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Significant projectiles (Read 7526 times)
Matthias
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Significant projectiles
Oct 28th, 2004 at 2:33pm
 
Ok, I'm currently working on a little program that I hope does a better job of simulating sling ballistics than what we've been able to find on the web. It takes into account fluid drag at varying Reynold no, density, size, surface roughness, wind speed, shape (sphere/ellipsoids only), height above ground at launch, angle.

I currently have dropdown menus allowing you to quickly select materials of various densities (lead,steel,concrete,stone,rubber) and properties of a few commonly slung balls (golf,base,tennis,soft)

I'd also like to add a list of "significant projectiles". I've been thinking along the lines of a few artifacts (roman lead glans etc) as well as modern one like Larry Bray's rock.

I think maybe forum favourites deserve a shot too - things like David's concrete tennisballs and Techstuf's 1" lead spheres spring to mind.

You guys want to help me fill out these categories? Bonus points if you include vitals (weight/dimensions etc) with your nominations!

Matthias
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KnollSlinger
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Re: Significant projectiles
Reply #1 - Oct 28th, 2004 at 7:33pm
 
Be sure to include a section for projectile orientation.

I learned in my last outing that when my bullets go thru plywood, the long side goes thru.  This is not like a bullet, where the point goes thru first.

Ie, the long axis of the eslipsoid is verticle.

This is because I use a sidearm technique, and the pocket holds the stone in verticle position, as  it is also released.
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Almulek
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Re: Significant projectiles
Reply #2 - Oct 29th, 2004 at 2:57am
 
Matthias,

Your program sounds great!  You are very ambitious.  Are you going to make it available?
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Matthias
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Re: Significant projectiles
Reply #3 - Oct 29th, 2004 at 12:04pm
 
Of course! That was mostly the point. Still working on a few interface bugs, but you guys will be the first to know when it's ready for play...

No attitude control for the short term at least... Same with spin. I agree that they would both be useful additions but things start to get complicated with lift forces. It will be there eventually, particularly because I don't like the approximation that the glans flies point first for the entire trip. If it is thrown point first at 40deg, with spin, it is going to be 40 degrees "nose up" (almost 70 relative to flow) be the time it lands. In between we've had regions of zero lift, "gliding" flight (big range boost here) and stall. Doing the calculations for _one_ projectile is pretty "easy" but doing a 6 dimensional fit so that any input value are accepted takes more work!

I'm serious about the call for projectile though guys! Let the suggestions fly!

Matthias
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Hobb
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Re: Significant projectiles
Reply #4 - Oct 29th, 2004 at 4:26pm
 
I'm in awe of your programming abilities...  Not to mention your grasp of physics! 

As for projectiles -- I vote for snowballs!  Tennis balls would also be good to include, since many of us city slickers are restricted to those (they keep fencing in all my best slingin' spots!) 

Truly and amazing project.  Good luck!
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Re: Significant projectiles
Reply #5 - Oct 30th, 2004 at 11:39am
 
My modifyed golf ball. It is 4 oz and is just a hollowed out golf ball.
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Matthias
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Re: Significant projectiles
Reply #6 - Oct 30th, 2004 at 11:46am
 
Nah, that is an easy one to for a user to enter as everything but the weight is the same as a regular golfball, so you just choose the gb from the menu then change the material...

Snow is a great idea for a material (you choose the size), though as one whose been hit by my fair share of slushballs (nice wet snow here on the coast) I'm not sure about what to pick as a "standard" for density...

I just remembered eggs, so that one is going on, and I have tennis balls already. Interestingly, the sim throws a tennis ball further than I would have thought possible. I'm pretty sure that my real world trouble with those things is lack of initial speed... something to check out. Maybe a weighted pouch would help get them up to full velocity?

Matthias
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Re: Significant projectiles
Reply #7 - Oct 30th, 2004 at 12:37pm
 
how about mouse balls?
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Yurek
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Re: Significant projectiles
Reply #8 - Oct 30th, 2004 at 3:07pm
 
Yeah. It's very difficult to simulate tennis balls or similar ammo. Due to their small desity, the ranges strongly depend on the spin and "shaggines". I see the clear difference beetwen new tennis balls and those tousled by my dog. The wet ones also fly further, and give a nice aerosol tail. Moreover, if I use the tennis balls wraped tight and smoothly with duct tape, I can even surpass the 100 m (110 yards) distance with them and my short 27" sling, what is absolutely impossible for me with naked ones. The wraped tennis balls look pretty nice, like silvery cannon balls.

Matthias, what about ice-balls formed inside dimidated broken tennis balls? Something like these David's concrete balls but made of water. Their density would be pernament.

Jurek
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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.
 
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Matthias
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Re: Significant projectiles
Reply #9 - Oct 30th, 2004 at 4:55pm
 
Duct tape has to be cheating Grin as it changes the weight significantly... wet balls too. How about burning the "fuzz" off with a torch?

Ice is a good addition.

What's a mouse ball? - oh, think I just figured it out. Nice ammo to be sure, though maybe a little delinquent.

Matthias
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lobohunter
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Re: Significant projectiles
Reply #10 - Oct 31st, 2004 at 1:26pm
 
so how about six ounce lead egg sinkers at 25 yards
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Re: Significant projectiles
Reply #11 - Nov 1st, 2004 at 3:28am
 
Hmmm... may I suggest to restrict the calculator to proper slings projectiles? Grin  Are we playing golf, tennis or throwing eggs to a bad speaker? Of course all this is very funny and every body has done it sometimes, but to simulate it as if it was a proper slinging modality is too much in my opinion  Tongue
What about to consider these sort of materials: common stones (limestone, granite, basalt, etc), clay, cement or concrete, lead, metals(iron, bronce, etc).
And about the shape: spherical, ellipsoide(various ratios), irregular(typical stones from railways).

And like significant projectiles  I think historical ones are are the best samples:  average Roman glans, Balearic stone (1 mina), Neolithic clay proyectil, Medieval stone projectil, etc.

Well, is only an idea. All depends of what we want to make, a professional calculator or an internet game  Grin  
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Matthias
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Re: Significant projectiles
Reply #12 - Nov 1st, 2004 at 2:21pm
 
Quote:
Hmmm... may I suggest to restrict the calculator to proper slings projectiles? Grin  ........
......common stones (limestone, granite, basalt, etc), clay, cement or concrete, lead, metals(iron, bronce, etc)......
spherical, ellipsoide(various ratios), irregular(typical stones from railways).

And like significant projectiles  I think historical ones are are the best samples:  average Roman glans, Balearic stone (1 mina), Neolithic clay proyectil, Medieval stone projectil, etc.


I'd have to argue that golf balls are a proper sling projectile for a lot of people! Particularily for those in the city. The calculator is quite flexible, and you can input any value you want. The idea of the library is to store some presets for people to work with. I'd like for someone to be able to take a few "standard" ammo types out to a field and measure their range, working back to launch velocity - then use the sim to check out what their "potential" is with true-slinger glandes! I bet we'd see a spike in glans casting posts! Wink

I have a materials list that includes most of the ones in your suggestion. I'll expand the stone category to include more types.

The sim is restricted to spherical/ellipsoidal projectiles (on axis) for the time being Sad

I completely agree about the value of the "historical projectiles" category! Are you able to post some characteristic properties?

Matthias
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Re: Significant projectiles
Reply #13 - Nov 1st, 2004 at 6:10pm
 
Quote:
Yeah. It's very difficult to simulate tennis balls or similar ammo. Due to their small desity, the ranges strongly depend on the spin and "shaggines". I see the clear difference beetwen new tennis balls and those tousled by my dog. The wet ones also fly further, and give a nice aerosol tail. Moreover, if I use the tennis balls wraped tight and smoothly with duct tape, I can even surpass the 100 m (110 yards) distance with them and my short 27" sling, what is absolutely impossible for me with naked ones. The wraped tennis balls look pretty nice, like silvery cannon balls.

Matthias, what about ice-balls formed inside dimidated broken tennis balls? Something like these David's concrete balls but made of water. Their density would be pernament.

Jurek

how about tennis balls soaked in gasoline and thrown thru a flaming hoop, thus setting them alight at the start of their journey?
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Yurek
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Re: Significant projectiles
Reply #14 - Nov 3rd, 2004 at 7:38am
 
Quote:
how about tennis balls soaked in gasoline and thrown thru a flaming hoop, thus setting them alight at the start of their journey?


We would get pretty nice comets. A haystack behind would be a nice addition Grin
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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.
 
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