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To be clear here, I'm going to pick up my first slingshot this afternoon. Meanwhile, I think I lost some vision reading and watching videos.

One thing that fascinates me are tapered bands. I use to uses coil springs on the design of some of my machines so fairly familiar with them. So.... "logically", I can see why and how tapered spring's work, but so far, I found no confirmation.

In my mind, from what I know about springs, two things are happening.

1....the narrower part stretches more then the wider part so it stores an equal amount of energy. In other words, if we hung a given weight (or pull), the band will have to stretch more where the band is narrower.

This would be easily proven by marking out the band in equal segments at rest and measuring the segments after stretching. The narrower segments should be longer.

I don't have a tapered band so can someone confirm my "theory"?

2....if the above is true, then the wider segments contract first because they have a higher tension rate, meaning they will return to their normal state faster, then followed down the line. This has the effect of giving the ball a higher and higher velocity as the spring, meaning band retracts faster......thus transferring more energy, thus more velocity.

Thinking it another way.....as the wider band retracts faster, the band right behind it is still trying to catch up because it has the weight of the ball it's trying to accelerate AND close to it's normal state (legnth) because it's stretched further. And so on behind it.

This is straight up "logic" theory and I haven't found any article with the "science" behind it.

Also if this is true, then someone smarter then me can do a mathematical formula that can predict the acceleration of the mass through the the variable tension rate of the spring (band).

So....

Do tapered bands stretch unevenly?

Are there articles out there with empirical testing on straight versus tapered bands?

Is the above "theory" already fact and I'm just another newbie that needs to shut up and learn more?

Or am I so far out into nutty land that I should chuck my theory into the trash heap and have another beer?
 

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I don't know the science behind tapered bands,but it is my belief that tapers retract faster than straight cuts because you are reducing the weight at the pouch end.
People have tried lots of things to reduce the weight of the pouch end such as lighter pouches, punching holes in the pouch end of straight cut bands and lighter tie materials.
 

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Ray Rowden
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I don't have the technical expertise to weigh in on your spring theory and its relevance to latex performance, but it sounds good.

I have done the experiment of marking off tapered bands at 1 inch increments, and can confirm that the narrow sections stretch more than the wider sections.

The calculations that have resonated most with me focus on the reduction in band mass at the pouch end. The result is less mass to accelerate and thus higher velocity.

Good stuff to ponder!
 

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Nothing scientific here, but my 'feel' is that they apply force longer and over a smoother power curve to transfer more energy ultimately to the ball. The snap of a straight band is noticably different than the steady, smooth action of a tapered band.
 

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Still waiting for the Amazon Gods to deliver!

This is going to be relativly easy to work on. I have a digital fish scale and an old fashion yard stick. I should be able to essily measure the draw against the legnth. That should tell me me the "power curve" from straight OR tapered.

A straight band should have a linear draw. If one pound of draw at X then two pounds at draw 2X, 3 pounds on draw 3X. If it has different draw at different legnths that are not linear, it should go to prove my theory.

.....

BTW.....springs like those used in your engine valves have a constant and measurable compression. They measure it in tenths of an inch. So IF the valve spring has 20lbs per 10th of an inch THEN it will have 80lbs at 4/10 of an inch. They also have measurable fatigue life. The numbers are astronomical but the more you compress them into their legnth, the shorter the life.

If anybody is interested, they can google it or i can find a link.

......

"Mass Reduction Theory" ....if the mass reduction theory is true then one can easily prove it. Measure the weight difference between the bands. Then file a steel ball to match the weight difference.

Fire a steel ball with full weight and one that is reduced by the weight of the lighter band in both a tapered band and a straight band.

IF the speed of the normal ball on the tapered band is equal to the speed of the lighter ball on straight band, the theory has weight....and possibly true.

Anybody have a very accurate scale and a chrony? Just make sure you use some type of T apparatus to have a constant, measured draw.

I have extremely accurate scales but no chrony.

.....

Soooo.....i have an engineering background...one theory or another, or both, or neither, I'm determined to find out. By mid summer, we will know.

Anybody have a chrono and in the Toronto area?
 

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Nothing scientific here, but my 'feel' is that they apply force longer and over a smoother power curve to transfer more energy ultimately to the ball. The snap of a straight band is noticably different than the steady, smooth action of a tapered band
Since the length is the same, then there HAS to be a different power curve.

Or is it because the band is lighter?

My theory.....the thinner sections are traveling further, in other words, they are longer and have to stay with the ball longer before they are fully contracted.

In rifles, we use longer barrels to increase bullet velocity. The charge is the same, but the longer barrel accelerates the bullet longer. Until the point where barrel friction offsets any more acceleration from the gas. Same "principal" but obviously not the same means.

Stay tuned.....
 

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Hi Spartan,

There are many additional variables in the system like:

  • air drag of the pouch and fins
  • latex dissipates heat, so cross section and surface changes on the elongated rubber also comes into play
  • tapered bands are tolerating draw fluctuations better, both ends are practically floating
  • various elastics --> various acceleration characteristics
  • self collision of elastics upon impact, it may be significant with non-flipped tubes
  • taper enables partial max elongation, this will reduce overall cut length, when cut length is shorter, that will result in a longer draw length too, that means additional acceleration path
  • time under tension --> longer hold, more cooling, less speed

Taper means not much if the ammo is NOT matching to the elastics and pouch.

In the book "man powered bullets" you may find experimental data. There are plenty of threads here on the forum as well. It is an interesting topic, but fairly complex compared to the fun of actual slingshot shooting.

Have fun,

Tremo
 

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I've referenced this experiment several times in the past but not lately. With enough digging I could probably find it. Unfortunately I can't remember the size of the ball or the actual velocity:

Several years ago I took a set of 1.0 inch straight bands and used a chronograph to measure the speed of the ball ( I can't remember the ball size or the actual velocities though it's somewhere in the slingshotforum stacks). I then disassembled the slingshot and, taking just one of the two one-inch bands, split it into two tapered pieces, each 3/8 x 5/8. I then reassembled the slingshot with the two tapered bands (remember that the slingshot now had 1/2 the rubber than it did before). I then shot the new arrangement and discovered the velocity was greater with half the rubber, tapered bands than it was with the two straight bands.

I'd like to see the formula for that.

winnie
 

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I found it:

More Speed with Half the Rubber

Posted 24 February 2016 - 09:17 PM

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On one of the hunting threads (Gunnar posted "Can't get away with body shots") I suggested that if he took his 1 inch straight cut band set and disassembled it and then took just one of the 1" strips, he could cut that single strip into two new bands that were tapered and that new band set (using 1/2 the rubber) would shoot faster than his 1" strips.

Out of curiosity I ran the experiment today. These are my results.

All shots were with 7/16 inch steel balls and the number represents the fastest shot from each group of 6. The tapered band set was cut from one of the strips from the 1" strip set after the 1" readings were taken:

1 x 13 inch straight cut band set: 184.9 feet per second

3/8 x 5/8 x 13 inch tapered set: 222.9 fps

Half the rubber with a 20% increase in speed and a much easier draw.

Latex is weird.

winnie
 

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Discussion Starter · #15 ·
Hi Spartan,

There are many additional variables in the system like:

  • air drag of the pouch and fins
  • latex dissipates heat, so cross section and surface changes on the elongated rubber also comes into play
  • tapered bands are tolerating draw fluctuations better, both ends are practically floating
  • various elastics --> various acceleration characteristics
  • self collision of elastics upon impact, it may be significant with non-flipped tubes
  • taper enables partial max elongation, this will reduce overall cut length, when cut length is shorter, that will result in a longer draw length too, that means additional acceleration path
  • time under tension --> longer hold, more cooling, less speed
Taper means not much if the ammo is NOT matching to the elastics and pouch.

In the book "man powered bullets" you may find experimental data. There are plenty of threads here on the forum as well. It is an interesting topic, but fairly complex compared to the fun of actual slingshot shooting.

Have fun,
Tremo
Agreed, it's a system. However, some of the varables are constant to both. The "heating" will happen to both and the differences in size "should be" almost negligble.

Maybe.

Meanwhile, i got my toy....so any cursing or screaming you hear, it's me....
 

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I found it:

More Speed with Half the Rubber

Posted 24 February 2016 - 09:17 PM

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On one of the hunting threads (Gunnar posted "Can't get away with body shots") I suggested that if he took his 1 inch straight cut band set and disassembled it and then took just one of the 1" strips, he could cut that single strip into two new bands that were tapered and that new band set (using 1/2 the rubber) would shoot faster than his 1" strips.

Out of curiosity I ran the experiment today. These are my results.

All shots were with 7/16 inch steel balls and the number represents the fastest shot from each group of 6. The tapered band set was cut from one of the strips from the 1" strip set after the 1" readings were taken:

1 x 13 inch straight cut band set: 184.9 feet per second
3/8 x 5/8 x 13 inch tapered set: 222.9 fps

Half the rubber with a 20% increase in speed and a much easier draw.

Latex is weird.

winnie
I'm a bit confused...but will reread it later and comment.

One of the big varaibles is draw weight/pull/force. What i know about springs is that they are a linear in that if you stretch them, or compress them, they sould be linear. Twice the stretch, twice the draw weight. If tapered and straight bands stretch the same legnth their draw weight should be different.

Changing the width changes the sprimoratnemee.

The The first thing i would look into are the....stretch...weight...chrono results.

All legnths equal...straight vs tapered...

Draw weight and chrono results for a straight band...a tapered band...a straight band with the average width of the tapered band.

Then repeat with different legnths.

That should give us 6 graphs based on emprical data...and some kind of conclusion....or more need for beer.
 

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It's the beer that is the real variable.

The reason I ran the test above was because I had experienced the phenomenon a number of times and wanted to see if I was correct in my assumption.

It is very possible that the draw length of the two systems were different but in both cases the bands were stretched to the point at which to stretch them further would have hurt the bands.

I was not surprised by the result. I have always understood it as a more uniform/continual force applied with a tapered band, yet it's just conjecture. To further complicate the issue, I would expect that using a larger tapered band 13 x 1 x 5/8 and the same 7/16 ball would clock slower than the 13 x 5/8 x 3/8. I may not be correct but I've built and clocked alot of bands through the years. Again, I have always understood it as a properly matched band/ammo combingation acting on the ammo longer as opposed to the quick snap of an over-powered band/ammo combination.

Again, latex is weird.
 

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Tapered bands are only faster than straight cuts if the same amount of latex is used...so you can't take a set of 1' straights and taper them to 1"-3/4" and expect them.to be faster...it doesnt worl thay way....they will actually be slower. You need to add whatever you remove from the pouch end to the fork end...so if you cut a set of 1-1/4"-3/4" tapers they will be faster than the 1" straights while using same amount of latex..

The draw will also be much lighter with tapers, and they will retract faster compared to straighyd...which translates to faster speeds and more FPE... .but there is a trade off because they will also fail sooner...the one benefit to this is that when tapered bands fail, its usually at the pouch end, so theres less chance of facial injury...

Also, i believe tapered bands are only really effective with light ammo. Heavy ammo doesnt seem to benefit as much from the taper. What little positive effect you do get is unnoticeable and isnt worth the band life trade-off. Thats just my opinion...i don't have chrony numbers to back this...

I use straights for target practice and hunting with heavy ammo such as 1/2" steel and .44 lead....and tapers for hunting with lighter ammo such as 3/8" steel and .36 or .38 lead

Hope this made sense...lol...

MW

Sent from my LG-M470 using Tapatalk
 

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Tapered bands are only faster than straight cuts if the same amount of latex is used...so you can't take a set of 1' straights and taper them to 1"-3/4" and expect them.to be faster...it doesnt worl thay way....they will actually be slower. You need to add whatever you remove from the pouch end to the fork end...so if you cut a set of 1-1/4"-3/4" tapers they will be faster than the 1" straights while using same amount of latex..

The draw will also be much lighter with tapers, and they will retract faster compared to straighyd...which translates to faster speeds and more FPE... .but there is a trade off because they will also fail sooner...the one benefit to this is that when tapered bands fail, its usually at the pouch end, so theres less chance of facial injury...

Also, i believe tapered bands are only really effective with light ammo. Heavy ammo doesnt seem to benefit as much from the taper. What little positive effect you do get is unnoticeable and isnt worth the band life trade-off. Thats just my opinion...i don't have chrony numbers to back this...

I use straights for target practice and hunting with heavy ammo such as 1/2" steel and .44 lead....and tapers for hunting with lighter ammo such as 3/8" steel and .36 or .38 lead

Hope this made sense...lol...

MW

Sent from my LG-M470 using Tapatalk
Actually, this is not true. Re-check what I wrote above. A 7/16 in steel ball shot with 1 inch straight bands 13 inches long went 184.9 fps. The bands were removed and then one of the two bands was discarded. The other band was cut into two pieces, each 13 inches long but now narrower and tapered to 5/8 x 3/8. Exactly 1/2 as much rubber. The tapered band set made from half of the original 1 inch straight band set shot the same 7/16 steel ball approximately 20% faster at 222.9 fps.

I'm the first to admit that it doesn't make sense, but that's the way it is. Obviously something else is going on here.
 

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You see this affect often with new shooters. They often will figure that if a single set of bands will shoot x fast then shooting double bands will shoot faster. Often the opposite happens. Doubling the bands will often result in a slower velocity.

I can't stress enough that higher velocities are the result of properly "balanced" band/ammo setups - which often means dialing back on the amount of latex - not increasing the band strength or weight of latex.
 
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