Thermo Cam: First pictures

Discussion in 'General Slingshot Discussions' started by JoergS, Jan 14, 2012.

  1. JoergS

    JoergS Administrator

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    The Thermo Cam arrived today. What a great toy!<br><br>I tested it with different stuff first, amongst them our christmas tree (which we won't throw out before Mariä Lichtmess, on the 2nd of February, for reasons of tradition and lazyness).<br><br><div style="margin:auto;text-align:center;width:100%"><a href="http://4.bp.blogspot.com/-QHhSFCBuZq0/TxGhkIVvngI/AAAAAAAABSg/qdfNN88tXxM/s1600/Tannenbaum.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://4.bp.blogspot.com/-QHhSFCBuZq0/TxGhkIVvngI/AAAAAAAABSg/qdfNN88tXxM/s320/Tannenbaum.JPG" border="0" alt=""></a></div>
    <br><br><br>As you can see the lightbulbs come out very clearly, with 22 centigrade, vs. the tree (around 19 centigrade). See the mirror behind the tree? The lightbulbs are half a degree warmer even in the mirrored image... interesting.<br><br>Then I took a few pics of the house.<br><br><div style="margin:auto;text-align:center;width:100%">
    <a href="http://3.bp.blogspot.com/-YJBvTafQXkQ/TxGiJtx37_I/AAAAAAAABS4/ZxS7-s4bVG8/s1600/Haus2.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://3.bp.blogspot.com/-YJBvTafQXkQ/TxGiJtx37_I/AAAAAAAABS4/ZxS7-s4bVG8/s320/Haus2.JPG" border="0" alt=""></a><br><br><a href="http://4.bp.blogspot.com/-cct_6QtpBNU/TxGiIgUdnWI/AAAAAAAABSw/0h1V0gi5aqM/s1600/Haus1.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://4.bp.blogspot.com/-cct_6QtpBNU/TxGiIgUdnWI/AAAAAAAABSw/0h1V0gi5aqM/s320/Haus1.JPG" border="0" alt=""></a>
    </div>
    <br><br>I left the door open, and you can see the warmth that flows out. You can even see where the heating and the pipes are running (in the second floor, on the front corner). <br><br>The camera software allows different colorings (remember it is not recording colors, just temperatures). Here is a different palette:<br><br><div style="margin:auto;text-align:center;width:100%"><a href="http://4.bp.blogspot.com/-BJ3U0uUf7HE/TxGirqKdjwI/AAAAAAAABTA/f8Gn2JUoeuc/s1600/Haus3.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://4.bp.blogspot.com/-BJ3U0uUf7HE/TxGirqKdjwI/AAAAAAAABTA/f8Gn2JUoeuc/s320/Haus3.JPG" border="0" alt=""></a></div>
    <br><br>Then I used it on a tapered rubber strip. First the relaxed picture:<br><br><div style="margin:auto;text-align:center;width:100%"><a href="http://3.bp.blogspot.com/-4kMZGlFtXis/TxGjfi7_f-I/AAAAAAAABTM/oacNiqxmAqs/s1600/Gummiband3.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://3.bp.blogspot.com/-4kMZGlFtXis/TxGjfi7_f-I/AAAAAAAABTM/oacNiqxmAqs/s320/Gummiband3.JPG" border="0" alt=""></a></div>
    <br> As you see the rubber has room temperature, whereas my hands have about 23 centigrade.<br><br><br><div style="margin:auto;text-align:center;width:100%"><a href="http://2.bp.blogspot.com/-l8vzmjOPmxQ/TxGjtIRVXCI/AAAAAAAABTU/yIWmbselcUQ/s1600/Gummiband1.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://2.bp.blogspot.com/-l8vzmjOPmxQ/TxGjtIRVXCI/AAAAAAAABTU/yIWmbselcUQ/s320/Gummiband1.JPG" border="0" alt=""></a></div>
    <br>Then I stretched the rubber... can you see that it heated itself up to about 30 degrees? Warmer than my hand. As expected, the heating was MUCH more dramatic towards the tapered end. <br><br>This is sooo much fun.
     
  2. Antraxx

    Antraxx #7

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    Never knew you can lend those.<br>How much is it for a weekend? I´m only asking to compare it to a expert opinion/appraisal for house isolation...with that kind of pictures you can do one on your own <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2"><br><br>that the mirror reflects the rays is no surprise...the radiation kinda behaves like light (infrared/electromagnetical).<br><br><br>Oh, and is it Pic´s only, or i it possible to shoot videos too?
     

  3. heeduisken

    heeduisken New Member

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    sehr cooles spielzeug <img src="http://illiweb.com/fa/i/smiles/icon_smile.gif" alt="Smile" longdesc="2">
     
  4. JoergS

    JoergS Administrator

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    Further tests are getting more and more interesting.<br><br>I took a rubber band (untapered) and stretched the middle part out, then waited until it had cooled down.<br><br>Then I relaxed it.<br><br>It was COLDER than the room temperature! The first pic shows the retracted band between my hands, the second one the whole band (with the ends beeing warmed from my hands). <br><div style="margin:auto;text-align:center;width:100%">
    <a href="http://2.bp.blogspot.com/-zLNPwm1xWfo/TxHL9PJXalI/AAAAAAAABTg/aJl9mpam5KE/s1600/Cooler2.JPG" class="postlink" target="_blank" rel="nofollow"><br></a><a href="http://2.bp.blogspot.com/-O3iBzOqgAT8/TxHL9nPvDQI/AAAAAAAABTk/5yup48lg4vs/s1600/Cooler1.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://2.bp.blogspot.com/-O3iBzOqgAT8/TxHL9nPvDQI/AAAAAAAABTk/5yup48lg4vs/s320/Cooler1.JPG" border="0" alt=""></a><a href="http://2.bp.blogspot.com/-zLNPwm1xWfo/TxHL9PJXalI/AAAAAAAABTg/aJl9mpam5KE/s1600/Cooler2.JPG" class="postlink" target="_blank" rel="nofollow"><br></a><br><br><a href="http://2.bp.blogspot.com/-zLNPwm1xWfo/TxHL9PJXalI/AAAAAAAABTg/aJl9mpam5KE/s1600/Cooler2.JPG" class="postlink" target="_blank" rel="nofollow"><img src="http://2.bp.blogspot.com/-zLNPwm1xWfo/TxHL9PJXalI/AAAAAAAABTg/aJl9mpam5KE/s320/Cooler2.JPG" border="0" alt=""></a><br>
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    <br><br><br>This means that you can - in theory - build a fridge (or an air condition) with rubber. Take a slingshot outside, draw it out, wait about 20 seconds, then go with the stretched band back into the house, and let go.<br><br>You can build a "Sterling cooler" with this, except that a Sterling normally uses gas and not rubber...
     
  5. horstel-1980

    horstel-1980 New Member

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    thanks for the pics! So my theory was right!!! they cool down to a certian level when you shoot slow and aim for a decent time.
     
  6. JoergS

    JoergS Administrator

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    Yes, they cool down, and loose power.
     
  7. Tobias

    Tobias New Member

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    Jörg, please check for me one thing:<br>is there a different pull the bands fast back or slow back. <br>I think they get more warm if you pull it fast back.
     
  8. horstel-1980

    horstel-1980 New Member

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    The one, which is pulled fast, will be warmer, but the difference is small. <br><br>The thermal energy produced is the same, but over a bigger timespan, were the <br><br>small pulled out band already cools down.
     
  9. JoergS

    JoergS Administrator

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    Tobias, this is my opinion as well. But I will test this tomorrow.
     
  10. horstel-1980

    horstel-1980 New Member

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    I think also interesting is, at which temperature the rubber works best.
     
  11. JoergS

    JoergS Administrator

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    Yes, I did make a video yesterday. It was perfect, cold enough to show every detail. <br><br>The results are astounding. <br><br>These tests also show why the tapered bands typically break about 7 mm in front of the pouch - because that is the hottest part! Obviously the leather pouch cools the band down a bit. The rubber breaks at the hottest point, which stores the most of the energy.<br><br><embed pluginspage="http://www.macromedia.com/go/getflashplayer" src="http://www.youtube.com/v/OL5C_JzZyV4" width="425" height="350" type="application/x-shockwave-flash" wmode="transparent" quality="high" scale="exactfit"></embed><br><br>The tests with Destin's high speed cam and this thermal cam help me understanding rubber. Of course it was a known fact that the bands shootbetter in warmer conditions, that the bands loose power when you keep them drawn out, that tapered bands tear at the pouch, and that the bands are getting warmer when you draw them out. But now there are explanations. I hope these tests will ultimately help us to make slingshots even better.
     
  12. DeathPickle

    DeathPickle New Member

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    I think that the flat bands would lose heat faster than tubular bands, as the flat bands have a greater surface area to volume ratio. Perhaps tubular bands might be better for applications where more time is required to draw/shoot, as they would not loose heat so quickly. <br><br>It would be interesting to make rubber composites, where the outer surface of the bands has some sort of insulating material, which prevents heat loss to the atmosphere.<br><br>I am just speculating of course, perhaps its just easier to shoot quicker haha!
     
  13. JoergS

    JoergS Administrator

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    I think that you are basically right, but the greater surface of the flat bands also explains why they are faster. Max speed and also speed/draw weight ratio is better. The reason: They pick up heat faster than tubes. <br><br>I am now thinking about a slingshot crossbow that has a 12V powered heating system built in.
     
  14. Rayshot

    Rayshot New Member

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    Two things;<br><br><strong>One-</strong> I am not a physics guy but am fascinated with the created laws of physics, so here is something that I don't quite get regarding something Jorge said if I get what he technically means.<br><br>He mentions that the bands are storing or gaining heat "energy" from stretching. And that the "heat energy" is what gives or adds the extra oomph, speed in a shot if done while the bands are warm.<br><br><strong>My Question;</strong> Is the heat the energy? Or because the bands are warmed from the stretching, increasing their ability to contract quicker. Maybe not the best comparison but like muscles warm or muscles cold. Or like liquids such as molasses and honey when warm they flow better than when cold.<br><br><strong>Two-</strong> When the bands are stretched, held and let cool they aren't as "fast". <br><br><strong>My Question;</strong> If the bands are stretched and let cool, then heat applied to warm them would they have the speed as if stretched and immediately released?<br>
     
  15. Bill Hays

    Bill Hays New Member

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    Ray it's an interesting experiment but don't get confused about what the heat means.... Think of it like this, a rooster crows every morning just before the sun rises, he does this every morning... after this behaviour and result is witnessed by a 3 year old child he may come to the conclusion that the rooster is making the sun rise... which of course is not true.<br><br>The heat is an indicator, not the cause of elastic tension and resulting retraction upon release.... adding heat after the band is already stretched will not add speed to the retraction. And in fact if you stretch the band out and hold it stretched out until the band cools to or below the temperature of the surrounding area, it will still retract... although slower than if released faster. <br><br>Now don't get me wrong, I'm not saying Joerg thinks "the rooster causes the sun to rise"... but for some of the less initiated younger members they may think that's what's basically being said... and it's not!
     
  16. tokSick

    tokSick Senior Member

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    Hello,<br>I' ve seen the vid on youtube yesterday, very hot, i mean cool, what ever.<br>It is too much technology for me so i don' t understand everything.<br>I leave it to the experts.
     
  17. Rayshot

    Rayshot New Member

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Bill Hays wrote:</b></span></td></tr>
    <tr><td class="quote">Ray it's an interesting experiment but don't get confused about what the heat means.... Think of it like this, a rooster crows every morning just before the sun rises, he does this every morning... after this behaviour and result is witnessed by a 3 year old child he may come to the conclusion that the rooster is making the sun rise... which of course is not true.<br><br>The heat is an indicator, not the cause of elastic tension and resulting retraction upon release.... adding heat after the band is already stretched will not add speed to the retraction. And in fact if you stretch the band out and hold it stretched out until the band cools to or below the temperature of the surrounding area, it will still retract... although slower than if released faster. <br><br>Now don't get me wrong, I'm not saying Joerg thinks "the rooster causes the sun to rise"... but for some of the less initiated younger members they may think that's what's basically being said... and it's not!</td></tr>
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    <span class="postbody"><br><br>one of my main points was that I think I got that the heat was a cause. Perhaps Jorge didn't mean to word it this way; "energy invested is converted into heat". "When released,<strong> heat is converted into kinetic energy</strong> of the bullet."<br><br>Also I am interested in what Jorge has followed up on my comment about applying heat to a stretched band that has cooled, regains draw weight tension to immediate draw weight tension. So now I am curious and would think; if the draw weight rebounds to initial stretch draw weight then the speed should also rebound to a quick draw and release. Or at least increase from the cold band speed.<br><br>Here is his test a day after I mentioned the heat applied to a band that was stretched and had cooled. <a href="http://theslingshotforum.forumotion.com/t789-triumph-of-the-mind-over-hysteris" class="postlink">http://theslingshotforum.forumotion.com/t789-triumph-of-the-mind-over-hysteris</a></span>
     
  18. JoergS

    JoergS Administrator

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Bill Hays wrote:</b></span></td></tr>
    <tr><td class="quote">he heat is an indicator, not the cause of elastic tension and resulting retraction upon release.... adding heat after the band is already stretched will not add speed to the retraction. And in fact if you stretch the band out and hold it stretched out until the band cools to or below the temperature of the surrounding area, it will still retract... although slower than if released faster. <br>
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    <span class="postbody"><br><br>Bill, that was my theory before I started the experiments. But actually, adding heat after you have stretched the bands DOES add speed. You can get the original speed back by doing that. <br><br>And yes, if you let the bands cool down to the temp of the environment, they still retract (as long as it is not very cold outside). The bands don't have to be warmer than the air to retract. Just warmer than the critical temperature. If they get colder than that, they loose all retraction capabilities (that temp is probably around 30 below centigrade).<br><br>All my experiments indicate that the "Entropy" physicists are entirely right. The bands do store their energy thermally. Let them cool in stretched condition, they loose that energy, the shot is weaker. Heat them up, the shot is faster. <br><br>The entropy theory isn't disputed, by the way.</span>
     
  19. yulzari

    yulzari New Member

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    This, of course, explains why a slingshot rifle will have some inherent inaccuracy due to the power of the rubber varying, not only with ambient temperature, but also with cooling once it is drawn. <br><br>The thought occurs to me that short fat speargun rubber will cool down more slowly as it has far less surface area for it's mass. Perhaps it could move in an insulated sleeve?<br><br>In the case of a coiled steel spring the same effect occurs but less so. The coiling means that any lengthening or shortening is translated into twisting of the coil so the coil changes in length far less than the actual steel wire. Think of it like screwing in a fine thread screw. You turn the screwdriver round a lot but the screw goes in very slowly.
     
  20. Pikeman

    Pikeman New Member

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    The Wikipedia entry for rubber bands explains the weird thermodynamics going on here. In summary, rubber bands are the work of the devil and trying to understand them will cause your brain to overheat. <br><br>Here is an extract:<br><table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Quote:</b></span></td></tr>
    <tr><td class="quote">
    <br><i>Temperature affects the elasticity of a rubber band in an unusual <br>way. Heating causes the rubber band to contract, and cooling causes <br>expansion.[9]<br><br>An interesting effect of rubber bands in <br>thermodynamics is that stretching a rubber band will cause it to release<br> heat (press it against your lips), while releasing it after it has been<br> stretched will lead it to absorb heat, causing its surroundings to <br>become cooler. This phenomenon can be explained with Gibb's Free Energy.<br> Rearranging &Delta;G=&Delta;H-T&Delta;S, where G is the free energy, H is the enthalpy, <br>and S is the entropy, we get T&Delta;S=&Delta;H-&Delta;G. Since stretching is <br>nonspontaneous, as it requires external work, T&Delta;S must be negative. <br>Since T is always positive (it can never reach absolute zero), the &Delta;S <br>must be negative, implying that the rubber in its natural state is more <br>entangled (fewer microstates) than when it is under tension. Thus, when <br>the tension is removed, the reaction is spontaneous, leading &Delta;G to be <br>negative. Consequently, the cooling effect must result in a positive &Delta;G,<br> so &Delta;S will be positive there.[10][11]<br><br>The result is that a <br>rubber band behaves somewhat like an ideal monatomic gas, inasmuch as <br>(to good approximation) elastic polymers do not store any potential <br>energy in stretched chemical bonds or elastic work done in stretching <br>molecules, when work is done upon them. Instead, all work done on the <br>rubber is "released" (not stored) and appears immediately in the polymer<br> as thermal energy. In the same way, all work that the elastic does on <br>the surroundings, results in the disappearance of thermal energy in <br>order to do the work (the elastic band grows cooler, like an expanding <br>gas). This last phenomenon is the critical clue that the ability of a <br>elastomer to do work depends (as with an ideal gas) only on <br>entropy-change considerations, and not on any stored (i.e., potential) <br>energy within the polymer bonds. Instead, the energy to do work comes <br>entirely from thermal energy, and (as in the case of an expanding ideal <br>gas) only the positive entropy change of the polymer allows its internal<br> thermal energy to be converted efficiently (100% in theory) into work.</i><br>
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    <span class="postbody"><br>So, it's all terribly simple and obvious really. <img src="http://illiweb.com/fa/i/smiles/icon_scratch.png" alt="scratch" longdesc="33"> For the full wiki article: <a href="http://en.wikipedia.org/wiki/Rubber_band" class="postlink" target="_blank" rel="nofollow">http://en.wikipedia.org/wiki/Rubber_band</a></span>