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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 10-07-2019, 06:36 PM   #31
Marcus
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Re: linking rubbers together for more speed?

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Originally Posted by Hpwatson View Post
Regardless of the physics you're trying to figure out, cutting a band in half and 'gluing' it back together isn't practical.
Yep, that's another point I was just thinking about.

Andersp90, please video/post your experiment. I'd recommend safety glasses.
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Old 10-07-2019, 06:42 PM   #32
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Re: linking rubbers together for more speed?

You could try some sort of ultra short wishbone between the two band ends or even a double sided bead or something with constrictor knots. I think I see what you're getting at but some of the comments about usability are worth considering. There is a max stretch point on any rubber you use where it becomes counterproductive to stretch the band further, and by linking two bands end-to-end you're trying to get more power from a 'single' co-joined band, but I don't think you're gaining any stretch. Its ether 100% or 50% + 50% from how I see it.
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Old 10-07-2019, 06:50 PM   #33
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Re: linking rubbers together for more speed?

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Regardless of the physics you're trying to figure out, cutting a band in half and 'gluing' it back together isn't practical.
No, im not sure such a glue exists.

I plan on using piercings to join the ends. 3 pr final rubber band.



Hunt is already making something similar, so mabye he will make me some: http://www.huntechnology.it/en/ogivepiercing.aspx
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Old 10-07-2019, 06:54 PM   #34
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Re: linking rubbers together for more speed?

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There is a max stretch point on any rubber you use where it becomes counterproductive to stretch the band further, and by linking two bands end-to-end you're trying to get more power from a 'single' co-joined band, but I don't think you're gaining any stretch. Its ether 100% or 50% + 50% from how I see it.
The setup wont provide added stretch, nor will it provide more power (the band wont have more power). The "new" band should release the same amount of energy - just twice as fast.

Hopefully, that will translate into a faster spear. Time will tell.

Last edited by Andersp90; 10-07-2019 at 07:10 PM.
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Old 10-07-2019, 08:27 PM   #35
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Re: linking rubbers together for more speed?

This entire discussion is insane!
Just take a magic marker and draw a line around the center of the band where the intended cut line is, now pretend you cut it and glued it back together, there you go, it is magically spliced together on the cut line, how much difference in power are you getting now!
And That is better than your idea of using "piercings"...you know of cource when you use those and tie the bands you have lost usable material that would have stretched..
Like I said, this is insane.
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Old 10-07-2019, 08:35 PM   #36
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Re: linking rubbers together for more speed?

I've done this experiment already. I cut my speargun bands into an infinite number of segments (of infinitesimal length) and then glued them back together in series. I didn't get supersonic speeds.
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Old 10-07-2019, 08:37 PM   #37
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Re: linking rubbers together for more speed?

I don't think using body jewelry to join two rubbers is safe.
When are you going to do your experiment?
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Old 10-07-2019, 08:45 PM   #38
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Re: linking rubbers together for more speed?

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I've done this experiment already. I cut my speargun bands into an infinite number of segments (of infinitesimal length) and then glued them back together in series. I didn't get supersonic speeds.
Yea, one of the thought processes I go thru to is to bring the experiment to absurd levels in both directions in order to create an outcome that is more easily understood. I didn't have to do this in order to understand this outcome...but still, it's a valuable tool for quick analysis.

Andersp90, don't think we're giving you a hard time out of meanness. I'm pretty sure everyone enjoys you posting the question. It's at least thought provoking and entertaining.
Be cautious of what body jewelry you intend to use. I've seen too many instances of use on people whereby the flesh doesn't snap back...ears for example.
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Last edited by Marcus; 10-07-2019 at 08:57 PM.
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Old 10-07-2019, 09:10 PM   #39
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Re: linking rubbers together for more speed?

A picture is worth a thousand words. If we shorten the bands we only get half the draw, so the spear would only be propelled on the gun body for half the distance acheived before, so we don't gain anything.
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Old 10-07-2019, 09:59 PM   #40
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Re: linking rubbers together for more speed?

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I am referring to a proven principle I learned in muscle physiology in medschool.
This is why I don't trust my doctor to be my car mechanic.
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Old 10-08-2019, 12:43 AM   #41
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Re: linking rubbers together for more speed?

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I don't think using body jewelry to join two rubbers is safe.
When are you going to do your experiment?
Im not planning to use jewelry. Im planning to use a straight wishbone. I even provided you with a link to someone who might be able to make them. The picture what just to show what it would look like.

Here is the link again: http://www.huntechnology.it/en/ogivepiercing.aspx

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I didn't get supersonic speeds.
Ofc you wouldent. Just like you dont have supersonic muscles. But if muscle A is 10 times longer than muscle B, A will be 10 times faster.

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Yea, one of the thought processes I go thru to is to bring the experiment to absurd levels in both directions in order to create an outcome that is more easily understood. I didn't have to do this in order to understand this outcome...but still, it's a valuable tool for quick analysis.
So you still dont think that linking contractile units in series, will increase speed?
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Old 10-08-2019, 01:20 AM   #42
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Re: linking rubbers together for more speed?

Energy stored in the bands gets turned into kinetic energy of the spear and to a lesser extent the gun because the diver is holding it. To increase the velocity or acceleration of the spear the extra energy would have to come from somewhere and chopping the bands up into segments does not do that. To think otherwise would be like believing in a perpetual motion machine.
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Old 10-08-2019, 01:22 AM   #43
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Re: linking rubbers together for more speed?

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Originally Posted by popgun pete View Post
Energy stored in the bands gets turned into kinetic energy of the spear and to a lesser extent the gun because the diver is holding it. To increase the velocity or acceleration of the spear the extra energy would have to come from somewhere and chopping the bands up into segments does not do that. To think otherwise would be like believing in a perpetual motion machine.
If you release the same amount of energy, but in half the time, wont that translate into speed?
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Old 10-08-2019, 01:45 AM   #44
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Re: linking rubbers together for more speed?

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If you release the same amount of energy, but in half the time, wont that translate into speed?
No, kinetic energy is given by 1/2 mass x velocity squared. To double the velocity we would need 4 times the energy. KE1 = 1/2 M.V1^2 and if V2 = V1 X2 then KE2 = 1/2 M.V2^2 = 1/2 M.(V1 X 2)^2 = 1/2 M. V1^2 X 4.

Power is the rate of doing work, and energy is the same as work. Using the energy in a shorter burst does not buy any more velocity as you only have the same amount of energy in either case.
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Old 10-08-2019, 01:59 AM   #45
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Re: linking rubbers together for more speed?

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No, kinetic energy is given by 1/2 mass x velocity squared. To double the velocity we would need 4 times the energy. KE1 = 1/2 M.V1^2 and if V2 = V1 X2 then KE2 = 1/2 M.V2^2 = 1/2 M.(V1 X 2)^2 = 1/2 M. V1^2 X 4.

Power is the rate of doing work, and energy is the same as work. Using the energy in a shorter burst does not buy any more velocity as you only have the same amount of energy in either case.
Im having a really hard time wrapping my head around why linking sarcomers will inscrease speed, but not rubbers.

Last edited by Andersp90; 10-08-2019 at 02:10 AM.
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