Solar motor--Free energy motor-- not electrical /// Homemade Science with Bruce Yeany

These devices are sometimes referred to as solar motors or thermal motors, or even thermal retraction motors. Sunlight hitting the strips is converted into thermal energy (heat) which then causes the rotor to turn without any electrical or other mechanical parts. The use of the term "free energy" in this context means that this device is converting energy that is "freely" supplied by our sun and is not meant to suggest that it violates any laws of thermodynamics, or that it is creating energy. Sunlight, wind, geothermal and damming water can all be thought of as deriving energy from "free" sources.
The earliest versions of these types of motors used rubber bands as the ribs. The movement of this motor is dependent on the unique property of the stretched trash bag strips. These strips are made from a plastic material called polyethylene. This chemical is a common example of a polymer. One of its characteristics is that it is made of very long molecular chains. Thin strips were cut out of a trash bag parallel to the top of the bag and then pulled, stretching the plastic about 5 times it's original length. The long polymer molecules are stretched to their elastic limit during the stretching process. If more force is applied, these long chains are broken when the plastic tears apart. When heating the strips, the polymer molecule chains contract, pulling the molecules closer together in a process called thermal retraction. They do not expand due to cooling as some students may suggest. The action of the polyethylene retracting or shrinking is quite different from a uniform expansion of matter as a result of kinetic energy. As this plastic is heated temporarily, the material pulls tighter and shrinks to a smaller size. The plastic remains “shrunken” until pressure is applied to stretch the molecular chains out again.
The movement of the motor is due to the materials at the top of the cup assembly contracting slightly; this action is pulling the cups together at the top. The action is not noticeable since it is so slight. It is noticeable if the plastic is heated sufficiently but too much heat may damage the rotor . As the cups are pulled together, the assembly becomes unbalanced. The motor is now top heavy and starts to turn and fall toward the bottom. As the assembly turns, a new section is then exposed to light and is heated. This new spot becomes top heavy causing this section to fall. The action is continually repeated making the top section always unbalanced; the cups are constantly trying to adjust to become balanced. The end result is the motor turning because it is trying to right itself. The highest speed for the cups in direct summer sunlight seems to top out around 65 RPMs.
The addition of mass to the flywheel directions has some benefits and drawbacks. This addition can make the cup more efficient, but it will not make it spin faster. The “good news” is that adding mass to the flywheel can enable this tiny motor to perform small tasks, however, it does not make it efficient enough that it can turn a small generator. This design simply does not generate torque to do so.
The "bad news" is that as more mass is added to the flywheel, it becomes more finicky and will require more adjustments for balancing.
Other videos are in the works so please subscribe and if you like what you see, let me know. Thanks
Homemade science is a collection of classroom tested ideas, suggestions, projects, and experiments that I have used in teaching physical science for the Annville-Cleona school district in central Pennsylvania. I am currently in my 40th year of teaching. My intention is to share these ideas with other teachers or anyone who has an interest in science. I have found that designing and building my own equipment has taught me more than any course that I have ever taken. I hope that you consider making or trying these experiments for yourself.

[@CURTISLWhite]

Mr. Yeany: My stepson won MS state science fair in 1978 ,building a solar motor like yours. I'm glad to see you showing everyone how to build them.

[@auxpowerunit]

I was waiting for him to pull out a larger one made from 55 gallon oil barrels.

[@YeanyScience]

LOL, I wish I could.

[@PrincessFaithPimentel]

+Bruce Yeany (Yeany Science) May I please ask where did you buy the solar strips or what is the technical name for it? I would like to create this!

[@YeanyScience]

they are made form plastic garbage bags, if you send me an email address, I will send instructions in how to make it

[@PrincessFaithPimentel]

[e-mail] Thank you so much! I appreciate it!

[@halfmeout]

Bruce Yeany make a video so we all know :)

[@outled]

This blows my tiny mind. I will definitely be having a go at making one in the summer. Thanks Bruce.

[@davidward1949]

Sir, This is great. I read about this when I was in High School back in the late 70's. We should be able to use some type of metal to make a heat engine that has a good torque level and get it to generate electricity.

[@Skipperj]

Wow who would of thought. Well i guess it was you ! Thanks and you have just gave me a flood of ideas.Something can come from a person sharing an idea and then the next guy does something along that line. Thanks Bruce.

[@DownhillAllTheWay]

Why does everybody want it to have an application? It's a fun thing that illustrates the contraction of the "solar bands". It goes around. That's its application.

[@YeanyScience]

Thanks Mike, For me that's enough

[@geromatezwanzig8789]

Well, I have an "application" :-) Glue small thin mirrors on the rim somewhere. They coud even be colored. You may get a nice light show in your room!

[@user-tn1ou4cb4d]

@@geromatezwanzig8789 You could glue mirrors on the base as well, theoretically that could increase the speed of the rotor due to rays from the sun touching both the top and bottom

[@mrdoge9508]

@@user-tn1ou4cb4d From the description of how it works in the video description, I'm pretty sure that having light on multiple opposite sides would likely greatly decrease the efficiency of, or even nullify the rotation entirely.

[@El_EspaciodeCesar]

Dear Professor Bruce , I'm an admirer of his work , I am a high school teacher in physics in Argentina . I copied the solar motor and managed to work some problems . The question is because it works , it's the principle of the radiometer mismpo ? Thank you very much . Sorry for my English ( google translator) :)

[@YeanyScience]

Espacio de César Hello Espacio, These two devices spin for different reasons. The movement of this motor is dependent on the unique property of the stretched plastic polyethylene strips. The chemical's characteristics is that it is made of very long molecular chains. These long molecules are stretched to their elastic limit during the stretching process. If more pressure is applied, these long chains are broken when the plastic tears apart. By heating the strips, the polymer chains contract, pulling the molecules closer together. They do not expand due to cooling as some students may suggest. The action of the polyethylene contracting is quite different from a uniform expansion of matter as a result of kinetic energy. As this plastic is heated temporarily, the material pulls tighter and shrinks to a smaller size. The plastic remains “shrunken” until pressure is applied to stretch the molecular chains out again. The movement of the motor is due to the materials at the top of the cup assembly contracting slightly; this action is pulling the cups together at the top. The action is not noticeable since it is so slight. With the top of the cups pulled together, the assemblybecomes unbalanced. The motor is now top heavy and starts to turn and fall toward the bottom. As the assembly turns, a new section is then exposed to light and is heated. This new spot becomes top heavy causing this section to fall. The action is continually repeated making as the top continues to turn and fall as it tries to right itself. I think a radiometer spins due to the dark colored side of the vanes being heated more than the lighter color on the opposite side of each vane. The heated side of the vane causes the gas particles near it to heat up and gain kinetic energy. The increased kinetic energy of these particles strike the dark side of the vanes and push it causing it to spin.

[@El_EspaciodeCesar]

Bruce Yeany Thank a teacher, I think I understood the concept , owned polyethylene , did a test did not work with electrical tape, now I understand . When presenting this work at my youtube channel in Spanish I will tie your channel. regards Caesar

[@YeanyScience]

Espacio de César Electrical tape would not work, You need to use thin black trash bags that are cut into strips and then stretched. If you send me an email address, I will send you a complete set of instructions on how to build this

[@El_EspaciodeCesar]

I did not understand how it worked so I put duct tape, but then I did with garbage bags and if it worked, I'd like to send me the material. I will spend my mail now a personal message. Thank you very much Professor

[@joshuamwangi8391]

I like. Please send me the instructions, I would like to try. [e-mail]

[@SciHeartJourney]

It would have been nice if he had provided a Theory Of Operation.

[@eventhisidistaken]

It's in the description text.

[@sevtecsev]

its obvious. The bands facing the sun are heated, and therefore expand, causing the axle to warp upwards, which moves the center of gravity of the rotor assembly upwards, and the rotor falls, further allowing subsequent bands to shrink when in the shade, and the rotor develops not much power. that is my guess.

[@mbaker335]

The explanation in the description says the opposite. Heat causes the bands to contract which makes sense for a polymer.

[@noahwilliams2662]

yes, contracting at the top would indeed pull it together thereby raising the CG, I wonder if this couldn't be used to construct a sort of van degraff generator to do useful work.

[@diceman199]

I doubt you'd get any useful energy out of them. The forces involved are so small anything drawing energy from it would brake it to a halt.

[@DesignedbyWill2084]

I am surprised how quickly it reacts to the temperature change. I have played with tightly wound mono-filament fishing line which behaves similarly to the stretched bag material. Twisting the fibers allows for a longer range of motion, will have to try this with the bag strips to see if it has the same effect.

[@MatteoMuccioliStudioMUMAlab]

Good morning, professor Yany, i am a designer of prototypes for solar energy use. Congratulations for this project: REALLY FANTASTIC!!!

[@MatteoMuccioliStudioMUMAlab]

Matteo Muccioli Excuse me, Professor Yany, is it a tipe of Crookes Radiometer?

[@YeanyScience]

Matteo Muccioli Hello Matteo, thank you for your comments. This is not the same as a Crookes tube. The motor turns because sunlight warms the strips at the top of the rotor and causes them to shrink momentarily. As they shrink the rotor becomes top heavy and becomes unbalanced. This then causes the wheel to turn, exposing new strips to the sun and the process repeats itself. If you are interested, I can send you more information on the solar motor. Just send me an email address.

[@MatteoMuccioliStudioMUMAlab]

Thank you so much for your reply ; I'll try to build the solar motor and I'll keep you updated . See you soon. Matteo

[@maurodebiasio1416]

Bruce Yeany

[@liborpaulik8098]

Bruce Yeany Hello, would you send me some more detailed informations about your awesome projects like this one? my email is pauliklibor @ gmail . com

[@VIDEOEPPO]

can you please explain what those solar strips are? Can we use just use black tape instead?

[@YeanyScience]

there is a brief explanation under the video, the strips are made by stretching black plastic trash bags, if you would like a set of instructions send me your email address and I will forward them to you

[@VIDEOEPPO]

Thank you very much. I read the description. I was in the thought that, the air was getting heated and escaping out. I surely would like to have the instructons. email ID [e-mail]. Thank you for your time and efforts sir.

[@YeanyScience]

they are sent

[@VIDEOEPPO]

Thank you so much

[@garryhrocketmailcom]

VIDEO EPPO I think you need the black plastic polimer bags cut horizontal to the openings. Don't forget to stretch the strips. You can try the black tape.let me know how it works..

[@justy256]

I LOVE these videos that mention 'free energy' that are actually based in reality +1

[@mrzorg]

So they produce very little torque, not enough to turn any DC motor, leaving it just as an experiment right?

[@mrzorg]

I wonder how well these could spin a satellite in space tho!!!!!

[@KOZMOuvBORG]

Without gravity, no

[@mrzorg]

Why does there have to be gravity for these to work?

[@KOZMOuvBORG]

Do you notice that the (slightly conical) containers are attached to the axle only by their bottoms? When the 'stretched' plastic is warmed, it contracts, pulling the contained towards each other on the sun-ward side, causing an imbalance and allowing rotation with an initial push (as described). Wouldn't work in micro-gravity Recall reading about this in Popular Science-ilk magazine some 30 years ago under the title "Solar Muscle". In that article, one of the foam cups used had a circle near its rim but the other was, as above, only attached to the axle by its base.

[@AnthonyHigham6414001080]

"When the 'stretched' plastic is warmed, it contracts, pulling the contained towards each other on the sun-ward side" Most materials expand when heated, are you sure it isn't the other way round with the cooling side doing the contracting?

[@ducetre7]

This really does work, it was a 5th grade science project for me back in 1981 Popular science mag had it as project for kids one side heats up expands and the shaded side contracts, much like you kicking your legs on a swing set to make it go, "showing my age do kids even go to the park anymore?"

[@jeremymmrobinson]

Really like your motors, Bruce! And the video production is decent, too. Thumbs up!

[@YeanyScience]

thanks Jeremy

[@hili467]

@@YeanySciencewhat the strips made of? How does it work?

[@lawrence8299]

obviously there are hamsters inside :P

[@jeinermarquez3128]

jajajajaja xD

[@elessal]

invicible hamsters. be got a giant one inside the our hollow planet. that is why ir spins.

[@mrspone1000]

hamsters are solar powered too.

[@junkyardnut2]

it is supposed to trun a lot faster if hamster in in there, dude!

[@rollingstopp]

the big one has 2 hamsters

[@AngelLestat2]

you did not explain how it works.. the physics behind it...

[@YeanyScience]

The basics are explained in the paragraph under the video, if you would like more information send me an email address and I will forward it to you

[@AngelLestat2]

ah ok.. now I see it.. Thanks.

[@parthsachdeva1087]

please can u send me more information about the model and how to make it my email address is [e-mail]

[@robinstuyvesant7187]

Off camera fan?

[@YeanyScience]

If I cheated, I'd never hear the end of it from my students. No fan, just sunlight

[@MagnaMoRo]

Nice! Like nitinol, the garbage bag strip shrink in the heat of the sun and expand in the cool of the unexposed side, thus drawing the top side of the cups or buckets closer together and away from the axis, making that side heavier to produce motion! One can join several of these in series to generate grater torque.

[@YeanyScience]

MagnaMoRo Thanks for your note. I haven't played around with the nitinol wire very much but have had some fun with it. I had a couple students bring some in to my class. What you describe is pretty much what is going on with these.. We have calculated the power exerted by these motors, the small one is running about 1.5 millionth of a horsepower so to get anything usable it would have to be ones much larger my biggest one these banded together. That might be more effort than what it would be worth. However, I still like these even if they are not the answer to the energy crisis.

[@crocobau2]

Do you know why nitinol is not yet used at large scale for solar energy?

[@bishankagrawal2948]

this is so amazing. I think for making the bigger ones more efficient we have to increase the length of the cylinder keeping radius same. I think RPM is directly proportional to length of the cylinder .

[@antigovment315]

You would get more gravity drag. That's why the bigger ones are slower.

[@Idolindo]

O princípio de funcionamento desse motor esta baseado na termodinâmica?

[@d0u6la5m]

what are solar strips?

[@YeanyScience]

they are made from stretched trash bags

[@juliotoru]

Doug Matthews they're like bacon except from the sun.

[@headhunter9414]

@@YeanyScience You are Trash talker right !!!!

[@judgeomega]

The transparency of the polyethylene seems to be inefficient for absorbing light energy. Perhaps with a backing of black painted strips (vertically so as not to interfere with contraction) more energy would be taken into the system resulting in increased revolutions per minute. Or perhaps a thin treatment of adhesive and charcoal.

[@NickNegoitaServingJesus]

Hi Bruce, this looks like an amazing experiment to try with my class, could you please send me some more details on how to build it. Thanks :)

[@brahmburgers]

Would a large one have enough torque to be useful? For pumping water, for instance? Also, Yeany should have explained how the solar strips work.

[@craigcamidge4144]

It works by exploiting expansion and contraction of the black plastic bag slats to change the centre of gravity. No useful power can be generated unfortunately. Nice toy though.

[@l0l0mgwtgdq]

+Craig Camidge he could hake them at a larger scale and then use a gearing system that will give you more power efficiency, cheap power coming from multiple places can make everyone happy, lower electric bills etc

[@craigcamidge4144]

Nicholas skinner Unfortunately not, the extra friction caused by the mechanical gearing would lower the overall efficiency and use as much or more than that generated output, better to take energy from the air using super refrigeration systems.

[@Wavefront101]

+Craig Camidge You could use magnetic gearing with no physical contact. Could also perhaps utilize nitinol wire.

[@antigovment315]

The drag of the magnets would stop this contraption. It is better to see it as a toy:) Over all its fun to watch and speculate and bring up other possibilities like what if the strips were aluminum or steel all balanced to perfection and in a larger scale! there are cloudy days:)

[@madscientistshusta]

Wavefront101 the problem with nitinol wire is all the energy it can produced is put into it when created thus it's not economical to use as a power source at all.

[@KurdstanPlanetarium]

Nice idea but what can it be done with it, how to harness that motion into something more useful ?

[@elektroatze7068]

what is the material out of the rotor ?

[@elektroatze7068]

ja genau ;) lg das hab ich erwartet hate mal weiter rumm

[@elektroatze7068]

nichmal schreiben kann er xD

[@elektroatze7068]

jo ganz genau weil du mich beleidigst ;) lg

[@elektroatze7068]

ich mach das auch genau so weiter so wie du ;) lg

[@attack125]

ElEkTrO AtZe i don't mind XD it just makes you look like some weirdo nazi that is talking to himself

[@rico-NOW-what]

Awesome, going to do this build with my grand-kids, thanks for the text outlining the solar material.

[@dmikulec]

Can't take much of a load.

[@mindaugasvaskevicius1818]

I wonder how big of a device i would need to put on a roof top to power a regular house :D

[@brianmorris8045]

Juat put in in the back yard somewhere...the sun will still hit it if there isn't any trees around to cast shadows. I just like the idea...I just made one while watching it...all I had was two white cups..already had the pins and a piece of dowelling...so made to the length of 18" dowel I had nearby. But the black plastic bag strips seem to work..not an overly fast spin...but it worked under my small lamp...will try it outside when I get a chance.

[@brianmorris8045]

By the way, the supports I used are not wood, but cut up pieces of a box made of thick cardboard. But the [principle is there. My granddaughters will love it..will get them to make one for themselves...well the eldest one anyway...she is 8, the little one is 3...but feed a young enquiring mind properly and you might produce the next Einstein maybe. Confucious (if you are into his stuff) said the start of every journey starts with the first step. I want my grandkids journey to be a good one for the future.

[@caracaes]

You could maybe use it to freely pump water from a lake (where there's no current to power a water wheel or a ram pump), but you'd have to set up some kind of gearing to amplify the torque, and it would definitely be slower than a ram pump. You'd be better off powering a 12V pump from a solar panel. The only advantage of this device is that you could potentially build that yourself, rather than buying an expensive photo-voltaic set-up. Anyway, I've also seen some homemade sterling engines powered by solar which are more efficient and more applicable than this.

[@brianmorris8045]

My solar thing worked by the way and the kids did like it.

[@chaosopher23]

Cool! Try different colour strips, and different colour buckets. It may not be the stretchy aspect of the strips doing it, but the heating of the buckets causing a thermal updraught. See if black buckets spin faster than white ones. You could also try ducting the bottom so that it draws cooler air in, and it might spin faster.

[@rayzimmermin]

that's not solar that's just heat expiation and contraction

[@aforsy]

where does the heat come from?

[@rayzimmermin]

Asa Forsythe any heat source heater oven hot breath induction plat holding your hand over it long enough

[@rayzimmermin]

Asa Forsythe you can make a small one and put it in your pc it will start to move

[@aforsy]

sure, but he was using the sun to heat it. ergo solar power. solar panels just use photons to bump electrons out of place which you could techinacally do with a non-solar source but it's still solar power if you use the sun.

[@rayzimmermin]

Asa Forsythe you cant have photons without light but you can have heat without light that is a thermal motor not a solar motor two different processes just because you can use the sun to run it dose not mean its the sun that runs it you cant use solar panels in the dark but you can still use this in the dark

[@coffeeman321]

very nice and simple to make. The next step is how to generate power and make a good use of it!

[@markallred1953]

I get really tired of reading the many inanities of folks trying to sound smart! If you really don't know what you're talking about, or need to use putrid words to express yourself, then please sit back and admire someone's new toy and be glad for them. I, for one, do not understand why the cylinders go round, but it is impressive to see protoperpetual motion, anyway.

[@markallred1953]

Gee, thanks! Never thot of it.

[@markallred1953]

This was fun to watch! I hope that this someday inspires someone to create a motor truly beneficial and useful to mankind.

[@ZER0--]

If you want to know how it works just read the description under the video.

[@sillypuppy1896]

It's not perpetual because it stops at night

[@artistpw]

All you need now is a lot of thin copper wire and magnets to generate electricity and a diode to keep whatever is getting the electrical charge to not bleed back when the generator isn't running. There is a gear in a book called 507 Mechanical Movements that has a bevel gear system to double the speed of something turning. This would be great to incorporate with a wind turbine to make a way to get some movement for a turbine.

[@Krommandant]

It's fun, now how do we harvest that mechanical force to make use of it? It would need a very good gear ratio to move anything since the force looks weak.

[@rmarsh9997]

the more i think about your neat project the more i find lots of applications for it

[@kevinarnold9623]

you can save weight by ditching the cups and just taping the solar strips to two plastic lids ,that will form the tube and 2 plastic strips taped to the lids on the sides to turn the axle

[@agrxdrowflow958]

I won a junior high science fair in 1978 using this exact same device. Somehow I don't think it's going to be a commercial success.

[@RijuChatterjee]

I feel that while these don't have enough torque to overcome any useful fixed resistance, It might be possible to use in in a situation where the resistance is viscous in nature. This would mean that the resistive torque increases with speed, so possibly the rotor would find some speed of equilibrium and keep spinning. Like turning a small fan or stirring something maybe.

[@fenkjones1172]

One could use mechanical advantage with them to store energy over time or have several of them working at the same time combined to a focal point to push heavier or faster.

[@RijuChatterjee]

Fenk Jones yeah that actually might work.... you might bag the record for the least efficient transducer in history lol....

[@fenkjones1172]

Right, the best and most efficient would be a newer tech called magnetic destabilization. And because these cylinders "move" they could be very effective in destabilization. Study up.

[@darwinmendoza2541]

Do you have a book cataloging your ideas? I would buy that. Love your work.

[@colleenforrest7936]

After watching Espacio de Ceasar's video attempt at making this motor, a thought struck me: Somewhere in here (comments or video?) It states that the garbage bag had to be stretched to 5 times it's original length. A stretched strip would be thinner at the middle than at the ends. So if you took one non-stretched strip that is the length of the two cups, stretched it to 5 times it's length, then cut it into five stretched strips to fit the length of the cups, the stretched strips would be of different weights and thickness. The thickness would even vary along the length of the stretched strip. But, if you measure a non stretched strip the length of the two cups, then cut this into 5 equal length non stretched smaller strips, then stretched these small strips equally 5 times their length (the length of the 2 cups with some extra length to tape the strip to the cup), now for each of these strips, the thin part will be in the middle of the strip and the ends will be slightly thicker. This should help to better balance the wheel. Putting extra pieces of tape inside the cups to act as weights could further help balance the wheel. Also, what mil thickness was the original bag?

[@YeanyScience]

I think they are .1 to .3 mm thick, regular garbage bags. when stretched it is unlike stretching gum or taffy, it will stretch evenly at the same thickness for the whole piece except for the very ends where you are holding it. I hope to post an update on this piece in a few months during the summertime

[@colleenforrest7936]

@@YeanyScience Looking forward to it!

[@DL-kc8fc]

This is due to a change in the center of gravity (such as when you break or bend the shaft). The weight is still the same. Inertia is crucial, because it must get the center of gravity above the shaft. The heat shifts the center of gravity smoothly under the shaft and this causes rotation when leveling (searching) the neutral position. The torque depends on the gravity and the difference of the center of gravity.

[@ralphparker]

I imagine you could do something similar with bimetallic strips. Say fastened to a solid rotor in the middle. as energy hits it they curl and cause the moment arm to increase to a larger radius than the cool side. Thus giving a torque. put some magnets on the rotor and a pickup coil on the frame and produce electrical energy. It will be ac so use a step up transformer and a rectifier and charge a capacitor.

[@WaltBankes]

The rotation speed is limited by the heating/cooling time constant of the plastic. It might be instructive to note that the rotational force (torque) is a result of the radius on the hot side being different than on the cool side - the weight of the plastic does not change. Only the distance from the rim to the axle changes as the heating and cooling takes place. Nice demo!

[@YeanyScience]

Thanks Walt, I appreciate your comments

[@MaxIzrin]

Upvoted for the description. Well done!

[@josephdupont]

How would this work on top of a wooden stove? Could it run some fans to move the air? The air the hot air

[@josephdupont]

Have you put magnets on it and see if you could generate electricity?

[@aslanburnley]

The rate of rotation is proportional to the intensity of the light from the sun. So, a larger rotor will spin proportionally slower than a smaller rotor.

[@1976ClassicCelica]

You could try placing two beside each other with opposing magnets and see if it repels to make it go faster and help under load. Kinda think like an opposing perendev motor combined with your concept.

[@tmhood]

Fascinating demonstration, thanks for posting!

[@eddw123]

Awesome physics principles involved here!

[@ubaldoadalbertolopezornela9570]

Excellent project Professor Yeany. Thank you very much for sharing your ideas. A big greeting from Guadalajara, Mexico

[@YeanyScience]

Thank you very much!

[@MasterMindmars]

Upper side is hottest than down side, so there is a mechanical tension that make a momentum that streches or shrink the wide of the motor... I think

[@manipunation]

As I viewed your video, I could see how it worked. The sun would expand the strips of plastic on the sunny side, and the strips on the other side would retain their original length but since they are pulled taut, this would cause the entire cylindrical structure's center of mass to move up towards the sun-ward side. This would create imbalance and since the center of mass was now HIGHER than the center of rotation, gravity would cause it to rotate as CoM tries to reach lowest point. So everything made sense... that is, until I read that you claim that the sun's heat actually causes the plastic strips to contract. Then it doesn't make any sense to me. However, very clever design I love the idea of making extraordinary things out of ordinary cheap materials as you have done here.

[@YeanyScience]

Hi Quazgaa, good to see most of it makes sense. The polyethylene strips of plastic are polymers made of long chains of molecules that shorten as they are heated. If I take a piece of it and hang a metal weight from it, I can then bring a 100 watt bulb near it and heat it up. When I do, the strip will actually lift the weight enough to measure it. Rubber will do the same thing. Interesting enough, my first motor used rubber. It looked like a bicycle wheel with the spokes replaced with rubber bands, however, it needed more energy than sunlight to make it turn.

[@Peebsfosho1]

Yet another fantastic video! I am sure there is a purpose for the spaces in between the strips, how would no gap affect it? What about using black containers?

[@edwardnasser8960]

The one we made does not work. Not sure if there's too much tension to it, or too less. Or maybe the holes in the cups are not centered. But, we've followed the instructions very carefully though. And our trash bag only contracts for 1 cm max when heated.

[@YeanyScience]

Were they my complete set of instructions? you did stretch the trash bags strips before putting them on? I have found that some trash bags strips were better than others but most of them that I've tried did work.

[@manojchaudhari5053]

Good Ideas Sir Thanks From INDIA MUMBAI (BOMBAY)

[@brianatkinson1399]

My next question would be is is possible to build one that would run a car type alternator to create power to run DC voltage appliances?

[@vorkvoyd]

Fun experiment, but if you can stop them easily with your hand, I can't see them providing any significant power. For your surface area, you can generate way more power with a solar panel. It is still pretty neat though.

[@YeanyScience]

thanks vorkvoyd, NASA produced similar type of motor that generated a few hundred watts but still not as efficient as the solar cells. I find it amazing that it turns at all

[@doxielain2231]

Neat! Question: do the walls of the drum need to be flexible to react to the shrinking of the polyethylene strips? Or could I make the rotor out of light wood? I'm a sculptor, and this seems to be a neat thing to play with. Thanks!

[@YeanyScience]

the cups can flex at the joint, one of the original ones I made were wood blocks as the drums, it worked but making it with the cups was so much easier

[@jimparsons6803]

Interesting and thanks. I think that I might have seen something like this on PBS a decade or two back using rubber bands? The rubber bands, when heated a little, expand a fraction, causing the cylinder to rotate in the direction same as that of the demonstration as the center of gravity would move ligtly further away from the axis.

[@SATXTradesman]

What will mixing the different sizes together bring? Perhaps setting up several devices in an array with one common axel suspended in equal distances from the orgin to the intersection of the axel supports. In theory, both descriptions should render better torque.

[@kjellg6532]

For this to work you should be aware of the construction of the cylinder, The axel is fixed to the bottom of two cups, it is not a rigid cylinder made from steel. So this cylinder can be bend. If you contract the two rims at the top due to the solar bands contracting, the “cylinder” will contract and bend. On the hot side the rim of the cup will move away from the axel. This will cause an unbalance and the cylinder will turn.

[@TheBanjonator]

Hmmm... I think the underlying theory may be a bit skewed. The sun's rays actually RELAX the upper black strips, thereby allowing the cup rims to move outward, and heavy cup bottoms to shift upward. That makes the unit top-heavy so it perpetually tries to right itself.

[@YeanyScience]

Hello Banajonator, the process the strips are going through is called retraction, the long polymer molecules are shrinking when heated and when you pull them they cool. Rubber bands do the same thing. If you cut a 3 inch piece of plastic trash bag 1 inch wide parallel to the top of the bag and pull it, it will stretch about 6 times it's original length. If you then hold that under a bright light you can actually feel it tightening up.

[@TheBanjonator]

Hi, Bruce. Polymers may well behave that way, but your description doesn't explain the motor's function. Were the dark bands to tighten in the presence of sunlight, the center of mass would be shifted downward, thereby stopping rotation.

[@McPrfctday]

What are the solar strips? Some kind of lightweight solar panels?

[@DownhillAllTheWay]

I made one of these the other day to interest my grandson, and yesterday, the sun came out for a while - but I couldn't make it work. Maybe it's because I used transparent plastic yogurt containers, which may allow enough light to pass through them to heat the back strips as well as the front ones, or maybe my trash bags are made of different stuff. More experimentation called for !

[@YeanyScience]

Hi MIke, I can't say what the trouble is without knowing more about how you built it. Did you stretch the plastic strips before adding them? If you want a set of instructions on building this, send me an email and I will forward the instructions

[@DownhillAllTheWay]

Hi Bruce. Yes, I know exactly what you mean by stretching the plastic. It stretches beyond its elastic limit, and it is clear from observation that something changes at a molecular level - any more stretching would tear it. I experimented with the stretched strips a bit, and they do contract, but so little it is just on the edge of my experimental limits of measurement. I put a bent paper clip so that the strip had to go through it in a Z - so that any contraction would have moved my paper-clip pointer. In strong sunlight, my motor does turn, but only about 2 turns per minute - it turns a bit,, then waits a bit, then turns a bit more. This is with the sun coming in at an angle, so it warms the 2-o-clock area of the cylinder, which is handy because it makes it self-starting. However, I do suspect that my trash bags aren't made of exactly the same stuff yours are. The motor was built pretty similarly, pivoted on pins, etc.

[@jpbd7574]

I still don't get how it works. "Sunlight hitting the strips is converted into thermal energy (heat) which then causes the rotor to turn", How does it turns?

[@YeanyScience]

HI JP BD, there is a description under the video

[@jpbd7574]

Hi Bruce. Many thanks for the response. I have read the description and i am starting to understand the perpetual motion is kept running due to thermal expansion. Very interesting phenomenon indeed. Is there any other material with this kind of properties? Thank you for your time. By the way, i wish to mention i really appreciate your videos. The subjects are very well chosen and the devices you create are really cool. I am really looking forward to some more great ideas comming from you in 2017! Cheers and happy new year my friend! JPBD.

[@YeanyScience]

thank you, and a happy new year to you also. The first time I saw the type of behavior was with rubber

[@eduardobucci3609]

Muy buen video!!!!! Soy un fanatico de todo lo que tenga que ver con movimiento!!!Asi que este motor sera mi proximo proyecto!!!Gracias y saludos desde Buenos Aires!!!!

[@DollopussD]

Weirdly, I want to make a smaller one. What's the smallest you can go and still get this to work? What materials do you recommend?

[@jayk806]

I wonder if instead of attaching to a generator, if you put neodymium magnets on the axle and wire windings nearby if the magnetic fluctuation could produce a usable current.

[@agoodsheperd880]

How much torque is generated? What work can these do? What are the solar strips made out of? Why is this generating enough torque to move?

[@thomasferko8666]

What seperates the plastic tumblers or drums inside the larger units. I bought your book but it shows the small unit.

[@bellybutthole]

Cool! Reminds me of nitinol, also I can't find my way home...

[@mheermance]

Neat. Does it scale linearly? Or would a big enough one eventually be unable to turn?

[@erictaylor5462]

It looks like it makes a cool declaration, but can you get any work out of it? Looks like there is very little torque.

[@jek__]

In that context of the word free, I wouldnt include wind necessarily because the act of capturing the wind slows down wind currents. I'm not climatologist, but wouldnt significant drag on the global wind map have potential to alter currents or stop them? I think wind drag "pollution" is a thing, we just havent run up against that wall yet. I suppose while making river powered machines if you build it in such a way that you maintain enough elevation while powering your machine to dump it back in the river at a lower point, you're not creating drag on the system, so long as the river is gravity fueled and velocity doesnt play a significant role. But I guess really thats just solar power when it comes down to it. You're getting that energy from the heat that evaporates water and causes it to rain on mountains to drive downhill rivers. I mean when it comes down to it theres basically solar power, galaxial power (geothermal got its energy from the rotation of the spinning galaxy iirc), and nuclear power

[@fvcostanzo]

How much usable torque do you get out of one of these things? Can it drive anything, or can it barely turn itself? Seems like it would take nothing to stall it, so it can't even run a tiny generator. Cute, but likely pointless. I did like the instrumental version of Blind Faith's "Can't Find My Way Home" playing in the background, though.

[@daddygr93]

can this be used to turn a small gear in order to facilitate the use in another mechanism..? if so how low should the resistance be?

[@JDeWittDIY]

+Bruce Yeany Could this be made more efficient by adding a shade around the sides and bottom of the rotor to keep the sun from heating them? Also the movement of the polymer makes the rotor unbalanced, but it's actually gravity acting on the mass of the rotor that gives it rotational energy. Perhaps there may be a way to use the pulling of a heated, stretched polymer to directly activate a piston of some kind, and turn the back and forth movement of the piston into rotational energy? Perhaps it would have to be some sort of material that has more movement than polyethylene.

[@aszi77]

Why didn't you explain how it works in the video?

[@YeanyScience]

good question, I planned to do it in two parts, for now I have the explanation under the video

[@joeamaral5215]

good job nice project . it is a good step to others thaks for the video . God bless all

[@lancethrustworthy]

Bravo. Well done; short and concise. I appreciate, too, the explanation on how it does what it does.

[@YeanyScience]

Hi Dan, thanks, there is an explanation under the video

[@tchippat7634]

This is real science. Very impressive.

[@YeanyScience]

thank you, while they can't do much work, it still amazes me just to watch them

[@murataydin6238]

I just saw this video it is reaaly amazing! Can you explain the science behind this in a separate video please?

[@stevenvlogsnc]

I thought running my solar panels into the house was pretty cool, but this is even better! I would like to know how I could make a "solar cylinder" of my own!

[@SuperChromer1]

nice post , thank you... this will be very useful in a solar convection application ( green house heating ) the process is simply to add direction fan blades to the end caps and thus better movement of air currents into directional applications ... also see solar black boxes for heating ... thanks again... but , post of video of making one , so others can expand on the concept through application of principle ... ttyl...T...

[@ProjectorsScreen]

Hi Do u think this get some heat near the window and heat the house in ? This could help in the winter

[@kakkinefatta]

Per favore mi sa dire la lunghezza dei nastri,i primi 2 e di quanti gradi i bicchieri sono inclinati nella parte piu bassa? gli altri nastri sono lunghi come i primi 2 o piu lunghi?Cordiali saluti Gianni

[@jimjakosh2506]

Please explain what the strips are made of and why when they are heated, it caused the drum to turn. what is the theory of operation? It sure looks slick but need more explanation. Thanks Jim Jakosh

[@YeanyScience]

Hi Jim, check out the description under the video, or send me an email address and I will forward ainstructions and description on it

[@here-Im]

interesting solar project- appreciate you sharing your project with others. you mentioned the use of solar strips? will you please share additional info in reference to the solar strip, are you using actual solar strip (as in solar pabels)or is it plain plastic? any info is greatly appreciated. Good work, keep it up.

[@visionmarvel9748]

AMAZING, ALL YOU NEED IS A GEARBOX AND A GENERATOR MOTOR👍👍👍👍👍👍👍👍👍👍💯💯💯💯💯💯

[@shatts]

Hello Bruce, loving your channel. You mentioned in the comments that you have written a book on science demonstrations for the classroom. My son is a Cub Scout leader who would be able to use these demonstrations with them. My question is what is the name of your book and is it available in Australia. Once again thank you

[@DAJedu]

My son does quite a few solar designs and has never heard of solar strips, would love to learn more about them and where they can be purchased. He is going pretty heavy with solar designs this year.

[@YeanyScience]

I will be sharing more information in upcoming videos. if you give me an email I can forward more information. thanks for watching

[@matthewcarder5927]

Could this be made more practical if the strips where to be made of bi-metals(2 different types of metal layered together as one) that react to temperature differently. maybe put a propeller on the shaft pointed at a low speed wind turbine, if built big enough?

[@JohnLeaf]

Do a giante projection with a small one thats 30 times stretch long and do a energy caption with it and see if we can make something work

[@onetruekeeper5055]

To be a true free energy motor it must not receive continuous energy from an outside source such as the sun for example and has to run independently from any power source once operational. It must also produce more energy than it requires to operate. To cold start a free energy motor a outside source of power may be momentarily needed to get the motor initially running such as from a battery or storage capacitor.

[@lexpee]

Ferry nice to see it turning but what can you do with it? There is not enough energy to drive a dynamo or a water pump. maybe a enormus model of 3 meters long by 1 meter diagonal. 9.8x3.2 feet.

[@coc7711]

i think they can be use as cooling fans in the house or in the factories

[@mttpsg00]

sir, thank you for sharing this nice experiment. i have one question: those strips, are they made of plastic , like adhesive bands? or is that a special material ? thanks

[@s7meastm]

This is similar to a Minto Wheel. Very cool.