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The physics of the sling (Read 33633 times)
Dravonk
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Re: The physics of the sling
Reply #60 - Aug 26th, 2007 at 9:15am
 
DesertPilot wrote on Aug 24th, 2007 at 1:46pm:
But I tried something similar several years ago to evolve a robot walker, so I have a very good idea just how time-consuming such a project might be.

Slightly different topic, but I am curious, how did it work? Did you actually build the walker?
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DesertPilot
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Re: The physics of the sling
Reply #61 - Aug 27th, 2007 at 1:28am
 
wanderer wrote on Aug 26th, 2007 at 1:42am:
You might also try a stroboscopic picture. With flourescent markers on the sling and the hand you should be able to manage a reasonable result by slinging illuminated by either a fluorescent light...

...As far as slinging at buckets of mud etc. I'm not sure many of us have had much success with ballistic pendulums...


A flourescent light!  I never thought of that!  What an awesome idea!  I shall have to give this a try.  If all goes as planned, I'll be on vacation in Maine next week -- a land full of many small smoothly rounded rocks -- which should allow some opportunity for experiments.  Do you have any recommendations for a suitable (and inexpensive) digital camera?

I finally ran across some of the old posts about ballistic pendulumns, so I see what you mean.  I'll still try it myself, on the off chance that I might, in my naive incompetence, stumble upon some brilliant idea that greater minds than mine have missed, but I'll probably just add to the long list of Embarassing Experiences I've managed to accumulate over the years Smiley
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Re: The physics of the sling
Reply #62 - Aug 27th, 2007 at 1:52am
 
Dravonk wrote on Aug 26th, 2007 at 9:15am:
DesertPilot wrote on Aug 24th, 2007 at 1:46pm:
But I tried something similar several years ago to evolve a robot walker, so I have a very good idea just how time-consuming such a project might be.

Slightly different topic, but I am curious, how did it work? Did you actually build the walker?


Alas, like all too many things in life, this idea never got past the simulation stage.  The biggest problem turned out to be modeling what happens when a foot hit the ground.  If I made the simulated ground too soft, it would sink under the robot's feet like a sagging trampoline.  If I made it too hard, the simulation could go unstable and shoot the robot into the air.  It was annoying... and also rather hilarious.  I could send you this code too, but this might be a complete waste of your time, because it was written in C++ using MFC for the graphics, and no one on Earth, including me, will ever be able to get the darn thing to run again.

Slings are more fun!  I just tried out some of the RoboSlinger results with my long-suffering indoor sling, and they seem to work.  But I'll save that for a later post 'cos I've already written too much this evening.  I have got to get that 3D version with gravity written!  Maybe next week...
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Dude
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Re: The physics of the sling
Reply #63 - Sep 5th, 2007 at 10:59pm
 
***Update on the attached file- added 1 & 2 oz then added weight in grams to the oz listings for the     varous columes

I finially joined the Form and decided to add my 2-bits to the subject Cool

I've attached a Zipped PDF file that I think does a fairly good job at helping one to see just what a Sling is capable of doing along side say...a standard pistol cartridge. I beleave that this should represent standard store bought loads.

Just a little background on the Calculations used

    Km/h = 1.6*MPH
   
    ft/sec = MPH*5280/60^2(60 squared)
    5280 ft per mile
   
    m/sec = km/h*1000/60^2(60 squared)
    1000 meters per km

    60^2(squared) gets the calulations down to the second

    Amount of Kinetic Energy = Weight of the projectile*Velocity in ft/sec^2(squared)/Constant

    Constant = 32.163^2(squared)*1
    Acceleration of Gravity = 32.163 ft/sec

Normally in the constant you will see instead of the number "1" for 1 pound, you will see the number "7000" because there are 7000 grains to the pound & bullet weight is in grains. Since that seems to be way too small of an increment of measurement for Sling Projectiles, I just left it at 1 pound.

I'm looking for ways to improve this, or add to it, or correct any mistakes

I hope this is of use to you
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« Last Edit: Sep 19th, 2007 at 3:04pm by Dude »  

 
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Dude
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Re: The physics of the sling
Reply #64 - Sep 6th, 2007 at 2:48pm
 
Would this apply? Undecided

I been thinking about the pressure that is being applied to the bottom of a high heel, worn by a lovely women of course! Would this also apply to a projectile at it's point of impact for a given amount of kinetic energy as measured in foot pounds?

weight in pounds/area in square inches

100# petite woman with with 4" heel whose tip is .25 square inches = 1600 PSI
110# petite woman with with 4" heel whose tip is .25 square inches = 1760 PSI
120# petite woman with with 4" heel whose tip is .25 square inches = 1920 PSI just short of a TON

Looking at these numbers, I think I've lost any interest in having in having one walk on my back with heels. It would be very embarrassing explaining to the medical stall in the emergency room how I got all of the punture wounds in my back and vital organs Wink.

If this would apply I have attached a Zipped PDF file that list the PSI for a given weight of 2 pounds to over 800 pounds for an area of .25 square inches or .0625 square inches
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PSI.zip (10 KB | )
 
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Curious Aardvark
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Re: The physics of the sling
Reply #65 - Sep 7th, 2007 at 11:29am
 
[quote]Looking at these numbers, I think I've lost any interest in having in having one walk on my back with heels[/quote]
lol that implies you'd thought about it before though ;-)

A slight play on words: The slinger of physics.
Gives you person who throws doctors around - I volunteer my gp who in the words of the specialist at the hospital is: 'f***ing useless !'
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Do All things with Honour and Generosity: Regret Nothing, Envy None, Apologise Seldom and Bow your head to No One  - works for me Smiley
 
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Re: The physics of the sling
Reply #66 - Sep 23rd, 2007 at 5:14pm
 
Just to let you'll Know that I uploaded an update "Energy02" in reply #63 that compares differnt size projectiles and speed to varous sizes of pistol cartridges Cool
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Re: The physics of the sling
Reply #67 - Oct 3rd, 2007 at 9:44pm
 
You people never cease to amaze me.  Not only do you sling, but you apply the scientific method of research to your slinging.

In most of the technical threads I am WHOLLY out of my depth, but I enjoy reading them, if only to see the quality and intelligence of the people who contribute.

(No, I ain’t a bloody toady.  Just amazed, that’s all.)

I do have one idea for the “compound sling” forum I want to think about before I post.  If it works it might solve a few difficulties.

Trebuchet
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Re: The physics of the sling
Reply #68 - Oct 12th, 2007 at 1:01am
 
how do you quote part of what someone posts? cant figure it out.. anyway, as far as flashing sling ammo goes, has anyone been to a dollar store and bought one of those rubber balls that have a built in led flasher that blinks when you bounce it? might be a good start to blinking ammo. fun to launch at night, and go find too.. Smiley
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OrangeDuck
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Re: The physics of the sling
Reply #69 - Oct 12th, 2007 at 1:04am
 
kellymcdman wrote on Oct 12th, 2007 at 1:01am:
how do you quote part of what someone posts? cant figure it out..


I really just wanted to do that to spite you  Cheesy Basically what you do is press the quote button, and when ou go to the page where you write your response, what you quoted is within two codes which are within brackets. Just erase the part you don't want to be quoted.
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Dravonk
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Re: The physics of the sling
Reply #70 - Oct 12th, 2007 at 1:05am
 
kellymcdman wrote on Oct 12th, 2007 at 1:01am:
how do you quote part of what someone posts? cant figure it out..

In the top right corner of each post there is a "Quote" button.
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