Welcome, Guest. Please Login
SLINGING.ORG
 
Home Help Search Login


Pages: 1 2 3 
Send Topic Print
Calculating Theoretical Sling Range (Read 11645 times)
mgreenfield
Funditor
****
Offline



Posts: 509
Milwaukee Wisconsin
Gender: male
Calculating Theoretical Sling Range
Jan 1st, 2004 at 5:11pm
 
Fellow slingsters, ....if we ignore air drag, and assume launch point and impact point are at the same elevation, calculation of range needs just two inputs:

*Projectile initial velocity
*Projectile launch angle above horizontal

Note that projectile weight isn't a factor.

For a quick calculator of range see:

http://id.mind.net/~zona/mstm/physics/mechanics/curvedMotion/projectile/Motion/c...

Just for fun, I assumed a sling with 1meter long cords, swung at an rate equal to 10rps for a projectile initial velocity of 63meters/sec.   I assumed a launch angle of 45deg above horizontal, and the calculator gave me an effective range of just over 400meters.

1meter long cords are certainly realistic, ...and I didnt add in any shoulder-to-fist swing length for the slingster.  The 10rps rate might be a little faster than normally possible.

Interesting, huh!        mgreenfield
Back to top
 
 
IP Logged
 
mgreenfield
Funditor
****
Offline



Posts: 509
Milwaukee Wisconsin
Gender: male
Re: Calculating Theoretical Sling Range
Reply #1 - Jan 1st, 2004 at 8:42pm
 
.....and according to the calculator, everytime you double your launch speed, you QUADRUPLE your range.  Just no substitute for launch speed!    mgreenfield
Back to top
 
 
IP Logged
 
Whipartist
Senior Member
Past Moderator
****
Offline


Stone Slinger/Stick Thrower

Posts: 377
Sand Creek, CA
Gender: male
Re: Calculating Theoretical Sling Range
Reply #2 - Jan 2nd, 2004 at 11:25pm
 
Pretty cool.  Too bad the real world's so complex.  Nah that makes it more fun huh.

                      Ben
Back to top
 
WWW  
IP Logged
 
JeffH
Senior Member
Past Moderator
****
Offline


Don't stand behind me,
I'm about to sling!

Posts: 354
Memphis, TN
Gender: male
Re: Calculating Theoretical Sling Range
Reply #3 - Jan 3rd, 2004 at 10:43am
 
One must not leave out air drag, however.  No matter what size or shape or material your stone is made from, it does not go through the air without resistance.

This is interesting:  two bullets with congruent shapes but of considerably different size have considerably different ballistic coefficients (the amount of "air drag", that is).  The larger bullet will have a better coefficient.  The same holds true for stones we sling.  The larger ones have LESS resistance to the air than smaller ones of similar shape.

As discussed before in another thread, the slinger has a maximum weight of stone he can sling before it is so heavy he can't get up the rotational velocity to make a good throw.  This is different with every slinger, tho most of us are of similar strength. ( Except for Jurek, who is much stronger than most!)  What is needed at this point is to discover the coefficients of spheres of a given sizes and weights (spherical is best here I believe.) 

Also what is needed if for David T to get those velocities from the State Trooper.  Did I miss the thread where he posted them?

Once we get real numbers on these things, we can help Jurek break the world record!!!!!!!!!!!!!!!!!  Well, maybe we can say we encouraged him even if we didn't actually help.

jeff <><
Back to top
 

So David triumphed over the Philistine with a sling and a stone. (1 Samuel 17:50)
 
IP Logged
 
David_T
Funditor
Past Moderator
****
Offline


Hooked on Sling'n

Posts: 756
Greenville,SC
Gender: male
Re: Calculating Theoretical Sling Range
Reply #4 - Jan 3rd, 2004 at 5:54pm
 
Jeff,

You didn't miss my post--the trooper had to take his car to the shop for repairs the day we were to meet, and we have not yet gotten together. We shall see about next week. Undecided
Back to top
 
 
IP Logged
 
Yurek
Funditor
Past Moderator
****
Offline


The best thing, is a good
sling.

Posts: 942
Poland
Gender: male
Re: Calculating Theoretical Sling Range
Reply #5 - Jan 4th, 2004 at 10:30pm
 
Quote:
Once we get real numbers on these things, we can help Jurek break the world record!!!!!!!!!!!!!!!!!  Well, maybe we can say we encouraged him even if we didn't actually help.


I see that I have no way of a retreat alredy Cry I may not fall short of your guys expectations. It would be better if I didn't vanut Wink But seriously I'm glad that you are supporting me. Now I really think about the attempt. Probably I haven't get this idea alone.  Just Ben has suggested it. Now I believe I can do it.

If I have time I will test the spherical projectiles and compare with the glandes. It is not easy to find the best weight because it require a lot of testings with a lot variables. It is true the bigger lead ball flies better than smaller one started with the same velocity, because the relation of mass to the cross-section surface is bigger (R^3/R^2, R-radius). But we need more power of a body to accelerate it. It makes the limit. Finding this one is a serious scientific problem. So we should believe own feeling and intuition.

Jurek
Back to top
« Last Edit: Jan 6th, 2004 at 5:34pm by Chris »  

In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
IP Logged
 
Hondero
Senior Member
****
Offline



Posts: 463
Madrid-SPAIN
Gender: male
Re: Calculating Theoretical Sling Range
Reply #6 - Jan 5th, 2004 at 3:11pm
 
Hi Yurek, I see that it has been created a group of support in your fight for the Guiness, so as you seem determined  Iīd like also to collaborate in the team.
With respect to the weight of the projectiles, I think that with heavy projectiles  the range is shorter. Let us suppose that the maximum muscular power that we can develop is transformed in the kinetic energy of the projectile:

Speeds of launching:
For an optimal mass M:  ― MV^2
For a double mass: ―(2M)V^2,,   V = V/1.2 (approx.)

Maximum reaches in vacuum:
D = V^2/10 (approx),,  D = D/1.4 (approx)

Air drag  for spherical projectiles):
F = K(S x V^2),,   F = F/2.25 (approx)

For the optimal speed that we are considering, the air drag could be translated in a reduccion of the reach of 30 % aprox., reason why its diminution when using great projectiles affects less to the range than the increase of it by diminution of the weight of the projectile

Ranges in the air:
D = (1- 0.3) x V^2/10 = 0,7 x V^2 /10
D = (1- 0.21) x V^2/10 = 0,54 V^2/10,,    
D= 1,3 D
The range with the optimal projectile is a 30% greater than the one of double weight.

(I call optimal mass or projectil, the one of less weight that can  get all the muscular power in the launching. Projectiles very small canīt do it).

Any way, an important aspect in the fight for the Guiness is to consider the relative influence of the different factors in play. To the optimization of the sling and the projectile I would give an importance of 15 % each and to the optimization of the technique of launching and to the muscular training  30 % each. I think  that in general the muscular training is the main factor to develop. Gym, launching with great weights, etc. I think you have to publish in the forum your body measures for consideration of the support team, and evaluate your possibilities... Itīs a joke.

Saludos

Back to top
« Last Edit: Jan 5th, 2004 at 4:42pm by Hondero »  

He brought a conquering sword..., a shield..., a spear... , a sling from which no erring shot was discharged.&&
WWW  
IP Logged
 
Yurek
Funditor
Past Moderator
****
Offline


The best thing, is a good
sling.

Posts: 942
Poland
Gender: male
Re: Calculating Theoretical Sling Range
Reply #7 - Jan 6th, 2004 at 10:10am
 
Hi Hondero,

Thank you very much. The Interesting post. I have read this through and this gives me a lot thinking. I understand the nitty-gritty. Your calculations drive to conclusion that we should try to find the minimal weight of the projectile, what we are able to control and what doesn't cause a idle run, with the specific sling (lengh, air drag of the sling etc.). Because of the adventage of a velocity is bigger than the adventage of the bigger relation "weight/fece" (R^3/R^2) of a more heavy projectile.

My idea have been different until now: just to determine the maximal weight of a projectile, what will not slow down me perceptable, so I will still have the adventage of the "weight/fece" (in simple words "a heavier projectile can overcome its own air drag easier than a lighter one, therefore doesn't lose a velocity so quickly").

I have used 100 g glandes for last testings. So it would make sense to try with 50-70g and with the reduced sling design of course. The lighter projectiles, the sling must be more aerodynamic. The Jeff has the good balistic software and if it can consider a size and mass of a ball, it would be good to plan the simulation for the sling velolocities range. Real testings are difficult due to a shortage of good amo and very incovenient measurements of ranges.

Anyway, first, the most important thing is a power delivery, as you mentioned, then next, don't waste it. So I must practise... and practise, but the winter so cold as I must use the hammer for tearing frigit stones out from the frozen ground. Brrr! The pretender's life is so hard Wink

Jurek
Back to top
 

In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
IP Logged
 
Chris
Slinging.org Administrator
*****
Offline


Slinging Rocks!

Posts: 1284
USA
Gender: male
Re: Calculating Theoretical Sling Range
Reply #8 - Jan 6th, 2004 at 5:38pm
 
Quote:
The larger ones have LESS resistance to the air than smaller ones of similar shape.


I think it's less resistance compared to change in volume or weight.  A Mac Truck has a lot more air resistance than a bullet, but volume wise, the ratio is less.  I think that is what it means. 

However, this property can be exploited, and is why super dense projectiles (like lead) have such good range.  Their weight to size ratio (which determines how much drag they have) is much much better than just stone. 

What is another material, like lead, but denser that doesn't cost a fortune.  Things like gold and uranium might not be so easy to get hold of. Smiley

Chris
Back to top
 
WWW  
IP Logged
 
mgreenfield
Funditor
****
Offline



Posts: 509
Milwaukee Wisconsin
Gender: male
Re: Calculating Theoretical Sling Range
Reply #9 - Jan 21st, 2004 at 12:05pm
 
I've found the calculator site hard to return to using the whole address.   But this works:

Go to - 
http://id.mind.net/~zona/mstm/physics/mechanics/curvedMotion

Select - projectileMotion/

Select - commonQuestionsCalcul..

Again Select - commonQuestionsCalcul..

FYI     mgreenfield
Back to top
 
 
IP Logged
 
Yurek
Funditor
Past Moderator
****
Offline


The best thing, is a good
sling.

Posts: 942
Poland
Gender: male
Re: Calculating Theoretical Sling Range
Reply #10 - Jan 21st, 2004 at 3:40pm
 
I have played with this simulator a bit. Here is one of the results:

Original velocity:  80.00 m/s
30.00 degrees N of E

x-component:  69.28 m/s
y-component:  39.99 m/s

Basic information about the trajectory:

Time till at top:  4.08 s
Total time:  8.16 s
Maximum height:  81.63 m
Range:  565.56 m

It is interesting but that one works as well for lead projectiles as for feathers bacause simulates the motion in the total vacum. So we know only the velocity may not be smaller than 80 m/s in real conditions for that range an angle.

I have found some free balistic software but it usually works corectly for the gun ammo velocities and for the much more flat shots Sad

Here is one of them which would be pretty good, but works with velocities at least 500 ft/s. Does know anybody a more proper one?

http://www.eskimo.com/~jbm/ballistics/maxdist/maxdist.html

Jurek


Back to top
 

In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
IP Logged
 
mgreenfield
Funditor
****
Offline



Posts: 509
Milwaukee Wisconsin
Gender: male
Re: Calculating Theoretical Sling Range
Reply #11 - Jan 21st, 2004 at 6:27pm
 
Yeah, Jurek, the assumption of vacuum conditions is a drawback, but I suspect the estimates might be pretty close for lead glades.    But it does give us a comparative idea what different launch velocities and angles do for range.   And it lets us use relatively slow launch velocities.    Neat thing is that is shows us shots of 1/2 kilometer AND longer are certainly possible.    Now THAT will be the day for me, .....especially if I can come close to a target at that distance!     Happy rockchucking!   mgreenfield
Back to top
 
 
IP Logged
 
Yurek
Funditor
Past Moderator
****
Offline


The best thing, is a good
sling.

Posts: 942
Poland
Gender: male
Re: Calculating Theoretical Sling Range
Reply #12 - Jan 21st, 2004 at 8:34pm
 
mgreenfield,

In vacum the best angle is exactly 45 degrees, but in air the optimal angle is usualy between 30 and 40 degs. It depends on a few main factors: size and shape of projectile, mass, velocity and weather conditions. I'm afraid we can't determine this angle precisely. Anyway we wouldn't be able to get this angle with the sling. So we should shot at angle of 30-40 degs at a guess. It will be close to the best angle.

To see what different angles do for range, play with this base-ball simulator, try find the best angle. You may experiment with the wind and Mangus effect too. Have a fun.

http://www.scri.fsu.edu/~jac/Java/baseball4.html

Jurek

Back to top
 

In the shape, structure and position of each stone, there is recorded a small piece of history. So, slinging them, we add a bit of our history to them.
 
IP Logged
 
mgreenfield
Funditor
****
Offline



Posts: 509
Milwaukee Wisconsin
Gender: male
Re: Calculating Theoretical Sling Range
Reply #13 - Jan 21st, 2004 at 8:57pm
 
Jurek, ....that baseball hit simulator is VERY! slick.   Our guys should be all over it.   Tnx!   Where do you suppose the drag should be set to approximate a spherical lead glande??    Also, it shows the importance of reducing drag.   Launching the same mass w 1/2 the drag makes a huge difference, ....and again takes us to the importance of launching "almond" glandes point first w stabilizing spin if at all possible.   For sure, you dont want to launch them crosswise to the wind!  mgreenfield
Back to top
 
 
IP Logged
 
Hondero
Senior Member
****
Offline



Posts: 463
Madrid-SPAIN
Gender: male
Re: Calculating Theoretical Sling Range
Reply #14 - Jan 22nd, 2004 at 11:43am
 
Very nice simulator this of baseball. I know some others for pinball, trebuchet, etc. The problem with all them is the air drag calculation, that must be an input in the simulator . Itīs a difficult problem that calculus, that in fire gun is foccused by means of tables as there arenīt precise formules to represent it. Unfortunatly I think there are not tables for the margin of sling velocities and ammo, or at least I donīt know them.
Would the slinging group be able to make an approach to the problem? Itīll be a rewarding task... may be exploring the net we can find some interesting approach  Roll Eyes.

Hondero, just feeling lazy today
Back to top
« Last Edit: Jan 22nd, 2004 at 4:16pm by Hondero »  

He brought a conquering sword..., a shield..., a spear... , a sling from which no erring shot was discharged.&&
WWW  
IP Logged
 
Pages: 1 2 3 
Send Topic Print
(Moderators: Rat Man, Masiakasaurus, Bill Skinner, David Morningstar, Curious Aardvark, Chris, Mauro Fiorentini) - (Moderator Group: Forum Moderator)