Fork/Pouch wide coefficient, less band but wider or more band but thiner?

Discussion in 'General Slingshot Discussions' started by otta88sun, Jan 1, 2013.

  1. otta88sun

    otta88sun New Member

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    As title says, i was in front this question:<br><br>Imagine (all the people... no its no that <img src="http://illiweb.com/fa/i/smiles/icon_wink.gif" alt="Wink" longdesc="15">) to have 4 bands per side of blue thera band (color don't make difference) with 26mm at fork and 9mm at pouch. The lenght of this bands is called H (height).<br><br>The fork/pouch coefficient is 2,89<br><br>Now, if i want use less band per side? for example 3 per side?<br><br>I guessed a wider fork size for band: 36mm -> then i let pouch size with 36/2,89 = 12,5mm at the pouch<br><br>Ok and now? can i for example let the areas of each band like the trapezium<br><br>First bands set) (26+9)/2*H*4 = 70H (the total area of a side)<br>Second bands set) (36+12,5)/2*H*3 = 72,75H (the total area of a side)<br><br>I don't know if is a good formula, but if my let is right, i should got<br>THE SAME SPEED, SAME TAPERING COEFFICIENT, SAME BANDS LENGHT, SAME DRAWLENGHT<br>WITH 1 PER SIDE LESS BAND<br><br>Is trapezium area calculation right and good for this question?<br><br>Thank you all
     
  2. zwillie

    zwillie New Member

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    <img src="http://illiweb.com/fa/i/smiles/icon_eek.gif" alt="Shocked" longdesc="5">.......... <img src="http://illiweb.com/fa/i/smiles/icon_idea.png" alt="Idea" longdesc="18"><br>I need a moment to understand what you mean.<br><br>I would say yes.<br><br>I do the same with tubes. (ring area)<br>Zwillie
     

  3. onnod

    onnod Im from Holland, isnt that weird?

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    Just thinking, do you want to have the same amounth of rubber with both sets? Because it is of now.<br>
     
  4. otta88sun

    otta88sun New Member

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    no, i want the same bullet speed at same drawlenght and everything like before,<br>i ONLY WANT LESS BAND PER SIDE.....
     
  5. onnod

    onnod Im from Holland, isnt that weird?

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  6. otta88sun

    otta88sun New Member

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    and i dont know if calculation is right or not... therefor i m asking ;D
     
  7. Arturo Borquez

    Arturo Borquez Administrator

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    I would say that your assumption is correct. I've simulated with a program based on <a href="http://slingshotforum.com/blog/11/entry-408-tapered-flatbands-mechanism-and-effect/" class="postlink" target="_blank" rel="nofollow">THIS</a> (it is based on finite differential analysis) and my results are:<br><br>case 1:<br><br>BANDA<br>cabezal(cm) : 2.600000<br>parche(cm) : 0.900000<br>largo(cm) : 25.000000<br>masa banda (gr) : 2.681692<br><br>proyectil(gr) : 10.000000<br>fuerza(kgf) : 2.000000<br>bandas : 4.000000<br><br>CALCULO<br>carrera(cm) : 64.517830<br>tiempo rel.(ms) : 14.812584<br>l. total(cm) : 89.517830<br>elongac. max(%) : 423.563610 (0%)<br>elongacion(%) : 258.071322<br>carga(kgf) : 16.000000<br>v-proyec(m/s) : 61.463323 201.651321 (fps)<br>energia(j) : 18.888700<br><br>------------------------------------------------<br>case 2:<br><br>BANDA<br>cabezal(cm) : 3.600000<br>parche(cm) : 1.250000<br>largo(cm) : 25.000000<br>masa banda (gr) : 3.716103<br><br>proyectil(gr) : 10.000000<br>fuerza(kgf) : 2.770000<br>bandas : 3.000000<br><br>CALCULO<br>carrera(cm) : 64.467918<br>tiempo rel.(ms) : 14.701074<br>l. total(cm) : 89.467918<br>elongac. max(%) : 423.354551 (0%)<br>elongacion(%) : 257.871671<br>carga(kgf) : 16.620000<br>v-proyec(m/s) : 61.893793 203.063624 (fps)<br>energia(j) : 19.154208<br><br>the legends are in spanish but I hope you'll understand them<br>... forgot to mention that the bands model are for TBG and the pouch + ties weights 4gr ...
     
  8. otta88sun

    otta88sun New Member

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    very interesting!<br>thank you!<br>can u translate result please? to english?
     
  9. Arturo Borquez

    Arturo Borquez Administrator

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    In english ...<br>case 1:<br><br>BAND<br>width at fork(cm) : 2.600000<br>width at pouch(cm) : 0.900000<br>band length(cm) : 25.000000<br>band mass(gr) : 2.681692<br><br>ammo weight(gr) : 10.000000<br>force(kgf) : 2.000000<br>number of bands : 4.000000<br><br>CALCULUS<br>net stroke(cm) : 64.517830<br>relaxing time(ms) : 14.812584<br>draw length(cm) : 89.517830<br>max. elongation(%) : 423.563610 (0%)<br>elongation(%) : 258.071322<br>draw force(kgf) : 16.000000<br>ammo speed(m/s) : 61.463323 201.651321 (fps)<br>energy(j) : 18.888700<br><br>------------------------------------------------<br>case 2:<br><br>BAND<br>width at fork(cm) : 3.600000<br>width at pouch(cm) : 1.250000<br>band length(cm) : 25.000000<br>band mass(gr) : 3.716103<br><br>ammo weight(gr) : 10.000000<br>force(kgf) : 2.770000<br>number of bands : 3.000000<br><br>CALCULUS<br>net stroke(cm) : 64.467918<br>relaxing time(ms) : 14.701074<br>draw length(cm) : 89.467918<br>max. elongation(%) : 423.354551 (0%)<br>elongation(%) : 257.871671<br>draw force(kgf) : 16.620000<br>ammo speed(m/s) : 61.893793 203.063624 (fps)<br>energy(j) : 19.154208
     
  10. otta88sun

    otta88sun New Member

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    Ok, now is very more clear, thank u very much for translating....<br>i really like ur work! XD<br>which program did u used?<br><br>However, yeah, seems that the trapezium theory area calculation works good!<br>So i thik to can say is a good calculation to get less bands per side!<br><br>Thank you very much again! <img src="http://illiweb.com/fa/i/smiles/icon_wink.gif" alt="Wink" longdesc="15">
     
  11. Arturo Borquez

    Arturo Borquez Administrator

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    otta88sun, there are SEVERAL combinations to achieve this results ... anyway what I've found (in theory and practice) is that the draw length and initial acceleration (16000+m/s2 for deep tapering, 6000m/s2 normal bands) are the principal variables ... that's why butterfly style gives maximum speed ...
     
  12. otta88sun

    otta88sun New Member

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Arturo Borquez wrote:</b></span></td></tr>
    <tr><td class="quote">otta88sun, there are SEVERAL combinations to achieve this results ... anyway what I've found (in theory and practice) is that the draw length and initial acceleration (16000+m/s2 for deep tapering, 6000m/s2 normal bands) are the principal variables ... that's why butterfly style gives maximum speed ...</td></tr>
    </table>
    <span class="postbody"><br><br>of course full butterfly and high tapering give u really best speed.<br>every band at each drawlengt got a maximum contract speed, i heard bout peolple that did 5 badns per side there band gold... a maximal muscle strenght for a min more speed.</span>
     
  13. Arturo Borquez

    Arturo Borquez Administrator

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>otta88sun wrote:</b></span></td></tr>
    <tr><td class="quote">
    <br>which program did u used?<br>
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    <span class="postbody"><br>The program is one I've did nothing standard and in a very weird language something like Joy, Cat or Forth cousin (a concatenative with combinators one), if you want I can PM it, but you'll need Linux or Unix to run the compilation (and several packages) ...</span>
     
  14. Arturo Borquez

    Arturo Borquez Administrator

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>otta88sun wrote:</b></span></td></tr>
    <tr><td class="quote">
    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>Arturo Borquez wrote:</b></span></td></tr>
    <tr><td class="quote">otta88sun, there are SEVERAL combinations to achieve this results ... anyway what I've found (in theory and practice) is that the draw length and initial acceleration (16000+m/s2 for deep tapering, 6000m/s2 normal bands) are the principal variables ... that's why butterfly style gives maximum speed ...</td></tr>
    </table>
    <span class="postbody"><br><br>of course full butterfly and high tapering give u really best speed.<br>every band at each drawlengt got a maximum contract speed, i heard bout peolple that did 5 badns per side there band gold... a maximal muscle strenght for a min more speed.</span>
    </td></tr>
    </table>
    <span class="postbody"><br>yes there is a limit where adding more bands gives only little or no more speed ... I use only 2 bands per side for my ammo (5-15gr) because high draw forces and accuracy don't walk together</span>
     
  15. tokSick

    tokSick Senior Member

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    <img src="http://illiweb.com/fa/i/smiles/icon_scratch.png" alt="scratch" longdesc="33"> That' s way to complicated for my pocket brain guys! Don' t make me think, my dreads are on fire!!! <img src="http://illiweb.com/fa/i/smiles/icon_biggrin.png" alt="Very Happy" longdesc="1">
     
  16. FIAAO

    FIAAO Failureisalwaysanoption

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>tokSick wrote:</b></span></td></tr>
    <tr><td class="quote">
    <img src="http://illiweb.com/fa/i/smiles/icon_scratch.png" alt="scratch" longdesc="33"> That' s way to complicated for my pocket brain guys! Don' t make me think, my dreads are on fire!!! <img src="http://illiweb.com/fa/i/smiles/icon_biggrin.png" alt="Very Happy" longdesc="1">
    </td></tr>
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    <span class="postbody"><br><br>+1 <img src="http://illiweb.com/fa/i/smiles/icon_lol.gif" alt="Laughing" longdesc="7"></span>
     
  17. otta88sun

    otta88sun New Member

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    ahahaha, little brain your? <img src="http://illiweb.com/fa/i/smiles/icon_wink.gif" alt="Wink" longdesc="15"><br><br>Arturo, should be interesting did a table for max speed for each TBG drawlenght, dont u?
     
  18. FIAAO

    FIAAO Failureisalwaysanoption

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    Maybe not small but lack of content? <img src="http://illiweb.com/fa/i/smiles/icon_lol.gif" alt="Laughing" longdesc="7">
     
  19. Arturo Borquez

    Arturo Borquez Administrator

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    Don't worry guys it is just a MODEL=GAME, reality is much more complex and what counts is REAL SHOOTING and FEELING ...
     
  20. Arturo Borquez

    Arturo Borquez Administrator

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    <table width="90%" cellspacing="1" cellpadding="0" border="0" align="center">
    <tr><td><span class="genmed"><b>otta88sun wrote:</b></span></td></tr>
    <tr><td class="quote">ahahaha, little brain your? <img src="http://illiweb.com/fa/i/smiles/icon_wink.gif" alt="Wink" longdesc="15"><br><br>Arturo, should be interesting did a table for max speed for each TBG drawlenght, dont u?</td></tr>
    </table>
    <span class="postbody"><br>I can summarize speed for a certain TBG with some ammo weight and pouch weight the tapering you want and number of bands for different draw lengths at 25°C if you want (you can abuse my new year holiday <img src="http://illiweb.com/fa/i/smiles/icon_lol.gif" alt="Laughing" longdesc="7">) ... but you'll find out what every ss fellow knows ... more elongation, more °C = more speed ... there is no such "maximum speed" for a band it depends on many factors ...</span>