Although my model had very low efficiency in converting heat energy into mechanical energy, it is interesting that the first piston steam engine developed by Newcomen was also only 0.2% efficient. They had a long way to go to reach even 7% to 11% efficiency achieved by more advanced steam engines.
nice... some possible development idea hydrostatic bearings(aka externally pressurised bearings) "floated" by pressurised steam for high speed, low leakage, and low friction bearings. increased nozzle pressure and temperature could be traded for increased exit velocity beyond sonic/choked flow limits with use of a higher inlet pressure and a de Laval (aka converging diverging) nozzle with no blade in path of steam... nozzle exit temperature could go lower without risk of condensed water droplets slamming into blades and quickly eroding them. higher efficiency and thrust improvement there can be an unusual, and often forgotten phenomena, called meta stable steam... where steam remains as vapour for a short while after pressure and temperature/steam tables say it should have condensed. It's same kind of thing as the more familiar "liquid water below zero, until disturbed when it then turns to ice in moments No blades to trigger the steam to water phase change. if possible to acheive some of the latent heat of condensation/boiling is extracted via expansion, rather than vented to exhaust casing around the turbine, then holds space for the steam to condense within. steam droplets would be travelling tangentially at a fair speed... casing could be shaped like a turbo pump volute, to ram the condensate into a boiler feed pipe. Much of the condensates KE could be recycled into pumping condensate back in to boiler. perhaps a closed cycle without extra pump, and condenser. when steam condenses in a box... pressure drops to boiling pressure given temperature. being closer to vacuum could mean lower drag on turbine.
@@stevecummins324 Thank you for a thorough and knowledgeable analysis. You have some excellent ideas. My thought is that there are two ways of looking at the technology: One is to try to stay as close as possible to the original Greek design to find out how effective or efficient their machine was. A second step in the process is to think about what additional design features they may have been able to consider to improve its function. I really focussed mainly on the first part. I deviated a bit from the original design of the boiler by adding tubes to increase the surface area. That could have been done just by making the boiler bigger, but these days there are legal restrictions and safety considerations that constrain our design, requiring a compromise. I was not aware of the reason for the design of the de Laval jets. Interesting. I wonder whether that is something the Greeks could have discovered by trial and error. Indeed it is possible they did things like that and the documentation no longer exists. Regarding the bearings. Steam suspension of the bearing surfaces is something I did consider, and came to the conclusion that the Greeks had done a pretty good job of it. Steam leaking around the tapered pivots does indeed allow the pivots to float on a layer of steam. You mentioned low steam leakage and you certainly have a point there. Otherwise a bigger boiler with more steam production would get around that, but wastes even more energy. Perhaps simple parallel bronze bearings with only a small leak would work better, but I tried that and they produced too much friction. Perhaps drilling holes to duct steam into the bearing surface would have worked better. For the first design, I tried using ball bearing races. The problem with that is that steam leaks between the balls and sealed ball bearings create too much friction, so it would not work at all. I also tried nylon bearings. In the end I decided the Greeks must have actually built this machine and worked out that it only worked with these tiny tapered pivots with minimal surface area to create friction. They knew what they were doing and probably figured this out after much trial and error. The concept of metastable steam makes perfect sense, but something I hadn't thought about before.
Agree with finding out baseline de laval jets... heron documented steam played trumpets.. with enough steam pressure on inlet the flow through narrowest part will choke (reach mach 1), an outward flair of trumpet could increase velocity past sonic. would that be noticed? perhaps
Robert Heinlein once wrote that the answer to every question starting with "Why don't they..." has the same answer: "Money". Metal was expensive, fine machining was VERY expensive, and you can't make a piston work worth beans unless you can make a solid cylinder that's less than a millimetre smaller than a hollow cylinder, both of which must be perfectly round. I'm not sure when that was possible (there were some pretty fine water clocks long before Newcomen), but for a long time, it would have been like building something out of gemstones now, to replace a $9/hour unskilled worker. My guess, anyway... I recommended "The Medieval Machine", by Jean Gimpel, to Evan. It's a careful look at medieval technology, and the author's theme is that technology progressed pretty well during the supposed "dark ages" - they definitely were into extracting energy from wind and water with their mills, which had complex gears and so forth on the water wheels and wind mills. The fun read, that ends with Newcomen's first product presentation, was the 3-volume, 3000-page opus, "The Baroque Cycle", by Neal Stephenson. It's a novel trilogy, with pirates and derring-do on the even chapters, and Isaac Newton struggling to invent calculus, and the British monetary system on the odds. The reader is taken across something like 60 years, seeing how both the technology, and the economic politics, had to evolve to make the Industrial Revolution possible. Back to the money point - inventing technology takes capital, and the nobility tended to spend it on war and luxury, not R&D.
Thanks Roy. I ordered the book and it was inexpensive. That is a good angle you have presented. The idea that they had basically unlimited cheap labour in the form of slaves to do work, and machines were unnecessary, is also hinting at an economic reason. Yes the cost of producing any kind of engine from metals would have been a difficult and expensive task. Hero did describe a wind organ powered by a piston pump driven by a windmill. It may have been easier to get a fair seal to produce enough air pressure to drive a pipe organ, but still a significant leap to expect steam pressure to drive the piston.
Yeeah, but…these are the people who built the Parthenon, came up with the Antikythera mechanism, determined the true size of the earth, invented double action piston pumps, knew all about levers and gears and most of the things you mention. I understand that labor was cheap and all too plentiful in an unpleasant sort of way and the people who had the money tended to want to keep the money. However, these guys running around Alexandria at the time all seem to be some pretty inventive thinkers and when Heron walked in and showed the boys his new toy, all they could come up with is …nothing. Apparently, Heron and his colleagues and students just stopped thinking about it that day, and that is the basis of my question. Why not follow through, knowing what you know (for the next 1700 years). Tolerances could have been addressed in the days or even weeks of extra thought on the matter. Money seems to be the consensus answer here.
Thanks for the numbers. Very interesting. I can't help but think what could have been if they had made improvements to this design. Improvements that they must have understood like, pressure or thrust is greater nearest the jet. It's likely this was understood so, why not place a series of close fitting plates around the path of the jets giving the pressure something to push against. Additionally, place the jets internally and angle them slightly more than 90 degrees giving the plates a closer fit thereby, increasing post jet pressure or even cups instead of plates utilizing their understanding of parabolic reflection. If they timed it just right I suspect they would have discovered an RPM that out performed all others due to the reflective pulse lag increasing back pressure for the next passing jet. What kind of increase would this have generated. Would it have been enough to catch the eye of a wealthy backer. I'm not an engineer or historian so maybe my thinking is misguided, but nonetheless, it's fun to think about. Thanks for the stimulation.
I want to see someone pick up where hero left off and try to make this engine more effective. Like contain it in another sealed chamber so that the pressure does not dissipate into the air and the steam expelled from the nozzles have something to push against harder and thus produce more mechanical energy.
Unfortunately jets and rockets do not benefit from having something to push against. Think of rockets in space. It is based on Newtons laws. For every action there is an equal and opposite reaction. The momentum of material leaving the jet or rocket nozzle imparts and equal and opposite momentum to the rocket. Al Din in the 1500's made a turbine with a jet of steam hitting blades making them spin around. This is the fore-runner of modern jet engines. But the thrust of a jet turbine is from the momentum of gasses ejected by the engine.
Thanks Colin. I love the math and engineering and spent part of my professional life building mathematical models of biological systems. If you REALY want to get into some math, go to my web site HeroSteamEngine.com and look at the appendices where I calculate the theoretical thrust of steam jets and calculate the expected power output. When I built it I only got about 1% of the calculated power output. This is probably due to steam leakage and friction in the pivots and gearbox. I should rebuild it with steam entering from both pivots instead of one side. That would balance the pressures and although some steam would still escape, it acts as a steam cushion, reducing pivot friction. Another comment was made saying that the worm gear is the most inefficient type of gear, so I could consider using plain spur gears. I am convinced the Greeks actually built it and had it working because only their exact design works.
Gabriel Bennet asked what gear ratio I used. The worm gear was 44 turns of the ball to one turn of the output shaft, which was connected to a (1/4 inch) spool or pulley with a circumference of 20mm, so the crane could raise 20mm for every 44 turns of the turbine. Lifting a weight 500mm in 15 to 25 seconds gives the RPM as follows: 500/20 x 44 revs in 15 to 25 seconds or 500/20 x 44 x 60 ( 15 to 25) = 2640 to 4400 RPM under load. The highest recorded RPM with no load was 5400 RPM but may have been higher. I had been aiming for 10,000 RPM. The steam leaving the jets at the speed of sound would give a theoretical speed of 54,000 RPM but of coarse we cannot expect to reach that speed in practice. The reason for having the jets close to the ball is to minimize air resistance. Since the sphere is not displacing any air as it turns it would be expected to have very low air resistance. Most models of Hero's engine have jets on the ends of long arms and I think that is a mistake because the arms would increase air resistance without increasing power output. I think it likely that the Greeks discovered that and came up with the design using a ball and very small pivots, probably as a result of trial and error. If you are interested in the theory and math behind it, take a look at the appendices on the web site HeroSteamEngine.com. I am now working on lathe software which can be found at HeroSteamEngine.com/RideTheGearTrain and my channel th-cam.com/users/evan-e-cent.
Hi Evan, The most important change in Watt's engine was that it provided Steam Power. ( unlimited Power and unlimited improvement in the future, eventually locomotives. ). And still in use today. Newcomen's Pump provided Atmospheric Power. ( 10psi Max ). And no room for improvement in the future. Even if Watt had improved it's efficiency ( which is the usual talk ) to 100% it would be 14.7 psi max. The one thing I've noticed in all these utube videos, even supposed experts, is that the change from Atmospheric Power to Steam Power is never ever mentioned! Very odd.
Nathaniel Kencke asked if the limiting factor determining rotation is friction. Yes I think you are correct. There are two sources of friction: air resistance, mainly from the jets moving through the air, and the other from friction in the pivot bearings. Steam flowing through the pivots could act as an almost friction free cushion, but wastes a lot of steam pressure. If the jets could reach the speed of sound it would rotate at 54,000 RPM. That can never happen because the thrust produced is determined by the difference between actual velocity through the air and the velocity of steam escaping from the jets and this would be zero at 54,000 RPM. Because of this, the thrust and torque which are causing it to spin decreases with RPM so it must reach a steady state where the decreasing torque is balanced by increasing friction.
Correction. There is a mistake I made here. This is not correct: 'the thrust produced is determined by the difference between actual velocity through the air and the velocity of steam escaping from the jets '. Thrust is not affected by the speed that the jet is traveling through the air. Thrust is determined by the momentum of steam leaving the jet ie mass per second or velocity of steam times mass. Think of a rocket in space. It works the same way and is based on Newton's laws. For every reaction there is an equal and opposite reaction.
Hi Apollo, Yes the "jet" size is the diameter of the hole in the nozzle. It is just a hole that the steam comes through, with no moving parts. I will add a comment about thrust in the description above.
What limits the maximum rotational speed of the engine? Is it that the speed increases until bearing friction balances the torque from the jets? Would there be no theoretical limit to the rpm if there were no friction?
The Newcomen Atmospheric Pump didn't convert the thermal energy of Steam into work. It converted Atmospheric Pressure into work. James Watt's engine converted the thermal energy of Steam into work through Steam Expansion.
It is all very well saying the Newcomen engine used the energy of atmospheric pressure, but you cannot use atmospheric pressure without first generating a vacuum. It takes a lot of energy to create a vacuum. Just look at any vacuum pump. It doesn't run itself. It requires considerable energy input, eg in the form of electricity. In the case of the Newcomen engine the energy comes from a fuel that is burned to make steam. The cooling steam creates a vacuum which allows atmospheric pressure to drive the piston down. So clearly, thermal energy is converted to mechanical energy, and that is the definition of an engine. There is no doubt that the Newcomen engine was an engine by that definition.
I'm sure it's been considered, but I'm curious if adding some bulk to the spinnie but would help. Like, maybe it spins slower but adds a bit of torque. I'm a dummy tho, I'm still flabbergasted by the wheel
Thanks for your suggestion. Yes, the flywheel idea has been considered. A flywheel does not actually increase torque, but smooths out any fluctuation in torque. This is necessary in piston engines because the power is produced in pulses, eg in a 4 stroke engine power is only produced in every fourth stroke. However, a turbine produces its power continuously and does not need to be smoothed. The fourth version of the Hero engine I built does have a heavier spinner axle, and all it does is make it take much longer to pick up speed when starting up. It is actually a disadvantage for low torque, high RPM engines like the Hero engine. Remember power output is RPM times torque and torque is produced by the thrust from the steam jets. Thrust is determined by the momentum (velocity times mass) of steam being ejected per second by the jets. If you have ever tried to hold on to a fire hose... The power can be used to do some kind of work, but is more useful at slower RPM eg by gearing it down through a gearbox or pulleys for example. Doing this does not alter the power output (except by losses caused by friction between gears and bearings which can be significant.) IF power is unchanged and we decrease RPM by a factor of ten, then torque must increase by a factor of ten because power=torque x RPM. That is how I increase torque with my design.
Would be interesting to know how fast the water is boiling, this would let you know how much energy is actually getting into the engine and you can calculate another relevant efficiency from that
Hi, thanks for your comment. Yes, this is how I actually calculated efficiency (See the appendix in the web site HeroSteamEngine.com). I put 500cc of water in the boiler and timed how long it took to boil. From that I calculated the Watts of heat being provided by the gas burner (Watts=Joules/second). When lifting a weight I calculated the Watts of mechanical energy required to lift the weight a measured distance in a certain amount of time. This is the mechanical work produced. Dividing mechanical work by the amount of heat from the burner gives the efficiency.
The video that you helped ‘How to Make Everything’ on constructing their own Aeolipile was recently uploaded (today about 12 hours ago). Anyway, I find your construction to be far and away a better formulation. No offense to ‘How to Make Everything’ as they are certainly knowledgeable, however their method of construction and tools they used were shockingly archaic for known technologies at the time of Hero/Heron. I’m wondering if you’ve tinkered with this any more to try and improve its RPMs, and by extension it’s Watts, using Hellenistic Era/ Early Roman Empire era technology?
I may have an opportunity to improve the design to reduce steam leakage in November. Thanks for your input! If you haven't seen it already you might like my web page HeroSteamEngine.com. I discovered several myths about Heron of Alexandria. The image of Heron was draw by a German artist in the 18th century and there is no description of his appearance (that we know of) so it is likely that this image is completely fabricated. When he lived in Egypt it was under Roman rule. I think he was called Greek because he wrote in Greek. The original manuscripts are missing and all we have are several copies but they all describe the design in great detail. The drawings in later copies have the same design but various artistic embellishments. We do not know exactly when he lived. He referred to Cebelius who lived about 200 BC and it was thought that they were contemporary. However, he referred to an eclipse that occurred about 79 AD so he must have been alive after that date. Some authors (quoted in Wikipedia) said that he used the Hero's steam engine to open temple doors. That is not correct. See my animation of the mechanism he described on my web page.
Hero or Heron? I have been criticized for using the name Hero instead of Heron. Both are considered correct and both used widely in the literature, and here is the reason - as explained in my original web page HeroSteamEngine.com: Why is he called either Hero or Heron of Alexandria? Paul Smith provided the explanation on another TH-cam channel. The word can be spelled either way, depending on how it is used in a sentence. Quote: "Both spellings and pronunciations are accepted in English. I believe this confusion has to do with case endings in Hellenistic Greek grammar between the nominative and accusative case. Depending on the place or role of the name in the sentence e.g. subject ,object of the verb, possessor or owner (genitive case ending), or object of a preposition (dative case ending) determines the ending of the name."
That is a good point.RPM does tend to slow down under load. Power output is proportional to RPM * Torque and at zero RPM there would be no work done and no power output. There is probably an ideal RPM giving maximum power.
I agree. Today I learned that the Egyptians mastered brazing 3000 years ago. Yet another technology to add to their tool box. They had ALL the pieces of the puzzle!
Electricity, hot water, water pressure, distilled water... any questions? Vote for world PEACE! Grow a home with your family and ditch the ballot box games!
They, like yourself, were and are a lot smarter than I... so how is it possible that NO-ONE came up with a working engine that could transmit continuous power to a machine until around 1712 (Newcomen) … instead of just a couple of days or even weeks of a little extra thought on the matter?
That is the great unanswered puzzle. It seem incredible that the technology of the Hero engine, piston pumps and gears were actually passed down with multiple copies of Hero's writing being transcribed right through the middle ages and no-one seems to have tried to develop it further. Perhaps the engineering methods explaining and associated skills required to actually make things like a copper boiler were lost.
They weren't smarter, they just had other things to think about! :) But you're right, it's surprising how long it took for steam engines to become a thing. My guess is that there just wasn't much need for them. If you wanted a crane, you could just use a horse: Cheaper, versatile, and reliable. However during the industrial revolution there simply was too many people for horses!
@@migueeeelet quite the opposite, actually. Conflict is great for generating new inventions. Any competent leader would encourage new inventions as much as possible during wartimes
A good thought, but a flywheel is best on machines that produce power intermittently, like piston engines. The flywheel stores energy to keep it spinning between power strokes and evens out the torque. But for this turbine the power of the jets is continuous and a flywheel would not provide any real advantage, unless you are driving a load that is intermittent.
@@christophernewton8443 Yes, but you can achieve the same by making each jet nozzle bigger, without adding more weight and air resistance. The problem with larger jets is that they take more steam and that requires bigger boilers so you have to scale everything up.
Sorry about the delayed response. Yes I have been following this work and the engineering discussions by ClickSpring in Australia. Both the original and his reproduction are incredible.
Thanks for the segway! Actually this is such a common misconception that it has appeared in academic literature. Heron did make a device for opening temple doors, but it was not driven by Hero's steam engine. I adapted his idea to open the door of my glasshouse when the temperature gets too high. How did it work? At the temple was an alter and when a fire was lit on the alter it caused air in a chamber underneath to expand. This air pressure was transmitted through a pipe to another closed container that was half full of water. The pressure caused the water to flow out through a pipe connected to the bottom of the chamber. This water drained through a pipe into a bucket which was connected by ropes and pulleys to the temple doors causing them to open. When the fire went out the whole process could work in reverse, sucking the water back out of the bucket ready to be used next time and allowing the doors to close. This is shown with an animation on my web site HeroSteamEngine.com.
Great idea to use liquid nitrogen. You could try dry ice which is easier to obtain. Some supermarkets ship food in packages with dry ice (solid CO2). Have to watch the pressure and use a pressure relief valve that releases pressure when it gets too high.
Thanks for the complement. I am giving a Zoom lecture on the history of steam engines, starting with the Greeks on Wednesday noon New Zealand time, for Auckland library. It will go on line later and I may make some more TH-cam videos when time permits.
Although my model had very low efficiency in converting heat energy into mechanical energy, it is interesting that the first piston steam engine developed by Newcomen was also only 0.2% efficient. They had a long way to go to reach even 7% to 11% efficiency achieved by more advanced steam engines.
It may be low efficiency, but with a gear system and a Flywheel...
th-cam.com/video/8X2U7bDNcPM/w-d-xo.html
nice...
some possible development idea
hydrostatic bearings(aka externally pressurised bearings) "floated" by pressurised steam for high speed, low leakage, and low friction bearings.
increased nozzle pressure and temperature could be traded for increased exit velocity beyond sonic/choked flow limits with use of a higher inlet pressure and a de Laval (aka converging diverging) nozzle
with no blade in path of steam... nozzle exit temperature could go lower without risk of condensed water droplets slamming into blades and quickly eroding them. higher efficiency and thrust improvement
there can be an unusual, and often forgotten phenomena, called meta stable steam... where steam remains as vapour for a short while after pressure and temperature/steam tables say it should have condensed. It's same kind of thing as the more familiar "liquid water below zero, until disturbed when it then turns to ice in moments No blades to trigger the steam to water phase change. if possible to acheive some of the latent heat of condensation/boiling is extracted via expansion, rather than vented to exhaust
casing around the turbine, then holds space for the steam to condense within.
steam droplets would be travelling tangentially at a fair speed... casing could be shaped like a turbo pump volute, to ram the condensate into a boiler feed pipe. Much of the condensates KE could be recycled into pumping condensate back in to boiler. perhaps a closed cycle without extra pump, and condenser.
when steam condenses in a box... pressure drops to boiling pressure given temperature. being closer to vacuum could mean lower drag on turbine.
@@stevecummins324 Thank you for a thorough and knowledgeable analysis. You have some excellent ideas. My thought is that there are two ways of looking at the technology:
One is to try to stay as close as possible to the original Greek design to find out how effective or efficient their machine was.
A second step in the process is to think about what additional design features they may have been able to consider to improve its function.
I really focussed mainly on the first part. I deviated a bit from the original design of the boiler by adding tubes to increase the surface area. That could have been done just by making the boiler bigger, but these days there are legal restrictions and safety considerations that constrain our design, requiring a compromise.
I was not aware of the reason for the design of the de Laval jets. Interesting. I wonder whether that is something the Greeks could have discovered by trial and error. Indeed it is possible they did things like that and the documentation no longer exists.
Regarding the bearings. Steam suspension of the bearing surfaces is something I did consider, and came to the conclusion that the Greeks had done a pretty good job of it. Steam leaking around the tapered pivots does indeed allow the pivots to float on a layer of steam. You mentioned low steam leakage and you certainly have a point there. Otherwise a bigger boiler with more steam production would get around that, but wastes even more energy.
Perhaps simple parallel bronze bearings with only a small leak would work better, but I tried that and they produced too much friction. Perhaps drilling holes to duct steam into the bearing surface would have worked better. For the first design, I tried using ball bearing races. The problem with that is that steam leaks between the balls and sealed ball bearings create too much friction, so it would not work at all. I also tried nylon bearings.
In the end I decided the Greeks must have actually built this machine and worked out that it only worked with these tiny tapered pivots with minimal surface area to create friction. They knew what they were doing and probably figured this out after much trial and error.
The concept of metastable steam makes perfect sense, but something I hadn't thought about before.
Agree with finding out baseline
de laval jets...
heron documented steam played trumpets.. with enough steam pressure on inlet the flow through narrowest part will choke (reach mach 1), an outward flair of trumpet could increase velocity past sonic. would that be noticed? perhaps
Robert Heinlein once wrote that the answer to every question starting with "Why don't they..." has the same answer: "Money".
Metal was expensive, fine machining was VERY expensive, and you can't make a piston work worth beans unless you can make a solid cylinder that's less than a millimetre smaller than a hollow cylinder, both of which must be perfectly round. I'm not sure when that was possible (there were some pretty fine water clocks long before Newcomen), but for a long time, it would have been like building something out of gemstones now, to replace a $9/hour unskilled worker.
My guess, anyway...
I recommended "The Medieval Machine", by Jean Gimpel, to Evan. It's a careful look at medieval technology, and the author's theme is that technology progressed pretty well during the supposed "dark ages" - they definitely were into extracting energy from wind and water with their mills, which had complex gears and so forth on the water wheels and wind mills.
The fun read, that ends with Newcomen's first product presentation, was the 3-volume, 3000-page opus, "The Baroque Cycle", by Neal Stephenson. It's a novel trilogy, with pirates and derring-do on the even chapters, and Isaac Newton struggling to invent calculus, and the British monetary system on the odds. The reader is taken across something like 60 years, seeing how both the technology, and the economic politics, had to evolve to make the Industrial Revolution possible. Back to the money point - inventing technology takes capital, and the nobility tended to spend it on war and luxury, not R&D.
Thanks Roy. I ordered the book and it was inexpensive. That is a good angle you have presented. The idea that they had basically unlimited cheap labour in the form of slaves to do work, and machines were unnecessary, is also hinting at an economic reason. Yes the cost of producing any kind of engine from metals would have been a difficult and expensive task. Hero did describe a wind organ powered by a piston pump driven by a windmill. It may have been easier to get a fair seal to produce enough air pressure to drive a pipe organ, but still a significant leap to expect steam pressure to drive the piston.
Yeeah, but…these are the people who built the Parthenon, came up with the Antikythera mechanism, determined the true size of the earth, invented double action piston pumps, knew all about levers and gears and most of the things you mention. I understand that labor was cheap and all too plentiful in an unpleasant sort of way and the people who had the money tended to want to keep the money.
However, these guys running around Alexandria at the time all seem to be some pretty inventive thinkers and when Heron walked in and showed the boys his new toy, all they could come up with is …nothing. Apparently, Heron and his colleagues and students just stopped thinking about it that day, and that is the basis of my question. Why not follow through, knowing what you know (for the next 1700 years). Tolerances could have been addressed in the days or even weeks of extra thought on the matter.
Money seems to be the consensus answer here.
@@rdwmt Thanks for your thoughtful reply.
thanks for this reply
I really appreciate the ancient work of the Greeks,thanks for this real experiments on modern replica of hero steam engine.
Thanks for the numbers. Very interesting. I can't help but think what could have been if they had made improvements to this design. Improvements that they must have understood like, pressure or thrust is greater nearest the jet. It's likely this was understood so, why not place a series of close fitting plates around the path of the jets giving the pressure something to push against. Additionally, place the jets internally and angle them slightly more than 90 degrees giving the plates a closer fit thereby, increasing post jet pressure or even cups instead of plates utilizing their understanding of parabolic reflection. If they timed it just right I suspect they would have discovered an RPM that out performed all others due to the reflective pulse lag increasing back pressure for the next passing jet. What kind of increase would this have generated. Would it have been enough to catch the eye of a wealthy backer. I'm not an engineer or historian so maybe my thinking is misguided, but nonetheless, it's fun to think about. Thanks for the stimulation.
I want to see someone pick up where hero left off and try to make this engine more effective. Like contain it in another sealed chamber so that the pressure does not dissipate into the air and the steam expelled from the nozzles have something to push against harder and thus produce more mechanical energy.
Unfortunately jets and rockets do not benefit from having something to push against. Think of rockets in space. It is based on Newtons laws. For every action there is an equal and opposite reaction. The momentum of material leaving the jet or rocket nozzle imparts and equal and opposite momentum to the rocket. Al Din in the 1500's made a turbine with a jet of steam hitting blades making them spin around. This is the fore-runner of modern jet engines. But the thrust of a jet turbine is from the momentum of gasses ejected by the engine.
Great little demo! Also, I love the included math in some of your videos!
Thanks Colin. I love the math and engineering and spent part of my professional life building mathematical models of biological systems. If you REALY want to get into some math, go to my web site HeroSteamEngine.com and look at the appendices where I calculate the theoretical thrust of steam jets and calculate the expected power output. When I built it I only got about 1% of the calculated power output. This is probably due to steam leakage and friction in the pivots and gearbox. I should rebuild it with steam entering from both pivots instead of one side. That would balance the pressures and although some steam would still escape, it acts as a steam cushion, reducing pivot friction. Another comment was made saying that the worm gear is the most inefficient type of gear, so I could consider using plain spur gears. I am convinced the Greeks actually built it and had it working because only their exact design works.
Gabriel Bennet asked what gear ratio I used. The worm gear was 44 turns of the ball to one turn of the output shaft, which was connected to a (1/4 inch) spool or pulley with a circumference of 20mm, so the crane could raise 20mm for every 44 turns of the turbine. Lifting a weight 500mm in 15 to 25 seconds gives the RPM as follows: 500/20 x 44 revs in 15 to 25 seconds or 500/20 x 44 x 60 ( 15 to 25) = 2640 to 4400 RPM under load. The highest recorded RPM with no load was 5400 RPM but may have been higher. I had been aiming for 10,000 RPM. The steam leaving the jets at the speed of sound would give a theoretical speed of 54,000 RPM but of coarse we cannot expect to reach that speed in practice. The reason for having the jets close to the ball is to minimize air resistance. Since the sphere is not displacing any air as it turns it would be expected to have very low air resistance. Most models of Hero's engine have jets on the ends of long arms and I think that is a mistake because the arms would increase air resistance without increasing power output. I think it likely that the Greeks discovered that and came up with the design using a ball and very small pivots, probably as a result of trial and error. If you are interested in the theory and math behind it, take a look at the appendices on the web site HeroSteamEngine.com. I am now working on lathe software which can be found at HeroSteamEngine.com/RideTheGearTrain and my channel th-cam.com/users/evan-e-cent.
Here is a Hero engine running on liquid nitrogen: th-cam.com/video/NBIt9iFEAJw/w-d-xo.html
Hi Evan,
The most important change in Watt's engine was that it provided Steam Power. ( unlimited Power and unlimited improvement in the future, eventually locomotives. ). And still in use today.
Newcomen's Pump provided Atmospheric Power. ( 10psi Max ). And no room for improvement in the future.
Even if Watt had improved it's efficiency ( which is the usual talk ) to 100% it would be 14.7 psi max.
The one thing I've noticed in all these utube videos, even supposed experts, is that the change from Atmospheric Power to Steam Power is never ever mentioned! Very odd.
Hmmm... I wonder whether using De Lavall nozzles on the jets would help to extract more kinetic energy from the exhaust.
Nathaniel Kencke asked if the limiting factor determining rotation is friction. Yes I think you are correct. There are two sources of friction: air resistance, mainly from the jets moving through the air, and the other from friction in the pivot bearings. Steam flowing through the pivots could act as an almost friction free cushion, but wastes a lot of steam pressure. If the jets could reach the speed of sound it would rotate at 54,000 RPM. That can never happen because the thrust produced is determined by the difference between actual velocity through the air and the velocity of steam escaping from the jets and this would be zero at 54,000 RPM. Because of this, the thrust and torque which are causing it to spin decreases with RPM so it must reach a steady state where the decreasing torque is balanced by increasing friction.
Correction. There is a mistake I made here. This is not correct: 'the thrust produced is determined by the difference between actual velocity through the air and the velocity of steam escaping from the jets '. Thrust is not affected by the speed that the jet is traveling through the air. Thrust is determined by the momentum of steam leaving the jet ie mass per second or velocity of steam times mass. Think of a rocket in space. It works the same way and is based on Newton's laws. For every reaction there is an equal and opposite reaction.
2:05 by "jets," i assume you are referring to the nozzle exit diameter.
Hi Apollo, Yes the "jet" size is the diameter of the hole in the nozzle. It is just a hole that the steam comes through, with no moving parts. I will add a comment about thrust in the description above.
What limits the maximum rotational speed of the engine? Is it that the speed increases until bearing friction balances the torque from the jets? Would there be no theoretical limit to the rpm if there were no friction?
The Newcomen Atmospheric Pump didn't convert the thermal energy of Steam into work. It converted Atmospheric Pressure into work.
James Watt's engine converted the thermal energy of Steam into work through Steam Expansion.
It is all very well saying the Newcomen engine used the energy of atmospheric pressure, but you cannot use atmospheric pressure without first generating a vacuum. It takes a lot of energy to create a vacuum. Just look at any vacuum pump. It doesn't run itself. It requires considerable energy input, eg in the form of electricity. In the case of the Newcomen engine the energy comes from a fuel that is burned to make steam. The cooling steam creates a vacuum which allows atmospheric pressure to drive the piston down. So clearly, thermal energy is converted to mechanical energy, and that is the definition of an engine. There is no doubt that the Newcomen engine was an engine by that definition.
I'm sure it's been considered, but I'm curious if adding some bulk to the spinnie but would help. Like, maybe it spins slower but adds a bit of torque.
I'm a dummy tho, I'm still flabbergasted by the wheel
Thanks for your suggestion. Yes, the flywheel idea has been considered. A flywheel does not actually increase torque, but smooths out any fluctuation in torque. This is necessary in piston engines because the power is produced in pulses, eg in a 4 stroke engine power is only produced in every fourth stroke. However, a turbine produces its power continuously and does not need to be smoothed.
The fourth version of the Hero engine I built does have a heavier spinner axle, and all it does is make it take much longer to pick up speed when starting up. It is actually a disadvantage for low torque, high RPM engines like the Hero engine.
Remember power output is RPM times torque and torque is produced by the thrust from the steam jets. Thrust is determined by the momentum (velocity times mass) of steam being ejected per second by the jets. If you have ever tried to hold on to a fire hose...
The power can be used to do some kind of work, but is more useful at slower RPM eg by gearing it down through a gearbox or pulleys for example. Doing this does not alter the power output (except by losses caused by friction between gears and bearings which can be significant.) IF power is unchanged and we decrease RPM by a factor of ten, then torque must increase by a factor of ten because power=torque x RPM. That is how I increase torque with my design.
Would be interesting to know how fast the water is boiling, this would let you know how much energy is actually getting into the engine and you can calculate another relevant efficiency from that
Hi, thanks for your comment. Yes, this is how I actually calculated efficiency (See the appendix in the web site HeroSteamEngine.com). I put 500cc of water in the boiler and timed how long it took to boil. From that I calculated the Watts of heat being provided by the gas burner (Watts=Joules/second). When lifting a weight I calculated the Watts of mechanical energy required to lift the weight a measured distance in a certain amount of time. This is the mechanical work produced. Dividing mechanical work by the amount of heat from the burner gives the efficiency.
Beautiful work!
The video that you helped ‘How to Make Everything’ on constructing their own Aeolipile was recently uploaded (today about 12 hours ago). Anyway, I find your construction to be far and away a better formulation. No offense to ‘How to Make Everything’ as they are certainly knowledgeable, however their method of construction and tools they used were shockingly archaic for known technologies at the time of Hero/Heron. I’m wondering if you’ve tinkered with this any more to try and improve its RPMs, and by extension it’s Watts, using Hellenistic Era/ Early Roman Empire era technology?
I may have an opportunity to improve the design to reduce steam leakage in November. Thanks for your input! If you haven't seen it already you might like my web page HeroSteamEngine.com. I discovered several myths about Heron of Alexandria. The image of Heron was draw by a German artist in the 18th century and there is no description of his appearance (that we know of) so it is likely that this image is completely fabricated. When he lived in Egypt it was under Roman rule. I think he was called Greek because he wrote in Greek. The original manuscripts are missing and all we have are several copies but they all describe the design in great detail. The drawings in later copies have the same design but various artistic embellishments. We do not know exactly when he lived. He referred to Cebelius who lived about 200 BC and it was thought that they were contemporary. However, he referred to an eclipse that occurred about 79 AD so he must have been alive after that date. Some authors (quoted in Wikipedia) said that he used the Hero's steam engine to open temple doors. That is not correct. See my animation of the mechanism he described on my web page.
one best Aeolipile experiments ive seen 1watt= 600rpm
Thanks for the complements! There are still things I would like to improve.
Amazing! Subscribed!
Love it!
Hero or Heron? I have been criticized for using the name Hero instead of Heron. Both are considered correct and both used widely in the literature, and here is the reason - as explained in my original web page HeroSteamEngine.com:
Why is he called either Hero or Heron of Alexandria?
Paul Smith provided the explanation on another TH-cam channel. The word can be spelled either way, depending on how it is used in a sentence. Quote: "Both spellings and pronunciations are accepted in English. I believe this confusion has to do with case endings in Hellenistic Greek grammar between the nominative and accusative case. Depending on the place or role of the name in the sentence e.g. subject ,object of the verb, possessor or owner (genitive case ending), or object of a preposition (dative case ending) determines the ending of the name."
With liquor nitrogen you can solve the heat problems in generators.
Dis you see this liquid nitrogen Hero Engine! th-cam.com/video/NBIt9iFEAJw/w-d-xo.html
It's still spinning really fast. You're not using all the energy output.
That is a good point.RPM does tend to slow down under load. Power output is proportional to RPM * Torque and at zero RPM there would be no work done and no power output. There is probably an ideal RPM giving maximum power.
That`s cool😍
Man they where very close to an industrial revolution.
I agree. Today I learned that the Egyptians mastered brazing 3000 years ago. Yet another technology to add to their tool box. They had ALL the pieces of the puzzle!
Impressive. But you wouldn't need to worry about leaks if you used a tesla turbine.
Electricity, hot water, water pressure, distilled water... any questions?
Vote for world PEACE! Grow a home with your family and ditch the ballot box games!
They, like yourself, were and are a lot smarter than I... so how is it possible that NO-ONE came up with a working engine that could transmit continuous power to a machine until around 1712 (Newcomen) … instead of just a couple of days or even weeks of a little extra thought on the matter?
That is the great unanswered puzzle. It seem incredible that the technology of the Hero engine, piston pumps and gears were actually passed down with multiple copies of Hero's writing being transcribed right through the middle ages and no-one seems to have tried to develop it further. Perhaps the engineering methods explaining and associated skills required to actually make things like a copper boiler were lost.
They weren't smarter, they just had other things to think about! :)
But you're right, it's surprising how long it took for steam engines to become a thing.
My guess is that there just wasn't much need for them. If you wanted a crane, you could just use a horse: Cheaper, versatile, and reliable. However during the industrial revolution there simply was too many people for horses!
Answer: CHEAP slave labor. With such an abundance of human bodies to do all the heavy tasks, innovations like this aren't seen as needed...
@@axelpatrickb.pingol3228 Also constant warring is bad for anyone with an innovative mind to stay inventing
@@migueeeelet quite the opposite, actually. Conflict is great for generating new inventions. Any competent leader would encourage new inventions as much as possible during wartimes
Commenting for TH-cam algorithm
It would be great if you attache a flying wheel on it.
A good thought, but a flywheel is best on machines that produce power intermittently, like piston engines. The flywheel stores energy to keep it spinning between power strokes and evens out the torque. But for this turbine the power of the jets is continuous and a flywheel would not provide any real advantage, unless you are driving a load that is intermittent.
@@Evan-e-cent what if you add more jet nozzles for a better trust? I believe it will do more work.
@@christophernewton8443 Yes, but you can achieve the same by making each jet nozzle bigger, without adding more weight and air resistance. The problem with larger jets is that they take more steam and that requires bigger boilers so you have to scale everything up.
Have you seen the latest BBC report on the Antikythera astronomical analogue computer: www.bbc.com/news/science-environment-56377567
Sorry about the delayed response. Yes I have been following this work and the engineering discussions by ClickSpring in Australia. Both the original and his reproduction are incredible.
I think the Greeks used this engine to open doors with no one around, which amazed the hoi polloi....
Thanks for the segway! Actually this is such a common misconception that it has appeared in academic literature. Heron did make a device for opening temple doors, but it was not driven by Hero's steam engine. I adapted his idea to open the door of my glasshouse when the temperature gets too high. How did it work? At the temple was an alter and when a fire was lit on the alter it caused air in a chamber underneath to expand. This air pressure was transmitted through a pipe to another closed container that was half full of water. The pressure caused the water to flow out through a pipe connected to the bottom of the chamber. This water drained through a pipe into a bucket which was connected by ropes and pulleys to the temple doors causing them to open. When the fire went out the whole process could work in reverse, sucking the water back out of the bucket ready to be used next time and allowing the doors to close. This is shown with an animation on my web site HeroSteamEngine.com.
Hey bro we tried liquor nitrogen. Just remember be careful it's fast
Great idea to use liquid nitrogen. You could try dry ice which is easier to obtain. Some supermarkets ship food in packages with dry ice (solid CO2). Have to watch the pressure and use a pressure relief valve that releases pressure when it gets too high.
@@Evan-e-cent I'm really interested in making a sustainable engine. Almost like free energy
@@BigDaddyKai620 Well at less than 1% efficiency the Hero engine is going to waste a lot of fuel. No where near carbon neutral!
Your like a modern archimedes
Thanks for the complement. I am giving a Zoom lecture on the history of steam engines, starting with the Greeks on Wednesday noon New Zealand time, for Auckland library. It will go on line later and I may make some more TH-cam videos when time permits.
Re- genius
industrial revolution
So, it can lift a bottle of water. Hmm. Cool...?? 🤷♂️🤣
The point was to find out how much work it could do. So many people have fanciful ideas about these engines being used in locomotives etc.
Massive leaks and terrible efficiency.