Special note for mirrors. Two mirrors are needed for a periscope; the first mirror reverses the image, and the second flips it back. Continuing on with curved mirrors, a concentrating mirror converges parallel beams into a cone, then past the focal point, it diverges. To make the beam parallel again, a second mirror is needed to reverse the beam from the cone shape. Advantage here is the choice of placement of the second mirror. This is the secret of the Archimedes Lighthouse, burning ships out to 25 miles away. Coincidentally, these Lighthouses were used for long-range communication and spying on other cities.
I think the most useful thing regarding making parabolic shapes I have found, you were the one to share, which was the beam of a light as it is cut in a cross section across something and trace where the edge of the light and shadow is, because you dont even need math or anything for that, and a whole unit made that way, you can quickly find the focal point using something like a stick since it burns so well LOL (just be sure to wear a welding hood or make a pair of polarized goggles with a second set turned 90º from the lenses (I am making a pair of steam punk like goggles that will have a rotatable for variable darkness, lenses using this, and 3 layers of polycarbonate lenses for a friend, and fellow researcher, for arc welding, cutting torch use ect, to protect his eyes, but not using brass making them a pair of brass goggles but rather pure titanium for the eye shields and the main lens rims LOL ) anyway, I seriously wanted to thank you for that info, so very useful. on the mylar durability, the one thing I can point out to help it last longer, Use a continuity tester like you test fuses with, and a little light comes on if the fuse is good, and test the sides of the mylar to make sure you have the metal coated side facing the sun, if you do, it can last 10 years easily in direct sun every day, but if you have the plastic side facing the sun and the metal facing down, depending on how much heat can build under it, you can have those mirror surfaces blasted off by the sun, in like 4 days or less, (I had a batch of pieces I cut up and hot melt glued down to a tarp, and did not pay attention to which side was facing which, and in 4 days of oklahoma summer sun (brutal) the sections that were facing the wrong way were mostly clear with only some faded mirroring around the edges and directly over the hot melt glue that apparently held the aluminum vaporized coating on the mylar plastic,)... one advantage to making sure it is facing toward the sun (the metal side) besides it lasting longer, is the fact that you are blocking all the frequencies that a clear substance will absorb like a sheet of black painted matt finish will absorb all the light making heat, and it blocks by reflecting it so you get a lot of IR and UV that bounces off and back into what you are heating. (or burning, I was thinking 30,000 square foot of them to melt sand and make blocks of quartz glass for glass brick roads that each brick has a solar cell under it, so all that fiddly worry about the vehicles destroying the glass is not a concern as its in say 6 inch cubes with a semi spherical divot behind it and some rounded grooves from that to the edge of the brick for the wiring, and glass does not work well when flexed (large sheet with something pressing down on the middle of it) but it works quite well when being compressed (something just squishing down on top of it not bending or flexing it and instead reinforcing it not being flexed) So that road just needs a good solid flat surface to lay them out on, and if one breaks, you grab it using either a tool that a gap is formed in the bricks to allow removal, or a suction cup shape to pull it out, then slip in a new brick and any components broke under it :) Most of the energy to make everything in that would come from concentrated sunlight from say a desert on the sunny side of a mountain (norther hemisphere as I live in, I would use a south facing slope of a rocky mountain in NM or AZ or something) cutting down on all the energy it normally takes to process the silicon and silica for solar cells and bricks, seems like it would make the whole process even for buildings with solar cells in blocks of glass held in place by the weight or better yet,... glass lego blocks! LOL anyway I have waffled on enough. Thanks again. great info series you got going on lately regarding the psychology behind science and tech, to help people have a more active and healthy attitude toward the work! :)
Also - Get a wide bucket or pan, fill it with a material that sets up, like plaster or cement, then spin it at a constant speed while it sets up. The centrifugal force causes it to form itself into a mathematically correct parabola, with a focus dependent on the speed of rotation. Then just layer on your reflective material. You could use it as a form to heat bend some stiffer material and go into production.
that sounds challenging mate - spinning a weight like that while it sets isn't an easy task - the change in viscosity as it sets will also mean spin speed will have to change or it will just be a lump - i amnot sure that is a particulalrly easy solution - have you tried it?
@@ThinkingandTinkering yes. I did it with plaster of paris on a potter's wheel and it set up long before I got tired. And once it gets up to speed, it takes the shape and doesn't change with viscosity. I was just making decorations, but it makes a true parabola. It doesn't take a lot of RPMs and once it's moving it doesn't take much to keep it moving. I suspect a small motor with a belt around the bucket would do a good job.Just hang the bucket from a hook in a bearing if you don't have a potter's wheel. A variable speed motor would give you a variable focal length. You can find the formula online.
Sounds like an interesting use for one of those kiddie pools you can find being tossed out somewhere in the neighborhood. I suppose the tricky part would be building the turntable to put it on for doing this.
@@pauljs75 to be sure, doing it with a larger size would be challenging. I was looking at his samples and remembering my efforts in a 5 gallon bucket. At about a meter in radius it would certainly start to be an engineering problem.
@@BillDeWitt Indeed it does become challenging, but it turns out at least one group (at the University of British Colombia IIRC) figured the challenge was worth it to build an 8 m telescope mirror using liquid mercury. Apparently the optical quality is superb and the cost is significantly less than grinding a mirror that size to similar precision. One major limitation is that you're limited to targets directly overhead.
Using the convex shape and putting the reflective surface on it, you could back it with spray foam and once hardened remove. Light weight and easily replicable! Cheers from Canada
Or form your initial surface and make a plaster mold. The foam will be lighter and easier to make. But the plaster would be more durable. It all depends on how many copies you want to make.
I built a cardboard & kitchen foil solar cooker from plans in Mother Earth News magazine back in the 70s. It barely fit in the back of my station wagon for transport and it was necessary to chase the sun around the yard just to tan a couple of hot dogs. Sun glasses were a must. The cooker had an adjustable curtain rod in the center to mark the focal length where a grill was put for the cook surface. Sure would have been better if it was a fold up design.
I really like that copper mirror effect! back in the day I carried a solar cigarette lighter, it was a conversation starter but not practical if you wanted to smoke at night or a cloudy/rainy day. That said I have a couple stashed away in different camp bags.. mostly as conversation starters..lol.. you can pick them up for a couple dollars or even make one by polishing the bottom of an aluminum can... I hadn't thought of it until you mentioned it but mylar glued to the bottom of a can would work and a LOT of folks carry those mylar space blankets... hhmmm food for thought...
Not solar but back in the day I carried a permanent match. Fuel was inside, unscrew a flint and strike it on the side. It had two geese pictured on it 'doing it' on the wing and the words "fly united" :)
An easy way to draw a parabola, to help align your pettals or whatever, is to draw a parabolic envelope. Basically you draw a bunch of tangents around the parabola. This is easier than it sounds, and many of us did this when we were kids. If you ever did that thing where you too a peice of paper and drew a bunch of equally spaced marks horizontally and vertically (same number of marks in each direction, all the same width). Then you draw a line from the top vertical mark to the innermost horizontal mark, then you draw another line from the next mark down to the next mark over and so on. That curve that forms is a full parabola.
Mirror silver/copper vinyl is primarily designed for decorative or visual purposes, such as creating mirror-like surfaces or adding reflective accents. While it may have some thermal reflective properties, its primary function is not focused on providing optimal thermal insulation or heat reflectivity. Typically made of multiple layers, including a Coating, reflective layer and an adhesive layer. Coatings or treatments can alter the surface properties and affect the material's ability to reflect heat effectively. I have tried these with parabolic antennas of dish tv with all materials... and just kitchen Al sheets are massively superior in thermal concentration with nearIR reflectivity at an astonishing 95% . However suntracking still remains elusive with robust, simpler methods.
Cool! Years ago I can remember seeing a guy cooking with a wooden frame covered in plastic (either the plastic had some give in it or stapled on so it wasn't bone tight) he supported this on 4 legs about 6-8 foot high and filled the plastic up with water to make a lens!
@@bradlafferty I forgot to add that the frame that the plastic was attached to was about 6ft across by the time it was filled with water the lens was about 4-5ft across!
@@ThinkingandTinkering The weight of the water against the plastic just forms a smooth surface, and the thickness of the lens can be increased by the tension of the plastic, the bit that I can't quite remember is how he had the cooking side of thinking set up! If I am correct a Fresnel lens has ridges the same as a lighthouse!? It's cheap and could be made portable!
I'm a career commercial sculptor. We have to make all sorts of shapes all of the time. One time I left a fun house mirror lying in a field...it wasn't even a parabola but within minutes there was smoke in the grass! Anyway...If I was going to make one of these cheap and durable, I would find a circular frame and stretch transparent vinyl (which you can find at the dollar stores as shower curtains and table cloths) then inflate it (as opposed to vacuum). That makes a mirror smooth surface that can be fiberglassed or sprayed with hydrocal (or plaster) and fibers. You could do the same by sucking out liquid hydrocal and fiber the way air was sucked out in the video.
Great vidio, like the idea for making the dish. Had plastic sheet miorr 1.5'×3' leaning against the house, plastic got hot and bent then the sun burnt a black make across a post 6' away. Thanks for the morning coffee...
You just saved me about $300. My microwave went out yesterday, and I have an old wok down in the cupboard. I'll know what I'll be doing tomorrow. THANKS!
I found an IKEA plant pot base that was formed in to a parabolic shape. It was made by rolling thin strips of ply wood. Rolled up to make a large disk. Then it must have been placed in a former to produce it's shape and then glued in place. All I did was spray paint it silver and applied strips of reflective mylar tape. I suppose the same thing could be done with strips off cardboard rolled up.
If you were to set your device on a solar tracking platform. Located at the south side of your house. With a looped copper coil placed in the heat tube, replacing the water with heat conductive oil. Use flex lines to connect the copper coil to an overhead insulated water tank, in a thermal siphon arrangement. By the end of a sunny day, you would likely have a lot of very hot water.
Thank you so much! this will shorten making it so much! Still struggling on the stirling, all I have is empty 2.5 kg nido milk can and empty 200g of can of vegetable. Most example use membrane I can't get around this so far.
Send it down to electro plater and turn it into chrome finish . Probably 20 pounds or so . I wonder how much better it would be with a polished chrome compared with foil?
as i said mate - there are a million ways to do it and it all depends on what you do it for, what equipment, skill and budget - but sure electroplating is a nice idea
Fresnel lens is another approach RMS. Build a 1 meter square frame from say 3 x2 timber. cover it in clear polythene, elevate it on a tower, say 2 meters, fill it with water and that will create a fresnel lens. Then focus it like a magnifying glass = fire from water. I'm gonna build one this year to act as a pool heater for the kids pool.
Seems to me the thing to do would be to have a couple of these simple mirrors - could be plastic covered with mylar, IDK - with a bit of framing that allows them to heat blackened "heat bricks" in the morning hours that you then place in an outdoor oven that you use for the cooking ... something like a tandoori oven, pizza / bread oven, a warming oven, or a base to use as a stove. Maybe focus light on an iron pot you can fill with river stones ... would the stones be ideal for controlling temperature? IDK. Seems to me this would keep cooking mess away from your reflector, and allow you to better control the heating in the oven(s) by adding and removing what amounts to "re-usable coals." Just be sure to start the oven in the morning and have all your cooking done by sundown. 🧐
I bought a Fresnel lens years ago from eBay that was for a projection tv or something and had fun burning things up like coins, etc. I was going to make a frame that swivels to mount it but never got around to it.
Idea. Use your metal fire pit as a form and do a plastic vacuum seal into it. A small air fitting in the back of the fire to pull a vacuum. Then one could produce limitless plastic parabolas.
I story I heard in school then I was 13 years old was the race between Stephenson's Rocket and Novelty, how was an early steam locomotive built by John Ericsson and John Braithwaite to take part in the Rainhill Trials in 1829. Why this cut story here. John Ericsson looses get him to run away too America And he build around year 1876 a heat air from sun/stirling variante! The solution for make sun to a energy source is a bit older then people in general know! As always I love your film Rob! keep up your great work! 🥸/Mikael
There are so many technologies decades old even centuries lying unused that could play a major part in our energy requirements it’s scandalous really but robs videos are showing us some
An old bin lid? Not a bad idea! I’d have many bin lids? Classic galvanised bin lid also have extra divets. So many focal points. The fire Pit lovely! Great job!
You can also pick up reflector telescopes dirt cheap at boot fairs, the mirrors at the back are really accurate parabola ( even the cheap ones) somewhere I have a 12 1/2" mirror that needs re-aluminizing I will have to dig it out and have a go.
The trick with mylar to keep it in shape without the continuous vacuum is to reverse the process i.e. use pressure to form the parabolic curve outwards, not inwards. Ensure the most reflective surface is on the inside of the curve, maintain pressure for the duration required to pour casting resin over the outside curve and set. Now you have a solid backed mylar mirror. Simples!
I like the idea of vacuum... then maybe use that as a cast or form for some sort of resin or such that could then be painted with reflective paint or material that could be polished.
What if we use a large wax coated wok / parable to make a mold out of ~ plaster, foam, paper mache', etc. Secure & seal the surface of the negative parable, then using mold release wax to coat the mold followed by application of a mirror surface then a light layer of flexible reinforcement so that the new parable can be peeled off of the mold? Just a thought from experience making boats as a teenager.
Now use the parabolic mirror to heat up a few tons of sand and use the heat to turn a Stirling engine to turn a generator. Also water cool the cold side of the Stirling for more efficient and use the hot water in your house!
@@ThinkingandTinkering It’s a time thing with me. But I can see advantages because you can make a printed version any size you want. And you can fine tune the shape. All you have to do is design a set of shapes that can be assembled into petals. Then assemble the petals into your reflector. If I had a faster printer, I might go that way.
@@ThinkingandTinkering About 10 years ago, you made moldable silicone by mixing cornstarch with cheap builder's silicone. (Some people do the same by adding dishwashing liquid. I don't know which way is better.) In this thread, we were talking about making petal parts for a reflector using 3D printing. But to build a reflector with a 3D printer would take an inordinate amount of time. On the other hand, you could print off the parts from one petal and then use your homemade silicone to make molds. After you've made molds, you can then mold parts out of urethane. As far as I can tell, you've never done a video on urethane molding. But this would be an excellent project for such a video. I just thought I'd mention it since I know you're always looking for useful video topics.
I like the way a spiral was cut in a piece of round tin and pulled tight and the 1" wide cut would tilt inward concentrating the sun and the thing was still flat. spiral solar concentrater
Some of the recent "chrome" spray paints are pretty good for this too. Looks like he had it on the desk, but forgot to give it a mention. It's probably one of the easiest things to apply once getting the dish part worked out. A lot easier than trying to cut up bits of film or tape and getting that to adhere to a surface. Also the method for the mylar dish can be copied with a plastic garbage bag instead, and that shape can be plastered over to make a release form for making non-reflective dishes that way. And then those can be further covered to make a reflective dish.
Many great projects may be constructed for education and everyday use. Typhoon season here in the Philippines certainly puts a damper on all the fun. We do not have bad weather the entire storm season so there are days you can still play. Our backups are in place so it is time to get on with it. One of the easiest finds is old satellite dishes. All we need to do is grab one from our roof as the "retirement project" house was pre-equipped. Thank you for the ideas and motivation.
You didn't remember to warn people to not leave it laying about in the garden when they've finished with it, those morning rays the next day could set their street on fire if they hit the dish at 'the wrong angle'!
Safer than a parabola, there are free plans online for a DATS cooker (double angle twelve side). I've used it effectively. No tight focal point means no fires or burnt retinas. Easier to build too. 49° North.
Made a really good one messing about in the 1970's. 3 feet across. backing was made on a huge balloon with papier mache. I burned a lot of stuff as a teenager...
Several years ago, I used unwanted TV Dishes lined with $1 emergency blankets for similar purposes. There is plenty of them to be had for for around here rural SC/USA and there was no measuring needed. the Angles and point-of-convergence are already there. And at 33.5° N, it quickly cooked our hot dogs (faster than the charcoal grill!) Now you've got me thinking about what I could do with all those giant C-Band dishes around here (there's at least three). All are at least 8'/2.4m diameter and 4.5m2 of area. Add a tracking system for maximum daily power, of course... Question for the Audience: What solar panel could I use on this system? It would need to survive the heat and be able to convert to maximum voltage.
No photovoltaic solar panel could handle that heat. In large scale systems they use molten salt reactors. Then use the molten salt to boil water and run a steam turbine. They run at night off the residual heat as well. These never came into large scale use, because they came under heavy attack by animal rights groups for killing birds. I am sure big oil likely played a role as well. As it is the most efficient and cost effective form of renewable energy, that I have ever discovered.
Look up Solar Funnel Cooker by Steven E. Jones. It is far safer than parabolic because it doesn't concentrate the Solar energy to a point, but to a more diffuse line. You can also make them foldable, so that it is more easy to transport. It's also easier to make.
Brilliant mate! Would your mirror paint give enough reflectivity? If so, then that is even easier than any kind of foil/mylar application. Just a thought. Cheers!
the aluminum foil for cooking I found has a line like pattern on it, and it runs along the length of the roll as it is rolled up so placing it with that facing so the lines run from center to outer edge while it may cause some bunching in parts of your troff design, I think in that format it still would ensure all the light is hitting that line of your heated tube you are cooking in, and the tube can then disperse the heat through out the inside for cooking. :)
@@ThinkingandTinkering yeah I rarely find the good stuff with out those lines, and they seem to run the direction that the rollers it was on leaving them seeming to be left over from turning the rollers on a lathe or something (ie the marks on the rollers go around the roller rather than down them) either way if you do have the marked stuff it seems like making sure they dont interfere is not that hard, just have to orient them correctly when using it :)
Nice and does work. Just don't try a 1.8 meter satalite dish covered with kitchen foil and then use an aluminum pan. It nearly melted the aluminum pan. Believe me I know. Maybe I had it too focused in the hot point. Haha
There was (not sure if it is still active) a website that had designs for parabolic cookers that I saw years ago. Solar cookers take a fragment of the parabolic idea and use a covered box to manage the heat. It does take an effort to plan your cooking ahead which is why solar cookers aren't as common in northern or rainy climates
@@ThinkingandTinkering indeed, and I know that everyone here deeply appreciates the information and ideas you've shared. What I'll be interested to see are the different and improved ways this group will expand on the concepts you've highlighted
Your good man. I wonder if you could use a stainless bowl. The restaurant style are very reflective. Also on your last video. I wonder if you used different color tubing if it would make the spectrum different. It would open up whole new door right?
Dear Murray, once again a great video. I have seen a documentary where they tried to burn ships in some hundred meters distance like the ancient Greek. It did not work, but they also just used several flat mirrors (each person holding one). I think it did not work due to human error (not all people could hold the mirror stable) and no focus. Can you manage this historic experiment with some improvements?
0:39 Robert, a mylar sheet on a pan with a mild suction applied to the back side doesn't form a parabolic shape. Like a bubble formed from a film, its curvature is spherical.
Try a used Satellite antenna. I have a 1.2 meter that I'm going to paint with Rust-Oleum Gold. I have the arms that came with and just need to flip them to the top to make a hook to run water through to heat the pool
Rob on your wind turbines, could you show us what is available to get the power into the home, is there a storage system and components that could get it to 240volts......In essence what do we do with the energy coming out of a wind turbine.....Brilliant channel thanks.
MIT Why doesn’t a plain, white piece of paper reflect light, but a mirror does? Almost everything reflects light - it’s how it reflects it that makes a difference… By Sajan Saini “I used to have a red car, when I worked at General Electric,” Department of Materials Science and Engineering Senior Lecturer Emeritus James Livingston recalls. One evening, walking back to the company parking lot, he was surprised to discover that his car had changed color. In fact, the street lighting in the lot had been switched to mercury lamps - which, Livingston explains, have almost no red in their light. His car thus appeared as black, with a touch of blue. After driving out onto the city street, with its conventional streetlights, the car’s color changed back to red. Livingston’s color-changing car highlights the fact that light sources, such as the Sun and tungsten filaments, emit a spectrum, or collection, of colors. When this spectrum of light falls on a surface, some colors are absorbed by its molecules or atoms. The remaining colors penetrate to within a few wavelengths, Livingston says, and partially reflect back. White surfaces are composed of molecules or atoms that don’t absorb any of the visible colors of light; our eyes perceive this reflected combination as the color white. But doesn’t a mirror also reflect all the colors of light? Why doesn’t the surface of a mirror appear white, rather than reflecting images into our eyes? The answer, Livingston explains, rests in part on the penetration by light. A mirror is essentially a plate of glass coated with a thin film of metal, such as silver. At the atomic scale, metals are a crystal network of atoms whose outermost electrons dissociate and wander with high mobility through the network. These mobile “conduction” electrons are the source of electrical conductivity in metals, and when light attempts to penetrate a metal, they “vibrate in such a way” that an opposing electrical field is created, canceling the electric field of light and prohibiting any of its colors from entering beyond a few atomic layers. When that occurs, the light has been effectively reflected from the surface of the metal. In addition, the smoothness of a mirror’s glass and metal coating ensure that this surface reflection is specular, says Livingston. As a result, rays of light bounce “like tennis balls,”, always maintaining an angle of reflection to the mirror’s surface, that matches in value the rays’ angle of incidence. Rays of light originating from a person’s ear, nose, and eyebrow, will “reflect with the same angle” off a smooth mirror surface and maintain their relative orientation, thus preserving the image that our eyes will perceive. White surfaces can reflect a considerable amount of light, but without the mobile electrons to oppose the electric field of light, white surfaces allow light to penetrate up to several wavelengths. This allows them to experience multiple reflections from crystal grains and other irregularities within the structure of the surface. Some multiple-reflected light can reemerge from the material surface, but without the same orientation, as that which reflects off a mirror. Surface roughness, Livingston says, also contributes “diffuse reflection,” causing the rays of light from different parts of a potential image to “bounce back at different angles.” Multiple and diffuse reflections scatter the reflecting rays, and all information about the image is lost. White paint or a piece of paper are classic examples of light scattering, he notes, as are clouds, the foam in your glass of beer, and snow. These latter examples are turbulent or irregular structures, containing “lots of air,” which causes “light [to] reflect off internal and external surfaces” and scatters the rays of an image. It is striking to consider, Livingston adds, how a still pool of water may serve as a poor mirror. Yet, when the same water crystallizes into irregularly packed snow flakes, multiple and diffuse light reflection results in a white surface. Posted: February 21, 2012
Thanks for sharing Rob. However experiments have been made using polished copper as a reflective surfaces and it has been shown it is not bright enough to light the interior of the pyramids as the light is too greatly reduced, so this could not have been a source of illumination for them. Interesting legends do come from South America however with some ancient writings stating that two large 4 meter mirrors where used to melt stones and therefore used in the construction of sites like Sacsayhuamán. It is also interesting to note that 2 sound waves are required to create a beat frequency! Is it possible to create a beat frequency using light?
I'm not technically minded, but I have this idea in my head.. Could you use concentrated solar thermal.. like the following Have a pressurized water container that was heated via the CST that when heated would behave like a steam engine to push pistons that would produce electricity. While the steam from the engine would be recirculated via a 'still' type set up so you could just keep using the same water, thus removing the need to constantly refuel the 'generator? Electricity stored in batteries, of course.
4:48 you mention a "Pennsylvanian" fire pit, lived in PA (that's what we call it, lol) since 1976. This is a new name to me, we just call them fire pits. Lmao
Those are pretty enough. There are some non-imaging reflectors that are somewhat cone shape that I thought would be nice to try because the focal point is at the bottom of the cone, so you don't have to figure a way to hang stuff in front of the mirror. No doubt uses more material per square meter though.
Can be done using mylar over a loop, pan, etc. Secure edges well, pull a vacuum on the pan to adjust the focus or carefully attach a cord to the back of the mylar and by pulling / releasing tension on the string the focus is adjustable. 👍 Have fun 👍
Hey love your video s Roberto , so how about , plastic dustbin lid , yeah , A vacuum So first secure mylar sheet around bin lid edge , Use vacuum pump ,or such to pull to shape , Jold pressure , then make a 4 inch card wall of sorts ... Weigh down mylar sheet , carefully , so if you release vac , it stays Then replace vacuum with spray foam .. Yeah ti's expensive poss.. And would take a knack , buy the pure mirror like quality should be worthy ... Oh amd aslong as the spray foam don't eat the mylar 😂
I came across an old video from 3 years ago entitled "The Future of the Channel" or something like that. It mentioned selling shares in your company. Do you still do that?
If you have a wood lathe , suppose you could , rim a bowl out , to required shape , Drill hundreds of vac holes , spray glue , and stretch mylar again, vacuum form it ??
Robert, could you focus that through a lens to create a concentrated beam? Could a series of lenses be used to further focus a concentrated beam of light to a distance? Thanks for all you do.
I think I recall that white is more light reflective than mirrors. Surprised to see everyone using mirrors for years after this was known. Any insight would be much appreciated.
@@ThinkingandTinkering There are super-white paints that are much more reflective than regular white. NightHawkinLight has made some. it is also made commercially as a coating for roofs to keep the cooler in summer. I'm wondering if that's what you have in that spray you used on the solar kettle.
For we Yanks, those radius measurements are as follows: golf ball, baseball, grapefruit and finally, bowling ball, because millimeters are not our thing. 🙂
can u place a magnified glass at the reflected focal point and get even more heat? is there a thermal loss if using multiple dishes and bouncing the light beam off of 1 to another and then finding a focal point. like using mirrors to carry light into the recesses of a tunnel? what is the heat loss, if any?
@@ThinkingandTinkering interesting, all this time I thought a magnifier glass would concentrated the ray and produce more heat. thanks for clearing that up.
Special note for mirrors. Two mirrors are needed for a periscope; the first mirror reverses the image, and the second flips it back. Continuing on with curved mirrors, a concentrating mirror converges parallel beams into a cone, then past the focal point, it diverges. To make the beam parallel again, a second mirror is needed to reverse the beam from the cone shape. Advantage here is the choice of placement of the second mirror. This is the secret of the Archimedes Lighthouse, burning ships out to 25 miles away. Coincidentally, these Lighthouses were used for long-range communication and spying on other cities.
So glad to see your comment 😅😅😅
I think the most useful thing regarding making parabolic shapes I have found, you were the one to share, which was the beam of a light as it is cut in a cross section across something and trace where the edge of the light and shadow is, because you dont even need math or anything for that, and a whole unit made that way, you can quickly find the focal point using something like a stick since it burns so well LOL (just be sure to wear a welding hood or make a pair of polarized goggles with a second set turned 90º from the lenses (I am making a pair of steam punk like goggles that will have a rotatable for variable darkness, lenses using this, and 3 layers of polycarbonate lenses for a friend, and fellow researcher, for arc welding, cutting torch use ect, to protect his eyes, but not using brass making them a pair of brass goggles but rather pure titanium for the eye shields and the main lens rims LOL ) anyway,
I seriously wanted to thank you for that info, so very useful.
on the mylar durability, the one thing I can point out to help it last longer, Use a continuity tester like you test fuses with, and a little light comes on if the fuse is good, and test the sides of the mylar to make sure you have the metal coated side facing the sun, if you do, it can last 10 years easily in direct sun every day, but if you have the plastic side facing the sun and the metal facing down, depending on how much heat can build under it, you can have those mirror surfaces blasted off by the sun, in like 4 days or less, (I had a batch of pieces I cut up and hot melt glued down to a tarp, and did not pay attention to which side was facing which, and in 4 days of oklahoma summer sun (brutal) the sections that were facing the wrong way were mostly clear with only some faded mirroring around the edges and directly over the hot melt glue that apparently held the aluminum vaporized coating on the mylar plastic,)...
one advantage to making sure it is facing toward the sun (the metal side) besides it lasting longer, is the fact that you are blocking all the frequencies that a clear substance will absorb like a sheet of black painted matt finish will absorb all the light making heat, and it blocks by reflecting it so you get a lot of IR and UV that bounces off and back into what you are heating. (or burning, I was thinking 30,000 square foot of them to melt sand and make blocks of quartz glass for glass brick roads that each brick has a solar cell under it, so all that fiddly worry about the vehicles destroying the glass is not a concern as its in say 6 inch cubes with a semi spherical divot behind it and some rounded grooves from that to the edge of the brick for the wiring, and glass does not work well when flexed (large sheet with something pressing down on the middle of it) but it works quite well when being compressed (something just squishing down on top of it not bending or flexing it and instead reinforcing it not being flexed) So that road just needs a good solid flat surface to lay them out on, and if one breaks, you grab it using either a tool that a gap is formed in the bricks to allow removal, or a suction cup shape to pull it out, then slip in a new brick and any components broke under it :) Most of the energy to make everything in that would come from concentrated sunlight from say a desert on the sunny side of a mountain (norther hemisphere as I live in, I would use a south facing slope of a rocky mountain in NM or AZ or something) cutting down on all the energy it normally takes to process the silicon and silica for solar cells and bricks, seems like it would make the whole process even for buildings with solar cells in blocks of glass held in place by the weight or better yet,... glass lego blocks! LOL anyway I have waffled on enough. Thanks again. great info series you got going on lately regarding the psychology behind science and tech, to help people have a more active and healthy attitude toward the work! :)
that was a nice post mate - thank yo for taking the time - i seriously enjoyed reading it - cheers
Also - Get a wide bucket or pan, fill it with a material that sets up, like plaster or cement, then spin it at a constant speed while it sets up. The centrifugal force causes it to form itself into a mathematically correct parabola, with a focus dependent on the speed of rotation. Then just layer on your reflective material. You could use it as a form to heat bend some stiffer material and go into production.
that sounds challenging mate - spinning a weight like that while it sets isn't an easy task - the change in viscosity as it sets will also mean spin speed will have to change or it will just be a lump - i amnot sure that is a particulalrly easy solution - have you tried it?
@@ThinkingandTinkering yes. I did it with plaster of paris on a potter's wheel and it set up long before I got tired. And once it gets up to speed, it takes the shape and doesn't change with viscosity. I was just making decorations, but it makes a true parabola. It doesn't take a lot of RPMs and once it's moving it doesn't take much to keep it moving. I suspect a small motor with a belt around the bucket would do a good job.Just hang the bucket from a hook in a bearing if you don't have a potter's wheel. A variable speed motor would give you a variable focal length. You can find the formula online.
Sounds like an interesting use for one of those kiddie pools you can find being tossed out somewhere in the neighborhood. I suppose the tricky part would be building the turntable to put it on for doing this.
@@pauljs75 to be sure, doing it with a larger size would be challenging. I was looking at his samples and remembering my efforts in a 5 gallon bucket. At about a meter in radius it would certainly start to be an engineering problem.
@@BillDeWitt Indeed it does become challenging, but it turns out at least one group (at the University of British Colombia IIRC) figured the challenge was worth it to build an 8 m telescope mirror using liquid mercury. Apparently the optical quality is superb and the cost is significantly less than grinding a mirror that size to similar precision. One major limitation is that you're limited to targets directly overhead.
Using the convex shape and putting the reflective surface on it, you could back it with spray foam and once hardened remove. Light weight and easily replicable! Cheers from Canada
Or form your initial surface and make a plaster mold. The foam will be lighter and easier to make. But the plaster would be more durable. It all depends on how many copies you want to make.
cheers mate
I built a cardboard & kitchen foil solar cooker from plans in Mother Earth News magazine back in the 70s. It barely fit in the back of my station wagon for transport and it was necessary to chase the sun around the yard just to tan a couple of hot dogs. Sun glasses were a must. The cooker had an adjustable curtain rod in the center to mark the focal length where a grill was put for the cook surface. Sure would have been better if it was a fold up design.
I have a factory made one up to 400f
I really like that copper mirror effect! back in the day I carried a solar cigarette lighter, it was a conversation starter but not practical if you wanted to smoke at night or a cloudy/rainy day. That said I have a couple stashed away in different camp bags.. mostly as conversation starters..lol.. you can pick them up for a couple dollars or even make one by polishing the bottom of an aluminum can... I hadn't thought of it until you mentioned it but mylar glued to the bottom of a can would work and a LOT of folks carry those mylar space blankets... hhmmm food for thought...
for sure mate
Not solar but back in the day I carried a permanent match. Fuel was inside, unscrew a flint and strike it on the side. It had two geese pictured on it 'doing it' on the wing and the words "fly united" :)
@@StrumHollow HA I remember those! I had a helmet sticker like that and one with 2 bigs makin bacon..
Don't forget the mirror paint you've mentioned previously for ease of application
An easy way to draw a parabola, to help align your pettals or whatever, is to draw a parabolic envelope. Basically you draw a bunch of tangents around the parabola. This is easier than it sounds, and many of us did this when we were kids.
If you ever did that thing where you too a peice of paper and drew a bunch of equally spaced marks horizontally and vertically (same number of marks in each direction, all the same width). Then you draw a line from the top vertical mark to the innermost horizontal mark, then you draw another line from the next mark down to the next mark over and so on. That curve that forms is a full parabola.
Mirror silver/copper vinyl is primarily designed for decorative or visual purposes, such as creating mirror-like surfaces or adding reflective accents. While it may have some thermal reflective properties, its primary function is not focused on providing optimal thermal insulation or heat reflectivity.
Typically made of multiple layers, including a Coating, reflective layer and an adhesive layer. Coatings or treatments can alter the surface properties and affect the material's ability to reflect heat effectively.
I have tried these with parabolic antennas of dish tv with all materials... and just kitchen Al sheets are massively superior in thermal concentration with nearIR reflectivity at an astonishing 95% . However suntracking still remains elusive with robust, simpler methods.
Cool! Years ago I can remember seeing a guy cooking with a wooden frame covered in plastic (either the plastic had some give in it or stapled on so it wasn't bone tight) he supported this on 4 legs about 6-8 foot high and filled the plastic up with water to make a lens!
A homemade Fresnel lens - how neat!
@@bradlafferty I forgot to add that the frame that the plastic was attached to was about 6ft across by the time it was filled with water the lens was about 4-5ft across!
Fresnel Lens?
@@ThinkingandTinkering The weight of the water against the plastic just forms a smooth surface, and the thickness of the lens can be increased by the tension of the plastic, the bit that I can't quite remember is how he had the cooking side of thinking set up! If I am correct a Fresnel lens has ridges the same as a lighthouse!?
It's cheap and could be made portable!
I think they are talking about green power science channel RIP it was a convex lens.
Focus that light onto a sand battery and it would heat an charge quite quickly I feel. That's bang on mate! Well done.
yes it would mate
@@ThinkingandTinkering lovely that so much of applied science is truly timeless eh?
Tomorrow we make a laser.
😂😂🎉
Archimedes! No!
And then a rocket stove powered by the laser
lol
@@moomoocowplus Yes !!!!!!
I'm a career commercial sculptor. We have to make all sorts of shapes all of the time. One time I left a fun house mirror lying in a field...it wasn't even a parabola but within minutes there was smoke in the grass! Anyway...If I was going to make one of these cheap and durable, I would find a circular frame and stretch transparent vinyl (which you can find at the dollar stores as shower curtains and table cloths) then inflate it (as opposed to vacuum). That makes a mirror smooth surface that can be fiberglassed or sprayed with hydrocal (or plaster) and fibers. You could do the same by sucking out liquid hydrocal and fiber the way air was sucked out in the video.
i have done it that way too mate - cheers
We has a storage shed catch fire when I was in Iraq because someone left a sheet of mild steel leaning against a building.
Great vidio, like the idea for making the dish. Had plastic sheet miorr 1.5'×3' leaning against the house, plastic got hot and bent then the sun burnt a black make across a post 6' away. Thanks for the morning coffee...
You just saved me about $300. My microwave went out yesterday, and I have an old wok down in the cupboard. I'll know what I'll be doing tomorrow. THANKS!
Hi, just of the subject. Used mylar vacuum system on my diy telescope to adjust focus. Works a charm...😁👌
I found an IKEA plant pot base that was formed in to a parabolic shape. It was made by rolling thin strips of ply wood. Rolled up to make a large disk. Then it must have been placed in a former to produce it's shape and then glued in place. All I did was spray paint it silver and applied strips of reflective mylar tape. I suppose the same thing could be done with strips off cardboard rolled up.
that is interesting thanks for sharing mate
If you were to set your device on a solar tracking platform. Located at the south side of your house. With a looped copper coil placed in the heat tube, replacing the water with heat conductive oil. Use flex lines to connect the copper coil to an overhead insulated water tank, in a thermal siphon arrangement. By the end of a sunny day, you would likely have a lot of very hot water.
Thank you so much! this will shorten making it so much!
Still struggling on the stirling, all I have is empty 2.5 kg nido milk can and empty 200g of can of vegetable. Most example use membrane I can't get around this so far.
I just had an idea earlier today about using a solar powered XY carriage that can use a magnifying glass to burn images into paper or anything else!
oh - i like that - thanks for sharing mate
Search for the Sun Cutter by Markus Kayser from 2011, using a spherical lens. He also sintered sand using the sun. Quite incredible.
Send it down to electro plater and turn it into chrome finish . Probably 20 pounds or so . I wonder how much better it would be with a polished chrome compared with foil?
I like the idea.
as i said mate - there are a million ways to do it and it all depends on what you do it for, what equipment, skill and budget - but sure electroplating is a nice idea
Fresnel lens is another approach RMS. Build a 1 meter square frame from say 3 x2 timber. cover it in clear polythene, elevate it on a tower, say 2 meters, fill it with water and that will create a fresnel lens. Then focus it like a magnifying glass = fire from water. I'm gonna build one this year to act as a pool heater for the kids pool.
Seems to me the thing to do would be to have a couple of these simple mirrors - could be plastic covered with mylar, IDK - with a bit of framing that allows them to heat blackened "heat bricks" in the morning hours that you then place in an outdoor oven that you use for the cooking ... something like a tandoori oven, pizza / bread oven, a warming oven, or a base to use as a stove. Maybe focus light on an iron pot you can fill with river stones ... would the stones be ideal for controlling temperature? IDK. Seems to me this would keep cooking mess away from your reflector, and allow you to better control the heating in the oven(s) by adding and removing what amounts to "re-usable coals." Just be sure to start the oven in the morning and have all your cooking done by sundown. 🧐
I bought a Fresnel lens years ago from eBay that was for a projection tv or something and had fun burning things up like coins, etc. I was going to make a frame that swivels to mount it but never got around to it.
Idea. Use your metal fire pit as a form and do a plastic vacuum seal into it. A small air fitting in the back of the fire to pull a vacuum. Then one could produce limitless plastic parabolas.
Thank you Robert , you've given me some new ideas...
I story I heard in school then I was 13 years old was the race between Stephenson's Rocket and Novelty, how was an early steam locomotive built by John Ericsson and John Braithwaite to take part in the Rainhill Trials in 1829. Why this cut story here. John Ericsson looses get him to run away too America And he build around year 1876 a heat air from sun/stirling variante! The solution for make sun to a energy source is a bit older then people in general know! As always I love your film Rob! keep up your great work! 🥸/Mikael
There are so many technologies decades old even centuries lying unused that could play a major part in our energy requirements it’s scandalous really but robs videos are showing us some
the ericsson engine is a landmark solar engine mate
An old bin lid? Not a bad idea! I’d have many bin lids? Classic galvanised bin lid also have extra divets. So many focal points. The fire Pit lovely! Great job!
You can also pick up reflector telescopes dirt cheap at boot fairs, the mirrors at the back are really accurate parabola ( even the cheap ones) somewhere I have a 12 1/2" mirror that needs re-aluminizing I will have to dig it out and have a go.
hat is interesting thanks for that mate
The trick with mylar to keep it in shape without the continuous vacuum is to reverse the process i.e. use pressure to form the parabolic curve outwards, not inwards.
Ensure the most reflective surface is on the inside of the curve, maintain pressure for the duration required to pour casting resin over the outside curve and set. Now you have a solid backed mylar mirror. Simples!
Thank you. That was more practical instead of a 3D printer of plastic
cheers
I like the idea of vacuum... then maybe use that as a cast or form for some sort of resin or such that could then be painted with reflective paint or material that could be polished.
What if we use a large wax coated wok / parable to make a mold out of ~ plaster, foam, paper mache', etc.
Secure & seal the surface of the negative parable, then using mold release wax to coat the mold followed by application of a mirror surface then a light layer of flexible reinforcement so that the new parable can be peeled off of the mold?
Just a thought from experience making boats as a teenager.
good idea mate - cheers
Now use the parabolic mirror to heat up a few tons of sand and use the heat to turn a Stirling engine to turn a generator. Also water cool the cold side of the Stirling for more efficient and use the hot water in your house!
Great video. While you were talking, I thought about 3D printing petal parts. But the fire pit is so much quicker that I abandoned the idea.
lol - oddly enough mate - i like your idea better lol
@@ThinkingandTinkering It’s a time thing with me. But I can see advantages because you can make a printed version any size you want. And you can fine tune the shape. All you have to do is design a set of shapes that can be assembled into petals. Then assemble the petals into your reflector. If I had a faster printer, I might go that way.
@@CCoburn3 that's what i was thinking mate
@@ThinkingandTinkering About 10 years ago, you made moldable silicone by mixing cornstarch with cheap builder's silicone. (Some people do the same by adding dishwashing liquid. I don't know which way is better.) In this thread, we were talking about making petal parts for a reflector using 3D printing. But to build a reflector with a 3D printer would take an inordinate amount of time. On the other hand, you could print off the parts from one petal and then use your homemade silicone to make molds. After you've made molds, you can then mold parts out of urethane. As far as I can tell, you've never done a video on urethane molding. But this would be an excellent project for such a video. I just thought I'd mention it since I know you're always looking for useful video topics.
I like the way a spiral was cut in a piece of round tin and pulled tight and the 1" wide cut would tilt inward concentrating the sun and the thing was still flat. spiral solar concentrater
Some of the recent "chrome" spray paints are pretty good for this too. Looks like he had it on the desk, but forgot to give it a mention. It's probably one of the easiest things to apply once getting the dish part worked out. A lot easier than trying to cut up bits of film or tape and getting that to adhere to a surface.
Also the method for the mylar dish can be copied with a plastic garbage bag instead, and that shape can be plastered over to make a release form for making non-reflective dishes that way. And then those can be further covered to make a reflective dish.
i mentioned it in the previous vid mate
reflecting light and reflecting heat are 2 different subjects. mylar does the 2nd part better and paint does the 1st.
Many great projects may be constructed for education and everyday use. Typhoon season here in the Philippines certainly puts a damper on all the fun. We do not have bad weather the entire storm season so there are days you can still play. Our backups are in place so it is time to get on with it. One of the easiest finds is old satellite dishes. All we need to do is grab one from our roof as the "retirement project" house was pre-equipped. Thank you for the ideas and motivation.
cheers mate
Don't forget to make the f-stop. A piece of cardboard with a cutout circle would do nicely.
something like an umbrella that is more parabolic rather than bowl shaped.
You didn't remember to warn people to not leave it laying about in the garden when they've finished with it, those morning rays the next day could set their street on fire if they hit the dish at 'the wrong angle'!
Yes
Please don’t ask.
you are right i didn't -thanks for correcting that
I'm thinking of trying some of the chrome spray paint on a Sat TV dish....
Muchas gracias por sus ideas.
Edmund Scientific used to sell large (approx. 1’ square) Fresnel lenses in a sheet of clear plastic that easily rolled up.
The polished bottom of a soda can was an old boy scout hack.
Safer than a parabola, there are free plans online for a DATS cooker (double angle twelve side). I've used it effectively. No tight focal point means no fires or burnt retinas. Easier to build too. 49° North.
cheers
Made a really good one messing about in the 1970's. 3 feet across. backing was made on a huge balloon with papier mache. I burned a lot of stuff as a teenager...
nice - very nice mate lol
Several years ago, I used unwanted TV Dishes lined with $1 emergency blankets for similar purposes. There is plenty of them to be had for for around here rural SC/USA and there was no measuring needed. the Angles and point-of-convergence are already there. And at 33.5° N, it quickly cooked our hot dogs (faster than the charcoal grill!)
Now you've got me thinking about what I could do with all those giant C-Band dishes around here (there's at least three). All are at least 8'/2.4m diameter and 4.5m2 of area. Add a tracking system for maximum daily power, of course...
Question for the Audience: What solar panel could I use on this system? It would need to survive the heat and be able to convert to maximum voltage.
No photovoltaic solar panel could handle that heat. In large scale systems they use molten salt reactors. Then use the molten salt to boil water and run a steam turbine. They run at night off the residual heat as well.
These never came into large scale use, because they came under heavy attack by animal rights groups for killing birds. I am sure big oil likely played a role as well. As it is the most efficient and cost effective form of renewable energy, that I have ever discovered.
Look up Solar Funnel Cooker by Steven E. Jones. It is far safer than parabolic because it doesn't concentrate the Solar energy to a point, but to a more diffuse line. You can also make them foldable, so that it is more easy to transport. It's also easier to make.
Brilliant mate! Would your mirror paint give enough reflectivity? If so, then that is even easier than any kind of foil/mylar application. Just a thought. Cheers!
the aluminum foil for cooking I found has a line like pattern on it, and it runs along the length of the roll as it is rolled up so placing it with that facing so the lines run from center to outer edge while it may cause some bunching in parts of your troff design, I think in that format it still would ensure all the light is hitting that line of your heated tube you are cooking in, and the tube can then disperse the heat through out the inside for cooking. :)
some does - some doesn't
@@ThinkingandTinkering yeah I rarely find the good stuff with out those lines, and they seem to run the direction that the rollers it was on leaving them seeming to be left over from turning the rollers on a lathe or something (ie the marks on the rollers go around the roller rather than down them) either way if you do have the marked stuff it seems like making sure they dont interfere is not that hard, just have to orient them correctly when using it :)
Nice and does work. Just don't try a 1.8 meter satalite dish covered with kitchen foil and then use an aluminum pan. It nearly melted the aluminum pan. Believe me I know. Maybe I had it too focused in the hot point. Haha
with that fire pit .. might have been able to get some metal polish and mirror that
The copper is fantastic for tanning your face too" says the old roofer! Lol!
lol - cool
There was (not sure if it is still active) a website that had designs for parabolic cookers that I saw years ago. Solar cookers take a fragment of the parabolic idea and use a covered box to manage the heat. It does take an effort to plan your cooking ahead which is why solar cookers aren't as common in northern or rainy climates
seriously mate - there are a lot of ways to do this
@@ThinkingandTinkering indeed, and I know that everyone here deeply appreciates the information and ideas you've shared. What I'll be interested to see are the different and improved ways this group will expand on the concepts you've highlighted
Your good man. I wonder if you could use a stainless bowl. The restaurant style are very reflective. Also on your last video. I wonder if you used different color tubing if it would make the spectrum different. It would open up whole new door right?
Dear Murray, once again a great video. I have seen a documentary where they tried to burn ships in some hundred meters distance like the ancient Greek. It did not work, but they also just used several flat mirrors (each person holding one). I think it did not work due to human error (not all people could hold the mirror stable) and no focus. Can you manage this historic experiment with some improvements?
easily mate
0:39 Robert, a mylar sheet on a pan with a mild suction applied to the back side doesn't form a parabolic shape. Like a bubble formed from a film, its curvature is spherical.
cheers mate
Try a used Satellite antenna. I have a 1.2 meter that I'm going to paint with Rust-Oleum Gold. I have the arms that came with and just need to flip them to the top to make a hook to run water through to heat the pool
Rob on your wind turbines, could you show us what is available to get the power into the home, is there a storage system and components that could get it to 240volts......In essence what do we do with the energy coming out of a wind turbine.....Brilliant channel thanks.
An umbrella might work as a 'former'.
MIT
Why doesn’t a plain, white piece of paper reflect light, but a mirror does?
Almost everything reflects light - it’s how it reflects it that makes a difference…
By Sajan Saini
“I used to have a red car, when I worked at General Electric,” Department of Materials Science and Engineering Senior Lecturer Emeritus James Livingston recalls. One evening, walking back to the company parking lot, he was surprised to discover that his car had changed color. In fact, the street lighting in the lot had been switched to mercury lamps - which, Livingston explains, have almost no red in their light. His car thus appeared as black, with a touch of blue. After driving out onto the city street, with its conventional streetlights, the car’s color changed back to red.
Livingston’s color-changing car highlights the fact that light sources, such as the Sun and tungsten filaments, emit a spectrum, or collection, of colors. When this spectrum of light falls on a surface, some colors are absorbed by its molecules or atoms. The remaining colors penetrate to within a few wavelengths, Livingston says, and partially reflect back.
White surfaces are composed of molecules or atoms that don’t absorb any of the visible colors of light; our eyes perceive this reflected combination as the color white. But doesn’t a mirror also reflect all the colors of light? Why doesn’t the surface of a mirror appear white, rather than reflecting images into our eyes?
The answer, Livingston explains, rests in part on the penetration by light. A mirror is essentially a plate of glass coated with a thin film of metal, such as silver. At the atomic scale, metals are a crystal network of atoms whose outermost electrons dissociate and wander with high mobility through the network. These mobile “conduction” electrons are the source of electrical conductivity in metals, and when light attempts to penetrate a metal, they “vibrate in such a way” that an opposing electrical field is created, canceling the electric field of light and prohibiting any of its colors from entering beyond a few atomic layers. When that occurs, the light has been effectively reflected from the surface of the metal.
In addition, the smoothness of a mirror’s glass and metal coating ensure that this surface reflection is specular, says Livingston. As a result, rays of light bounce “like tennis balls,”, always maintaining an angle of reflection to the mirror’s surface, that matches in value the rays’ angle of incidence. Rays of light originating from a person’s ear, nose, and eyebrow, will “reflect with the same angle” off a smooth mirror surface and maintain their relative orientation, thus preserving the image that our eyes will perceive.
White surfaces can reflect a considerable amount of light, but without the mobile electrons to oppose the electric field of light, white surfaces allow light to penetrate up to several wavelengths. This allows them to experience multiple reflections from crystal grains and other irregularities within the structure of the surface. Some multiple-reflected light can reemerge from the material surface, but without the same orientation, as that which reflects off a mirror.
Surface roughness, Livingston says, also contributes “diffuse reflection,” causing the rays of light from different parts of a potential image to “bounce back at different angles.” Multiple and diffuse reflections scatter the reflecting rays, and all information about the image is lost. White paint or a piece of paper are classic examples of light scattering, he notes, as are clouds, the foam in your glass of beer, and snow. These latter examples are turbulent or irregular structures, containing “lots of air,” which causes “light [to] reflect off internal and external surfaces” and scatters the rays of an image.
It is striking to consider, Livingston adds, how a still pool of water may serve as a poor mirror. Yet, when the same water crystallizes into irregularly packed snow flakes, multiple and diffuse light reflection results in a white surface.
Posted: February 21, 2012
So it boils down to smoothness a lot too
Thanks for sharing Rob. However experiments have been made using polished copper as a reflective surfaces and it has been shown it is not bright enough to light the interior of the pyramids as the light is too greatly reduced, so this could not have been a source of illumination for them. Interesting legends do come from South America however with some ancient writings stating that two large 4 meter mirrors where used to melt stones and therefore used in the construction of sites like Sacsayhuamán. It is also interesting to note that 2 sound waves are required to create a beat frequency! Is it possible to create a beat frequency using light?
What about a solar powered flash steam generator 😁👍👍
this would run it add a copper coil and bingo
I made one yesterday with an old satellite dish. I’ve been having so much fun. Want to heat water with it.
awesome mate
Good stuff Rob🎉
I'm not technically minded, but I have this idea in my head.. Could you use concentrated solar thermal.. like the following
Have a pressurized water container that was heated via the CST that when heated would behave like a steam engine to push pistons that would produce electricity. While the steam from the engine would be recirculated via a 'still' type set up so you could just keep using the same water, thus removing the need to constantly refuel the 'generator? Electricity stored in batteries, of course.
An old satellite dish as former, of course if you have the LNB arm you know where the focal point is.
4:48 you mention a "Pennsylvanian" fire pit, lived in PA (that's what we call it, lol) since 1976. This is a new name to me, we just call them fire pits. Lmao
All we need now is a lot more sunny days in Britain.
Cool. You could cut small sqares out of old cds and glue to any dish shape.
awesome suggestion mate
Those are pretty enough.
There are some non-imaging reflectors that are somewhat cone shape that I thought would be nice to try because the focal point is at the bottom of the cone, so you don't have to figure a way to hang stuff in front of the mirror. No doubt uses more material per square meter though.
cheers mate - but it doesn't take a lot of figuring does it?
Look up the Solar Funnel.
If you were to use this for continuous use - for heating water, for example - you'd need it to track the sun.
It would be interesting to see if there's an easy way to make an adjustable focus version, so it can be made suitable for different situations.
Catching the neighbor on
Can be done using mylar over a loop, pan, etc.
Secure edges well, pull a vacuum on the pan to adjust the focus or carefully attach a cord to the back of the mylar and by pulling / releasing tension on the string the focus is adjustable. 👍
Have fun 👍
That'll be in the Tinker cad version coming in a few days, I reckon.
read my reply above about spinning a bucket with plaster in it.
good suggestions given by others mate
There's a a range of reflective metallic paint pens available too. 👍
cheers mate
And, just as it was a laser - don't look (directly) into or at the beam.
Remember, the sun also emits UV and IR - which can't be seen, but you do you
cheers
You will take a large satellite dish, and you will rub it very well with graphite powder. It will become like a mirror.
nice one mate - cheers
Hey love your video s Roberto , so how about , plastic dustbin lid , yeah ,
A vacuum
So first secure mylar sheet around bin lid edge ,
Use vacuum pump ,or such to pull to shape ,
Jold pressure , then make a 4 inch card wall of sorts ...
Weigh down mylar sheet , carefully , so if you release vac , it stays
Then replace vacuum with spray foam ..
Yeah ti's expensive poss..
And would take a knack , buy the pure mirror like quality should be worthy ...
Oh amd aslong as the spray foam don't eat the mylar 😂
I've got a 2.4m diameter satellite dish under the house that I picked up off the side of the road that I intend to do something with....
ok - i am officially jealous lol
Thanks a lot....
cheers mate
You have a 3D printer, use it to make parabolic shape. Then you can decide the focal point.
Briiiant prgramme yet again! Is the spray flexible when administered because, what about a converted umbrella!!! Just a crazy thought LoL!
What solution would you use to heat the water in a garden paddle pool?
Spray Paint The Sky Dish With Mirror Paint?
Bless Up Fella
for sure mate
while its not going to be as big. you could 3d print a parabolic dish and use your mirror effect paint.
nice idea mate - i was mulling it over lol
You could just print the interlocking petals that could form the dish. Then cover it with whatever reflective material at hand.
Can you put them in a line ; hot spots to another dish, to another, etc.? to be a super laser?
What if you put a lense at the focal point would it concentrate the rays further?
I came across an old video from 3 years ago entitled "The Future of the Channel" or something like that. It mentioned selling shares in your company. Do you still do that?
0:40
What if you put a liquid epoxy resin or some similar in to the container before evacuating it and then put it with its face down and let it cure?
If you have a wood lathe , suppose you could , rim a bowl out , to required shape ,
Drill hundreds of vac holes , spray glue , and stretch mylar again, vacuum form it ??
So how close would the ancient Greeks had to have been to burn their enemies ships?
Copper is beautiful. Much more steampunk :) I wonder if there are silver paints that would work
@@kensmith5694 Thanks mate
I use a solar cooker and enjoy it over bbq pit every time
Robert, could you focus that through a lens to create a concentrated beam? Could a series of lenses be used to further focus a concentrated beam of light to a distance? Thanks for all you do.
i would think so mate
If only you could use that expanding foam to back the mylar, it would be ridgid.
I think I recall that white is more light reflective than mirrors. Surprised to see everyone using mirrors for years after this was known. Any insight would be much appreciated.
not an expert but my guess is white spreads the light in all directions and a mirror actually directs it where you want to
@@strongforce8466 wouldn't that be the shape?
white is not more reflective
@@ThinkingandTinkering There are super-white paints that are much more reflective than regular white. NightHawkinLight has made some. it is also made commercially as a coating for roofs to keep the cooler in summer. I'm wondering if that's what you have in that spray you used on the solar kettle.
For we Yanks, those radius measurements are as follows: golf ball, baseball, grapefruit and finally, bowling ball, because millimeters are not our thing. 🙂
can u place a magnified glass at the reflected focal point and get even more heat? is there a thermal loss if using multiple dishes and bouncing the light beam off of 1 to another and then finding a focal point. like using mirrors to carry light into the recesses of a tunnel? what is the heat loss, if any?
what do you mean by more heat? if you mean more heat but a smaller area - then yes - if you mean more heat but the same area then no
@@ThinkingandTinkering interesting, all this time I thought a magnifier glass would concentrated the ray and produce more heat. thanks for clearing that up.
Have you ever seen those two guys discovery who made a giant paella pan
on solar with a big mirror?? It was a great video
i didn't see it
would all materials for the mirroring have the same reflective quality?
@@kensmith5694 Ultimately wouldnt mirrored glass be the best option?