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Old 02-16-2019, 12:56 AM   #31
spearq8
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by mclane234 View Post
Dont mean to be rude, but is there a topic, or post where the term terminal velocity is explained in detail? Lot of people like to mention this term, and i am yet to see some proper data to show what that velocity is. My understanding of some of the things you said is a bit different.

I think I might have been the first one to use the term "Terminal Velocity" for spear shafts. It was after I was in the pool trying to squeeze more power out of a setup with a certain shaft. I realized that adding more band power simply did not increase penetration on target and you reached a situation where you just couldn't squeeze out any more shaft velocity unless I used a heavier shaft that was able to absorb more energy. This reminded me a lot of sky diving where you accelerate, but then the air resistance reaches a point where you it will stop any further acceleration … thus the term Terminal Velocity. This got me to realize that for the best setup, there were other factors that would give me more power or more retained velocity for a certain setup … and it was not by adding more band power. I found that rather than adding bands, you could gain more power by designing the gun so that it would throw the shaft out super stable. This caused less water drag and thus more retained velocity downrange. This could be done by using small ID bands and designing the handle so that it would it would reduce vertical muzzle lift and linear side shift when the gun was fired. The addition of a trigger with a back roller rather than a shaft sear notch also helped in keeping the shaft super stable. All this added quite a bit performance wise and what was even better was that you got a side benefit of incredible accuracy to boot as well. Even with only 3 x 14.5mm bands, you were able to throw out a heavy 8.5mm shaft at very high velocity that could easily outperform the older tuna guns that used 6 and sometimes even 8 bands. You can see some of the videos on the theory I used for all this in these 3 videos. Here is the first part and you just follow the links for the other 2 parts.

https://www.youtube.com/watch?v=9Hz-4mgnvYM
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Old 02-16-2019, 06:08 PM   #32
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Re: Rollergun Recoil and the Jerk (not the owner!)

You have written about this on other threads and I have refrained from commenting, but now you put it up here I am obliged to say something. Your observations are obviously correct, but your analysis is wrong. A shaft can be blasted out of a gun at much higher velocity than you are obtaining, so the terminal velocity concept is wrong. There is no “terminal velocity” per se, what there is instead is a limit to unsupported shaft acceleration for a shaft that for its length and diameter would usually buckle as the shaft column cannot withstand the rapid loading on its tail and transit that force through to the shaft tip while pushing water out of the way. Accelerate the shaft at a slower rate, but for longer and you will build up shaft speed to higher levels, which requires a longer gun or band drive stroke.

In pneumatic guns and band guns the maximum propulsive force is applied as the drive starts and then falls away as the bands contract and the pressure in a pneumatic gun falls. Pneumatic guns have an advantage as the bending shaft is supported by the tubular barrel wall and the water in the barrel creates a squeeze film wherever the shaft touches as it skates along inside the inner barrel. For strong armed guys there have been 150 cm pneumatic guns and from memory maybe 160 cm that can give the shaft a long acceleration phase. The problem with enclosed track band guns, which you would expect to be similar, is that the bending shaft drags on the enclosed track adding to friction because the track slot for the shaft tabs prevents a squeeze film generating and actually creates a shaft gripper, although not much of a one it all adds a bit more to drag. Consequently the more band power you need on an enclosed track gun, but you get to shoot thinner spears.

The super grunt hydropneumatic guns have fully supported spears as the clearance between shaft and barrel bore is about 0.5 mm and barely enough to have a decent stop diameter on the shaft tail and that is why they tend to demolish their line slides when on the way out of the gun the line slide is instantly accelerated to 45 meters per second as it is collected by the tail stop. This can be ameliorated by the advancing annular "tube" of water blowing the line slide forwards on the shaft, however often the shooting line is holding it in place against the muzzle nose.

Last edited by popgun pete; 02-18-2019 at 07:38 PM. Reason: typo, shaft not shift
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Old 02-19-2019, 05:36 PM   #33
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Re: Rollergun Recoil and the Jerk (not the owner!)

As all but a handful reading this thread read the Alcedo "Hydra Sprint 62" attachment (about 10 views!) I now add it here. This should put the skids under the concept of shaft "terminal velocity" as once a shaft flies from a gun what ejected it is irrelevant, it is basically a long piece of pointed metal dragging in its wake a shooting line to a victim.

The improvements made on the former model, that never the less keeps being quite handy and functional, are:
- 30% more power, loading effort being the same
- Higher loading speed
- Possibility to adjust the supply of compressed air to a maximum storage at 40 atmospheres.

The gun meets the following specification:
- Adjustable power
- Least effort and highest yield
- Output power

70 atmospheres for the normal model
100 atmospheres for the gun with compressor

Actual straight firing distance underwater ranging from 1 to 15 meters. Initial power and speed at least three times as great as those of the most powerful hand loaded gun, at least equal to those of powder guns.

https://forums.deeperblue.com/thread...tic-gun.96940/

Last edited by popgun pete; 02-20-2019 at 06:19 PM. Reason: added a photo
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Old 02-20-2019, 01:51 AM   #34
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by popgun pete View Post
You have written about this on other threads and I have refrained from commenting, but now you put it up here I am obliged to say something. Your observations are obviously correct, but your analysis is wrong. A shaft can be blasted out of a gun at much higher velocity than you are obtaining, so the terminal velocity concept is wrong. There is no “terminal velocity” per se, what there is instead is a limit to unsupported shaft acceleration for a shaft that for its length and diameter would usually buckle as the shaft column cannot withstand the rapid loading on its tail and transit that force through to the shaft tip while pushing water out of the way. Accelerate the shaft at a slower rate, but for longer and you will build up shaft speed to higher levels, which requires a longer gun or band drive stroke.

In pneumatic guns and band guns the maximum propulsive force is applied as the drive starts and then falls away as the bands contract and the pressure in a pneumatic gun falls. Pneumatic guns have an advantage as the bending shaft is supported by the tubular barrel wall and the water in the barrel creates a squeeze film wherever the shaft touches as it skates along inside the inner barrel. For strong armed guys there have been 150 cm pneumatic guns and from memory maybe 160 cm that can give the shaft a long acceleration phase. The problem with enclosed track band guns, which you would expect to be similar, is that the bending shaft drags on the enclosed track adding to friction because the track slot for the shaft tabs prevents a squeeze film generating and actually creates a shaft gripper, although not much of a one it all adds a bit more to drag. Consequently the more band power you need on an enclosed track gun, but you get to shoot thinner spears.

The super grunt hydropneumatic guns have fully supported spears as the clearance between shaft and barrel bore is about 0.5 mm and barely enough to have a decent stop diameter on the shaft tail and that is why they tend to demolish their line slides when on the way out of the gun the line slide is instantly accelerated to 45 meters per second as it is collected by the tail stop. This can be ameliorated by the advancing annular "tube" of water blowing the line slide forwards on the shaft, however often the shooting line is holding it in place against the muzzle nose.

I agree that Terminal Velocity might not have been the best choice of words in the scientific sense ... but it was the best I could come up at the time. A better term would probably have been something like PODR or Point of Diminishing Returns ... but very difficult to remember that. The idea was to understand that more band power does not equal more shaft velocity and that much more important was to get the shaft out of the track super stable and to understand that for each shaft weight, there is a point where that mass can only absorb an X amount of band energy before you start going backwards in performance. In several videos I actually have a setup where by adding more band power I could show that I got less performance. I think very few people understood that and this was very hard to convince people of ... I mean even my brother who I spearfish with was hard to convince.

This really was a game changer and if you look at spearguns today, you hardly see any guns with more than 3 bands in classical configurations. There simply is no need for that as with 3 bands you can reach very close to the TV (I still like to use that term) of an 8.5mm shaft if you have 135cm+ of band stretch. I also think this is why there is a disparity in performance figures when someone uses a roller or invert roller compared to a classic gun. If you have a poorly configured classic gun and switch to a properly configured roller setup, the roller setup will blow away the classic setup ... and of course vice versa. Many times it is testing apples to oranges. But the TV of a shaft will always be the same whether it is being thrown out by an invert roller setup or a simple classic setup. Now with regards to pneumatics ... I really have no clue how they compare to banded guns but in general I think they don't perform as good. The simple reason is that to load the gun you need to use a certain amount of force in one stroke ... and that power load is dependent on how strong you are. With bands you load in increments and thus you can pack more power. I did hear that there is a way for a pneumatic gun to also pack power with multiple loading stroked but I have never seen or tried it. It is possible that the shaft profile of a pneumatic is much more streamlined than a banded gun profile, and thus can gain by being more stable and thus has less drag loss than a banded gun ... maybe even some super cavitation effect can occur ... but I really doubt it. A shaft shot by a pneumatic gun will probably also have a TV, however that profile would be different than a banded gun profile as drag factors are different. My guess would be that the spring at the back of the shaft would have a large impact on drag factor and would hurt shaft performance more than a banded gun.
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Old 02-20-2019, 05:36 AM   #35
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by spearq8 View Post
I agree that Terminal Velocity might not have been the best choice of words in the scientific sense ... but it was the best I could come up at the time. A better term would probably have been something like PODR or Point of Diminishing Returns ... but very difficult to remember that. The idea was to understand that more band power does not equal more shaft velocity and that much more important was to get the shaft out of the track super stable and to understand that for each shaft weight, there is a point where that mass can only absorb an X amount of band energy before you start going backwards in performance. In several videos I actually have a setup where by adding more band power I could show that I got less performance. I think very few people understood that and this was very hard to convince people of ... I mean even my brother who I spearfish with was hard to convince.

This really was a game changer and if you look at spearguns today, you hardly see any guns with more than 3 bands in classical configurations. There simply is no need for that as with 3 bands you can reach very close to the TV (I still like to use that term) of an 8.5mm shaft if you have 135cm+ of band stretch. I also think this is why there is a disparity in performance figures when someone uses a roller or invert roller compared to a classic gun. If you have a poorly configured classic gun and switch to a properly configured roller setup, the roller setup will blow away the classic setup ... and of course vice versa. Many times it is testing apples to oranges. But the TV of a shaft will always be the same whether it is being thrown out by an invert roller setup or a simple classic setup. Now with regards to pneumatics ... I really have no clue how they compare to banded guns but in general I think they don't perform as good. The simple reason is that to load the gun you need to use a certain amount of force in one stroke ... and that power load is dependent on how strong you are. With bands you load in increments and thus you can pack more power. I did hear that there is a way for a pneumatic gun to also pack power with multiple loading stroked but I have never seen or tried it. It is possible that the shaft profile of a pneumatic is much more streamlined than a banded gun profile, and thus can gain by being more stable and thus has less drag loss than a banded gun ... maybe even some super cavitation effect can occur ... but I really doubt it. A shaft shot by a pneumatic gun will probably also have a TV, however that profile would be different than a banded gun profile as drag factors are different. My guess would be that the spring at the back of the shaft would have a large impact on drag factor and would hurt shaft performance more than a banded gun.
The most powerful pneumatic guns don't load in one stroke, they have an auxiliary pumping barrel of a smaller bore size than the shooting barrel. It gets pumped say 5 times, then the spear transfers across to the loading barrel. The Mares "Mirage" works this way and now a "Mirage Evo" has been developed by Diving Gecko.
https://forums.deeperblue.com/thread...-parts.113094/
https://youtu.be/wp4VkaJzvEQ


Most pneumatic guns don't have a spring shock absorber on the spear tail any more as they use stretchy shooting line and some have hydraulic line slide stoppers where the spear stop diameter slides into a close matching counter bore in the rear of the line slide. What you think a pneumatic gun is has moved on somewhat in recent years. The hydropump guns, or compressor guns, use multiple loading strokes to charge guns from 40 atmospheres to 100 atmospheres. The most powerful guns start at 100 atmospheres and you go up from there, so these guns are super powerful. A carbon dioxide gun is only 60 atmospheres.

The point of diminishing returns in a band gun is due to rubber being a poor energy storage medium, but if you pile on the bands and spread the rubber mountain out then you can get a lot of power as in Jack Prodanovich's "Tuna Gun". This gun has been mentioned earlier and a shaft shaped like a multi-stage rocket with rear fins and a smaller front end zoomed towards the target propelled by two band groups of 5 bands each.

The basic limitation is the force that can be applied in a short time interval to a shaft, band guns have an unsupported shaft in that it is not confined on top or to the sides, so to pour more energy into it the spear has to grow thicker or be accelerated at a lower rate for longer, or the shaft is made up of varying diameters, thicker at the rear and thinner at the front. In pneumatic guns the shaft is restricted on all sides, as the shaft emerges from the gun muzzle the length protruding is short and stiff and cannot bend, when more of the shaft emerges the acceleration is decreasing and the shaft column can now withstand the drive at the tail as it is insufficient to buckle the spear. The sudden impulse drive of the band gun is what kills the spear, however if the drive takes place at several locations along the spear then the force is distributed as it is not all being applied at the tail end, hence the tandem layout on Jack's gun.
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Last edited by popgun pete; 02-23-2019 at 04:44 PM. Reason: added a diagram
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Old 02-20-2019, 07:32 AM   #36
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by spearq8 View Post
[edit]A shaft shot by a pneumatic gun will probably also have a TV, however that profile would be different than a banded gun profile as drag factors are different. My guess would be that the spring at the back of the shaft would have a large impact on drag factor and would hurt shaft performance more than a banded gun.
My dear Majd
I know you are deep into the rubber guns, but things have changed in Airland and my shafts may have less drag than you guys' GR(?), Hunt or whatever nice shafts you like to use. I have a slider which is 2mm larger in OD than the shaft with a small loop for tying the line. No spring, no big washer and as such, I think I have about the same or less drag than a shaft with three sharkfins would have;-). Or at least a whole lot less than you expect.

You can even shoot "nude" shafts with zero metal hardware on them - but the line will then be tied just aft of the barb so you will have the increased drag of the line running the length of the shaft.

Attaching some pics with measurements. While my slider "fin" is higher than on the Pathos sharkfin shaft, there is only one on an airgun. This slider works by the principle that Pete mentioned above - by "hydro braking" where trapped water between the slider and the tail end acts as a shock absorber. If designed and machined well in suitable materials, it actually works. No jamming or mushrooming of the parts yet for me. (These parts are from UBL/Dima who is a one man band, but I think Palengas which is a bigger operation may make something very similar now, though maybe slightly bigger).

I am beginning to think, from comparing my friend's Albacore 130 with my two longest airguns (which still only shoot 125cm and 145cm long shafts) that single stage loading airguns (traditional ones) may now not be able to compare to the best tuned and optimized classic guns. But if we compare shaft sizes in an apples to apples way, then it may still be close but the problem is that when you move to e.g. "doggie guns" then you will soon find that you can't even buy an over the counter air gun that shoots anything bigger than a 145cm x 8mm shaft. If that gun is a traditional one with "single stage loading" then it may not have as much power as you need. But e.g. I am using old Mirages or variations of that design that are comparable to multibanded guns in that you can partition the total loading effort. I'd still like to put a Denton 100/110 up against my Mirage with a similar sized shaft. My feeling is that with same shaft size guns, the multi stage airguns will win. Whether a "classic" airgun can beat a Denton, I don't know. Ship me some of your foam, and I will make it happen;-).

It's always hard to judge from a hunting video and this is not even a good one at that (it was to share a sad loss of medium DT that wiggled off the shaft) but it may give you some sort of an idea of the speed of the shot (shaft is a 145x8mm Salvi single barb shaft with a cone):


And sorry for the thread drift;-)
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Last edited by Diving Gecko; 02-20-2019 at 08:21 AM.
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Old 02-20-2019, 02:48 PM   #37
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Re: Rollergun Recoil and the Jerk (not the owner!)

Rollergun 22 shows a double "Wiggler" gun with a sequential band drive, the rear "Wiggler" powers the full stroke, the mid "Wiggler" powers the front spear section using the mid shaft tab. Both Wigglers power the shaft to the muzzle, but this gun will not be the most maneuverable as the Wiggler units are shielded to protect lines and fingers with open bottom housings, similar to the "Arrow Gun". The fish would probably have all departed for parts unknown while you recharged this cannon after the first short. Thicker bands change the power of the gun which is a cable gun.
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Old 02-21-2019, 01:50 AM   #38
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Re: Rollergun Recoil and the Jerk (not the owner!)

The pneumatic guns I am familiar with are the air guns which use the air as a "spring" and are lossless (almost). Basically you just pressurize the cylinder and then you load the gun by imparting a force that compresses that air and when the air expands again it pushes the shaft out. This obviously has a limitation as you have to put all the energy to push the shaft in one stroke ... and usually even the strongest person cannot put that much energy in one stroke. Now having multiple strokes to load seems like a very nice improvement ... but haven't seen these guns on sale or never so someone using such a gun.

As for the C02 guns or "lossy" guns that use the compressed air as a propellant ... I remember watching a video very long time ago where a french guy in Gabon was using a small compressed cylinder to propel a shaft and shooting Goliath Grouper with it in the oil rigs there. From the video it looked like some air or gas was lost as the shot went off. Now if that is sort of a gun you are talking about, it certainly is a non starter here as it would be classed as a firearm as it uses a propellant (air or C02). We have a hard time now with just normal spearguns. I am surprised that in the US this is not classed a firearm ... but if you travel with something like that outside the US I am pretty sure it will be flagged.

As for testing ... no need for me to send anything. You have the Pathos and with a 120 barrel this will perform equal to a Denton 120 if setup the same. Really it is all about band stretch and mass of shaft. You could compare that to a similar setup of your customized air gun. I actually would be very interested in the results!
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Old 02-21-2019, 02:07 AM   #39
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Rollergun Recoil and the Jerk (not the owner!)

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[edit]

As for testing ... no need for me to send anything. You have the Pathos and with a 120 barrel this will perform equal to a Denton 120 if setup the same. Really it is all about band stretch and mass of shaft. You could compare that to a similar setup of your customized air gun. I actually would be very interested in the results!


Good point. We have plenty of Dentons, too in China now so a comparison should happen:-). Just that my friend with the cool band guns is a 3h flight away in south China and though we just spent 10 days together in Indo, it's hard to go into testing mode when you are on a spearing trip.

As for the traditional airguns which are the ones you are referring to, I still shoot those and just a few years back I would take such an airgun sans the old school line sliders and springs (but upgraded with a vacuum muzzle) head to head with most euro guns and expect the airgun to come out on top.
I've speared with people shooting e.g. RA 110s, a Beuchat roller and a Bleutec 115(?) and they were all perplexed/impressed with the speed of the shaft (not sure about punch as the shafts were shorter than theirs). But with the way you, other spearos and a few manufacturers have pushed performance recently I am not so sure anymore.

The gun in the posted video above is my own take on an old Mirage design (which has not been produced for a few decades) using some over the counter parts, a healthy dose of reverse engineering of the original and some homemade parts. Hopefully, the result is a small improvement over the original which is hard to get your hands on in the first place, had some ailments and never came in anything longer than a 100 model whereas mine is about 40cm longer.
But it still takes all my own force to load the gun. Just that I can pump it up a tad more than had it been a traditional single stage airgun.

I am not surprised you haven't seen any airguns other than the traditional ones. As mentioned, the Mirage has not been produced since the late 80s/early 90s(?) and the other options are out of Russia, Belarus or Ukraine and still there are not many of them and they can be hard to get. Furthermore, they tend to be either short or heavy or both. There's probably not a long, neutrally balanced and easily available airgun with partitioned loading effort on the market at all.

The French guy in Gabon is indeed shooting an expellable gas gun - an old Pelletier CO2 gun. And personally, I wouldn't shoot anything that just loads by the flick of a switch. Unless, I had an injury or a handicap preventing me from loading a normal gun.

Anyways, this is all talk and speculation until I do get a proper comparative test done. So let me not let this thread drift any further;-)


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Old 02-21-2019, 02:07 AM   #40
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Re: Rollergun Recoil and the Jerk (not the owner!)

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The pneumatic guns I am familiar with are the air guns which use the air as a "spring" and are lossless (almost). Basically you just pressurize the cylinder and then you load the gun by imparting a force that compresses that air and when the air expands again it pushes the shaft out. This obviously has a limitation as you have to put all the energy to push the shaft in one stroke ... and usually even the strongest person cannot put that much energy in one stroke. Now having multiple strokes to load seems like a very nice improvement ... but haven't seen these guns on sale or never so someone using such a gun.

As for the C02 guns or "lossy" guns that use the compressed air as a propellant ... I remember watching a video very long time ago where a french guy in Gabon was using a small compressed cylinder to propel a shaft and shooting Goliath Grouper with it in the oil rigs there. From the video it looked like some air or gas was lost as the shot went off. Now if that is sort of a gun you are talking about, it certainly is a non starter here as it would be classed as a firearm as it uses a propellant (air or C02). We have a hard time now with just normal spearguns. I am surprised that in the US this is not classed a firearm ... but if you travel with something like that outside the US I am pretty sure it will be flagged.

As for testing ... no need for me to send anything. You have the Pathos and with a 120 barrel this will perform equal to a Denton 120 if setup the same. Really it is all about band stretch and mass of shaft. You could compare that to a similar setup of your customized air gun. I actually would be very interested in the results!
Did you actually read anything of what we wrote or did you just start typing? All the guns we mentioned, bar the passing reference to the CO2 gun, are all muscle powered.
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Old 02-21-2019, 10:40 AM   #41
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Did you actually read anything of what we wrote or did you just start typing? All the guns we mentioned, bar the passing reference to the CO2 gun, are all muscle powered.
Actually my response was for Diving Gecko as we have corresponded before about some of this stuff by email and were both curious about how banded and pneumatic guns compare and wanted to find a testing platform where we can get some data. Your wiggler roller post came before I responded to him and maybe I should have quoted his post in my post. No reason to get all excited.
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Old 02-21-2019, 02:16 PM   #42
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Actually my response was for Diving Gecko as we have corresponded before about some of this stuff by email and were both curious about how banded and pneumatic guns compare and wanted to find a testing platform where we can get some data. Your wiggler roller post came before I responded to him and maybe I should have quoted his post in my post. No reason to get all excited.
I am not the type who gets excited and my comments were directed at your last set of pneumatic comments as you clearly appeared not to have absorbed anything written on that here. A depressing aspect of forums is people read the thread topic and maybe the penultimate post and then start typing often asking questions answered several posts back. No point in spelling things out if people don't read it, plus you then confuse others.

Now your pool experiments are quite valuable, but the swimming pool is not spearfishing and many spearoes shoot close rather than at a long distance so that the fish absorbs the full power of their weapons. I am all about death and destruction, the death of the fish and the destruction of its swimming capability and helm control. Preferably in that order. For that I use wedge bladed tips like the old Undersee Mako to cause damage and not just poke a fish with an oversize knitting needle. I need all the shaft’s kinetic energy to smash through the less heavily armored parts of the fish. Having a Kentucky Long Rifle is good, but shots are more effective well inside the fish’s "radius of immunity".
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Old 02-23-2019, 03:30 AM   #43
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by popgun pete View Post
I am not the type who gets excited and my comments were directed at your last set of pneumatic comments as you clearly appeared not to have absorbed anything written on that here. A depressing aspect of forums is people read the thread topic and maybe the penultimate post and then start typing often asking questions answered several posts back. No point in spelling things out if people don't read it, plus you then confuse others.

Now your pool experiments are quite valuable, but the swimming pool is not spearfishing and many spearoes shoot close rather than at a long distance so that the fish absorbs the full power of their weapons. I am all about death and destruction, the death of the fish and the destruction of its swimming capability and helm control. Preferably in that order. For that I use wedge bladed tips like the old Undersee Mako to cause damage and not just poke a fish with an oversize knitting needle. I need all the shaft’s kinetic energy to smash through the less heavily armored parts of the fish. Having a Kentucky Long Rifle is good, but shots are more effective well inside the fish’s "radius of immunity".
You are right, spearfishing and pool tests are not the same thing, you just have to take the data that they do give that is relevant, just like a test drive isnt the same as driving the car every day. I laughed about the death and destruction part.

But anyway, can we get back to topic? Has anyone tried if heavier shaft equals more recoil?
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Old 02-23-2019, 05:40 AM   #44
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Re: Rollergun Recoil and the Jerk (not the owner!)

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Originally Posted by mclane234 View Post
You are right, spearfishing and pool tests are not the same thing, you just have to take the data that they do give that is relevant, just like a test drive isnt the same as driving the car every day. I laughed about the death and destruction part.

But anyway, can we get back to topic? Has anyone tried if heavier shaft equals more recoil?
It is rather funny and I used that kind of over the top statement when an earnest young woman approached me as I readied myself for the return journey with my catch on a secluded beach near a section of offshore reef. This woman was no admirer and I quickly ascertained from her pointed line of questioning that she was working herself up to a cutting condemnation of my activities. Tiring of the conversation on my way back which I was not encouraging by saying very little in response I eventually got rid of her with the “I am all about death and destruction” comment and she then got a funny look on her face and stormed off in a huff. I made a mental note not to dive there for a while as she was bound to be back as she seemed to be the type who was on a mission.

Yes, a heavier shaft does mean more recoil, stick a much heavier shaft in a light body eurogun and you get more recoil especially if you increase the band power. The original design of the eurogun was a balanced weapon, it was matched to its spear and band power, had a high center of grip pressure and in-line pull of the bands. The gun was about a meter long, had a screw socket band anchor muzzle plate and no barrel track as the idea was a slingshot mounted on a distancing pole that replaced your hand holding the band(s) back with a trigger mechanism installed in a grip handle. This balanced design all went out the window when the guns got longer, the spear got heavier and the use of a band anchor slot muzzle caused a departure from in-line band pull and the guns began to develop undesirable traits with spears bouncing off the barrels, inaccurate shots, etc.

Here is the relevant page from the Cavalero "Champion" catalog of 1946, one of the first, which I have translated from the French. It is a bit of an eye opener if you read it as it shows back then that they understood exactly what we know today.

P.S. You can tell this catalog is early because the spearfisherman is not wearing fins as they are yet to be produced in the rubber form that we know today in large volumes, and only fins for the military had been available. Louis de Corlieu had invented metal sheet blades covered with crepe rubber fins in 1933, but the rubber version comes later in a lesser known patent from de Corlieu where the fin is molded from different grades of rubber placed at certain locations in the pressure mold to distribute the correct mechanical properties throughout the fin.
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Last edited by popgun pete; 02-23-2019 at 08:12 PM. Reason: more info
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Old 02-23-2019, 06:24 AM   #45
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Re: Rollergun Recoil and the Jerk (not the owner!)

You can use heavier shafts with roller guns successfully without the recoil....
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