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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here! |
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10-15-2019, 12:46 PM | #16 |
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Re: Slingshot Weapon with pulleys
I downloaded their catalog which was easier than going through the website menus. The "Sea Slinger" reminds me of Jack Prodanovich's underwater bow seen being held by Terry Mass. (video frame from the Bottom Scratchers' 70th).
Apparently it was later manufactured as the Leach "Pro Sling" speargun. Here is the Sea Slinger with a capture. Last edited by popgun pete; 10-19-2019 at 05:30 PM. |
10-17-2019, 02:30 AM | #17 |
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Re: Slingshot Weapon with pulleys
Good observation but withouth even reading the description of the Sea Slinger I could foresee a few issues with Prodanovichs gun... In that design, the bands not only contract, they also need to travel sideways through the water (lot of drag) which reduces a lot the power applied to the shaft.
Seems like the Sea Slinger, with the help of those rollers, aligns the stretched bands with the shaft (pretty much inline) so most of the energy of the band contraction is applied to the shaft. Cool gadget, I guess is the way to go for those places where any underwater gadget with a trigger is now allowed.... Mikel |
10-17-2019, 08:18 AM | #18 | |
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Re: Slingshot Weapon with pulleys
Quote:
Last edited by popgun pete; 10-17-2019 at 11:42 PM. Reason: added Sea Archer photo |
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10-18-2019, 04:18 PM | #19 |
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Re: Slingshot Weapon with pulleys
Pete,
The Barnett fish bazooka is the same concept as the Scope Arrow which is intended to be shot into the water from the shore. A few years ago I had the opportunity to snag one off Craigslist while visiting LA from Hawaii. It was $40 and I should have grabbed it. Oh well. There is also the gun caster also shot from the shore, but shoots bait, arrows, darts, and harpoons: http://www.retiredlures.com/2011-lotm-may.html I have considered creating a roller sling similar to a sling I've already made. A roller head would slip over the end of the barrel. The bands would be secured at the back of the sling to a plate, reverse of where they attach now. |
10-18-2019, 05:58 PM | #20 |
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Re: Slingshot Weapon with pulleys
Looks like the Bandito guy has a "Sea Archer" and may have got the tooling that made them, as Aquacraft made the alloy tube spearguns that he now makes and the "Sea Archer" as well. Lionel Long developed those guns and the variation sold as a Sportsways gun, in fact Terry Maas used the Sportsways mech in his Bluewater gun.
https://www.facebook.com/BanditoSpea...type=1&theater |
10-18-2019, 07:27 PM | #21 |
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Re: Slingshot Weapon with pulleys
The key to the "Sea Archer" is the raised fence on the pulley that the band wraps against as the pulley rotates as that changes how the band pulls on the pulley in terms of offset and alignment to the pulley axis. In the flat section of the fence the band pulls much closer in to the pulley axis and that lowers the torque being applied, but as the pulley rotates the band leans on the fence at full diameter and the torque goes up. The thin cable that drives the spear tail is running at a constant diameter in a groove on the periphery of the pulley, so at full draw you have the mechanical advantage over the band and can hold it as the torque is lower due to the band running close to the pulley axis. On the bottom there is another pulley that takes care of the band on the other side by wrapping on a mirror image fence on the bottom face of the lower pulley and it also has a peripheral groove for the other end of the drive cable. As spearfishing markets are more segmented now the “Sea Archer” would find a place in locations where spearguns are no longer allowed.
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10-19-2019, 05:36 PM | #22 |
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Re: Slingshot Weapon with pulleys
Seems that Bandito Spearguns still has the pulley drive "Sea Archer" in stock and I have ordered one. You need to supply your own spear, I intend to chop the tail off one of my spare shafts of which I have many in all sizes.
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10-25-2019, 09:37 PM | #23 |
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Re: Slingshot Weapon with pulleys
Part of the slingshot gadget arrived the other day, the item is sent in two separate boxes as ostensibly the final product is too heavy, hence only one box arrived so far with assorted parts and zero instructions. Inside were painted metal and black plastic parts that seem rather toy-like, although not flimsy. You get a fishing reel as well of the closed face type that seems the cheapest item possible, I have seen one before on another Chinese fishing gadget that shot straight off the reel. Fishing line on the reel is of very light gauge, so must be for shooting tiddlers (maybe not too many big fish left in China, plus concerns about pollution affecting the safety of the meat in larger local specimens).
This device also shoots ball bearings, but beats me what that would be good for. Hitting a bird on the wing with a ball bearing would be a complete lottery. May be for shooting beer cans off a fence if you have nothing better to do. Darts/arrows are supplied, but have yet to see them. Last edited by popgun pete; 10-25-2019 at 10:01 PM. |
11-01-2019, 04:37 PM | #24 |
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Re: Slingshot Weapon with pulleys
Another cardboard box arrived today with a longer length of barrel and a whole bunch of fasteners and the red rubber bands (which look like shoelaces), but zero instructions for putting it all together. Some fasteners had come loose from their glad wrapped package and fell out as I pulled the black painted barrel out of the box and rolled off in all directions on the kitchen floor. As such things go some will have disappeared under the fridge et al and I will have to search them out. Seems a lot of gun for not much “engine” and no sign of any darts or arrows.
Update: found the various screws and nuts that hit the floor, but looks like the trigger is missing as have the sear lever, but nothing like the trigger in sight. Photo from the adverts shows what it looks like, a speargun trigger mech of the forward rocking yoke type. Last edited by popgun pete; 11-02-2019 at 04:24 AM. |
11-10-2019, 07:41 PM | #25 |
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Re: Slingshot Weapon with pulleys
Here are some photos of all the parts laid out. Still need the trigger, but I think everything else is there. Note that no projectiles come with this package, they have to be ordered separately, something that I missed out on noticing when I placed the order.
No instructions, but the seller sent some photos which are also on the webpage advertising the slingshot. Now I have to figure out which nuts and bolts go where. To make some semblance of order I screwed the nuts on whatever screw or bolt that they fitted. |
11-18-2019, 09:07 PM | #26 |
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Re: Slingshot Weapon with pulleys
Still waiting for the missing trigger piece, but it is now obvious that this is really a ball bearing shooter. Ball bearings are loaded in the long upper slot of the barrel which serves as a sprung loaded horizontal magazine holding a lot of steel balls. The band anchor arms are attracted to a magnet, so they must be glossy black painted steel, while the other metal parts being not attracted must be painted alloy, including the barrel slide and main barrel extrusions. The barrel slide carries the sets of pulleys front and rear which are mounted on identical sets of horizontally deployed arms, the front set of “stacked” rollers being used to fold the quad band travel and shorten the gun while the rear rollers guide the cable which is the counterpart of a wishbone. The band anchors are also mounted on the barrel slide.
I don’t see much here applicable to spearguns as with such low mass projectiles (ball bearings) the gun does not have be overly powerful compared with a speargun, however for what it shoots it is quite powerful. I have yet to see the projectiles that are attached to the reel via a shooting line, but that seems to more of an afterthought given that built-in ball bearing magazine feature on all these guns. There is even another version with a wider barrel that has two ball bearing magazines side by side! https://www.ebay.com.au/itm/Neptune-....c100005.m1851 Also this model has now been superseded by another version with a more military looking folding stock. https://www.ebay.com.au/itm/Newest-v....c100012.m1985 Their real name seems to be "Neptune" with different models denoted by a number series, the gun I purchased being a "Neptune 8". The double row magazine gun is a "Neptune 12". The dragon's head version with gold painted arms that hold the pulleys is the "Neptune 16". https://www.ebay.com.au/itm/New-Nept....c100005.m1851 Last edited by popgun pete; 11-19-2019 at 12:32 AM. |
11-18-2019, 09:36 PM | #27 |
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Re: Slingshot Weapon with pulleys
This photo shows the gun cocked to shoot, note the run of the cable. The stroke of the cable or drive length is very short compared with the length of the gun. As a shaft shooting gun that short power stroke would make it hopeless as any form of speargun, something that I should have realized just by looking at it from the start, but like many I was distracted by its cool and seemingly complicated looks.
Last edited by popgun pete; 11-18-2019 at 11:41 PM. Reason: added propulsion length photo |
11-19-2019, 09:22 AM | #28 | |
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Re: Slingshot Weapon with pulleys
Quote:
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11-19-2019, 11:54 PM | #29 |
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Re: Slingshot Weapon with pulleys
Energy imparted to a projectile is directly related to the work done in loading the weapon and that is the force applied over the draw distance, the force increasing until the weapon is latched. That is why you see those triangle sitting on a rectangle graphs which show the energy as the area located under the graph. For a very low mass projectile, such as a ball bearing, that draw length is more than enough, the balance of the barrel being a long guide tube for the ball to fly along before it exits the muzzle.
For spears or arrows you need more energy and although there is no rule I think the draw should be 2/3rds of the projectile length at least. As the spear tip has to protrude you cannot get 100% drive of the shaft length. Some experimenters have tried launching spears much shorter than the barrel so that the spear is driven much more than 100% percent. The spear on one test drove forwards from the gun and then elevated from the shaft guide track like the space ship in the “When Worlds Collide” movie and cleared the surface of the water as watchers around the pool immediately dived for cover as like a submarine launched missile the shaft, no longer subjected to hydrodynamic drag, flew the length of the building and crashed into a wall. Such tests were soon terminated! |
11-20-2019, 09:14 PM | #30 |
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Re: Slingshot Weapon with pulleys
A look through the wide range of these "Neptune" slingshots shows that most are subtle variations on the same theme with the rear pulley set defining how far forwards the wishbone cable can travel. As they are situated a relatively long way back from the front pulleys that travel on the same moving barrel slide then the cable stroke is short compared with the overall length of the barrel. However one defining limitation is the band anchors are inboard of the cable and they will stop the cable even if there were no rear pulleys! To obtain a long wishbone draw the band anchors need to be placed outboard of the cable which would then allow long arrows to be shot with more than just a short flick from most of these existing designs.
It appears there is a model with outboard anchors, it is number 11 (enhanced version), but the power arrangement is kind of mind boggling and one wonders why flexing bow limbs have now been incorporated. To add embellishments you can get a reel and a led torch, but no travelling led line display with stroboscopic action and sound effects, yet! Last edited by popgun pete; 11-21-2019 at 05:54 PM. |
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