Bluewater Pneumatics - Pros and Limitations

[Diving Gecko]

I did the math.
50 bar on your gun is about the same as 19 bar on a normal Italian gun. So, very far from the 30-45 bar guns we are talking about here. You would need about 100-120 bar in your gun to compare to guns in this thread...

Even if your pistonless design is more efficient it’s not efficient enough to make that much up. Also, I still have reservations as to if a Vlanik design can shoot a long 125-150cm, +8mm shaft accurately since there’s no piston to hold the shaft end centered. This is not a question so don’t reply to this on this thread. If you really want to, then there’s a specific thread for your gun and you can post there.

Sorry Gazz and Chris for trying to police your thread but our friend here has trolled one of my threads before he deleted most of his posts and though I should probably not even have answered here I’m trying to reason with the guy and explain to him why he needs to read and understand context before posting... just that the tone gets a bit harsh as it didn’t work last time around.


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[Diving Gecko]

I’m talking about neutral when loaded with the shaft. There’s so much extra floatation on the gun in the trevally pic that it hurts my eyes. But I guess that’s normal in your parts of the world. You like to make your guns skinny but then often when I see a pic of one it has had to have extra flotation on it. Probably often to make up for the reel, but still, not my cup of tea.


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[tromic]

I thought about this some more and since I like what @quakeos is trying to do I don't want to see him get burned on misunderstandings once he starts sharing his articles with a wider audience. So, in case we haven't scared him off already, I'd just share some comparisons.

I tested the very popular Small ID in 14mm and it took about 24kg to pull it by 300%, or factor x4 (in SpearoSpeak this is often called 400%...). This was actually a tad more than Primeline's own force calculator had predicted, but that might be because my bands were 14.2mm and not 14mm.
Anyhow, it's very close to Triton's tests here. I run my bands at around 3.7 as a lot of us do with the thinner bands, so that's probably about 22kgf which on a circular band is 44kgf and since I have two of those, we end up with a total of 88kgf.
I don't even think this is high for a two banded gun but it is 2.6 times more force on the wishbone than what a 25bar (13mm) gun would put on the piston of its shaft (34kgf). Now, 25 bar is about the upper limit of what most oleo spearos can manage to load at (I can't, but a fair bunch can).
What's interesting is that your 45 bar gun - which to us in the know is incredibly high - still puts less force on the shaft than a normal two banded gun: 61kgf for the 45bar gun and 88kgf for the two-banded gun.

So, long story short, it's def all about efficiency as even a 45 bar super gun stores less energy than all BW bandguns and even less than most reef guns. Heck, even a one banded gun easily stores 1.3 times more energy than a highly charged 25 bar airgun.

As always, I might have gotten something wrong as perhaps we can't equate stored energy to force on the wishbone? But at least, it was nice for myself to do this comparison. I never actually had done so and never realized how crazy efficient even normal oleo at about 20-22bar is.

Davide, in your estimation of energy stored, you are missing the length on which the force is applied.
Energy (E) stored would be equal to work (W) of mean force (F) along some path (s): W = F*s (J).

 

[Vlanik]

bravo tromik

 

[popgun pete]

Yes, the band gun draws seem a lot, but remember the work energy graph is only a triangle, whereas a pneumatic gun work energy graph is a rectangle with a small triangle on top. Even rollerguns are still a triangle, only with preload you shoot with the larger part and don't use the thin tip. Pneumatic guns and hydropneumatic guns need a good push from the start of loading, while band guns only develop the force level once the bands are drawn well back. In a sense band guns are short impulse weapons, especially standard band guns, while pneumatic guns are more or less constant force drivers. A very low compression ratio, big tank, ultra-high pressure pneumatic is the closest approach to a constant drive gun as its work energy graph will be a big rectangle.

An example is the Dreamair and its comparison with a conventional pneumatic, note the pistons move in different directions.

 

[Diving Gecko]

@tromic @popgun pete Ah, of course guys. I have been "hanging out" with you both here for so long I should have remembered by now
Chris was probably talking about exactly what you guys are, too and I was missing the bigger picture.
At least it does go to show, yet again, how much more of an efficient platforms ours are.

Also, the fact that we need a high force to load for the full duration of the loading cycle on a traditional airgun also explains why I still feel like it can be a hard job to load them even if the final force to click into the trigger is less than what it is loading a single band of my bandgun. I like the "short impulse" explanation of Pete's.

I hope @quakeos gets back here and shares a bit more info on his loading method, especially about the out of the water part I was asking about earlier.

It's funny how personal this stuff is, though. For Quakeos, a pulley loader or EasyLoader is scary, but for Pete and Tomi(?) the idea of inserting a shaft into an already loaded piston is more scary. Personally, I am not sure yet on the scary part, but both the pulley loader and EasyLoader offer the advantage that we don't have to remove water from the barrel. And while I always wanted any external loader to be as small as possible and found the EasyLoader a bit too big for my taste, when you compare it to a pump all of a sudden, it's not bad at all.
I am not sure what the limit is for my pulley loader in terms of controlling bananai'ng of the the shaft, but the Easy Loader with the clip-on guides has an advantage there. As it stands, I don't think I could get to 45 bar with my loader. Lately, I have been thinking about adding a bit more purchase to my pulley system. It will make the line longer but the fact that I'll need even less force to pull on the line may mean I will have an easier time controlling the shaft while pulling. I actually did buy the parts to make this modification months ago, but they got stranded when the world shut down.

 

[Vlanik]

[QUOTE = "popgun pete, post: 992293, member: 18674"]
График рабочей энергии - это всего лишь треугольник, пневматический пистолет - это прямоугольник с маленьким треугольником сверху. Даже в виде треугольника, только с преднагрузочной выгрузкой. Пневматические пистолеты и гидропневматические пистолеты нуждаются в хорошей загрузке, в то время как ленточные пистолеты развивают уровень сил только после того, как ленты отведены назад. Ленточные пистолеты являются короткоимпульсным оружием, особенно стандартным ленточным оружием, в то время как пневматические пистолеты являются более или менее постоянными драйверами. Очень низкая степень сжатия, большой бак,

Обратите внимание, что поршни движутся в разных направлениях.
[ATTACH = полный] 55987 [/ ATTACH]
[/ QUOTE]
another nonsense ... do not confuse the force that acts on the harpoon and the kinetic energy of the harpoon when fired ...

 

[popgun pete]

Inserting a spear into an already cocked pneumatic gun can be very dangerous if the piston tail suddenly breaks free of the sear lever as you would never hold it. For the same reason you are told not to pull the spear from a cocked gun. Guns need to be fired with the piston propelling something, so an empty barrel shot might damage the gun. In such a situation the gun should be switched to low power. On hydropneumatic guns the spear can be pulled out and a dummy shot made as the gun has no piston. The exception is the RPS-3 as the mechanism holds the spear tail, but the hydrostatic charged pressure in the gun can be released by pushing the trigger forwards which operates a bypass port in the back end of the gun.

 

[quakeos]

I am alive! just been very busy as diving over here is very popular right now.. will slowly start to reply to threads

 

[quakeos]

First of all ill get the simple part done - I run a riffe "teacup" slide ring with no washer on my spears - very streamlined and very strong. I run minimal overhang for a few reasons such as just being able to reach the shaft when loading on a 115 (favourite size), having a stiffer shaft and also so the integrity of the rubber vacuum cuff on the salvimar muzzle has enough force to centre the shaft, which it does very well. No accuracy issues to be heard of and I will send a video shortly showing how the vacuum cuff centres the spear for me instead of a washer.

 

[quakeos]

perhaps the own weight of the shaft could cause a minute or so or downwards tilt which for all intents and purposes I think is negligible and perhaps it's corrected as soon as the shaft is powered. rapid tracking could perhaps also tilt it by a minute or so which again I imagine would be corrected for the very brief half a second pause between shooting and tracking, not to mention track shots tend to be at shorter ranges. If I see any issues with my upcoming tests I'm happy to revert back to washers if it proves worthy.

 

[ECK]

A very long time ago I proposed the idea of a hydraulic pump with a lever.

Garpun.spb.ru :: Просмотр темы - Гидрозаряжалка

garpun.spb.ru

But this did not arouse interest.
This is just a diagram and it is not a drawing.
But I do not see any technical problems to adapt it to any gun.
I agree with popgun pete this charging method is dangerous.
But if necessary, you can take precautions.
When charging, you need to control the tench so that it is away from you.
You need to control the position of the Slaider so that it cannot hit your fingers.
quakeos with your hydro pump there is no absolutely easy charge? If the gun is 40bar
How much force do you need to apply to a hydro pump?

 

[Vlanik]

A very long time ago I proposed the idea of a hydraulic pump with a lever.

Garpun.spb.ru :: Просмотр темы - Гидрозаряжалка

garpun.spb.ru

But this did not arouse interest.
This is just a diagram and it is not a drawing.
But I do not see any technical problems to adapt it to any gun.
I agree with popgun pete this charging method is dangerous.
But if necessary, you can take precautions.
When charging, you need to control the tench so that it is away from you.
You need to control the position of the Slaider so that it cannot hit your fingers.
quakeos with your hydro pump there is no absolutely easy charge? If the gun is 40bar
How much force do you need to apply to a hydro pump?

Another miscarriage ...

 

[Diving Gecko]

It would be amazing if this forum has a dislike button or blocking option. With a dislike button, Vlanik could see how disrespectful and out of line he is and with a blocking option, other members could choose never to see his posts.

 

[Diving Gecko]

[...]
quakeos with your hydro pump there is no absolutely easy charge? If the gun is 40bar
How much force do you need to apply to a hydro pump?

In the latest version, he is using the pump that came with the gun. That pump has ø10mm piston, so at 40bar the force will be about 32kgf. With 45 bar the starting force would be 36kgf.
Now, it will be a bit more at the end because of the compression, but I don't know the ratio, perhaps 1.15 times more.

 

[Vlanik]

Похоже, что появилась еще одна песочница, бесполезных идей ... И все, что должно быть изучено как внутренняя, так и внешняя баллистика.

It would be amazing if this forum has a dislike button or blocking option. With a dislike button, Vlanik could see how disrespectful and out of line he is and with a blocking option, other members could choose never to see his posts.

It seems that there is another sandbox, of useless ideas ... Instead of studying internal and external ballistics and learning to count the created weapons even before they are embodied in the finished product ... you create non-working freaks ...

 

[ECK]

In the latest version, he is using the pump that came with the gun. That pump has ø10mm piston, so at 40bar the force will be about 32kgf. With 45 bar the starting force would be 36kgf.
Now, it will be a bit more at the end because of the compression, but I don't know the ratio, perhaps 1.15 times more.

Diving Gecko If we reduce the diameter of the pump we can win in power,
but you will need to do more movements.
Everyone can find a compromise.
I see two sides in this charging method.
To load long 9mm thick shafts and vice versa are very thin.
Has anyone tried to shoot a 4mm harpoon ???

 

[popgun pete]

Hand pumps for spearguns usually have a smaller bore than the barrel, so you gain some advantage using it as a water pump as you are pushing on a smaller cross-section for the same pressure. There are a few guns that have a hand pump of the same bore as the inner barrel, thus no advantage in using them as a water pump. One way to have a small water pump bore is to use a needle displacement pump where as the needle pushes in the pump bore it displaces its volume in water.

 

[Diving Gecko]

Diving Gecko If we reduce the diameter of the pump we can win in power,
but you will need to do more movements.
Everyone can find a compromise.
I see two sides in this charging method.
To load long 9mm thick shafts and vice versa are very thin.
Has anyone tried to shoot a 4mm harpoon ???

Sure, and Quakeos' first pump was indeed smaller in piston diameter but I guess he has the strength to use the bigger one. I am not sure I do.

4mm shafts? I understand your point about how a pump would make it possible to load very thin spears. Personally, I don't see why you would do it. If you can shoot a fish with a very light shaft shaft, you are probably very close and then somehow I don't want the complication of an external pump. But I think that's for another thread.
In this thread, let's stick to bluewater hunting where we have to go in the opposite direction than skinny shafts. To punch all the way through a big fish like a +40kg dogtooth tuna you need mass. And dogtooth need thicker lines than pretty much every other fish in the ocean, so you will have more drag on the shaft slowing it down, so again you need mass to keep the speed up. Also, DT don't always come super close. So, we are talking about 8.5, 9, perhaps even 10mm shafts.

 

[popgun pete]

Well you could have a 4 mm pump rod in a displacement type pump, but it would take a lot of strokes to push a piston back in say a 13 mm inner barrel. However that would break the loading effort down into smaller chunks. Note that this type of displacement water pump is what is used in the "Alcedo Hydra" hydropump. This type of pump is analogous to filling a glass brimful with water and sticking your finger into it which displaces the same volume of water as your finger displaces.