# Physics and Forks



## MikeyLikesIt (Oct 19, 2018)

I wasn't sure if this question should go in the Newbie section or General, but here goes.

I was wondering what difference, if any, fork width plays in velocity. For example, say we have a SS with a 2.5" fork gap, set it up with bands, draw back to 30" and release. We can measure the velocity of the projectile, and say it went X fps

Now what if we take the exact same setup, same bands and ammo, etc, and mount it on an identical SS frame with a 3.5" fork gap. We draw back to 30" and release, and measure the velocity at Y fps. Would the velocity of Y exceed the velocity of the first SS, X?

I feel like it would, simply because the bands are being stretched a greater distance. But they are being stretched out laterally, as opposed to parallel to our ammo and target. What do you guys think? Or is there a thread that covers this? I passed high school physics by the grace of God and the generosity of my teacher. Anytime I start thinking about these concepts in regards to archery or gun ammunition my head starts to get all fuzzy, and SS are no different. Usually when these terrible questions sneak into the recesses of my psyche, I start chucking marbles downrange and take primitive solace in the fact that "Rubber band sproings, marble go fast, can rattles." However, this question has been sticking with me for a while, so I thought I'd try and educate myself for a change.

On a side note, if the wider forks do indeed increase velocity, why don't we seem them more often on SS designs? Is it because the difference in performance is negligible? Or perhaps it's all about aesthetics or cost of materials. I'd be interested to know your thoughts.


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## treefork (Feb 1, 2010)

Here is some previous discussion on the topic :

https://slingshotforum.com/topic/21898-fork-width-and-speed-two-different-test-results/

https://slingshotforum.com/topic/26095-fork-width-power-differences-exactly-as-i-said-proven-using-an-oversived-adjustable-slingrifle/


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## Bob E (Mar 23, 2015)

I haven't encountered anything that makes me think there is enough difference to matter.

Most aimers want a fork width that coincides with a preferred anchor point and point of aim with a given ammo weight, band strength, and shooting distance. The instinctive shooters are usually more interested in something that aids their natural pointing ability. And I think almost everybody wants something that will fit in their hand and pocket.


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## MikeyLikesIt (Oct 19, 2018)

Thanks guys. Treefork, those links you posted were great, and really got into some of the math that's been bouncing around in my head. And Bob, that was my suspicion. I figured if there was a big performance boost we'd all be walking around with 12" forks.


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## Ibojoe (Mar 13, 2016)

Cool pooch


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## Tag (Jun 11, 2014)

I agree with Ibojoe, cool pooch


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## MikeyLikesIt (Oct 19, 2018)

Thanks guys! She's a 12 y/o papillon. Started dating my wife and got the dog in the deal! That's a win win! She's not built for trails, so I threw her in the bag for most of the hike.


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## urbanshooter (Aug 23, 2017)

The math of fork widths bothered me only very briefly. While it is interesting to know, I think it makes little practical difference to everyday shooting. What matters more to me is a fork width that is comfortable, balanced and doesn't mess too much with the elevation I am used to, especially when shooting TTF. The little bit more of power if desired can be easily achieved with bandset tweaks. This makes the metric of fork width for power quite insignificant IMHO. I would rather have a set of forks that is comfy in hand which I can be accurate with. Some forks are just more naturally aligned (may vary for individual depending on style and grip) and require less effort to shoot. I'd rather have that. YMMV.


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## skropi (Mar 22, 2018)

@urbanshooter
I totally agree. The difference in fps is very minor anyway. Oh and when you find a frame that you shoot more accurately than any other, don't do what I did.....and trade it ????


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## Bill Hays (Aug 9, 2010)

The very point of all the testing was because we had some members who insisted that narrow fork widths were inherently much faster than forks of a standard width... in fact it was said, up to 30% faster

What we found out through simple testing was, not only is there not enough difference between a narrow and standard fork to make a difference in real life shooting.... wider forks are actually a little faster due to the added draw length.

The testing proved, use whatever slingshot you feel works best for you... there will be no big benefit going to a PFS, just as you will get only a slight bump in FPS going wider.

Shoot and use what works best for you and your wants and needs.

IF you feel like you shoot a wide forked slingshot with greater precision and less possibility of fork interference... then going to a PFS and learning a different style of shooting to simply accommodate extremely narrow forks so you can gain power... is not necessary because it won't happen.

Of course the reverse is true too... if you happen to like shooting a PFS, then you will not all the sudden gain a huge power boost by going wider... only a few FPS extra is all you'll get.


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## MikeyLikesIt (Oct 19, 2018)

Ah, gotcha. I did get a chance to watch your video with the slingshot bow with different forks widths. Very cool, and it definitely helped demonstrate the physics in a simpler manner. I'm not to concerned with speed right now, but I've been trying to make a couple frames with some spare lumber and it's gotten me thinking about different designs, which led me down the rabbit hole of fork widths.


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## Randroid (Sep 26, 2018)

Wide fork, narrow fork,velocity is irrelevant if you don't hit the target. Interesting discussion, however.


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## ForkLess (Aug 15, 2018)

I am not sure, I have a crony and all I know is my forkless sling you see in my photo shoots at 30 foot pounds. I have herd wide gaps give more fps and also heard the same about forkless gaps. My tiny turtles are also forkless and they have a lot of power and speed. I am going to have to dig deeper into this subject. Still faster then any wristrocket.


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## Randroid (Sep 26, 2018)

ForkLess said:


> I am not sure, I have a crony and all I know is my forkless sling you see in my photo shoots at 30 foot pounds. I have herd wide gaps give more fps and also heard the same about forkless gaps. My tiny turtles are also forkless and they have a lot of power and speed. I am going to have to dig deeper into this subject. Still faster then any wristrocket.


How did you determine 30 ft lbs of energy ?


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