stirling engines have a theoretical efficiency of 40%, but apparently a lot less in practice, one bachelor's thesis shows about 20% and some sources claim less than 10%. For waste heat anything is better than nothing.

[@peymanalayee]

I am from Kurdistan I am very interested in stirling engine and I want to build one and combine it with my boiler and pyrolysis reactor to produce both diesel and electricity from waste heat. I can honestly say it was the best explanation I heard during my research. Finally, after a long time, I understood Sterling's working process correctly. Thank you

[@wumarNart]

11:13 This opens the potential of using fire to produce light....

[@JackieTheTruck]

What a novel idea! 😂

[@Alfaduk]

Very cool. As a range extender for an electric vehicle, like the submarine example you gave, they could work well. It would be interesting to know what sort of temperatures the pistons are subjected to. Creating a very low friction engine using Teflon pistons and bores might be possible. Having opposed pistons, rather than in a V configuration, could provide some nice benefits to smoothness. Especially if there are 6 or more pistons. And having the non-working piston a better fit in its bore, but with passages for air to travel through the piston, might also reduce some of the rattling noise it makes. As for wasted heat. I work at a steel works. We cast slabs of steel and plonk them on the ground to cool down in the open air. 1 of the biggest running costs for the steel works is electricity............... Australia............

[@sierraecho884]

The newest gen. of commercial Stirling engines use no oil ( also an ignition problem) they use PTFE rings and work for ca. 24 years constant without fail. So they are incredible reliable. Their downside is they need to be big to create a good power output. They are also what´s called a FPSE Free Piston Stirling Engine (beta configuration) with even less moving parts, specialized to create electricity. There is basically only one cylinder sharing the power piston and displacer piston which is more space efficient. They are also completely sealed and run off helium which is a ligther gas to increase power. They are also pressurized so about 3-5 atmosphere. Even NASA used them in their space exploration program to generate electricity (same free piston design I mentioned before)

[@Erik_Swiger]

This is something I've thought of since I was a kid. It's always been met with, "It's not cost-effective to use waste heat." My thinking is, ANY energy you recover, is better than no recovery at all. If you put a Stirling in the exhaust stream of an Atkinson-cycle engine, or even a turbocharged engine, there's plenty of heat energy to create electricity. And the Stirling doesn't need to be some high-tech, overly-engineered design, either. As you've shown in the video, a basic machine made of simple parts performs well, and if car makers say it's "not as efficient as it could be," who cares? I can see creating an aftermarket unit than can be adapted to at least a few cars. It's not just electric hybrids, either. You could add a Stirling generator to most any car or truck and make 12 vdc for the battery, taking some load off the alternator.

[@ls6097]

Carmakers are not concerned with innovation and engineering solutions in the sense that the public uses those terms. Carmakers are concerned with complying to government dictates. You will find plenty of engineers working for carmakers who are not in charge of anything but are as enthusiastic and capable as possible for true innovation and engineering solutions in the sense we think of, but that is precisely why they are not in charge of important decisions. When they adopt the mindset of satisfying government dictates rather than what makes the most sense, then they are permitted to take the reigns of the company. Welcome to totalitarian America, you were born it. Covid just accidentally made it possible for you to peek behind the curtain to see how plain this fact is.

[@petevenuti7355]

​@@ls6097you sound like that was your job for a while.

[@Crosshair84]

"ANY energy you recover, is better than no recovery at all." Incorrect. Would you work for $1 an hour as a second job? Of course not. Because the resources you put into the process, your time and effort, is not worth the resources you are getting out of it, the $1 an hour. Likewise here. What do you gain by spending $10 recovering energy from waste heat if you only get $5 worth of energy out of it? You don't gain anything, you are actively wasting resources by trying to recover this energy. "If you put a Stirling in the exhaust stream of an Atkinson-cycle engine, or even a turbocharged engine, there's plenty of heat energy to create electricity." This is true. There is plenty of heat energy to work with there. "And the Stirling doesn't need to be some high-tech, overly-engineered design, either." This is where you are wrong. It absolutely DOES need to be a high tech design in order to be light enough, compact enough, and generate enough power to be worthwhile to fit into a car. Which is why nobody does it. Because it's too expensive to do. "As you've shown in the video, a basic machine made of simple parts performs well". Sterling engines are deceptive. Due to the Square-Cube Law, they work well at very small scales. Like here. Because the surface area of the cylinders is large relative to the volume of the cylinder. So transferring heat into the working medium is easy. However, the larger you make them, the less and less well they work. Because it gets harder and harder to transfer heat into the working medium. You have to start doing things like using a pressurized working medium, fins on the inside of the cylinder head, and other elaborate engineering. "You could add a Stirling generator to most any car or truck and make 12 vdc for the battery, taking some load off the alternator." You'd probably get enough energy doing that, with simple engines like these, to charge a cell phone. You'd spend far more energy installing such a system than you would ever get out of it. Which is why nobody does it.

[@petevenuti7355]

@@Crosshair84 it does make sense for a stationary application like a wood stove or a home generator to make combined-heat-and-power.. but in that application you end up paying triple anyway because you got to get certified by all the unions and agencies (multiple overlapping UL listings too) associated with electrical as well as heating and plumbing excetera.... It sad when red tape becomes most of the cost...

[@flexairz]

The efficiency is way less, can only be used to convert residual heat in boilers and things like that. But we need to look at energy return on invested (EROI). If not positive then..

[@dominichayes9808]

Another really cool and educational video. Many thanks.

[@slicedbread9003]

Thank you for that. I first experienced Stirling engines at an Antique engine display. I came away impressed. Did research and saw the downsides. It is good to see that those are being overcome and organizations are getting good power output now.

[@fluiditynz]

External combustion engine have a lot more efficiency promise than internal but stirling engines have a power to weight ratio that is fundamentally constrained by the the regenerator's surface area drag on the working fluid which squares with RPM.

[@slartibartfast2649]

Also high specific output requires high pressure low molecular weight gas. This is usually Hydrogen, which permeates straight through metal, and so leaks out of the cylinder block. Stirling engines certainly have their place, but it isn't in cars like GM tried in the 50s. Constant power output is where they really shine

[@Gearz-365]

I have a beam Stirling engine that powers a small DC generator. Its a nice little machine

[@Brian-bh2ix]

Awesome video, can you do a second one going into the different configurations of Sterling engines and the pros and cons of each one

[@shailendrajha9280]

Being PhD researcher, I fascinated by the potential of Stirling engines in clean energy drive. I am working on designs where striling engine can be used in opposite way- to cool the surrounding by providing mechanical energy.

[@chuckrock6765]

Could it run on solar heat? Heating it with some sort of solar oven.

[@hans-uelijohner8943]

Good video, but like any thermal machine, the Stirling engine underlies the limits of the Carnot cycle, so it needs a high input temperature to have a significant efficiency. An even bigger problem is that, again for high efficiency, it needs a high pressure low density working medium like 300 bar hydrogen, which is very difficult to seal for a long time.

[@teebob21]

Yep. You can quickly tell in this comment section who has never taken a Thermodynamics course, and those who have.

[@deusexaethera]

I see you've discovered these fun little toys too. 😁 They are indeed intriguing, considering they can run off solar heat, especially if the cold end is buried underground where it will stay chilly all the time. I once "turbocharged" one of my toy Stirling engines by putting the hot side on a cup of hot tea with an ice cube sitting on the cold side. (video on my channel.) I even made one that's baby-powered. (also a video on my channel. 😁) However, as a means to harvest solar power it's still more maintenance intensive than good old photovoltaic solar panels.

[@frequentlycynical642]

Been hearing how Stirling engines were going to save the world since I was a kid. That was sixty years ago.

[@thomascorbett709]

Gotta love a Stirling engine, I've got a big beta Stirling engine in a workshop, you light a fire underneath and it runs, I got to see Dad run it once on a cold day. Fascinating contraption, it was made by an acquaintance in the area decades ago when he was trying to sell them I believe.

[@mojoomla]

I learnt so much from this lovely video ! Got to see those shining Stirling beauties for the first time ever. Thank you for producing this video.

[@LelekKozodoj69]

I think that power modulation is not so big issue these days as it was couple od decades ago. Now we have hybrid cars and the excess of energy can be easily stored in battery.

[@Pyroteknikid]

These can run on solar energy if the hot side is dark to absorb sunlight and the cold side is shaded. Bonus points if you use the flywheel as a fan for the cold side.

[@ben501st]

A magnifying glass or mirror(s) could concentrate solar energy on the hot side. Might not be practical but could work in theory.

[@wiegraf9009]

@@ben501stThe problem is tracking the position of the sun with the glass

[@matouskolator40]

You can actually power them with waste from conventional nuclear powerplants. Nasa uses that in space, with some slow decaying isotopes of something to generate heat for the stirling engine to make electricity. Nuclear waste has similar properties so you theoreticaly could just hook them up to some used uranium rods and let them run xd

[@GamerKiwi]

My late step grandfather built these (and made little buggies that ran on them) and learning more about them was really nice.

[@spyforcekid]

I must commend the way you explain the technicalities of the subject matter. Your accent leads me to suspect your not an Englishman but your English is top notch and your explanation spot on👍

[@TundeEszlari]

Brilliant content, keep it up. :)

[@dimikraa1135]

Very nice video, Maybe they can also be applicable to scooters as they don‘t change their rpm (well they do but only at max speed or at start). also scooters might be a lot lighter and even more cost effective?

[@Ramonatho]

Wouldn't a Sterling scooter require a clutch which kinda defeats the purpose of most CVT "twist and go" scooters?

[@dimikraa1135]

@@Ramonatho actually a cvt scooter also uses a clutch 😅 its controlled by the power the engine produces (aka the RPM) so basically you could control the power of a sterling scooter with controlling the clutch instead of your throttle. So the clutch becomes the new gas pedal and you change the amount of grip the clutch has with your hand. but well that causes other problems, the clutch has to work a lot harder than usual i guess

[@poodlescone9700]

I am surprised the Stirling engine is not used more in conjunction with solar reflectors. Environmentalists love to push for solar, but ignore the damage done from mining for rare earth elements to produce those panels and there is currently no way to recycle them profitably to make it widespread. Solar reflectors and the stirling engines do not go bad, can be repaired and can be recycled with regular scrap metal.

[@user-kp1ml5wq4d]

This is the coolest thing I have seen in a while bravo man bravo. This is the future of education.

[@jsw060943]

Finally I now understand how this marvelous engine works. Now we want to industrialize their use in electric power generation. How to collect all that unused heat and pass it to a Stirling based generator? Interesting. Great video. Thank you for posting.

[@diegojines-us9pc]

for over 100 years these motors have proven to have the strength to run itself, and nothing more. they teach that in the 6th grade.

[@customsongmaker]

Go back to 6th grade and see if they had a fire burning under it

[@dannypipewrench533]

As demonstrated in the video, even a small one seems to be able to run an electric generator. That gives it a lot of potential.

[@theglitch99]

If the governments could get one of those external combustion engines to run off of people's dreams and aspirations, they would mandate them.!😂

[@noahway13]

This guy talks like he just got his kid to sleep in the next room.

[@AlphaPoppa38]

When those kids wake up it is the worst feeling in the world

[@2degucitas]

He's the anti-WATOP

[@MaseraSteve]

My very first KZbin video also sound quite awkward because of that issue, shared household.. It's embarrassing but as time goes on I don't care..

[@MarikoRawralton]

Speak softly and carry a big stick

[@LOFIAD]

😂

[@DespaceMan]

I built one from scratch as a kid but instead of using a burner to heat up cylinder 1 it was mounted to a parabolic reflector. With some tweaking & alignment plus a long connecting pipe including a long crank arm to reach cylinder 2 behind the reflector it actually worked very well. I attached a dyno from the fly wheel shaft & it was able to produced around 3 to 4 amps constant while the sun was shining, charged up my 12v battery for free thanks sun. I actually one first prize when I entered into my school science fair, being a 14y old I was quite proud that day. You can make energy just about from everything besides fossil fuels but you will still need oil for lubrication, sure my project worked great but prolong use did cause detrimental wear & tear especially the hot piston without lubrication. I guess with further designing & adding oil rings, bushing & lubrication injectors plus a oil cooler it's possible to make it work for long durations, only when it's sunny that is 😁maybe combining it with solar you can boost your charging capacity.

[@Ajagodkin]

What a great explanation. It does seem crazy we don't use this for waste heat everywhere

[@lenbones7940]

hands down you still hold the crown as the internets professor anything that burns fuel and can convert said fuel into motion.. keep doing u homie it's a legit master craft to continue to make such brass tacks engine description video essays and in a appropriate amount of time with what's taking place breakdowns and not have it be extremely dry and overly technical... i stand by the fact that with your channel alone the world on a true global scale could end engine and automobile ignorance if all middle schools just took a month outta one of the middle school years and back to back binged your channel perhaps with a shop teacher or something... sure it can be said it's knowledge that's not important enough to do that but when society has for decades and will continue to use engines for people's personal transportation as well as electricity generation and everything from maritime to long haul trucking all the way down to everyone whose ever pulled the string on a lawnmower all of this has been taken for granted on a mass scale for so long its almost viewed as magic by some and wouldn't it make sense that innovation would prolly favor the death of ignorance meaning the more of the population that's knows the pros and cons all forms of fuel combustion energy systems the more likelihood for a truly huge step taken in new technologies or even just new better takes on old stuff... surely that situation is far more bountiful then a world where we have to just deal with what ever the same old mega corporation just hack together and give us the finger tell us to deal with it then mark it up just becuz they can.. it's no mystery how things have gotten so outta control.. when the masses don't know how things work you cannot ever expect them to understand the vast effect that has become reality after some much time of just not even pretending to be trying to do it better and safer with less fuel and more out put... that whole sentence is almost by definition the opposite of how capitalism works

[@paull6425]

Thank you for highlighting this engine and exploring pros and cons. Scaled up, it could at very least supplement domestic power supply. Bottom line however is that we simply have to consume less power and overall ecoligical resource.

[@soupernutt9508]

Nice video. These have been around since 1699, when Robert Stirling invented it. That's why you were able to order a kit and build a very small one. Though in theory, they are very efficient-- in use, they aren't nearly as thermally efficient as internal combustion engines. And that's why in the 400+ years of their existence, they haven't caught on except in tiny hobby kits.

[@Jeff_Seely]

When I was a youth I hungered for knowledge of how things worked mechanically. I was exposed to the Sterling engine at a young age and many other engines and I was hungry to know more. Now I am older and I work with electro mechanics and have so for decades. It is my hope that that is not lost and I am sharing videos like this with the youth that I know to spur an interest I once had in my youth. I encourage everyone who watches this too forwarded to their youth that they know. Pick five kids and share the video!

[@markbrown9765]

Years ago I machined a Stirling engine, from a set of plans I got online, that ran on the difference in temperature of the ambient room air and the palm of my hand.

[@tuna22lm]

Wow sterling engines are pretty cool that's for sure, need to be installed in useful applications.

[@ManyHeavens42]

I'm disappointed nobody discovered induction heat or acoustic heat

[@lesking6541]

Ive watched many explanations of the Stirling Engine. This is the best.

[@standlegweak9854]

I think that's the best explanation of the Stirling cycle I've ever seen. I'll forget it, of course, but I can always come back to this video to learn it all over again.

[@dans-designs]

I do love these engines! I can imagine a small stirling engine running off a sand battery that is heated by the power collected from the stirling engine.. it may need spinning up with a drill for a little bit first but after that it might be self powering

[@YayComity]

Good video. I especially appreciate how the comments reflect how it spawns imagination.

[@JeanSchlemaan]

dude. you should be teaching world peace to everyone too or something. i wonder if this guy should run for president of the world? greatest teacher/explainer ive ever seen.

[@GNU_Linux_for_good]

I like the way you're narrating things.

[@BenzinioB]

I'm a huge, huge, huge fen of the idea... and I really dont understand why they are not more popular. Combined with geo-thermal and CNG this should be the base power of the future!

[@markissboi3583]

Make a one the size of 20ltr drum that turns a pump to water the garden or such

[@markissboi3583]

talking about engines all day dont make hay

[@urvhalt]

I have seen that, but even larger, like 200 ltr. A large combined striling engine / water pump, utilizing the passing water to also help keeping the cold side cold. A small wood fire poweered the thing.

[@Erik_Taurus]

Thanks! This was very informative! I tried watching other "How Sterling engine work"-videos and I knew less about these engines watching those videos. Watching this video I know (almost) exactly how the Sterling engine work!

[@rianmacdonald9454]

Very good video, very well put together and very good clear explanations of the topic. Enjoyed the video a lot. Thank you. You also reminded me a guy I went to High School with.

[@justinanderson267]

The first thing I noticed about the difference between internal and external combustion is the rhythm. Internal combustion is prone to misfires and skipping, whereas the external combustion engine keeps a relatively steady tempo

[@Linusgump]

This is a Sterling engine (I’m sure he says it, I haven’t watched but 1:45 of it so far), but it doesn’t even need combustion to operate, just a temperature differential. The Swedish navy uses one to power a submarine, using the heat of the people and computers inside as the hot side and the sea water as the cold side. It is so quiet and efficient it was able to sneak into a US aircraft group and torpedo the carrier during a war game. They have been around since before or right near the first steam engine, but were more difficult to design into a mobile use like trains and ships, which is why the steam engine won out.