Vlanikgun

[Vlanik]

Не эффективно...
===============
Not effectively...

 

[popgun pete]

Не эффективно...
===============
Not effectively...

Diagram posted just for interest as I had already mentioned it in my post #7 on this thread where I described the shortcomings of this "dual power" design. I only just found the diagram again. Not enough volumetric difference between inner barrel at 14 mm ID and outer tank at 20 mm ID.

It all seemed like a good idea at the time! Vladimir sent the drawing back (see attachment) with the inner barrel shown vented with port holes and the blades on the "turbine piston" reduced to stubs, the "power dial" arrangement being discarded. He was already working on the inner barrel idea when I wrote to him.

 

[tromic]

I don't see why it would not work, as idea. Just have to make good design. But it would be more complicated. Have you a drawing of charging the gun through the muzzle? I was also thinking about that, but maybe is easier to have the valve on the rear of the gun.

 

[Vlanik]

 

[tromic]

OK, I've got idea how it might work, but how would use the pump?

 

[Vlanik]

 

[tromic]

OK, so you calculate energy from speed. Than better question would be how you calculate the speed (v)?

Here is how speed of the shaft changes with distance:
For 20 cm Vlanikgun: v(s)=23,18*EXP(-0,8025425*s);
For 90 cm Vlanikgun: v(s)=30,21*EXP(-0,43568197*s).

 

[tromic]

Is this your hand pump?

 

[popgun pete]

Is this your hand pump?

The handpump can be seen in one of the photos at http://apox.ru/weapon/gun-handmade/19-besporshnevye-podvodnye-ruzhya-vlanik.

Dismantled components of "Vlanik 48" are shown in photo 8 of 16, handpump (Hacoc) is at the bottom.

The earlier "Vlanik" spearguns used much higher pressures, above 70 atm, which are difficult to produce with a handpump unless it has a very small bore. This small pump bore size requires many pump strokes to move the required volume of air into the gun in order to achieve very high pressure, so an alternative was to pressurize the gun with carbon dioxide gas instead. Carbon dioxide liquid transforms into a gas at around 900 psi or 60 atm. The compression ratio of the gun raises this chamber pressure to over 70 atm when the gun is cocked. A disposable carbon dioxide cartridge could be used to fill the gun provided that it was fitted into a suitable housing and I suspect that the last photo shows such a device rather than a pump.

 

[tromic]

Here is how speed of the shaft changes with distance:
For 20 cm Vlanikgun: v(s)=23,18*EXP(-0,8025425*s);
For 90 cm Vlanikgun: v(s)=30,21*EXP(-0,43568197*s).

I made one formula for both cases based on Vladimi's speadsheet for Vlanikgun. Input parameters are: starting velocity (v0), and mass of the shaft (m), and distance (s) of course.
But I am not sure how confident those spreadsheet data are. I would rather if they were based on measurement data.

 

[tromic]

The handpump can be seen in one of the photos at http://apox.ru/weapon/gun-handmade/19-besporshnevye-podvodnye-ruzhya-vlanik.

Dismantled components of "Vlanik 48" are shown in photo 8 of 16, handpump (Hacoc) is at the bottom.

The earlier "Vlanik" spearguns used much higher pressures, above 70 atm, which are difficult to produce with a handpump unless it has a very small bore. This small pump bore size requires many pump strokes to move the required volume of air into the gun in order to achieve very high pressure, so an alternative was to pressurize the gun with carbon dioxide gas instead. Carbon dioxide liquid transforms into a gas at around 900 psi or 60 atm. The compression ratio of the gun raises this chamber pressure to over 70 atm when the gun is cocked. A disposable carbon dioxide cartridge could be used to fill the gun provided that it was fitted into a suitable housing and I suspect that the last photo shows such a device rather than a pump.

That makes sense. Thanks, Peter.

 

[tromic]

I was looking on Vlanikguns specifications again (for different models/lengths). Although not verified jet and not 100 % true, formula given on the following link, for speed and energy, convinced me that most of the specifications, for most of the guns could be OK. On effective range of the gun speed is about 10 m/s and energy more that 5 J what as minimum might be sufficient for 1 kg fish. Would be better if energy of the shaft on effective range is minimum 15 J.

http://forums.deeperblue.com/pneumatic-spearguns/90690-balisic-shaft.html#post843902

 

[tromic]

To increase reliability of "sealed" tail cap design I would make something like this on drawing. Sealing o-ring is shielded from scratches as seen on the picture. Rubber plug makes friction to the cap so ensures more reliability in case of o-ring sealing failure. Air bubbles after shooting could indicate bad sealing.

This would be a mixture with Vladimir's design. I believe design with neoprene would also work.

There is an another problematic statement regarding performance of Vlanikgun. I do not believe that 28 cm long gun can have 2,8 m effective range. That range is obtained by calculation taking initial speed of shaft in air to be same in water, what is not true. According to that calculation, 70 cm long gun has range 5,6 m. That gun has about the same shaft acceleration distance as my Cyrano 850 (64 cm). My Cyrano (Tomba) with 100/7 mm shaft has effective distance to 4 m. Vlanik 70 might have to 4,5 m because of thicker shaft, not 5,6 m.

I must make a correction to this statement. According to my latest measurement the speed of the shaft in air and in water is almost same.

 

[Vlanik]

This not quite so...
The Resistance of water, influences upon initial velocity of the harpoon...
Though results close...
I like твои approaches in analysis of the work undersea ружей...
Can has already approached time and you itself изготовиш like handgun...
I certain, beside you are got...

 

[tromic]

This not quite so...
The Resistance of water, influences upon initial velocity of the harpoon...
Though results close...
I like твои approaches in analysis of the work undersea ружей...
Can has already approached time and you itself изготовиш like handgun...
I certain, beside you are got...

What is a difference in starting speed of the shaft in air and in water according to your calculation Vlanik? I am sure in water must be smaller than in air but it is difficult to measure with my device if the difference is only few %. My result for speed is probably higher than the actual speed, due to bouncing time of switch contacts which is maybe more than 0.1 ms. It depends on the type and quality of the switch used, and on the speed of switching so the error is higher with higher speeds of the shaft. I have a different schematic to minimize the error but that would overload the battery used to charge the capacitor.

I am not planing to make my design of pneumatic gun.

 

[Vlanik]

Diagram posted just for interest as I had already mentioned it in my post #7 on this thread where I described the shortcomings of this "dual power" design. I only just found the diagram again. Not enough volumetric difference between inner barrel at 14 mm ID and outer tank at 20 mm ID.

It all seemed like a good idea at the time! Vladimir sent the drawing back (see attachment) with the inner barrel shown vented with port holes and the blades on the "turbine piston" reduced to stubs, the "power dial" arrangement being discarded. He was already working on the inner barrel idea when I wrote to him.

Ïîäâîäíûå ðóæüÿ Vlanik

 

[tromic]

Vlanik, what kind of material is the O-ring you use for Vlanikgun... NBR, HNBR, Silicone...? I ask it because you use it on high pressure, more than 50 bar. I suppose normal NBR is not the best choice.

 

[popgun pete]

Has anyone purchased one of these "Vlanik" spearguns? I notice that the design has been refined in recent years to minimize the possibility of the spear tail cap falling off inside the gun.

The prices of the guns are:
50 cm model gun 7800 rubles AU$158.82 ; spare spear shaft 800 rubles AU$16.30
70 cm model gun 9000 rubles AU$183.37; spare spear shaft 1000 rubles AU$20.37

 

[popgun pete]

I asked Vladimir if he would sell his guns internationally. He replied that he will not, but suggested that anyone wanting to purchase a "Vlanik" gun should arrange for an intermediary in Russia to order and buy the gun on their behalf and then ship it out to you.

 

[popgun pete]

As you can see from the parts photo there is not much to the "Vlanik" gun as with no inner barrel the spear just sit inside the air reservoir and is driven out by the pressure acting on its spear tail which is much higher than ambient pressure acting on the nose of the spear.

The "cockscomb” shaped line release wraps all but the last wraps that wind back and forth on the top or the side of the gun using the lower section of the "cockscomb" with only the last wrap at the top. This last wrap produces a higher pull (i.e. torque) that will tip the line release over thereby allowing all the rest of the line wraps to escape from the gun without any resistance. Note that the lower wrap position does not produce enough torque to flip the line release over being closer to the line release pivot pin.