1643 How To Make A Parabolic Mirror
Вставка
- Опубліковано 19 жов 2024
- Don't forget to check out our other channel found here / @tntomnibus
If you want to have a look at those special videos become a member and join by clicking this link / @thinkingandtinkering
Don't forget that you can buy my books and materials for your own experiments including our conductive inks at secure.working... - and for the many who have asked, yes, you can also donate to further our work, again through the shop.
I would love to see the creation of the mirror in a little more detail. Especially the chocolate😁 seriously if like to see the creation of the mirror step by step.
Love these kind of videos, your creating a real reference library for people to use. Simple, short clips like this are gold on here. I bet there were some out takes on this one though, ie mylar ripping, coming unglued, the mess of fibre glassing :D Thanks for the time spent making these kinds of videos.
Well Done Again Robert.
I would Never have Thought of using a Torch, Simple Clever Method.
That’s really awesome! I would use such a mirror to heat up the boiler section of an absorption refrigeration system. We just need to figure out a passive heliostat of some kind.
Just what I needed! Thanks, man, you're the best! 🎉
And thanks for the mad laugh 😂
always my pleasure mate - cheers
This is great - although I would have liked to have seen you drawing the parabola using the flash light. Brilliant stuff, though. I'd like a parabolic microphone for when the nightingales come back to the river next year - I see a project coming on.
I was sure that someone else would have pointed out the math error; 36 / 4 is not 8. Also shining a flashlight on your board to hit three given points wont necessarily give you a parabola. In fact you can get any one of the four conic sections to hit the three points depending on where you place the flashlight. He demonstrated it earlier!
I was doubting my own math momentarily. :D
I’m excited to see where you go with this.
I’ve given it a fair bit of thought myself and I think preheating the water to nearly boiling prior to the introduction to your flash steam generator might be something to consider.
@GreenPowerScience did a lot of videos a few years back on making these mirrors. Great channel.
Man, what ever happened to greenpowerscience? Those videos are old, but their website store is still up.
That was freaking brilliant
Thank you hope you all have fun with it
It is wonderful work. Thank you very much.
Many thanks!
Very nice. Explanation Robert. Give been wanting to grow some pezioeletric crystals (Rochelle salt) lately using the sun and cooling by night air. Crazy thing is i just made some parabolic mirrors with mylar solor blankets I glued the mylar on a big mixing bowl then poked a hole installed a tube and sucked the air out to form the shape. I placed water in the bowl mirror and The water temp can be controlled by focal point. Again Great👌video. Thank you.
Your comment “I had to come in by feel” revealed a grin from ear to ear on my face 😁
Wow you make science (and math) fun! 😊
It would be cool to make one in sand and using something weighed on a string to either scoop or displace the sand. Maybe even start one by hand or use something of a similar shape and refine it with the previous method. Also could you use a vacuum? Once you have the right material you could apply the mylar to it but you'd probably need something similar.kar to an air hockey table in reverse to pull the mylar down evenly. My original idea was to make the shape and then apply it like window tint. But no matter how it's made, it's a very cool idea and I appreciate watching and learning. It reminds me of the cool science experiments my teacher's would do in the Forestdale school system on Cape Cod. Without my teacher's I wouldn't enjoy life very much. Most of my teachers really cared and tried their best to teach and did a very good job at it. Nowadays, teachers like that are hard to find from what I've heard and seen.
Hey, cool video. Just one small correction:
36/4 = 9
Great video mate, very interesting, thanks 👍
really nice ideea ... using a torch to define a parabolic curve!
chocolate must have been good 😂
So good I had thought of using hanging chain
Mr. murray have always the greatest ideas!........but if you glue the reflecting foil on rubbermat, and attach a screw in the center and pull on the backside........is it possible that you have a variable focuspoint!???........by the way....you let my old brain buzz with your videos.great work!
Inspirational!😇👍
Conic Sections! Yes! Analytic Geometry is always so practical.
I agree
That is one hell of a fruit bowl you've got there Rob. Nice method, I wonder if the vacuum method would work on thicker sheets of aluminium, could you deform them enough so that after they spring back there was still enough curve? I ask because I know there is a type that is actually sold for this task that is highly reflective and removing the other steps would speed up making multiple copies.
I had the idea two years ago thinking that no one had done it of using a parabolic mirror to generate electricity
the moment I watched that thumbnail I was like, ouch I'm dumb, I have been looking for easy way to make parabola and failing, but now I realize I knew the solution all along, make a cone, cut it diagonally, hey presto! a parabola! now I can use that to shape everything.
If we use an old oil drum (or some other large cylinder) instead of a bicycle rim, it would allow one to connect a pump and pull a vacuum to adjust it to whatever focal point we choose, limited by the deflection the mirror material is capable of. It also lends the option of being able to create a convex shape as well, a small controller used to regulate the pump and a cheap pressure transducer could automate it. Kind of reminds me of some ideas I had back when I was working on spherical/liquid lenses for high performance metrology in extreme environments.
Cover the back of the rim , pull vacuum through the valve port.... I did it with the frame of a broken personal trampoline...
LOVE THIS ONE!!! One more thing and a bit of off topic but related to Parabolic Mirrors.... can such a device be upscaled like how Archimedes had intended as a defensive weapon against wooden ships, but INSTEAD of burning wooden ships, can the parabolic mirror be coupled with a powerful magnifying glass to create a Solar Laser Beam? also can these kinds of mirrors be used again to create cool holograms like the ones Athanasius Kircher was building in the 1665s?
The sun is not a coherent light source, it doesn't produce light by stimulated emission. What you could do is use mirrors and a grating pair to make an adjustable spectral filter, and use that light to pump a gain medium to get a laser
"I can feel people groaning already!" .. 🤣😂😀
great content thanks
Cushdy video, thanks. Always good ideas. Maths is not my strong point, but you explained the formulas pretty well. Did you offer your helper milk or dark chocolate? Curious.
Thanks again professor Robert! Amazing one! I can use this for produce steam and try a little little steam machine work?? without copper nanoparticles i mean
Have you thought about putting your play lists on DVD so we can have them in case there is no internet some day. I would pay for that.
Easiest method of drawing a correct parabolic curve is :
1) Make an isosceles triangle whose base is the diameter of the reflector and the altitude is TWICE your focal point.
2. Place numbered divisions say 1 cm apart on EACH leg of the isosceles triangle
3. On one leg REVERSE THE ORDER. So one side A (left ) 1 to 30 therefore on side B (right ) it goes 30 to 1 .
4. With a RULE connect the SAME NUMBERS .
5. When all numbers are connected a parabolic shape is formed .
BTW if you need a hyperbola, for applications like Viktor Schauberger used in his water implosion devices, then the easiest way for a backyard inventor is to place a heavy weight onto the center of an elastic sheet that is stretched across a circular frame. Then coat it with epoxy.
Such a shape is used for degassing water efficiently for example. And degassed water forms very hard hard ice. A hyperbola creates a strong vortex when gas or liquid flow through, and in the case of water, the dissolved gasses are sucked out of the liquid.
Once you get into it the whole world is just math!
I understand that people can have a problem with math, I am in my 60's and still can't do my "times table" .... Complex lines in space or different infinities or complex numbers, I can do though! Simply equating a torch beam on a flat plane to the curve of a thrown ball, in my opinion, is a touch of genius (as is the chocolate trick)!
Just to throw a curved ball in there (see what I did?) ..... a 2D parabola may be a better option for a solar boiler ..... just orientate the axis' and you are golden!
I think using something that is free (if of limited availability here in the UK) is a bonus!
Hey Rob, would you get more or less heat if you polished the mirror with graphite?
Also curious to see the result of that. Although I don't know if the current version would handle the polishing well without putting your hand through it?
We have a lot of hot springs in our region and I was thinking a basic thermal siphon would work to heat our clean water instead of having to deal with a nice soak in sulfur and other minerals (unless that's your thing, of course).
Awesome!
Thank you! Cheers!
A number of years ago when I was investigating how to make a large accurately shaped parabolic reflector I came across a paper by NASA which dealt with the concept Robert used here, of applying a vacuum (or positive pressure) to one side if a taught reflective membrane such as the space blanket Robert used. The paper showed that the shape created is not a true parabola but is a close approximation.
Perfectly adequate for heating applications where a true point of focus is not needed, but useless for optical purposes such as a telescope. For the same reason, if a point source of light is placed at the focal point, it will not produce a parallel beam as in a searchlight or from a laser. The beam width will increase with distance from the reflector.
If you take a reflector such as this one, and point it straight up at the cloudless night sky, will it focus the absorption effect of the black body absorber that is space?
What is the back metal part made of ? And how is it glued on so smoothly ?
Copper particles to water? 😛 colour me intrigued - definitely needs a simple solar tracking mechanism
I'll do a video on it mate
Cool, next stop death ray
It's like:
Step number 1: Draw a line 1
Step number 2: Draw the line 2
Step number 3: And voila, you got a paint of Mona Liza.
That's how you can become an artist. Hope you've enjoyed this video, don't forget to like subscribe and share. See you in next video.
Nice one
cheers mate
isn't a parabola like part of a sphere that is cut away. so the true focal point should be the center of a sphere. or may there is multiple focal points
Hey Rob great video but please wear sunglasses when you are using these ,i made the same mistake my first time with these ,the concentrated light can be very harmful to the eyes.
i understand, but cringe, when you say _unfortunately_ we need to do some maths. i would hope your audience is not afraid of some calculations.
Im afraid to do them because im liable to lose them and have to redo them at least 7 times
TNT, check out Wolfgang Scheffler reflectors
What did you put on the back of the mylar that made it so stiff. I find that you jump over steps and assume people will know the missing bits.
Howabout carving spray foam? I just made a foam knife w a laptop supply, ss wire and a bucking circuit. I can bend the curve into the wire. As I practice, I can attempt the bowl shape and sand out imperfections. 3m adhesive will hold the mylar or... rub in CaCO2 or d.e. and spray clear polyu? Also, The fresnel layer in old big screen tvs do this if you see one on the curb.
I want to distill water at midday sun. Carving is going to allow an asymmetric shape cooperating with the limits of my light tracking (stepper motor on timer, trying to automate with relay n sensor in tube)
Did you all know. This is ancient tech at work again! This type of Mirror was thought to be what Archimedes used as the basis for his DEATH RAY. Them people, the Mythbusters, did an episode on how it would work with a HUGE Parabolic Mirror mounted on a high Turret and angled to focus the beam onto the wooden enemy ships.... But its missing something. A Question for Rob and for the whole community. Is it possible to take on of these Parabolic Mirror and run the focused beam through a series of Magnifying Glasses to turn the sun light into an even more focused point, like a solar laser beam?
Build a resilient mirror at the focal point and shape it how you like to get the parallel beam and direction you want...Like a decent telescope
@@RupertBruce whoa.... Like how the James Webb is set up?
Nice.
Thank you! Cheers!
It can follow the sun if little solar panels, possibly 4, are hidden slightly in its shade which drive a small motor to keep it focused
cheers mate - I have seen that vid but nice pointer
Could nighthawks solar tracking setup be added ?
My friend and I were planning to try something like this a old 8 foot satellite dish but we were wondering what to used instead of metal
sheeting.
Some of the newer chrome "mirror" paints are extremely reflective. At 8 foot it's actually going to quite dangerous, I'm sure you know.
this mirror isnt astronomical grinded quality, but i would still build monumental scopes with ur expertise
How does the space sheet stiffin up after the stretch.. ?
He mentions fibreglass, looks like after the shape was formed there was a layer of fibreglass applied to the back (could be wrong here, just working it out from the video)
Just imagine what you could do with an old satellite receiver dish from the '70s-'80s!
Yes do it
Lots are available on ebay
I bought a couple of solar cookers x China. 1.8 m dia satellite dishes covered in mylar film. Cooks a steak in three minutes on a cloudy day. Vicious heat. Great to use as a cooker, but would require a tracking system for all-day operation.
There is s a far easier way to make a parabola. Put two nails in a sheet of plywood, cardboard, etc. Get a loop of string that will fit loosely around the nails. Take a pencil and draw the string tight and, while keeping the string taught, draw a completed loop. This will make your parabolic shape. Pull the nails, use the holes to line up a straight edge and draw a line through to make the dish shape.
That’s a standard method of drawing an ellipse, not a parabola, sorry. In any case, a full ellipse is always a closed shape whereas a parabola is always open at one end.
@@ianmathieson65 Yes, that is why the last sentence was to line up a staight edge across the nail holes to draw a line across to finish the shape.
How come I haven't seen a holographic Fresnel reflector just like the holographic wrapping paper? Who makes that stuff, I should send in a request...
I thought about this at length especially since the idea is a stationary reflector. His previous video of using graphite is better for this because you need to form bubble ridges. I thought using a fiber laser would do, but it would have to be on a 3-axis controller and tuned to specific depths over a period of multiple passes which would require a parabolic substrate that would be thick enough to handle the etching. So while you could bend a piece of aluminum and laser little micro V's in it., do the overall losses ever exceed a suntracker? I doubt it. So I think a better idea would be to place micro bubbles of graphite on a stationary concave surface. But then with all of these, the collector casts a shadow. With a suntracker you could put a cone on the collector and reflect into the parabola. I have several fresnels, one glass and several plastic ones. I believe they are all made by stamping. So I see the value of creating an inverse holographic style metal stamp as a precursor leaving concentric grooves to apply graphite into. Reducing the bounce out effect. man i sound like a nutjob, oh well. I do own laser, and I do understand the math. but the chems and application are beyond me. The mylar just isn't efficient for broad spectrum UV as the graphite is. I'll stop talking to myself. One of these days the local airport is gonna get complaints about light pollution tho.
@@patrickmcginnis7 if you're that good at math that you could backwards calculate the ridge dimensions of a holographic reflector from the pattern you want to create with it , then you are way ahead of me, figuring out how to build it seems the easy part by comparison to me.
Imagine a hologram of the Sun, as you walk around the hologram it's always going to look like the same ball in the same spot. Now reverse that, as the sun 'walks' across the sky the focal point will always be in the same spot. Holographic tracker.
No moving parts.
Now how the hell do you do the math , help!
No you're not talking to yourself.
Graphite bubbles does sound crazy when taken at face value out of context. Practically though both silicone and graphite are hydrophobic and should stick to each other on the surface interface and you could probably mold a bubble print.
@@petevenuti7355 What's beyond us is the scale...like in nanometers to get the desired efficiency result. If you could imagine a clear balloon. On the exterior of the top would be tiny fresnels tuned to hit certain focal points on the interior of the bottom of the balloon. Those points could be micro parabolas directing the rays to a centralized collector. Someone did something similar, but the heat was used to spin an interior cone, and it was debunked as being efficient at all except for a small range of angles of incidence. Which is counter to the overall proposal. Like a crooks radiometer fitted correctly would certainly create passive electricity, but would it create more per cm² than a normal solar panel or collector...not imo. beyond the scope of a solar cooker obviously. Keep being inspirational. :)
@@patrickmcginnis7 have you ever seen any of the holographic chocolate videos? Say , from the thought emporium?
Anyway the hologram idea I mentioned just before, went beyond just making a Fresnel, more wondering if an interference pattern exists that would allow a single focal point at a wide range of angle of incidence to avoid tracking. The biggest problem I can think of is that it might only work at a single frequency, and that other frequencies may be completely blocked or diffused, not even approximately focused.
My original comment about putting a Fresnel on a reflector , one would have to be calculated for the double passage of light, because it would be better to have a back surface reflector.
The scale of the grooves doesn't have to be that small for that. A silicone mold would do.
@@petevenuti7355 cool chocolate. That I think it's a combination of absorption and reflectivity cause it filters colors.
@Robert Murray-Smith >>> 👍👍
Death ray, here we come!!! 😈👍
How the hell did you get fiber glass on the back of it when only the front is accessible while it's being deformed by the air? I feel like I've been trolled somehow
36 divided by four is nine.
Eye protection
I am still at large about how did you end up at 8 when dividing 36 by 4. It seems 9 to me.
to me too
7:17 Magnifying you :)
Was it MIT or Rice U.?
one of the two - just do a google search on copper nano particles and steam - you will come across it for sure
36/4=8????
and the correct answer is?
@@ThinkingandTinkering 9
@@wr6293 lol
Large telescope incoming?
🔭prays for a telescope next. :D
JFC you skipped the most important part - how to make the parabolic mirror.
it's in another video this is the explanation video
No gold over beryllium mirrors? You're not holding out on us, now are ya? Lol
lol
English math must be different than American math. lol
TLDR the comments, but surely someone else has caught your math error where you divide 36 by 4 and get 8 (er, 9 on this side of the pond?) 😉
I think you left something out.
Indeed. Did you know the inventor Archimedes used the same technique and technology thousands of years ago to create an anti ship defensive weapon. Like a death ray. The Mythbusters people did an episode on it. Did you also know these types of mirrors were used in the 1665s by Athanasius Kircher to create holograms?
Relatively easy and cheap way to do some subcritical water hydrolysis of cellulose experiments with a parabolic solar trough
1) A Parabolic trough focused on a black painted copper heat pipe with a pressure release valve at the condenser end.
2) Insert the boiler end inside a florecent tube to minimize convective heat losses with heat resistant silicon rubber O-rings for spacing the pipe in the center. They need to be cut to prevent pressure buildup inside the glass.
3) fill it with wood dust and and some water.
In the sun, The water should turn to steem and travel down the pipe under pressure pushing oxygen and air to the condenser side where the air can be purged at the valve. The water condenses and falls back down trickling through the wood dust washing the broken down hydrolyzed cellulose products into the boiler at the bottom.
Wood to sugars for rocket candy rocket fuel? Note. Take care to know the pressure raiting of the copper pipe and that the pressure release always remains free of obstructions and set a safe level below the copper pipes rated pressure.
So if I set one of these up near someone's car that I dislike a huge huge amount. Would it be classed as arson or an act of God. Obviously asking for a friend 🤣🤣🤣
This already happened in real life. TOTALLY by accident too. If you look into the history of the Construction of the Disney Concert Hall in los angeles, They constructed a building with shiny mirror surfaces that were parabolic. The end result was the neighbors of the building were getting COOKED. The sun would focus and reflect onto the old folks home next door and it would focus on the street parking below. The City of Los Angeles asked the construction company to do something about it and they did. They went back and sandblasted the mirror surfaces into something way WAY less reflective. Funny story. First published in the Los Angeles Times.
Why you laughing like that?
Nine minutes of BS.
8:02 - EMPEROR PALPATINE?!