The Stirling Engine Project 

"Without a way to quantify engine power, you're just jerking off in circles". That's one way to put it. Subscribed

After seeing this, I feel my life won't be complete if I do not build my own version.

How this channel hasn't got a hundred thousand subscribers is beyond me. Thanks Leo for your videos, and even more for your passion.

This is just an amazing design! Thank you so much for sharing the project with us! Are you sharing the 3D model files? I would love to print one for me.

I like how you use whatever seems to do the job without staying at conventional materials and techniques. Looking forward to what this engine evolves into.

Love this video, it perfectly explains my thoughts on the sterling engine. I live in Canada where it gets to -35° Celsius for a couple of weeks a year and inside we have a fireplace roaring. I've always thought a sterling engine attached through the wall from the fireplace to the outside would produce quite alot of energy. Keep going with the project, can't wait for an update!

Your sterling engine design is unique from other sterling motors. Your on to something of immense value to all mankind. The is ready for simplicity. I wish you well in your endeavor. Live long and prosper 🖖.

I've been a Sterling fan since I was 12yo. I'm 69 now and still a fan. A Regenerator actually is very important for the overall thermal efficiency of the engine. Why I never thought of a Displacer/Regenerator combo' is beyond me. It helps to address the 'dead volume' issues associated with a dedicated, external regenerator and associated plumbing. Great Work!

Wonderful ! I have been building Power Stirling engines for 40 years, & never thought of a Plastic Body! Genius!! I also use thin Drawn Stainless Steel "Cups" most flour & sugar "Dredges". My Hot End gets Red Hot and I attach it to the threaded Stainless cylinder ring with brazing. I used to use JB Weld where you are using the Silicone. Great work & Thanks for show it to us!!

The stirling bug bites hard. Lol I just love the whole idea in these amazing engines. Your take on it is very nice! Cheers

Underrated. Thanks for outlining the psychological pitfalls.

I completely understand your addiction and I completely understand your need to build these engines. Around 15 years ago I saw my first Stirling engine and it immediately transformed me into something I didn't recognize.....and I have never looked back. The addiction has become so strong I bought a Bridgeport a lathe and a plethora of other machine shop tools. My background as a machinist also came into play. I live for these engines.. well that and metal detecting. But these engines are certainly at the forefront of a lot of my free time. I live in the snow belt so I have a lot of time to work on these engines when I can't swing a detector. I have to say that your engine is absolutely beautiful! you did a fantastic job on it. That is an engine that any builder would be proud of! You'll get the bugs worked out of it, that I'm sure of. These engines look so simple and so easy and yet they're extremely complex as you were saying. I made the mistake of thinking it was a cakewalk making one of these engines and I failed miserably again and again because of that. I didn't give these engines the credit and the respect that they deserved on the onset of building these and I paid for it with failed end product.

That must be so satisfying when you hand crank that engine and it starts up :D

What an elegant design. Could help looking deeper into 3D-printed ceramics or some aerogel parts to deal with thermal issues. Very good editing style! Thank you for sharing.

I am more impressed with your ''stick-to-it'' attitude more than the actual engine. Thank you for the factual , no nonsense , very helpful project. Keep on , Sir. !!!

What an entertaining and educational video! Thank you for sharing your experiences with us. I really appreciate it.

Well done on your brilliant design. I built a small eddy current dynamometer about 20 years ago for characterising small electric motors. However the interesting thing about a sterling engine is its efficiency, not is power output which is low. So measuring the output power of your engine in its current configuration is pointless, because you cannot measure the power in, and therefore you cannot optimise it. You probably need to change it so the power in is through a electric heating coil, then you can measure Watts in and compare that with Watts out.

I have been wondering just how many stirling engines there must be out there. I am starting on my third engine. I built one that i remember seeing when i was 10 in a popular science magazine 1960 . I found the article on the internet, and after 62 or so years of yearning to build one i did. These are wonderful toys for 74 year old dudes to play with, in my opinion.

Congratulations, you make a fantastic job!! I have seen a lot of Stirling engine videos at internet but yours shows a trully revolution at the area!! Making the cold side of engine with plastic material will keep the cost of equipment achieveble by the majority of people!!

Leo, as a dynamometer use a permanent magnet model aero electric motor as a generator. Couple it directly or via a belt drive to one output shafts of the engine. Measure its output with a small digital wattmeter. First Calibrate the efficiency of the generator itself using an identical motor to drive it. Measure the speed using a tachometer. Use an identical second motor to drive the first motor used as the generator. The input and output power to motor can be measured with digital wattmeters. The generator can be loaded with 3 identical resistors in a star connection. Instead of digital wattmeters, ammeter and voltmeters can be used to measure input and output power. For example, the output load resistor current can be measured with an ammeter. The power output is 3x I×I x R where I is the current through each resistor. Obviously, the efficiency of the generator is equal to the output power divided by the input power. When using a second motor and a resistor load, the efficiency of each motor/generator is equal to SQRT (3 IxIXR/W) where W is the input power read by the digital wattmeter. This efficiency should be about 95-99%. Then the engine power output can be measured as equal to the ojtput wattmeter reading divided by the generator efficiency at that speed. Speed dependence of generator efficiency could be a problem, so you will have to measure it at various speeds. The motor-generator setup would facilitate that.

This is the most awesome thing I’ve seen in a long time.

Love this subject. Designed a Sterling engine 40 years ago - wow - that was tough to type. Have had a warm place in my heart for them ever since. The Reverend was a phenom. Check out the Philips Stirling engine. Cool stuff.

Hey Leo, this is the first Stirling engine video I've clicked on. Thanks for the addiction warning. I haven't watched your other two yet so maybe you have already employed the MPD-L1060 in your dyno design. I found brushless motors to be an excellent load when used as elecrical generators. If you mount them to be rotatable about the shaft axis and measure the torque with a strain gauge you can get a very dynamic data set that is easy to read with microprocessors. The speed is easy to pick from the output voltage waveform.

I have a toy sterling engine, but want to build a thermoacoustic resonator with reasonable power. One thing you might consider is a hybrid thermoacoustic / sterling engine which uses a speaker for the piston and another speaker driver inside the chamber to move the displacer, while making the displacer far less dense and much lighter with air holes (think swiss cheese displacer which doesn't get so close to the heated surface), which has much shorter travel and requires less energy to move back and forth due to much less linear motion. This design would be all electronic powered by a microcontroller and audio amplifier and some fast accelerometers or linear position sensors. Efficiency of heat engines is limited by thermal difference, and the holy grail is high efficiency with low thermal difference. Also measuring the power produced in this case is easy, speaker output is the sine wave output into a resistive load with voltage and current monitoring through the microcontroller. But I love this video, thanks for making it, but as you can see, I've caught the mental sterling bug. There are some very interesting commercial thermoacoustic devices and research lab prototypes out there to gawk at.

I used to work for a canning company and the packs were wrapped in shrink film, the heat tunnels that the packs passed through to shrink it would feel hot from the outside. As it happens they had cold water drains running underneath them. My idea to them was create a sterling motor that extracted the heat from the outside of the tunnels with the other end in the cold water. From my understanding the hotter one side is in relation to the other produces more drive. We had 3 massive units that would run 24/7. They wouldn't spend the time even considering it even though we had engineers doing nothing half the time. I am sure it was possible and would have produced a lot of energy over time. It would not have been anything like your design though. You speak of optimization but those units were at a constant 160 degrees C. If anyone can figure out a good design i would think companies would take it up as how many companies shrink wrap their packs and saving energy is becoming a big issue in industry.

I have been fascinated with Stirling engines for many years. never tried to build one I think I may have to now. Great video, you got a new subscriber

Good to see your engine in working condition. The regenerative displacer is one of the biggest challenge I think. Low friction, good volume of steel wool, but the stainless steel better for this, and the low as possible leakage. I mean the displacer leakage how big portion of gas not goes trough the regenerator section. For a long time usage the cold side plastic part should be shielding from the hot side with a trap for the flame also some high temp insulator blanket between the surfaces. Are the gears in good condition? I will follow your work, because it is so detailed and precise. I like to use 3D printed parts, but actually mine doesn't work well. So keep up the good work! Congratulation! BLADE

Very nice to follow the construction of your engine and I am happy that you visited my channel. Really, what is simple about a Stirling engine, it is not at all simple to get good results, the amount of challenges that the engine presents, is addictive. Let's see your dynamometer, I always wanted to make one, it will be a pleasure to see your walk.

Thanks for the ride along and the video! Making these is difficult and sharing your experiences is a very caring act. Thanks again Leo!.

I can relate to this. From time to time I also have the urge to build one. Sadly I don't have the manufacturing capabilities so I got a small teacup version and like to watch it

the displacer shape reminded me of a Sloan toilet/urinal flush valve inner parts, great video

Thanks be to youtube algorithm for bringing this one up. Amazing design, you are lightyears ahead

For the dyno I would suggest using an electromagnetic break system(a tube within a tube with iron powder between them and an electromagnet in the center tube would do the trick) with a load cell to to get the torque, but I cant wait to see what you come up with.

Loved this presentation.. I built one way back in the 1970's and yet the rabbit hole was very deep... Great engineering!

I designed a simple dynamometer that has a mountain bike brake rotor mounted to the shaft and an arm supported by a bearing on the shaft which has the brake caliper mounted to it. The arm is linked to a small hydraulic cylinder. The length of the arm and the diameter of the hydraulic piston are such that a pressure gauge will give a direct read-out of foot pounds of torque in pounds per square inch. I am hoping to build a Stirling engine that is light enough to power an aircraft. Thank you for sharing your work. It is inspirational!

The thermal isolation with this thing is super impressive

You're sucking me back into my old stirling engine obsession. :) But if you could maybe create a github repo with your fusion360 and/or stl files, you could get some contributions from nerds like me. Help us, help you, help everybody. Thanks man!

Subscribed and Liked. Really like the way the information is presented. More logical and better explained than lots of other channels. I hope you will continue this project and go into the actual power output across temperature ranges. One thing that did occur to me was the use of a passive water cooler using the heat difference to induce flow. That would, for me, be an intersting addition to the project.

Great video, Leo. Congratulations. I love Stirling engines since the 80s. Without the Internet, the most I could get was to find a great technical book about them in the university. There was little material information to get about Stirling engines. I remember that when the Internet was initially fledgling, to "test" how was it: the very first query that I submitted was precisely "Stirling engine". I still remember the feeling of getting all that information! Wow! Internet was great if it could easily get all that info about a theme that was so "difficult" to know in those days.

Hello, Leo, Excellent videos! I will be watching more of them. Keep up the great presentations!

Hi, Leo this is another Leo. I have build a stirling engine and fussed with a displacer. Idea I came up with was to use course steel wool as there are more air gaps than fine which allows for better heat transfer between between hot and cold strokes. I also used small pieces of 1/4" mesh screen and very thin large washers to capture the course steel wool and form the displacer piston.

Stirling engines are highly addictave and often called a 'gateway project' to even more hardcare projects such as quadcopters and even small scale hydroelectricity.

Several years ago I got sucked into Tim Sefton's Kickstarter Stirling engine project. Got nothing for my several hundred dollars. It's the technology that's always just out of arm's reach. I developed a heliostat prototype hoping to eventually be able to run a Stirling engine off of solar power, but never got a practical engine to try it with. Keep the flame alive brother.

Excellent video, totally captavating stuff.... Thanks ..... Thom in Scotland.

Print the upper parts in ASA, this is able to work in hot ambient (Print-Temperature ca. 240-260°c) and you can close the cappilars by flushing it once with e.g. isopropanol, an alcohole. I printed a little Arielle for my daughters aqarium of it. I placed the figure some minutes hanging in a closed glas with a shape of alcohol on its bottom. The cold steam is enough to do the job. While drying, the surface gets fluid and melts together - so the capillars disapper. If you let it too long in the glas, the chemical melting gets deeper in the figure, so it gets weak and may loos its form. so, be careful. ... and of cause .. dont breath in too much of it 🤪

You are right about that trap! I feel like many an engineer has spent their career searching for the answer to stirling engines and CVT's. My mind has been on this for 20 years! I like the next step of measuring. Please show that dyno build!

These engines are fascinating to me as well! I tend to like the variations that are capable of running on low temperature differentials. They run beautifully smooth and suffer much less from melting and oxidizing components (provided you don’t try to over clock them). The big challenge with them is reducing friction as much as possible. That’s very difficult with so many moving parts. Great video! I suffer from the same obsessive behavior, but it’s so much fun so I wouldn’t have it any other way.

man you made me stay the entire video, great job!

Really enjoyed this video. Good luck!

This was very fascinating! I wholeheartedly enjoyed your video ! Your Stirling engine has to be one of the most unique I've seen to date. Thanks for sharing.

It's criminal that you only have 3k subs! This is amazing!

Very cool, and it sounds great. I remember reading about a Army project for a sterling engine generator, something like 30kw with a swash plate crank. They used helium for the working gas but it kept leaking out. Keep up the great work

That's a beautiful build! Thanks!

As always, your projects are worth the waiting, well-thought-out and very informative. Thank you for sharing.

"A perverse desire for symmetry," I like that.

A thermodynamically pleasing design

Hey Leo! thanks for the amazing vid. I really think with the level of execution you have done, you should attempt building a thermoacoustic sterling engine its even more simple.

Leo: Man you are getting really good at this. Nice production value and easy to follow commentary. I like the window into the mind of Leo and how you make decisions. Have to call you for questionable use of the word Sexy as it pertains to any part of this project. I am grateful people like you find this stuff addictive so I can do my part for the world and watch South Park. Please save me a space on the exit pods near you. I’m afraid I will be eaten by the locals for having mostly useless skills when push comes to shove. More projects please.

Hello buddy wanted to tell you you have the very best engine build on the RU-vid trust me iv watched them all thanks for you tinkering on this project I'm going to try my best to run with you on this project design iv never seen anything as nice as this setup very well achieved keep going with this I'm wanting to see someone use this engine to do something cool a fan or some kinda of electric generator needs a good use for this engine thanks your new friend Shane

That regenerator/displacer is really cool. It would work wonders with helium as the working fluid and not rust or burn away the displacer.

Nice vid m8. Immediately voted up when you warned about stirling engines addictive properties. ;]]

Amazing and beautiful Sterling engine. Great job.

Nice job!! To improve it further a careful choice of materials should be done, to reduce amortization and energy/efficiency losses. One hint (though probably quite advanced) is, as I'm sure you know Stirling engine is a heat engine, and as such it efficiency is MUCH higher when the cold chamber temperature is closer to 0ºK For example the theoretical max efficiency of any heat engine with cold tank at room temp, lets say 20ºC and hot temp, say at 240ºC is about 42%, while for the same temperature difference if your cold tank is at -200ºC (little colder than air condensation temp.) and the hot tank is at room temp of 20ºC you'll get 75% max.theoretical efficiency. If cold-hot tanks are at -200ºC & 240ºC you'll get over 85% max.theoretical efficiency Of course practical efficiency would always be lower, depending on the engineering of the engine. You also might want to have a look (if you haven't already) at this old video showing efficiency optimizations ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-GqIapDKtvzc.html I see you're using heat-regenerator as the displacer-piston - don't know which works better, but your approach is definitely simpler (and have much less surface for energy losses to external environment - only the cylinder walls). The rhombic drive is also very nice touch, but you can see the counter-weight optimization they did to make it as close to perfectly balanced as possible, and thus allow it the operate at much higher RPMs. And of course if you want to increase the amount of work done (if you're planning to put it to some real use) you would want to increase the pressure of the gas inside, and also probably to replace the air with some gas with better heat conductivity like hydrogen or the safer option helium (though it's rather deficit at the moment :/) Good luck with the project! And keep us updated - it's very interesting indeed! :)

This really is awesome, I had the exact same idea xD If interested you (or your viewers) can improve the efficiency further by - using helium instead of air inside the engine. - adding a "regenerator", in fact this part makes a hot air engine into t true Stirling engine, this is the main contribution by Mr. Stirling which increased efficiency significantly - replacing the rhombic drive with a simpler "half rhombic drive" or drop it entierly and make a free displacer Rimgbom Stirling engine - replace all the linkages by a diaphram and use the liniar actuation to generate electricity

I've been thinking about 3D printing one as well, you have done an incredible job!

Interesting video, i draw a drawing of a stirling engine almost similar but i didnt built a stirling engine. The most efficient stirling engine is the stirling engine well designed and reintroducing the lost of heat in the stirling engine system.

nice, i like it almost like 'barumman Stirling Engine with Rhombic Drive Part 1' tip, rather than use a flame make one of Roberts low power conductive ink paint on heaters for direct localised heating it. 'Robert Murray-Smith How To Make A Heater From Paper'

12:32 Leo warning us about the addictive properties of a Stirling Engine. Me: Already sniffing my 3rd build of Stirling Engine.

Thanks! Awesome engineering always :D I cant wait to see more contend like this.

It has been nearly 10 years for me, I still have outbreaks of stirlingittis. No sleep, dry erase board covered with scrawls, the stench of burning polyethylene, the humiliation of defeat, depression, there must be a 12 step plan be for us...

You have the rhombic drive! This is so cool. But I think you forgot the counterweights. Splendid job though! X M

You need to add an intake compression expansion and exhaust then have the normal up down up down to make it a total of 8 cycles. It would use compression to make it's own heat and it would run pretty good without fire

Just found your channel and Subscribed. Nice work

As always, great content. Waiting for the improved version of your Stirling Engine.

I love the design. Only thing i would add is a bike valve. It makes it easy to increase the pressure in the chamber increasing the power.

You sir just gave me a new project that thing is amazing!!!

This is so satisfying to watch. Thanks for sharing!

Use copper wool for your cylinder head and put a disk of aluminum on the bottom to make it mostly airtight. The heat transfer will be much better and copper wool won’t melt. You can use 2 hex nuts and a washer to attach the piston shaft to the cylinder head. Air will still leak around the edge but if you cut it close enough there should be less than half a mm all around for air to get by.

You should have it drive a water pump to supply the cooling water, you could also have a small generator that you could put progressively more load onto to work out how much power it produces. Great project, its something ive thought about for a long time too but never taken the plunge!

Thanks for sharing. All points made were spot on and I agree 100% regarding the warning of how a Stirling Engine build / design is going to be very addictive for those with mechanical interest. Yes it does seem fairly straight forward at first glance. :-)

After you have the dyno done it would interesting to do some maths and see if the sterling does a better job of converting heat differentials to electricity than pnp/npn junctions. Micro electro mechanical old tech VS old mechanical tech :)

It is best to think of a Stirling Engine as *a Temperature **_Difference_** Engine* instead of as "a Heat Engine". That mindset actually helps.

Great work. Love the design. If you get moderately favorable dyno results, you should try hooking it up to an electrical generator. I would love to see how it fairs/how much electrical power it could produce.

Love your engine. A couple of thoughts. Scotch yokes are simpler and take up less space. I am astounded by the fact that this engine isn't in a production car. There's a plastic called Torlon that could be used to make these ridiculously light and withstands very high heat.

Congratulations my friend, great job.

I would love to have the STEP files of your design. It is innovative and unique!

I too am afflicted but with an Alpha....really enjoyed this presentation....subscribed....looking forward to the dyno project. I would like to be able to measure the mechanical output once my engine is optimized.....I agree that Stirling Engines are addictive and mentally stimulating.....thanks for sharing your work.

I would make a spiral inside the water jacket with the inlet and outlet at opposite ends. That way the water is forced all the way around. You can also pressurize the jacket with air to 5 psi and then use soapy water to find the leaks. Also integza has a few videos on measuring dynamic torque and rpm which will allow you to determine the available power of the engine.

Great, i learned a lot as far as the addition thing u are so right,please make more videos

This is a massive flashback to a tween obsession with Lindsay's Technical books, a lot of their -smelt and forge yer own machine shop❤- ethos was just a prelude to their real goal of Sterling engines for all! They were a source of massive Dunning Krueger fantasies for me...::😂😅 Yes, I always wanted a Sterling engine!! It's probably good I didn't have a brilliant mentor like you back then, to help me interpret the unknown bits in Lindsay's; or else I would have forged my own lathe and attempted world domination. Both Dad and Step Dad were quite technical and good at teaching sometimes but their buffers were full of Vietnam and I can't actually blame them for not being super helpful. Yep, now I can clearly see without their wierd different polarities of PTSD working against each other I would have crafted a ufo flagship and massive autonomous improvised munition drone swarm and comitted terrible self righteous atrocities that I would regret in my old age; which I wouldn't reach because of the regretful consumption of ornery extracurricular molecules. Thanks Dads, you actually saved me from a fate worse than death, and probably 8.53 billion others! And before I quit drinking, the spirits revealed the banality of all human evil, so my delusions of righteous conquest are long gone, never fear!😎🤞💢 Just a lot of terrible remorse for my hubris and hibris, I really hope the rest of the n-dimensional super being that I'm a small part of knows and understands how sorry I am..::: It feels sincere when I think it!? 🌤🌱💛

Thanks! Well explained and well put together.

An axial temperature gradient in the regenerator can boost its effectiveness, since it's no longer limited to 50% (acts like multiple regenerators in series). Stacking steel mesh sheets would accomplish this, it'll have sufficient contact resistance.

Really cool stuff mate I look forward to seeing more! :)

I was thinking of an engine that is low cost, reliable, and possibly a flex-fuel solution. A bunch of tiny engines insulated and cooled are not going to be as hot as a bigger engine. 3D printed tiny engines with very simple functionality. It would be a hybrid with little engines like generators, or possibly building up pneumatic pressure.

Fantastic - super interesting project and well-done video as usual. Keep it up, proud to be a Leo Fan Boy!

Amazing stuff! Cool desogn and you are able to explain and break it down in a very good way!

Very nice video. I've been into DIY solar/powerwalls the last 3 years, and the addiction of finding / processing used 18650 cells into large batteries is a similar addiction. I'd LOVE to acquire (build I guess) a stirling engine in the 5-10hp range as a wood fired generator - but as you know, there's nothing available on this that I can find or buy in any reasonable price range. Again, really enjoyed this inspiring video - good luck on your work.

very nice effort and even a better presentation, Would love to work with you on building a practical one

I want to combine a Stirling engine with an internal combustion engine. Then I could switch to Stirling power whenever I'm idling, significantly reducing fuel consumption without having to worry about the fuel spent starting the engine back up, and also without having to worry about wrecking my torque converter. If the RPM ever gets too low, then I could also have a Hit-and-Miss system to provide very tiny bursts of fuel to get the flywheel back up to the correct speeds to prevent a stall.

Utilize a Solar Evacuated Tube, on the heat receiving point. No solar tracking necessary, unless you just HAVE to squeeze it out. These are sold in minimum lots of 40 some lots from one company, and create I believe 3 to 10 kilowatts each.