# Increased projectile velocity



## Chevas (Oct 29, 2012)

Hi everyone,

I am in the process of making a shooter, the design is new and currently a mold is being made. I'm psyched. My question is whether projectile speed is increased if the forks push the bands foreward at release. In other words, the device will compress into the hand with a spring system at the palm. As energy is used to pull, springs are compressed, upon release of the pouch the device unloads the compressed energy, forks "jolting" foreward about 3/4 inch. I have shout the device without springs, it's already very fast. I tapered 1 1/2 to 1 on Gold Theraband with silver theraband on top. It's a good combination I haven't heard much about. With a logarithmic increase in energy with elastics, I'm wonder if the jolt foreward would have an impact, whether it's a lot of time spent where I just need to pull back the band 3/4 inch further, or the jolt at the beginning of an Expotential system could make a real difference. Appreciate any input, Thanks, Chevas


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## Tentacle Toast (Jan 17, 2013)

Sounds good in theory, but I'm no physicist. I'd wonder though if as the springs wore, however, if they might not "buffer" the recoil of the bands. I'm assuming they'd need to be significantly stronger to maintain that effect, but again, I don't know, & I just had a half-bottle of a Hobbs cabernet with dinner, so I'm not even sure if this post made a lick of sense. Godspeed either way, friend. I'm looking forward to seeing what you end up with there...


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## Chevas (Oct 29, 2012)

Thank you for the input, the spring effect must be subtle lest it be difficult to handle. I would like to convert the energy from holding device into kinetic energy. Your post makes perfect sense, I think I'll pour a glass myself, Cheers, Chevas.


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## Viper010 (Apr 21, 2012)

'flipping' the frame forward upon release increases shot energy & projectile velocity. your proposed idea does the same, but mechanicly instead of by a flick of the wrist.

your idea sounds great to me, very curious to see what you came up with.
only way to tell if it really works is by testing on a shot chrony.

good luck, please keep us posted.
cheers, remco


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## Arturito (Jan 10, 2013)

mmm ... I am old fashioned, I would not like to have a spring between my hand and the fork, even more I hold the frame "lazy" grip, the best I know to add power is flipping and butterfly without loading too much the draw to not lose accuracy ...

Cheers

Arturo


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## Henry the Hermit (Jun 2, 2010)

I consider it an unnecessary complication with little, if any, benefit. It will probably decrease accuracy, because of the extra moving parts. There is already a commercial model from China using the same idea. It's discussed somewhere on the Forum, but I don't remember where.


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## Hrawk (Oct 25, 2010)

While there have been many attempts in the past to do this, from the rather basic to the extremely over complex, I am yet to see any figures to justify the extra complication.

Personally, I'd rather put those extra few pounds of pull into some extra rubber as it has a much quicker contraction rate than most springs.


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## Charles (Aug 26, 2010)

My intuitions are with Henry ... I doubt that springs will add much if anything. In order for the springs to compress, there must be enough tension on the bands to compress the springs ... so why not just add 3/4 inch of band length? I also wonder about the relative response time of the springs, vs the rubber. Will the corresponding spring decompress as fast as the rubber will? If not, then there will be no gain. The thing about the "quick flip" is that you are using your wrist to put out more power at the crucial instant than the bands are capable of putting out. But if the springs are more powerful than the bands, then the tension on the bands will not compress the springs.

By analogy, think of having a forward fork on a hinge, so it can only fold forward. Band the fork up as usual. Instead of using a spring to fold the fork, just use a strip of rubber. Again, if the shooting band tension is not greater than the folding band tension, the forks will just stay in the forward position. So the shooting band tension must be made greater than the folding band tension. Now, where is the gain over just having a little extra shooting band length?

And all in all, how much extra speed do you think you will achieve? We already know how to get very high speeds out of rubber bands ... and how to get high power. If the increase in speed is only a few fps, then it just does not seem to be worth the bother.

During WWII, the OSS experimented with a spring driven pistol as a "silent" weapon. As I recall they required 600fps in order to penetrate clothing and flesh. They had great difficulty get anything to work. In the end, they developed a coil spring that was hollow inside. But it required a big crank to cock it for each shot. The project was abandoned. Springs just were not well suited to the rapid movement of projectiles, unless one is using the stored energy in a spring to compress air, as in an air rifle.

It is possible to get a significantly higher rate of speed by eliminating the slack length of the bands ... effectively increasing your draw length. That is the arrangement on the ComBow Sling. By having the bands double back through pulleys at the fork tips, you get zero slack band length. Adding an extra 6 or 7 or 8 inches to your draw length gives you a really significant increase in speed.

Now, having said all this ... my opinions are just idle speculation. The only real test is experimentation. By all means, if you have the wherewithal to do it, I would love to see the results of your experiment. Do not let my musing dampen your enthusiasm.

Cheers ..... Charles


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## Charles (Aug 26, 2010)

Hrawk, I was typing while you were posting! Those are pretty bizarre set-ups! What a great collection those would make!

Cheers ..... Charles


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## All Buns Glazing (Apr 22, 2012)

Thanks Dan, I was looking for those pics!

And like most people, I don't see the benefit from springs and I'm dubious as to their benefit. I think some things are perfect to begin with, and don't need mechanical assistance.

I suspect the starship shooters are most likely the best modification of a slingshot type that increases velocity of a shot.


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## Tentacle Toast (Jan 17, 2013)

I think it's all good. Looking at those pics of hrawk's reminds me of some of those old photos of flight contraptions prior to the Wright brothers...not really practical, but one has to admire the "hope" built into them. But then again, I'm a sucker for oddities. Personally, I'd think if one were to go the spring route, one would be better than multiples, due to differences in ware from one to the other(s). I think they're neato regardless, & would probably waste my money on them knowing full well they'd leaveme shy of sustained satisfaction.


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## Tentacle Toast (Jan 17, 2013)

...they've almost got a fantasy steam-punkish feel about them, unnecessary, but fun. I agree with most of these guys that it wouldn't be "needed", but hey, have fun


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## Charles (Aug 26, 2010)

Tentacle Toast said:


> I think it's all good. Looking at those pics of hrawk's reminds me of some of those old photos of flight contraptions prior to the Wright brothers...not really practical, but one has to admire the "hope" built into them. But then again, I'm a sucker for oddities. Personally, I'd think if one were to go the spring route, one would be better than multiples, due to differences in ware from one to the other(s). I think they're neato regardless, & would probably waste my money on them knowing full well they'd leaveme shy of sustained satisfaction.


But they have a certain "steam punk" allure ... very hard to resist!

Cheers ...... Charles


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## ZorroSlinger (Dec 12, 2012)

Holy S---! Those pics of those mechanical spring assisted slingshots are amazing . I dig mechanical things & designs but I sure can't fit those slingshots in my back pocket . I wonder if fork tab attachments at forks help increase speed or the flipping effect. For me, trying out tabs does seem to flip the bands more & I don't get as much hand slaps but not sure about speed increase. I'm definitely not experienced enough compared to others more expert at this forum. Jorg Sprave is 'The Man' to check-out about all varieties of slingshot designs, mechanical types, experimental, to wild & crazy. I don't think he posts here anymore. He's a big time celebrity now, ya know!


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## All Buns Glazing (Apr 22, 2012)

haha, fair point, Tenticle!


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## Hrawk (Oct 25, 2010)

Well the bottom one is only $425, have fun.

http://www.ebay.com.au/itm/ToKing-Powerful-Slingshot-Accelerate-Spring-Actuator-Hunting-Wrist-Catapult-/130700305529#ht_3488wt_1064


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## Chevas (Oct 29, 2012)

Thank you for the great info. The pictures are great. One my mold is made and I make a few of my protype it's easy to experiment. My design already has the bands about 8 inches further in front than standard, it's almost like a pistol, just going into seperate forks and filling the hand. I will experiment but I believe the consensus is that the energy to make it more machanical will likely not result in adequate foreward thrust to justify, with just enough philosophic wiggle room to not bash hope. well done, I hope to have some pictures posted soon, I want the presented piece to be perfect.

Thank you for the time gentlemen, I'll do some testing and see how she does, Chevas.


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## Hrawk (Oct 25, 2010)

Chevas said:


> Thank you for the great info. The pictures are great. One my mold is made and I make a few of my protype it's easy to experiment. My design already has the bands about 8 inches further in front than standard, it's almost like a pistol, just going into seperate forks and filling the hand. I will experiment but I believe the consensus is that the energy to make it more machanical will likely not result in adequate foreward thrust to justify, with just enough philosophic wiggle room to not bash hope. well done, I hope to have some pictures posted soon, I want the presented piece to be perfect.
> 
> Thank you for the time gentlemen, I'll do some testing and see how she does, Chevas.


Awesome man. I'd love to see the results of some solid testing with this concept.

Keeping my fingers crossed for ya!


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## Chevas (Oct 29, 2012)

Thanks Hrawk, 
I wanna make the fastest slingshot without a metal wrist brace. Why I do not know.


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## Hrawk (Oct 25, 2010)

Chevas said:


> Thanks Hrawk,
> I wanna make the fastest slingshot without a metal wrist brace. Why I do not know.


Because you can, THAT'S WHY!


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## Viper010 (Apr 21, 2012)

Hrawk said:


> Chevas said:
> 
> 
> > Thanks Hrawk,
> ...


best reason there is! keep us posted plz, n good luck!


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## Chevas (Oct 29, 2012)

Yes, I think I can. The design looks good, I'll have to work the devices a bit when they return from the mold, but when complete; It will be something new. I think I'll put a small bottle opener on the side of the handle. That would be cool. Thanks for your advise may man, in 2 weeks I should be able to post a picture, without the mechanical apparatus.


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## Chevas (Oct 29, 2012)

Thanks Viper


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## Viper010 (Apr 21, 2012)

cool! bottle opener is a great idea too, sippin a brewski or two n shooting a slingshot goes hand in hand for many of us! i cant wait to see what you came up with.

cheers, remco


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## Chevas (Oct 29, 2012)

Thanks Remco, when I get back the mould I'm gonna paint one and post it without all the gadgetry. My "propulsion" mechanism is subtle, not like the previous pictures but I will post one prior to the propulsion mechanism. Thanks again Remco.


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