# The quest of A-Ping for Slingshot power



## aiping (May 31, 2016)

Hi community, as I mentioned in my introduction, I want to tell
you about my one year journey to find a slingshot which is capapble
to take revenge on a piece of 12 mm plywood, simply means
piercing it with a 13 mm steelball.

Here are the beginning and the end of my quest in a nutshell, two pictures at the end of this report.

Now for those who are interested in details:

the Chinese rod slingshot with these yellow tubes obviously was not capable, 
in fact responsible for the riccochet which hit me so badly in the...

So I started to research and found two ingenious shooters:
- 1611torsten (http://m.youtube.com/user/1611torsten) 
- romanianshadow (http://m.youtube.com/user/romanianshadow) 
- (both vanished from the public...)

Lesson learned:
- TBB black is the best balance of speed and energy transfer for me
- Taper increases speed and decreases draw weight
- One wide piece is better than a couple of strips
- (don't use YouTube?)

Furthermore I went into physics of penentration.
Lesson learned:
- as smaller the surface of the impact area of the projectile, as
bigger the weight and as harder the projectile material as better the penetration
- speed can compensate a lack of them within a certain range.

Now as I wanted to use a 13 mm steelball, the impact area, weight and hardness
were fixed, so I could only play with TBB, width, length, taper, amount of stripes
(I did not want use my fist for bare bone shooting....my deepest respect to 
romanianshadow!!!)

Eperiments following the instructions of 1611torsten I stopped soon
due to bandlife time of about 10 shots max and as if only one strip ruptures 
you should exchange the whole bandset, the intact bands will follow soon
tired from roller cutting.

The best results I achieved by wrapping two piece of tapered TBB (9/3,5/27) arround
the rods of the Chinese slingshot, the rods are covered with the rest of tubes
to protect the TBB and increase the diameter. With this setup I could drive in
the 13 mm steelball half way into the 12 mm plywood and dent out the other side,
but that was the maximum achievement.

So I reduced my target just to just pierce the %&&#& piece of wood.

A spend half year experimenting with lead from fisher sinkers and odd shapes,
but the lead was too soft, hexnuts, washers, no progress, I only 'earned' my first scar 
when a sinker RTS went over the index finger, it was like a electric shock, the area 
went thumb, spilled blood, I lost a lot of self confidence. That was the end of odd spapes.

Pausing a couple of weeks, I learned that Antimone hardens lead, got it from
burning a scooter battery, dangerouse and stupid, you guys teached me about 
wheel weights as a safe source, thanks again for the tip!

Hardened lead drove in the ball deeper, but not through. I reached a limit.

So, I needed to work on the efficiency stretching the rubber as I estimated
friction of touching rubber as source of energy losses.

So I came up with the idea to increase the diameter of the fork rod so
the 9 cm span would fitt perfectly around the rod. 
But that looked odd, clumsy, bulky and narrowed the fork distance at
point of ball trajectory, already a 'burned child', I wanted the forks not too
close.

Than it came like a flash: oval forks.

So I put all lessons learned together:
- Cones to prevent friction of the stretched band
- Fork tilt , as my ellbow started aching when the arm stretched and
the wrist tilted. Now it became much better, without pausing!
- ball dispenser tired of getting the balls out of my deep! pockets
- holder for a flashlight to find the balls in the dark corners of the attick

Some prototypes later I went upstairs, put the plywood board in position...
...and shredded it with pleasure. I shot and pierced everything I could find,
laminated & natural wood, steel cans, stainless steel serving plate, etc., etc

So, that's it. Here are some links if you want to try it out.
Use this slingshot with caution, respect, be a responsible and descent shooter,
never harm other people!

All the best from A-Ping

Show off shooting (https://www.sendspace.com/file/i1rjn9)

Remark: these numbers are the read out from ChronoConnect on my Android Tablet! 
The external micro is positioned direct over the newspaper impact area.
The read out numbers are may be not be the real physical values but they are 
consistent and correspond very good to the damage which I could
do with free fall experiments 'steel ball / disk magnet / hammer head / ledder'
Engergy = mass x gravity constant x hight

Result table (http://slingshotforum.com/topic/19722-speed-freaks-ssf-300-club/page-22)

Download for dominant right
http://www.thingiverse.com/thing:1589828

Download for dominant left
http://www.thingiverse.com/thing:1598585

Locator for a 3D printer hub in your proximity
https://www.3dhubs.com/

Google: Semi Tube Slingshot


----------



## inconvenience (Mar 21, 2016)

The science behind bands is something I'd like to understand more. You need a certain thickness to launch a given projectile but it seems thinner bands retract faster.

The fastest speeds Joergsprave was able to achieve with a decent weighted projectile were also with full strips of TB black.

But on the other hand I have seen Hayes break 415 fps with .33 cal lead using pseudo-taper tubes.

So really I don't get it at all.

Right now I am shooting .040 latex. It's very powerful. Only need a half inch to throw marbles and 3/8ths steel at decent speeds. But since I usually don't shoot heavier than that I wish I had ordered .030. I think it retracts faster. Even though I would need full inch ×3/4 tapers.

I put 1/2" steel through 3 glossy magazines and most of a fourth with doubled 1 1/4× 11/16 tbg. But my frame flexed from the pull. I wanted to see how far it would go into 1/2" plywood but only had some with water damage on hand so that doesn't count.

Anyway, this was a good story my friend. Thank you for sharing it.

Does anyone know how accurate the chrony app is?

Sent from my SAMSUNG-SM-G920A using Tapatalk


----------



## Genoa Slingshot (Oct 29, 2015)

@aiping
Congrats for the positive end of your journey and thanks for share your experience with us with this very detailed and intresting post.


----------



## aiping (May 31, 2016)

@inconvenience

About rubber science, the higher speed of thinner and tapered bands I
have my own explanation:

- as thin as fast=> the band consists of single molucular springs. These 
tiny springs are orientated randomly, but some of them are alligned
in stretch direction. These orientated springs are the most efficient,
the others pointed in worst case 90 degree to the stretch is dumb weight. Imagine, what is 'thin' for our eyes, but the elastic molecule
is some nanometer, a hair is for example about 100.000 nanometer.
So I think, the process to produce thin bands alignes more efficient molecules than dumb molecules as the process for thick bands. If you could manage to align ALL molecules into stretch direction by for example applying a magnetic or electric field, that would be a superband and probably very resistant to rupture.

- fast taper 
=> first, I think its all about direction of the force vectors, if
you focus the force vectors (taper) to one point you are most efficient, like a lense. A taper 1/0 is the perfect focus, but band life time...
=> second, taper cut off / eliminates the unefficient band area so reduces weight, which does not need to be accelerated

A-Ping


----------



## aiping (May 31, 2016)

Hi Genoa, thanks for your kind post!


----------



## inconvenience (Mar 21, 2016)

aiping said:


> @inconvenience
> 
> About rubber science, the higher speed of thinner and tapered bands I
> have my own explanation:
> ...


Good theory. I love the fact that slingshots are in effect powered by entropy. I guess everything is eventually.

But I find poetry in how directly it is exemplified in the need for the latex to go from an organized (stretched) state to a disorganized (relaxed) state.

I think the slingshot could be used to teach an entire year of physics.


----------



## aiping (May 31, 2016)

@inconvenience, thanks!

about

'...But I find poetry in how directly it is exemplified in the need for the latex to go from an organized (stretched) state to a disorganized (relaxed) state...'

you inspired me to this photo, in fact witout bands my slingshot can also be used as table decoration, statue of...? I will put it in ' Show off your homemades'


----------



## aiping (May 31, 2016)

Skulpture


----------



## aiping (May 31, 2016)

Another, thing

As I wanted to keep my previous report reasonably short, I did not went too deep into
'penetration'. For those who are interested, here we go:

First, if you want to shoot with high velocity and a weight of 3,5 to 7 grams, which I found
for me as a sweet spot, you must stick to balls, spheres due to security reasons.

Flechets may seem to be a good idea, as you can pack the mass behind a small
impact area. But as for maximum velocity full butterfly is the draw of choice, well,
I don't want to draw a flechet behind my neck....

Now, if you look the record of Tobse, he used 25 mm steel balls. Lets
compare diameter, effective impact area (simplified as a circle)
and energy per impact area:

Diameter 9.5 mm / 71 mm2 / 50 Joule? => 0.7 Joule/mm2
Diameter 25 mm / 491 mm2 / 108 Joule!! => 0.22 Joule/mm2

So if Tobse wants to catch up in (force/area) he must change to lead, gold, 
....or tungsten carbid.

That's it, in a nutshell. Have a nice day.

A-Ping


----------



## aiping (May 31, 2016)

Surprise! Tobse already did it! But no numbers, no center hit, think the bullet would have went straight through...cool






I think that's worth a new thread.

A-Ping


----------



## aiping (May 31, 2016)

For the one who are interested in more slingshot science, this link is great, if not already well known...

www.numericana.com/answer/slingshot.htm

A-Ping (the newbie)


----------

